Abstracts
Clostridium perfringens is a gram-positive, anaerobic, fermentative, spore-forming bacillus that may be found in the environment but is more commonly found as part of the microbiota of humans and animals. The bacterium is considered a common enteric pathogen; however, the pathogenesis and predisposing factors of the disease can differ among species. Therefore, specific studies are necessary for understanding the role of this pathogen, how to diagnose it and which control measures are applicable. The aim of this paper is to review the current knowledge regarding C. perfringens infections in pigs, horses and broiler chickens
diarrhea; enteritis; equine; swine; poultry
Clostridium perfringens é um bacilo anaeróbio, Gram positivo, formador de esporos que pode ser encontrado no ambiente e, principalmente, como parte da microbiota de humanos e animais. É considerado um patógeno entérico comum, mas a patogênese e os fatores predisponentes da doença normalmente diferem entre as espécies, sendo necessários estudos específicos para compreender os mecanismos de ação do patógeno, como diagnosticá-lo e apresentar quais as medidas de controle são aplicáveis. O objetivo deste trabalho é revisar as atuais descobertas a respeito da infecção de C. perfringens em suínos, equinos e frango de corte
diarreia; enterite; equinos; suínos; aves domésticas
INTRODUCTION:
Clostridia produce the largest number of toxins of any type of bacteria. Among Clostridium species, C. perfringens is the major toxin producer and is also the most widespread, being found as part of the microbiota of animals and humans and also in soil. The microorganism was first named Bacillus aerogenes capsulatus, then Clostridium welchii and finally C. perfringens.
C. perfringens is a gram-positive, anaerobic, fermentative, spore-forming
bacillus that is classified into five types according to the production of four major
toxins: alpha (α), beta (β), epsilon (ε) and iota (ι) (Table 1). In addition to the major toxins, C. perfringens can
produce more than 15 other known toxins. Some of these additional virulence factors,
including enterotoxin, necrotic enteritis like-B toxin (NetB) and beta-2 toxin, have
received more attention than others, most likely due to their role in the pathogenesis
of C. perfringens-associated disease (CPAD) in humans and animals (POPOFF & BOUVET, 2013NOWELL, V.J. et al. Clostridium perfringens in retail chicken. Anaerobe,
v.16, v.3, p.314-315, 2010. Available from:
<http://www.sciencedirect.com/science/article/pii/S1075996409001711>. Accessed:
Out. 29, 2014. doi:10.1016/j.anaerobe.2009.11.004.
http://www.sciencedirect.com/science/art...
).
C. perfringens is recognized as one of the most important causes of
foodborne disease in humans and is also commonly involved in human and animal cases of
gas gangrene (TAYLOR, 1999TANSUPHASIRI, U. et al. Antimicrobial resistance among Clostridium
perfringens isolated from various sources in Thailand. Southeast Asian Journal of
Tropical Medicine and Public Health, v.36, n.4, p.954-961, 2005. Available from:
<http://www.ncbi.nlm.nih.gov/pubmed/21673152>. Accessed: Out. 29,
2014.
http://www.ncbi.nlm.nih.gov/pubmed/21673...
; MIYAMOTO et al., 2012MICLARD, J. et al. Clostridium perfringens beta-toxin targets
endothelial cells in necrotizing enteritis in piglets. Veterinary Microbiology,
v.137, p.320-325. Available from:
<http://www.sciencedirect.com/science/article/pii/S0378113509000467> Accessed:
Nov, 30. doi: 10.1016/j.vetmic.2009.01.025
http://www.sciencedirect.com/science/art...
). In veterinary medicine, C.
perfringens is responsible for several, mostly enteric, diseases. In the last
few years, significant progress in the understanding of C. perfringens in
animals was achieved (UZAL et al., 2014TIMONEY, J.F et al. Antibody responses of mares to prepartum vaccination
with Clostridium perfringens bacterin and beta2 toxin. Veterinary Record, v.157,
n.25, p.810-812, 2005.). There
are some reviews about the current knowledge in ruminants and also in small animals, but
the literature lacks in reviews about C. perfringens infection in other
species. In addition, there is no review about current studies with C.
perfringens in Brazil. Here, it is reviewed the most recent advances in the
understanding of C. perfringens disease in pigs, horses and broiler
chickens, also focusing in studies conducted in Brazil.
Swine
C. perfringens type A is considered by some researchers as the main cause
of neonatal diarrhea in piglets (SONGER & UZAL,
2005SONGER. J.G.; GLOCK, R.D. Enteric infection of swine with Clostridium
perfringens types A and C. Journal of Swine Health and Production, v.6, p.223-225,
1998.; CHAN et al., 2012CHAN, G. et al. The epidemiology of Clostridium perfringens type A on
Ontario swine farms, with special reference to cpb2-positive isolates. BMC Veterinary
Research, v.8, p.156, 2012. Available from:
<http://www.ncbi.nlm.nih.gov/pubmed/22947389>. Accessed: Out. 29, 2014. doi:
10.1186/1746-6148-8-156.
http://www.ncbi.nlm.nih.gov/pubmed/22947...
). However, the
pathogenesis of this bacterium in swine remains unclear, leading to some difficulties in
the diagnosis and also making it impossible to determine its true prevalence.
C. perfringens type A commonly affects neonates in the first week of life.
Once it is part of the microbiota in swine, sows can transfer this bacterium to piglets.
The disease is described as a non-hemorrhagic mucoid diarrhea and is characterized by
mucosal necrosis and villus atrophy, without attachment and invasion by the
microorganism (SONGER & UZAL 2005SONGER. J.G.; GLOCK, R.D. Enteric infection of swine with Clostridium
perfringens types A and C. Journal of Swine Health and Production, v.6, p.223-225,
1998.). According
to some studies, lesions may also be absent; in light of this, some groups have stated
that C. perfringens diarrhea in neonatal piglets might be secretory (SONGER & UZAL, 2005SONGER. J.G.; GLOCK, R.D. Enteric infection of swine with Clostridium
perfringens types A and C. Journal of Swine Health and Production, v.6, p.223-225,
1998.; CRUZ-JUNIOR et al., 2013CRESPO, R. et al. Toxinotypes of Clostridium perfringens isolated from
sick and healthy avian species. Journal of Veterinary Diagnostic Investigation, v.19,
n.3, p.329-333, 2007. Available from:
<http://www.ncbi.nlm.nih.gov/pubmed/17459870>. Accessed: Out. 29, 2014. doi:
10.1177/104063870701900321.
http://www.ncbi.nlm.nih.gov/pubmed/17459...
).
In the late 1990s, it was shown that C. perfringens strains positive for
the beta-2 gene (cpb2) were more frequent in diarrheic piglets than in
healthy piglets (GILBERT et al., 1997GIBERT, M. et al. Beta-2 toxin, a novel toxin produced by Clostridium
perfringens. Gene, v.203, n.1, p.65-73, 1997.; KLAASEN et al., 1999KEYBURN, A.L. et al. Maternal immunization with vaccines containing
recombinant NetB toxin partially protects progeny chickens from necrotic enteritis.
Veterinary Research, v.44, n.1, p.108, 2013b. Available from:
<http://www.veterinaryresearch.org/content/44/1/108>. Accessed: Out. 29, 2014.
doi: 10.1186/1297-9716-44-108
http://www.veterinaryresearch.org/conten...
). Thus, cpb2
was used as a virulence factor marker for the diagnosis of C. perfringens
type A diarrhea in swine. However, some recent results, including one study performed on
Brazilian farms, showed no differences between the prevalence of
cpb2-positive strains in diarrheic and non-diarrheic piglets (WOLLSCHLÄGER et al., 2009WEESE, J.S. et al. A prospective study of the roles of Clostridium
difficile and enterotoxigenic Clostridium perfringens in equine diarrhoea. Equine
Veterinary Journal, v.33, n.3, p.403-409, 2001. Available from:
<http://onlinelibrary.wiley.com/doi/10.2746/042516401776249534/abstract>.
Accessed: Out. 29, 2014. doi: 10.2746/042516401776249534
http://onlinelibrary.wiley.com/doi/10.27...
; CRUZ-JUNIOR et al., 2013CRESPO, R. et al. Toxinotypes of Clostridium perfringens isolated from
sick and healthy avian species. Journal of Veterinary Diagnostic Investigation, v.19,
n.3, p.329-333, 2007. Available from:
<http://www.ncbi.nlm.nih.gov/pubmed/17459870>. Accessed: Out. 29, 2014. doi:
10.1177/104063870701900321.
http://www.ncbi.nlm.nih.gov/pubmed/17459...
; FARZAN et
al., 2013ENGSTRÖM, B.E. et al. Molecular typing of isolates of Clostridium
perfringens from healthy and diseased poultry. Veterinary Microbiology, v.94, n.3,
p.225-235, 2003. Available from:
<http://www.sciencedirect.com/science/article/pii/S0378113503001068>. Accessed:
Out. 29, 2014. doi: 10.1016/S0378-1135(03)00106-8.
http://www.sciencedirect.com/science/art...
). In addition, molecular studies showed a slight difference in the
genetic composition and activity of cpb2-positive swine isolates (JOST et al., 2006JOST, B.H. et al. Association of genes encoding beta2 toxin and a
collagen binding protein in Clostridium perfringens isolates of porcine origin.
Veterinary Microbiology, v.115, n.1-3, p.173-182, 2006a. Available from:
<http://www.ncbi.nlm.nih.gov/pubmed/16513295>. Accessed: Out. 29, 2014. doi:
10.1016/j.vetmic.2006.01.012.
http://www.ncbi.nlm.nih.gov/pubmed/16513...
a; JOST et al., 2006JOST, B.H. et al. Association of genes encoding beta2 toxin and a
collagen binding protein in Clostridium perfringens isolates of porcine origin.
Veterinary Microbiology, v.115, n.1-3, p.173-182, 2006a. Available from:
<http://www.ncbi.nlm.nih.gov/pubmed/16513295>. Accessed: Out. 29, 2014. doi:
10.1016/j.vetmic.2006.01.012.
http://www.ncbi.nlm.nih.gov/pubmed/16513...
b). Taken together, these recent results suggest that beta-2
toxin is not important for C. perfringens diarrhea in piglets and also that
the use of cpb2 as a virulence factor marker is not appropriate for
diagnosis.
Therefore, the diagnosis of CPA infection in swine is challenging. Most authors agree
that the clinical signs of clostridial diarrhea are similar to those of several other
enteric diseases; it is also still not possible to differentiate between pathogenic
C. perfringens type A and C. perfringens type A that is
part of the microbiota (SONGER & UZAL, 2005SONGER. J.G.; GLOCK, R.D. Enteric infection of swine with Clostridium
perfringens types A and C. Journal of Swine Health and Production, v.6, p.223-225,
1998.).
Accordingly, the presumptive diagnosis of CPA infection in piglets should be based on a
combination of the isolation of C. perfringens and the absence of
histological lesions (or laboratory detection) of other enteropathogens, such as
rotavirus, enterotoxigenic Escherichia coli, C. difficile and
Isospora suis. Even with this approach, most pathologists have expressed
reservations about making a diagnosis of CPA enteritis. In addition to the difficulty in
diagnosing CPA infection in piglets, a recent survey showed that practitioners generally
diagnose the disease only according to the age of onset of diarrhea (between 1 and 7
days old) and that they also report a high confidence in their diagnosis method (CHAN et al., 2013CHAN, G. et al. The epidemiology of Clostridium perfringens type A on
Ontario swine farms, with special reference to cpb2-positive isolates. BMC Veterinary
Research, v.8, p.156, 2012. Available from:
<http://www.ncbi.nlm.nih.gov/pubmed/22947389>. Accessed: Out. 29, 2014. doi:
10.1186/1746-6148-8-156.
http://www.ncbi.nlm.nih.gov/pubmed/22947...
).
C. perfringens type C is also well known as a swine pathogen and is characterized by hemorrhagic necrotic enteritis in neonatal piglets, mostly in animals from one to four days old. This age is commonly affected because of the low secretion of trypsin in the gut, which in adults commonly inactivates the beta toxin. In addition, the colostrum contains protease inhibitors, which could also prevent the degradation of beta toxin in the gut of neonatal animals (NIILO, 1988NETHERWOOD, T. et al. Foal diarrhoea between 1991 and 1994 in the United Kingdom associated with Clostridium perfringens, rotavirus, Strongyloides westeri and Cryptosporidium spp. Epidemiology & Infection, v.117, n.2, p.375-383, 1996.; SONGER & UZAL, 2005SONGER. J.G.; GLOCK, R.D. Enteric infection of swine with Clostridium perfringens types A and C. Journal of Swine Health and Production, v.6, p.223-225, 1998.).
Beta toxin, produced by C. perfringens type C, induces vascular necrosis,
hemorrhage and subsequent hypoxic tissue necrosis (MICLARD et al., 2009MICLARD, J. et al. Clostridium perfringens beta-toxin targets
endothelial cells in necrotizing enteritis in piglets. Veterinary Microbiology,
v.137, p.320-325. Available from:
<http://www.sciencedirect.com/science/article/pii/S0378113509000467> Accessed:
Nov, 30. doi: 10.1016/j.vetmic.2009.01.025
http://www.sciencedirect.com/science/art...
). In light of this, affected piglets commonly show
bloody diarrhea and hemorrhagic necrotic enteritis in the small intestine. In contrast
with C. perfringens type A lesions, deep intestinal layers can be necrotic.
The known clinical signs in association with macroscopic and histological alterations
and isolation of C. perfringens type C from the intestinal contents
strongly suggest necrotic enteritis by this agent; nonetheless, the detection of beta
toxin is necessary for a confirmatory laboratory diagnosis (SONGER & UZAL, 2005SONGER. J.G.; GLOCK, R.D. Enteric infection of swine with Clostridium
perfringens types A and C. Journal of Swine Health and Production, v.6, p.223-225,
1998.).
Commercial vaccines containing beta toxoids, which provide passive immunity to piglets
via the colostrum, appear to be efficient for controlling C. perfringens
type C diarrhea in swine (SCHAFER et al., 2012SALVARANI, F.M. et al. Vaccination with recombinant Clostridium
perfringens toxoids α and β promotes elevated antepartum and passive humoral immunity
in swine. Vaccine, v.31, n.38, p.4152-4155, 2013.).
The use of autogenous toxoids for the prevention of CPA-associated diarrhea has been
reported in some studies (SONGER & GLOCK,
1998SONGER, J.G. Clostridial enteric diseases of domestic animals. Clinical
Microbiology Reviews, v.9, n.2, p.216-234, 1996.; HAMMER et al., 2008GIBERT, M. et al. Beta-2 toxin, a novel toxin produced by Clostridium
perfringens. Gene, v.203, n.1, p.65-73, 1997.); however,
thus far, there is no evidence of their efficacy in preventing disease. Some authors
have also reported the efficiency of toxoids or recombinant immunogens containing alpha
and/or beta-2 toxins for inducing antibodies in swine (SPRINGER et al., 2012SONGER, J.G.; UZAL, F.A. Clostridial enteric infections in pigs. Journal
of Veterinary Diagnostic Investigation, v.17, n.6, p. 528-536, 2005. Available from:
<http://www.ncbi.nlm.nih.gov/pubmed/16475510>. Accessed: Out. 29,
2014.
http://www.ncbi.nlm.nih.gov/pubmed/16475...
; SALVARANI et al.,
2013SALVARANI, F.M. et al. Antimicrobial susceptibility of Clostridium
perfringens isolated from piglets with or without diarrhea in Brazil. Brazilian
Journal of Microbiology, v.43, p.1030-33, 2012.). Regardless, the presence of antibodies does not confirm that these
vaccines would be able to prevent the disease in an experimental model or in the field.
It is also important to note that a piglet model of CPA diarrhea has not yet been
developed; furthermore, the evaluation of a toxoid in a natural infected herd is
difficult because other management variables are often present.
Despite vaccination, the prevention of CPA-associated diarrhea is commonly achieved by
maximizing colostrum uptake by piglets and reducing this and other pathogens in the
environment. This includes washing the sow prior to farrowing, the routine disinfection
of farrowing rooms and the use of antimicrobials in the sow's feed during the
pre-farrowing period. Finally, in cases of disease onset, injectable antibiotics are an
option for the treatment of piglets; bacitracin, lincomycin, sulfa-trimethoprim and
tylosin are commonly used in feed, whereas penicillin is an injectable drug commonly
used in the field (SONGER & GLOCK, 1998SONGER, J.G. Clostridial enteric diseases of domestic animals. Clinical
Microbiology Reviews, v.9, n.2, p.216-234, 1996.).
Studies from several countries, including Brazil, have shown that most C.
perfringens isolates from piglets are resistant to tylosin and
oxytetracycline, although resistance to beta-lactam antibiotics has not been detected
until recently (TANSUPHASIRI et al., 2005SPRINGER, S. et al. Occurrence and control of the Clostridium
perfringens type A associated diarrhea of the suckling pigs with special
consideration of the immunoprophylaxis. Tierärztliche Praxis. Ausgabe G,
Grosstiere/Nutztiere, v.40, n.6, p.375-382, 2012. ; SLAVIĆ et al., 2011SCHOSTER, A. et al. Presence and molecular characterization of
Clostridium difficile and Clostridium perfringens in intestinal compartments of
healthy horses. BMC Veterinary Research, v.29, n.8, p.94, 2012. Available from:
<http://www.biomedcentral.com/1746-6148/8/94>. Accessed: Out. 29,
2014.
http://www.biomedcentral.com/1746-6148/8...
: SALVARANI et al., 2012RIDDELL, C.; KONG, X.M. The influence of diet on necrotic enteritis in
broiler chickens. Avian Diseases, v.36, n.3, p.499-503, 1992. Available from:
<http://www.ncbi.nlm.nih.gov/pubmed/1417581>. Accessed: Out. 29,
2014.
http://www.ncbi.nlm.nih.gov/pubmed/14175...
).
Horses
C. perfringens type C is one of the most important causes of enteric
infection in foals (BUESCHEL et al., 2003BUESCHEL, D. et al. Prevalence of cpb2, encoding beta2 toxin, in
Clostridium perfringens field isolates: correlation of genotype with phenotype.
Veterinary Microbiology, v.94, n.2, p.121-129, 2003. Available from:
<http://www.ncbi.nlm.nih.gov/pubmed/12781480>. Accessed: Out. 29, 2014. doi:
10.1016/S0378-1135(03)00081-6.
http://www.ncbi.nlm.nih.gov/pubmed/12781...
). This
enterotoxemia is more common in neonatal animals, but older foals and adult horses can
also be affected. The disease is acute, characterized by bloody diarrhea, and commonly
fatal due to the absorption of toxins into systemic circulation. On post
mortem examination, the small intestine, and eventually also the large
intestine, is diffusely hemorrhagic and necrotic, sometimes with the presence of ulcers
and pseudomembrane. Mucosal and submucosal thrombosis is also common (HOWARD-MARTIN et al., 1986HERHOLZ, C. et al. Prevalence of beta2-toxigenic Clostridium perfringens
in horses with intestinal disorders. Journal of Clinical Microbiology, v.37, n.2,
p.358-361, 1999. Available from: <http://www.ncbi.nlm.nih.gov/pubmed/9889218>.
Accessed: Out. 29, 2014.
http://www.ncbi.nlm.nih.gov/pubmed/98892...
; DROLET et al., 1990DIAB, S.S. et al. Pathology of Clostridium perfringens type C
enterotoxemia in horses. Veterinary Pathology, v.49, n.2, p.255-263, 2012. Available
from: <http://www.ncbi.nlm.nih.gov/pubmed/21502373>. Accessed: Out. 29,
2014.
http://www.ncbi.nlm.nih.gov/pubmed/21502...
; DIAB et al.,
2012CRUZ-JUNIOR, E.C. et al. A surveillance of enteropathogens in piglets
from birth to seven days of age in Brazil. Pesquisa Veterinária Brasileira, v.33,
n.8, p.963-969, 2013. doi: 10.1590/S0100-736X2013000800002.
https://doi.org/10.1590/S0100-736X201300...
).
For neonatal foals, the main predisposing factor is similar to that cited for young
piglets: a typically low trypsin secretion associated with colostrum intake. For older
foals or adult horses, the predisposing factors are not completely known; however,
malnutrition, trypsin deficiency, pancreatic diseases and a diet rich in trypsin
inhibitors may predispose an animal to C. perfringens type C infection
(DIAB et al., 2012CRUZ-JUNIOR, E.C. et al. A surveillance of enteropathogens in piglets
from birth to seven days of age in Brazil. Pesquisa Veterinária Brasileira, v.33,
n.8, p.963-969, 2013. doi: 10.1590/S0100-736X2013000800002.
https://doi.org/10.1590/S0100-736X201300...
). Some authors also
reported that certain antibiotics could play a role in C. perfringens type
C infection, although this is only speculative (DIAB et
al., 2012CRUZ-JUNIOR, E.C. et al. A surveillance of enteropathogens in piglets
from birth to seven days of age in Brazil. Pesquisa Veterinária Brasileira, v.33,
n.8, p.963-969, 2013. doi: 10.1590/S0100-736X2013000800002.
https://doi.org/10.1590/S0100-736X201300...
). Co-infection of C. perfringens type C and C.
difficile, another common clostridial foal enteropathogen, could also be
possible (UZAL et al., 2012UZAL, F.A. et al. Clostridium perfringens type C and Clostridium
difficile co-infection in foals. Veterinary Microbiology, v.156, n.3-4, p.395-402,
2012.).
The laboratory diagnosis of C. perfringens type C infection in horses is
similar to that in other species and is based on the detection of beta toxin in the
intestinal contents in association with post mortem findings when death
occurs. The absence of bloody diarrhea does not exclude the diagnosis of C.
perfringens type C infection, as some animals can show acute colic without
diarrhea or even sudden death (DIAB et al.,
2012CRUZ-JUNIOR, E.C. et al. A surveillance of enteropathogens in piglets
from birth to seven days of age in Brazil. Pesquisa Veterinária Brasileira, v.33,
n.8, p.963-969, 2013. doi: 10.1590/S0100-736X2013000800002.
https://doi.org/10.1590/S0100-736X201300...
). Because C. perfringens type C is rare as part of the
microbiota of horses, the isolation of this microorganism in combination with the
typical lesions has a high diagnostic value. However, it is possible that C.
perfringens type C may not be isolated, leading to some toxin-positive but
isolation-negative cases. This might be due to the growth of C. perfringens
type C in only some intestinal segments, leading to lesions and enterotoxemia despite a
lack of the microorganism in the content of some segments (SONGER, 1996SLAVIĆ, D. et al. Antimicrobial susceptibility of Clostridium
perfringens isolates of bovine, chicken, porcine, and turkey origin from Ontario.
Canadian Journal of Veterinary Research, v.75, n.2, p.89-97, 2011. Available from:
<http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3062930/>. Accessed: Out. 29,
2014.
http://www.ncbi.nlm.nih.gov/pmc/articles...
; DIAB et al.,
2012CRUZ-JUNIOR, E.C. et al. A surveillance of enteropathogens in piglets
from birth to seven days of age in Brazil. Pesquisa Veterinária Brasileira, v.33,
n.8, p.963-969, 2013. doi: 10.1590/S0100-736X2013000800002.
https://doi.org/10.1590/S0100-736X201300...
).
C. perfringens type A is also implicated as a cause of diarrhea in adult
horses and foals (HAZLETT et al., 2011HAMMER, M.J. et al. Serological evaluation of a Clostridium perfringens
type A toxoid in a commercial swine herd. Journal of Swine Health and Production,
v.16, n.1, p.37-40, 2008.; DIAB et al., 2012CRUZ-JUNIOR, E.C. et al. A surveillance of enteropathogens in piglets
from birth to seven days of age in Brazil. Pesquisa Veterinária Brasileira, v.33,
n.8, p.963-969, 2013. doi: 10.1590/S0100-736X2013000800002.
https://doi.org/10.1590/S0100-736X201300...
). It is well known that healthy
equines can harbor C. perfringens type A strains, but studies have shown
that diarrheic animals are more likely to be positive for the isolation of this
microorganism than healthy horses and foals (NETHERWOOD
et al., 1996NAUERBY, B. et al. Analysis by pulsed-field gel electrophoresis of the
genetic diversity among Clostridium perfringens isolates from chickens. Veterinary
Microbiology, v.94, n.3, p.257-266, 2003. Available from:
<http://www.ncbi.nlm.nih.gov/pubmed/12814893>. Accessed: Out. 29, 2014.
doi:10.1016/S0378-1135(03)00118-4.
http://www.ncbi.nlm.nih.gov/pubmed/12814...
; SCHOSTER et al., 2012SCHÄFER, K. et al. Detection of Clostridium perfringens type C in pig
herds following disease outbreak and subsequent vaccination. Veterinary Record,
v.171, n.20, p.503, 2012. Available from:
<http://www.ncbi.nlm.nih.gov/pubmed/23100304>. Accessed: Out. 29,
2014.
http://www.ncbi.nlm.nih.gov/pubmed/23100...
;
SILVA et al., 2013a). Additionally, the cpb2 gene was found to be more
common in horses with intestinal disorders compared with healthy animals or those that
were hospitalized for reasons other than intestinal problems (GIBERT et al., 1998GIBERT, M. et al. Beta-2 toxin, a novel toxin produced by Clostridium
perfringens. Gene, v.203, n.1, p.65-73, 1997.; HERHOLZ et al.,
1999HAZLETT, M.J. et al. Beta 2 toxigenic Clostridium perfringens type A
colitis in a three-day-old foal. Journal of Veterinary Diagnostic Investigation,
v.23, n.2, p.373-376, 2011. Available from:
<http://www.ncbi.nlm.nih.gov/pubmed/21398467>. Accessed: Out. 29,
2014.
http://www.ncbi.nlm.nih.gov/pubmed/21398...
). In another study, BACCIARINI et al.
(2003BACCIARINI, L.N. et al. Immunohistochemical localization of Clostridium
perfringens beta2-toxin in the gastrointestinal tract of horses. Veterinary
Pathology, v.40, n.4, p.376-381, 2003. Available from:
<http://www.ncbi.nlm.nih.gov/pubmed/12824509>. Accessed: Out. 29, 2014. doi:
10.1354/vp.40-4-376.
http://www.ncbi.nlm.nih.gov/pubmed/12824...
) reported that beta-2 toxin was more common in horses with
gastrointestinal disease than in control horses (from a slaughterhouse), as demonstrated
by immunohistochemistry. There was also a significant correlation between the isolation
of cpb2-harboring C. perfringens and the identification of
beta-2 toxin in the intestinal content (BACCIARINI et
al., 2003BACCIARINI, L.N. et al. Immunohistochemical localization of Clostridium
perfringens beta2-toxin in the gastrointestinal tract of horses. Veterinary
Pathology, v.40, n.4, p.376-381, 2003. Available from:
<http://www.ncbi.nlm.nih.gov/pubmed/12824509>. Accessed: Out. 29, 2014. doi:
10.1354/vp.40-4-376.
http://www.ncbi.nlm.nih.gov/pubmed/12824...
). One possible predisposing factor could be antibiotic treatment
with aminoglycoside antibiotics, as a previous study showed an association between the
lethal progression of colitis associated with cpb2-positive C.
perfringens and antibiotic treatment (gentamicin-penicillin). Additionally, an
in vitro experiment showed that gentamicin could induce beta-2 toxin
production in C. perfringens beta-2 isolates from horses (HERHOLZ et al., 1999HAZLETT, M.J. et al. Beta 2 toxigenic Clostridium perfringens type A
colitis in a three-day-old foal. Journal of Veterinary Diagnostic Investigation,
v.23, n.2, p.373-376, 2011. Available from:
<http://www.ncbi.nlm.nih.gov/pubmed/21398467>. Accessed: Out. 29,
2014.
http://www.ncbi.nlm.nih.gov/pubmed/21398...
; VILEI et al., 2005VAN IMMERSEEL, F. et al. Rethinking our understanding of the
pathogenesis of necrotic enteritis in chickens. Trends in Microbiology, v.17, n.1,
p.32-36, 2009. Available from: <http://www.ncbi.nlm.nih.gov/pubmed/18977143>.
Accessed: Out. 29, 2014.
http://www.ncbi.nlm.nih.gov/pubmed/18977...
). In foals, HAZLETT et al. (2011HAMMER, M.J. et al. Serological evaluation of a Clostridium perfringens
type A toxoid in a commercial swine herd. Journal of Swine Health and Production,
v.16, n.1, p.37-40, 2008.) recently reported a beta-2 toxigenic C.
perfringens type A colitis in a three-day-old animal. The animal experienced a
worsening of the clinical signs after treatment with gentamicin. Colitis and typhlitis
were observed in the post mortem examination, and an abundance of
cpb2-positive C. perfringens was isolated from both the
small and large intestines. In this case, other enteropathogens were absent, suggesting
that C. perfringens was responsible for the intestinal disease.
In addition to beta-2 toxin, WEESE et al. (2001VILEI, E.M. et al. Antibiotic-induced expression of a cryptic cpb2 gene
in equine beta2-toxigenic Clostridium perfringens. Molecular Microbiology, v.57, n.6,
p.1570-1581, 2005. Available from:
<http://www.ncbi.nlm.nih.gov/pubmed/21673152>. Accessed: Out. 29,
2014.
http://www.ncbi.nlm.nih.gov/pubmed/21673...
)
reported an association between gastrointestinal disease and the presence of enterotoxin
in stool samples from mature horses and foals. However, the actual roles of both toxins
have remained unclear, and some recent studies, including one with horses from Minas
Gerais and Sao Paulo States in Brazil, showed no differences in the isolation rates of
cpb2- and cpe-harboring C. perfringens
among animals with gastrointestinal disease or a control group (SILVA et al., 2013a:
SCHOSTER et al., 2013SCHOSTER, A. et al. Presence and molecular characterization of
Clostridium difficile and Clostridium perfringens in intestinal compartments of
healthy horses. BMC Veterinary Research, v.29, n.8, p.94, 2012. Available from:
<http://www.biomedcentral.com/1746-6148/8/94>. Accessed: Out. 29,
2014.
http://www.biomedcentral.com/1746-6148/8...
). In fact, further
studies are needed to confirm the role of these toxins in the development of
gastrointestinal disease in horses and also to determine whether they could be used in
the diagnosis of C. perfringens type A infection in equines.
Studies on the antimicrobial susceptibility of C. perfringens isolates from
equines have shown a high susceptibility to penicillin, vancomycin, chloramphenicol and
metronidazole. In contrast, resistance to macrolides (commonly erythromycin) and
oxytetracycline is common (SILVA et al., 2013; LAWHON et
al., 2013KLAASEN, H.L. et al. Detection of the beta2 toxin gene of Clostridium
perfringens in diarrhoeic piglets in The Netherlands and Switzerland. FEMS Immunology
& Medical Microbiology, v.24, n.3, p.325-332, 1999. Available from:
<http://www.ncbi.nlm.nih.gov/pubmed/10397318>. Accessed: Out. 29,
2014.
http://www.ncbi.nlm.nih.gov/pubmed/10397...
). It is also important to remember that, despite the high
susceptibility, some studies suggest that exposure to gentamicin and penicillin could
predispose equines to C. perfringens type A infection (HERHOLZ et al., 1999HAZLETT, M.J. et al. Beta 2 toxigenic Clostridium perfringens type A
colitis in a three-day-old foal. Journal of Veterinary Diagnostic Investigation,
v.23, n.2, p.373-376, 2011. Available from:
<http://www.ncbi.nlm.nih.gov/pubmed/21398467>. Accessed: Out. 29,
2014.
http://www.ncbi.nlm.nih.gov/pubmed/21398...
; VILEI et al., 2005VAN IMMERSEEL, F. et al. Rethinking our understanding of the
pathogenesis of necrotic enteritis in chickens. Trends in Microbiology, v.17, n.1,
p.32-36, 2009. Available from: <http://www.ncbi.nlm.nih.gov/pubmed/18977143>.
Accessed: Out. 29, 2014.
http://www.ncbi.nlm.nih.gov/pubmed/18977...
; HAZLETT et al.,
2011HAMMER, M.J. et al. Serological evaluation of a Clostridium perfringens
type A toxoid in a commercial swine herd. Journal of Swine Health and Production,
v.16, n.1, p.37-40, 2008.)
Similar to the reports for swine, the vaccination of mares with beta toxoid to prevent
type-C enterotoxemia in foals is common in some countries, although studies regarding
the immune response of equines to this or other clostridial antigens are rare (TIMONEY et al., 2005TIMBERMONT, L. et al. Necrotic enteritis in broilers: an updated review
on the pathogenesis. Avian Pathology, v.40, n.4, p.341-347, 2011. Available from:
<http://www.ncbi.nlm.nih.gov/pubmed/21812711>. Accessed: Out. 29, 2014. doi:
10.1080/03079457.2011.590967.
http://www.ncbi.nlm.nih.gov/pubmed/21812...
). Considering that the main
virulence factors involved in C. perfringens type A infection in equines
are still unknown, no conclusions can be made regarding the composition of a vaccine to
prevent this infection.
Broiler chickens
Necrotic enteritis (NE) is caused by C. perfringens type A and, more
uncommonly, by C. perfringens type C. NE is one of the most common
infectious diseases in poultry, resulting in an estimated annual economic loss of more
than $2 billion, largely related to impaired growth performance (COOPER et al., 2009COOPER, K.K.; SONGER J.G. Necrotic enteritis in chickens: a paradigm of
enteric infection by Clostridium perfringens type A. Anaerobe, v.15, n.1-2, p.55-60,
2009. Available from: <http://www.ncbi.nlm.nih.gov/pubmed/19186215>. Accessed:
Out. 29, 2014. doi: 10.1016/j.anaerobe.2009.01.006.
http://www.ncbi.nlm.nih.gov/pubmed/19186...
; VAN IMMERSEEL et
al., 2009UZAL, F.A.; SONGER, J.G. Diagnosis of Clostridium perfringens intestinal
infections in sheep and goats. Journal of Veterinary Diagnostic Investigation, v.20,
n.3, p.253-265, 2008.). This enteric infection is commonly well controlled by
anticoccidials or antibiotic growth promoters, but the use of these compounds has been
banned in animal feed in the European Union, and there is pressure to reduce their use
worldwide because of the risk of multiple antimicrobial-resistant strains (VAN IMMERSEEL et al., 2009UZAL, F.A.; SONGER, J.G. Diagnosis of Clostridium perfringens intestinal
infections in sheep and goats. Journal of Veterinary Diagnostic Investigation, v.20,
n.3, p.253-265, 2008.). Thus, NE is re-emerging
as an important disease in poultry, and there is concern about the increased risk of
contamination of poultry products for human consumption, as C. perfringens
is one of the most common causes of foodborne illness worldwide (NOWELL et al., 2010NIILO, L. Clostridium perfringens Type C enterotoxemia. Canadian
Veterinary Journal, v.29, n.8, p.658-664, 1988.; CDC,
2012CENTERS FOR DISEASE CONTROL AND PREVENTION (CDC). Fatal foodborne
Clostridium perfringens illness at a state psychiatric hospital--Louisiana, 2010.
Morbidity and Mortality Weekly Report, v.61, n.32, p.605-608, 2012.)
Little is known about the susceptibility of poultry lines to NE; however, a recent study
suggests that Cobb chickens are more susceptible to necrotic enteritis compared with
Ross and Hubbard chickens (JANG et al., 2013HOWARD-MARTIN, M. et al. Clostridium perfringens type C enterotoxemia in
a newborn foal. Journal of the American Veterinary Medical Association, v.189, n.5,
p.564-565, 1986. Available from: <http://www.ncbi.nlm.nih.gov/pubmed/2875986>.
Accessed: Out. 29, 2014.
http://www.ncbi.nlm.nih.gov/pubmed/28759...
).
The disease occurs mostly in animals between 2-6 weeks of age and can vary from an acute
to a subclinical form. The subclinical form is more prevalent, being responsible for the
greatest economic losses in poultry production due to NE, and is characterized by
chronic intestinal mucosal damage, which leads to poor digestion and absorption (LONG, 1973LEPP, D. et al. Identification of accessory genome regions in poultry
Clostridium perfringens isolates carrying the netB plasmid. Journal of Bacteriology,
v.195, n.6, p.1152-1166, 2013. Available from:
<http://www.ncbi.nlm.nih.gov/pubmed/23292780>. Accessed: Out. 29,
2014.
http://www.ncbi.nlm.nih.gov/pubmed/23292...
; VAN
IMMERSEEL et al., 2009UZAL, F.A.; SONGER, J.G. Diagnosis of Clostridium perfringens intestinal
infections in sheep and goats. Journal of Veterinary Diagnostic Investigation, v.20,
n.3, p.253-265, 2008.; TIMBERMONT et al.,
2011TAYLOR, D. Clostridial infections. In: STRAW, B.E. et al. Diseases of
swine. Ames: Iowa State University, 1999. p.395-412.). In this case, hepatitis or cholangiohepatitis is often found at
processing, leading to an increase in liver condemnation (LEE et al., 2011LAWHON, S.D. et al. Frequency of resistance in obligate anaerobic
bacteria isolated from dogs, cats, and horses to antimicrobial agents. Journal of
Clinical Microbiology, v.51, n.11, p.3804-3810, 2013. Available from:
<http://www.ncbi.nlm.nih.gov/pubmed/24025899>. Accessed: Out. 29,
2014.
http://www.ncbi.nlm.nih.gov/pubmed/24025...
). The acute form is less common and is
characterized by a sudden increase in mortality, which can reach 50% (RIDDELL & KONG, 1992POPOFF, M.R.; BOUVET, P. Genetic characteristics of toxigenic Clostridia
and toxin gene evolution. Toxicon, v.75, p.63-89, 2013. Available from:
<http://www.ncbi.nlm.nih.gov/pubmed/23707611>. Accessed: Out. 29, 2014.
doi:10.1016/j.toxicon.2013.05.003.
http://www.ncbi.nlm.nih.gov/pubmed/23707...
; TIMBERMONT et al., 2011TAYLOR, D. Clostridial infections. In: STRAW, B.E. et al. Diseases of
swine. Ames: Iowa State University, 1999. p.395-412.).
The pathogenesis of NE is not completely understood. Several years ago, it was believed
that alpha toxin was the main virulence factor involved in these cases, although some
recent studies have shown that this is not completely true (MCCOURT et al., 2005LYHS, U. et al. Characterization of Clostridium perfringens isolates
from healthy turkeys and from turkeys with necrotic enteritis. Poultry Science, v.92,
n.7, p.1750-1757, 2013. Available from:
<http://www.ncbi.nlm.nih.gov/pubmed/23776261>. Accessed: Out. 29, 2014.
http://www.ncbi.nlm.nih.gov/pubmed/23776...
; BUESCHEL et
al., 2003BUESCHEL, D. et al. Prevalence of cpb2, encoding beta2 toxin, in
Clostridium perfringens field isolates: correlation of genotype with phenotype.
Veterinary Microbiology, v.94, n.2, p.121-129, 2003. Available from:
<http://www.ncbi.nlm.nih.gov/pubmed/12781480>. Accessed: Out. 29, 2014. doi:
10.1016/S0378-1135(03)00081-6.
http://www.ncbi.nlm.nih.gov/pubmed/12781...
). In one these studies, KEYBURN et
al. (2006JOST, B.H. et al. Clonal relationships among Clostridium perfringens of
porcine origin as determined by multilocus sequence typing. Veterinary Microbiology,
v.116, n.1-3, 158-165, 2006b. Available from:
<http://www.ncbi.nlm.nih.gov/pubmed/16650661>. Accessed: Out. 29, 2014. doi:
10.1016/j.vetmic.2006.03.025.
http://www.ncbi.nlm.nih.gov/pubmed/16650...
) showed that an alpha toxin null mutant was able to produce NE
lesions in a chicken experimental model, suggesting that alpha toxin might contribute to
the lesions but is not essential for the development of the disease. It has also been
speculated that beta-2 and enterotoxin are involved in NE, but there is little evidence
that both toxins are involved (VAN IMMERSEEL et al.,
2009UZAL, F.A.; SONGER, J.G. Diagnosis of Clostridium perfringens intestinal
infections in sheep and goats. Journal of Veterinary Diagnostic Investigation, v.20,
n.3, p.253-265, 2008.; CRESPO et al., 2007COOPER, K.K. et al. Immunization with recombinant alpha toxin protects
broiler chicks against experimental challenge with Clostridium perfringens.
Veterinary Microbiology, v.133, p.92-97, 2009. Available from:
<http://www.sciencedirect.com/science/article/pii/S0378113508002150>. Accessed:
Out. 29, 2014. doi: 10.1016/j.vetmic.2008.06.001.
http://www.sciencedirect.com/science/art...
).
Several studies have investigated the role of other toxins in NE. One of the most
interesting of these is Necrotic Enteritis toxin B (NetB), a pore-forming toxin capable
of causing lesions typical of NE in experimental models (KEYBURN et al., 2008KEYBURN, A.L. et al. NetB, a new toxin that is associated with avian
necrotic enteritis caused by Clostridium perfringens. PLOS Pathogens, v.4, n.2, p.26,
2008. Available from: <http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2233674>.
Accessed: Out. 29, 2014. doi: 10.1371/journal.ppat.0040026
http://www.ncbi.nlm.nih.gov/pmc/articles...
). In addition, it was demonstrated that the
NetB-encoding gene (netb) is common in C. perfringens type
A isolates from NE birds, whereas it is rare in healthy birds (KEYBURN et al., 2008). A
similar association was recently reported in turkeys: netb was
identified in 6.6% of the C. perfringens strains isolated from turkeys with
NE but in none of the strains isolated from healthy animals (LYHS et al., 2013LONG, J.R. Necrotic enteritis in broiler chickens. I. A review of the
literature and the prevalence of the disease in Ontario. Canadian Journal of
Comparative Medicine, v.37, n.3, p.302-308, 1973.). Because reports have indicated that C.
perfringens netb-negative strains can cause NE, it appears that there are
other virulence factors involved (LEE et al.,
2011LAWHON, S.D. et al. Frequency of resistance in obligate anaerobic
bacteria isolated from dogs, cats, and horses to antimicrobial agents. Journal of
Clinical Microbiology, v.51, n.11, p.3804-3810, 2013. Available from:
<http://www.ncbi.nlm.nih.gov/pubmed/24025899>. Accessed: Out. 29,
2014.
http://www.ncbi.nlm.nih.gov/pubmed/24025...
).
Several predisposing factors for NE have been identified. One of the most important is
nutrition: any diet that may lead to a decrease in nutrient digestibility and a
reduction in intestinal transit may predispose an animal to overgrowth of C.
perfringens in the gut. For instance, diets with a high concentration of
water-soluble, non-starch polysaccharides or poorly digestible proteins are commonly
incriminated in NE cases (COOPER & SONGER,
2009COOPER, K.K.; SONGER J.G. Necrotic enteritis in chickens: a paradigm of
enteric infection by Clostridium perfringens type A. Anaerobe, v.15, n.1-2, p.55-60,
2009. Available from: <http://www.ncbi.nlm.nih.gov/pubmed/19186215>. Accessed:
Out. 29, 2014. doi: 10.1016/j.anaerobe.2009.01.006.
http://www.ncbi.nlm.nih.gov/pubmed/19186...
; LEE et al., 2011LAWHON, S.D. et al. Frequency of resistance in obligate anaerobic
bacteria isolated from dogs, cats, and horses to antimicrobial agents. Journal of
Clinical Microbiology, v.51, n.11, p.3804-3810, 2013. Available from:
<http://www.ncbi.nlm.nih.gov/pubmed/24025899>. Accessed: Out. 29,
2014.
http://www.ncbi.nlm.nih.gov/pubmed/24025...
). Coccidiosis is
also a well-known predisposing factor due to mucosal damage, which leads to plasma
leakage into the gut. Additionally, the immune response to coccidial infection increases
the amount of mucus in the intestinal tract; both mucus and plasma are used as a
substrate by C. perfringens (COLLIER et al.,
2008CHAN, G. et al. The epidemiology of Clostridium perfringens type A on
Ontario swine farms, with special reference to cpb2-positive isolates. BMC Veterinary
Research, v.8, p.156, 2012. Available from:
<http://www.ncbi.nlm.nih.gov/pubmed/22947389>. Accessed: Out. 29, 2014. doi:
10.1186/1746-6148-8-156.
http://www.ncbi.nlm.nih.gov/pubmed/22947...
).
Some studies have also indicated that, in addition to all other predisposing factors,
the presence of poultry pathogenic C. perfringens strains is necessary for
the occurrence of the disease. In fact, different genotypes are present in healthy
flocks, whereas a single clonal strain is generally disseminated among birds in flocks
with NE. After treatment, the birds can again carry multiple genetic types. These
results were confirmed by pulsed-field electrophoresis, by multilocus sequence typing
analysis and also in an experimental model (ENGSTRÖM et
al., 2003DROLET R. et al. Necrohemorrhagic enterocolitis caused by Clostridium
perfringens type C in a foal. Canadian Veterinary Journal, v.31. n.6, p.449-450,
1990. Available from: <http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1480657/>.
Accessed: Out. 29, 2014.
http://www.ncbi.nlm.nih.gov/pmc/articles...
; NAUERBY et al., 2003MIYAMOTO, K. et al. Enterotoxigenic Clostridium perfringens: detection
and identification. Microbes and Environments, v.27, n.4, p.343-349, 2012. Available
from: <http://www.ncbi.nlm.nih.gov/pubmed/22504431>. Accessed: Out. 29, 2014.
doi: 10.1264/jsme2.ME12002.
http://www.ncbi.nlm.nih.gov/pubmed/22504...
; BARBARA et al., 2008BARBARA, A.J. et al. Necrotic enteritis-producing strains of Clostridium
perfringens displace non-necrotic enteritis strains from the gut of chicks.
Veterinary Microbiology, v.126, n.4, p.377-382, 2008. Available from:
<http://www.ncbi.nlm.nih.gov/pubmed/17850994>. Accessed: Out. 29,
2014.
http://www.ncbi.nlm.nih.gov/pubmed/17850...
). A recent study evaluating
netb-positive C. perfringens identified a specific
chromosomal locus in these strains, suggesting that this chromosomal background can
confer a selective advantage to NE-causing strains, possibly through mechanisms
involving iron acquisition, carbohydrate metabolism or even plasmid maintenance (LEPP et al., 2013LEE, K.W. et al. Avian necrotic enteritis: experimental models, host
immunity, pathogenesis, risk factors, and vaccine development. Poultry Science, v.90,
n.7, p.1381-1390, 2011. Available from:
<http://www.ncbi.nlm.nih.gov/pubmed/21673152>. Accessed: Out. 29,
2014.
http://www.ncbi.nlm.nih.gov/pubmed/21673...
).
The isolation of C
. perfringens alone is not sufficient for diagnosis because this bacterium
is commonly part of the microbiota; however, the absence of C. perfringens
can rule out the involvement of this agent (COOPER et
al., 2013COLLIER, C.T. et al. Coccidia-induced mucogenesis promotes the onset of
necrotic enteritis by supporting Clostridium perfringens growth. Veterinary
Immunology and Immunopathology, v.122, n.1-2, p.104-115, 2008. Available from:
<http://www.ncbi.nlm.nih.gov/pubmed/18068809>. Accessed: Out. 29, 2014. doi:
10.1177/1040638713483468.
http://www.ncbi.nlm.nih.gov/pubmed/18068...
). Based on recent reports describing the association of
netb and NE, the detection of this gene might also be interesting
for a complete laboratory diagnosis (KEYBURN et al.,
2008KEYBURN, A.L. et al. NetB, a new toxin that is associated with avian
necrotic enteritis caused by Clostridium perfringens. PLOS Pathogens, v.4, n.2, p.26,
2008. Available from: <http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2233674>.
Accessed: Out. 29, 2014. doi: 10.1371/journal.ppat.0040026
http://www.ncbi.nlm.nih.gov/pmc/articles...
). Intestinal damage and increases in liver condemnation during
slaughterhouse inspections strongly suggest NE. The lesions are commonly restricted to
the small intestine, which is filled with gas and has thin walls. Confluent mucosal
necrosis may be observed, sometimes also covered by a pseudomembrane (COOPER et al., 2013COLLIER, C.T. et al. Coccidia-induced mucogenesis promotes the onset of
necrotic enteritis by supporting Clostridium perfringens growth. Veterinary
Immunology and Immunopathology, v.122, n.1-2, p.104-115, 2008. Available from:
<http://www.ncbi.nlm.nih.gov/pubmed/18068809>. Accessed: Out. 29, 2014. doi:
10.1177/1040638713483468.
http://www.ncbi.nlm.nih.gov/pubmed/18068...
). Histological evaluation is
important for confirming typical lesions and also to rule out the involvement of other
possible enteropathogens, including coccidial infection, ulcerative colitis by C.
colinum and histomoniasis (TIMBERMONT et al.,
2011TAYLOR, D. Clostridial infections. In: STRAW, B.E. et al. Diseases of
swine. Ames: Iowa State University, 1999. p.395-412.; COOPER et al., 2013COLLIER, C.T. et al. Coccidia-induced mucogenesis promotes the onset of
necrotic enteritis by supporting Clostridium perfringens growth. Veterinary
Immunology and Immunopathology, v.122, n.1-2, p.104-115, 2008. Available from:
<http://www.ncbi.nlm.nih.gov/pubmed/18068809>. Accessed: Out. 29, 2014. doi:
10.1177/1040638713483468.
http://www.ncbi.nlm.nih.gov/pubmed/18068...
). The lesions
can vary depending on the stage of the infection. In early stages, a strong inflammatory
reaction with heterophilic granulocytes in the lamina propria may be observed, whereas
in later stages, diffuse coagulative necrosis of the mucosa may be present, with
gram-positive rods associated with the lesions but not invading the epithelium (TIMBERMONT et al., 2011TAYLOR, D. Clostridial infections. In: STRAW, B.E. et al. Diseases of
swine. Ames: Iowa State University, 1999. p.395-412.).
Several proteins have been evaluated as immunogens against NE. Most studies have
addressed the effect of vaccines containing alpha toxin (commonly as a toxoid or in a
recombinant form), but the results vary widely in the literature. In general, vaccinated
birds were found to be more resistant to challenge compared with a control group, but
the vaccines were not able to prevent lesions (LEE et
al., 2011LAWHON, S.D. et al. Frequency of resistance in obligate anaerobic
bacteria isolated from dogs, cats, and horses to antimicrobial agents. Journal of
Clinical Microbiology, v.51, n.11, p.3804-3810, 2013. Available from:
<http://www.ncbi.nlm.nih.gov/pubmed/24025899>. Accessed: Out. 29,
2014.
http://www.ncbi.nlm.nih.gov/pubmed/24025...
). Recently, studies with a NetB recombinant protein showed that the
vaccination of poultry or maternal immunization can partially protect broiler chickens
from necrotic enteritis (KEYBURN et al., 2013aKEYBURN, A.L. et al. Vaccination with recombinant NetB toxin partially
protects broiler chickens from necrotic enteritis. Veterinary Research, v.44, p.54,
2013a. Available from: <http://www.veterinaryresearch.org/content/44/1/54>.
Accessed: Out. 29, 2014. doi: 10.1186/1297-9716-44-54
http://www.veterinaryresearch.org/conten...
;
KEYBURN et al., 2013bKEYBURN, A.L. et al. Maternal immunization with vaccines containing
recombinant NetB toxin partially protects progeny chickens from necrotic enteritis.
Veterinary Research, v.44, n.1, p.108, 2013b. Available from:
<http://www.veterinaryresearch.org/content/44/1/108>. Accessed: Out. 29, 2014.
doi: 10.1186/1297-9716-44-108
http://www.veterinaryresearch.org/conten...
). Considering the
pressure to reduce or ban growth promoters from animal feed, the development of a potent
vaccine against NE might be an important step for poultry production in the next few
years.
CONCLUSIONS:
C. perfringens is well recognized as an important enteric pathogen for all domestic species. Specifically for broiler chicken, some recent advances have been made in the pathogenesis and diagnosis of C. perfringens infection. On the other hand the current knowledge regarding this bacterium in pigs and horses is still clouded.
- BACCIARINI, L.N. et al. Immunohistochemical localization of Clostridium perfringens beta2-toxin in the gastrointestinal tract of horses. Veterinary Pathology, v.40, n.4, p.376-381, 2003. Available from: <http://www.ncbi.nlm.nih.gov/pubmed/12824509>. Accessed: Out. 29, 2014. doi: 10.1354/vp.40-4-376.
» https://doi.org/10.1354/vp.40-4-376» http://www.ncbi.nlm.nih.gov/pubmed/12824509 - BARBARA, A.J. et al. Necrotic enteritis-producing strains of Clostridium perfringens displace non-necrotic enteritis strains from the gut of chicks. Veterinary Microbiology, v.126, n.4, p.377-382, 2008. Available from: <http://www.ncbi.nlm.nih.gov/pubmed/17850994>. Accessed: Out. 29, 2014.
» http://www.ncbi.nlm.nih.gov/pubmed/17850994 - BUESCHEL, D. et al. Prevalence of cpb2, encoding beta2 toxin, in Clostridium perfringens field isolates: correlation of genotype with phenotype. Veterinary Microbiology, v.94, n.2, p.121-129, 2003. Available from: <http://www.ncbi.nlm.nih.gov/pubmed/12781480>. Accessed: Out. 29, 2014. doi: 10.1016/S0378-1135(03)00081-6.
» https://doi.org/10.1016/S0378-1135(03)00081-6» http://www.ncbi.nlm.nih.gov/pubmed/12781480 - CENTERS FOR DISEASE CONTROL AND PREVENTION (CDC). Fatal foodborne Clostridium perfringens illness at a state psychiatric hospital--Louisiana, 2010. Morbidity and Mortality Weekly Report, v.61, n.32, p.605-608, 2012.
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Publication Dates
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Publication in this collection
17 Mar 2015 -
Date of issue
June 2015
History
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Received
21 June 2014 -
Accepted
19 Sept 2014