Print version ISSN 0080-6234
Rev. esc. enferm. USP vol.46 no.2 São Paulo Apr. 2012
Microorganismos de la subclase Coccidia: resistencia e implicancias para el procesamiento de materiales de atención a la salud
Rafael Queiroz de SouzaI; Lilian Machado TorresII; Kazuko Uchikawa GrazianoIII; Ruth Natália Teresa TurriniIV
IRN. Doctoral Students, Graduate Program in Adult Health Nursing, School of Nursing, University of São Paulo. São Paulo, SP, Brazil. email@example.com
IIRN. Master Student, Graduate Program in Adult Health Nursing, College of Nursing, University of São Paulo. Specialization in Hospital Infection Control Epidemiology. Belo Horizonte, MG, Brazil. firstname.lastname@example.org
IIIRN. Full Professor, Medical-Surgical Nursing Department, School of Nursing, University of São Paulo. São Paulo, SP, Brazil. email@example.com
IVRN. Ph.D. Professor, Medical-Surgical Nursing Department, School of Nursing, University of São Paulo. São Paulo, SP, Brazil. firstname.lastname@example.org
This theoretical study proposes a reflection on the intrinsic resistance of the subclass Coccidia, particularly the genus Cryptosporidium, considered to be potential pathogens for immunocompromised patients, and the implications for nursing practice. Currently, the international and national guidelines support the chemical disinfection of digestive system endoscopes after their cleansing as a safe and effective procedure. However, studies show that microorganisms of the subclass Coccidia, namely Cryptosporidium, responsible for enteric infection, are more resistant than mycobacteria and are not inactivated by high-level disinfectants, except for hydrogen peroxide 6% and 7.5%, which are not currently available in Brazil. We conclude that the legislation should include this agent among test microorganisms for approving high-level disinfectants. Health authorities should make efforts to ensure that healthcare institutions have access to effective disinfectants against Cryptosporidium.
Descriptors: Disinfection; Endoscopes; Cross infection; Coccidia; Immunocompromised host
Estudio teórico que propone reflexión sobre la resistencia intrínseca de la subclase Coccidia, particularmente el género Cryptosporidium, considerado agente potencialmente patogénico para pacientes inmunocomprometidos, y sus repercusiones para práctica asistencial. Actualmente, las normativas internacionales y nacionales aprueban como procedimiento seguro la desinfección química de alto nivel de endoscopios digestivos, luego de su limpieza. Mientras tanto, los estudios evidenciaron que microorganismos de subclase Coccidia, específicamente el Cryptosporidium, responsable por infección entérica, son más resistentes que las microbacterias y no son inactivados por desinfectantes químicos de alto nivel, excepto el Peróxido de Hidrógeno a 6% y 7,5%, formulación aún no disponible en Brasil. Se concluye en que la legislación debe incluir este agente entre los microorganismos de prueba para aprobación de desinfectantes químicos de alto nivel y que las autoridades sanitarias deben esforzarse para que los Establecimientos de Atención de Salud tengan acceso a productos eficaces contra el Cryptosporidium.
Descriptores: Desinfección; Endoscopios. Infección hospitalaria; Coccidios; Húesped inmunocomprometido
In 1968(1), the biocide action of disinfectants used in healthcare products was classified according to the intrinsic resistance of microorganisms. According to this classification, in a high-level disinfection, the biocide effect must include the tuberculosis bacillus, vegetative bacteria, lipid and medium viruses, non-lipid and small viruses and most of the sporulating microorganisms. The effect of intermediate-level disinfectant does not include spores and, in a low-level disinfection, the biocide action is limited to the vegetative bacteria and to lipid and medium viruses.
Years later, the biocide action of the disinfectants was better specified(2) and described based on the most resistant element in each group of microorganisms: bacterial spores (B. subtilis), mycobacteria (M. tuberculosis), small or non-lipid viruses (Poliovirus), fungi (Candida spp), vegetative bacteria (P. aeruginosa), and medium or lipid viruses (hepatitis B virus - HBV). This classification has been supporting health professionals until the present regarding the choice of disinfectants to be used on healthcare products.
Nevertheless, over the course of time, new infectious protein particles and agents were highlighted as important in the epidemiology of transmissible diseases. In face of scientific evidence, regarding the resistance of some of these agents, the resistance factor of microorganisms to high-level disinfectants initially proposed in 1968 and reviewed in 1991, underwent changes in 1999(3) and in 2008(4). These two new proposals are presented in Table 1.
The data in Table 1 shows the inclusion of new elements: prions and protozoans (Coccidia and others, such as trophozoites and cysts).
Proposal I presents Coccidia as more resistant than bacterial spores(3), which until then were considered the most resistant form of microbial life in the classification of resistance to high-level disinfectant agents. The authors did not specify the criteria used to establish the order of classification of the microorganisms, but they recognized that the action of disinfectants against protozoans had still not been broadly studied. In proposal II, the authors consider that the mechanisms of intrinsic resistance to chemical agents are varied, but there is no clear reason for the definite position of the Coccidia microorganisms, which are more resistant than bacterial spores, in the order of resistance or criteria used for its establishment.
The subclass Coccidia was presented in Proposal I differently from other cystic and trophozoite forms of protozoans, due to the peculiar resistance of the genus Cryptosporidium to the disinfectants currently in use. It is also observed that in both proposals the resistance of this subclass is higher than the resistance of mycobacteria, which require high-level disinfection as the minimum in processing, raising questions regarding the type of processing (disinfection or sterilization) that would be sufficient to assure the reuse of materials contaminated by this agent.
This study identified the pertinence of rediscussion regarding practices for the processing of endoscopes in contact with the digestive tract, considering the importance of the decreasing order of resistance of microorganisms to disinfectant agents, broadly reproduced in reference studies(1-4), for the practices of hospital infection control, including the aseptic processing of products and equipment and the appearance of microorganisms that had not been previously valued as risky until that time. Therefore, this theoretical study will provide a reflection regarding the need to disinfect or sterilize endoscopes in contact with the digestive tract, based on the risks related to the subclass Coccidia, whose microorganisms are resistant to the disinfectants in use in the country and potentially pathogenic for immunocompromised patients.
The term Coccidia designates a subclass of protozoans belonging to the phylum Apicomplexa and to the class Sporozoea(5). The characteristic that best defines this group of microorganisms is the resistant oocyst with a protective wall(6). In this subclass, the genus Cryptosporidium has epidemiological relevance as an etiological agent of infections related to healthcare, due to its cystic and trophozoite forms that, through cytological and physiological changes, could change its resistance to antiseptic agents and disinfectants. Other agents such as Isospora and Cyclospora, despite causing infection in humans, until now have not stood out in the order of intrinsic resistance to disinfectants(3-4). The genus Cryptosporidium consists of obligatory intracellular parasites, whose infecting form is the sporulating oocyst. The main species associated with infections in humans are Cryptosporidium hominis and Cryptosporidium parvum(7). They are associated with enteric infections and the ingestion of only 30 oocysts is capable of producing infection(8). There are also reports of infections in humans caused by a single oocyst(9). This information was also confirmed in laboratory by the inoculation of only one oocyst in immunocompromised mice(10).
The wall of an oocyst may have variable thickness the forms with a thick wall are resistant to environment conditions, are infectious, and released in the feces, thus guaranteeing the continuity of the cycle(9). This wall provides the oocyst with the capability of resisting physical and chemical damage. It is also impermeable to common disinfectants used in the hospital setting(6), and also to the chlorine used in the treatment of water(11). There are studies stating this mechanism is responsible for the survival of oocysts in humid environments for long periods, varying from months to years, preserving their infectivity(6).
The first two cases of infection in humans were reported in 1976 in the United States of America. In one of them, the parasite was detected in the intestinal mucosa of an immunocompromised patient and, in the other case, in a child with gastroenteritis(12). Infection with Cryptosporidium is associated with an increase in morbidity in immunocompromised patients(13) and, in patients with Acquired Immune Deficiency Syndrome (AIDS), the infection can lead to death(14).
In humans, infection can occur through contact with people and animals eliminating the oocysts in feces, ingestion of contaminated water or food and inhalation of the oocyst in contaminated environments(5,9). Possible sexual transmission has also been documented(9). The development of parasites occurs in the microvilli of the cells in the gastrointestinal tract, but they can also be found in the lung parenchyma, gallbladder, pancreatic ducts, esophagus and pharynx(5). There is a report regarding the presence of the parasite adhered to the surface of the apical membrane of the gastric epithelial cells, following a kidney transplant(15).
There were no records found regarding the iatrogenic transmission of Cryptosporidium through endoscopic procedures. However, considering that the microorganism may be found in the intestine of immunocompromised patients, there is the potential risk of transmission during colonoscopies, which leads to the need to ponder this agent in the processing of colonoscopes.
COCCIDIA AND THE PRACTICES OF ASEPTIC PROCESSING OF MATERIALS
Cleansing followed by disinfection seems to be safe to prevent the transmission of the infection associated with healthcare procedures; for instance, the endoscopes that are in contact with the digestive tract(16), despite the recognition of the resistance of these oocysts to disinfectants and the lack of studies related to the impact of infections by Coccidia in the hospital environment.
Based on the new proposals of resistance order of hospital microorganisms presented, which highlight the resistance of microorganisms of the genus Cryptosporidium to disinfectant agents, it becomes urgent to question whether the current practice of high-level disinfection would be sufficient to assure the safety in the use of these materials. Stating that the subclass Coccidia is more resistant than a spore also implies that the material that contains it must be sterilized, considering its methods of transmission.
A study from 1990(17), in establishing recommendations to assure the execution of endoscopies in patients with HIV, admitted that the agents used for the disinfection of the gastrointestinal endoscopes do not need to be sporicidal, but the activity against Cryptosporidium and non-tuberculous mycobacteria would constitute a protective measure for immunocompromised patients undergoing this procedure. The authors found that immunocompromised patients are vulnerable to non-pathogenic microorganisms from immunocompetent carriers, thus the simple rinsing of gastrointestinal endoscopes in tap water would constitute a risk of infection, both for Cryptosporidium (without reference to primary studies) and for non-tuberculous mycobacteria. The sterilization of these materials would be recommended as a protective measure for these patients; however, the authors list strategies for the safe aseptic processing of endoscopes, for instance: precise cleansing, compliance to the minimum time recommended for disinfection, which could reduce the number of Cryptosporidium and non-tuberculous mycobacteria to a safe quantity and, lastly, rinsing in sterilized water or 70% alcohol to eliminate contamination from the tap water.
The strategies presented are questionable, since they did not consider that a small number or even one oocyst is sufficient to cause infection in vulnerable subjects. Moreover, the authors did not present any experimental data or primary study that would characterize the "safe quantity of Cryptosporidium" for immunocompromised patients.
Another study from 1999(16) tested commercial formulations based on hydrogen peroxide, peracetic acid, sodium hypochlorite, phenol, ammonium quaternary, glutaraldehyde 2% and orthophthaldehyde against a suspension containing 105/106 oocysts of the Cryptosporidium parvum. The only product that was able to reduce over 3 logs of oocysts was the hydrogen peroxide in concentrations of 7.5% and 6.0% (products still not available in Brazil), at a temperature of 20º C, with 20 minutes of exposure. Lower concentrations or time of exposure to the product did not result in an effective performance.
In the same study, the authors studied the survival of the oocyst in the environment and evidenced a reduction of infectivity on dry surfaces and at an ambient temperature approximately 2.9 logs in 30 minutes.
The authors in the above study believe the results did not reveal a need to change the aseptic processing practices of endoscopes, based on the reasoning that material cleansing would remove about 104 microorganisms, and that the viability of the Cryptosporidium parvum is reduced with time, especially when on dry surfaces(16).
Although publications state that, until now, there would be no reason for changes in the aseptic processing practices of endoscopes, this position is controversial due to the fact that high-level disinfectants such as glutaraldehyde, paracetic acid and orthophaldehyde, usually employed in the high-level disinfection of the endoscopes, are ineffective against the complete inactivation of Cryptosporidium(16), which requires the use of hydrogen peroxide 6% or 7.5%, still not available in Brazil. Therefore, this study leads to the acceptance of the intrinsic resistance order of the microorganisms presented in proposal II, since high-level disinfection is sufficient, as long as it is performed with an effective disinfectant. However, this position requires discussion regarding two aspects aimed at the control of infections by Cryptosporidium.
The first aspect resides in Brazilian legislation. The Resolution of the Collegiate Board (RCB) number 35(18), from August 16, 2010, defines the test-microorganisms for the evaluation of antimicrobial actions. For a high-level disinfectant, the RCB recommends that the product must be capable of eliminating the following microorganisms: Staphylococcus aureus, Salmonella choleraesuis, Escherichia coli, Pseudomonas aeruginosa, Trichophyton mentagrophytes, Candida albicans, Mycobacterium smegmatis, Mycobacterium bovis, Mycobacterium massiliense, Bacillus subtilis and Clostridium sporogenes. The American legislation, less rigidly, adopts the methodology of the Association of Analytical Communities (AOAC International)(19), including only Staphylococcus aureus, Salmonella choleraesuis, Pseudomonas aeruginosa, Trichophyton mentagrophytes, Mycobacterium smegmatis and Mycobacterium bovis.
As evidenced in the referred RCB, and also in the methodology of the AOAC International, there is no reference to the subclass Coccidia when establishing microorganisms used in the evaluation of disinfectants for semi-critical articles. This fact is disconcerting, since the products currently in use for high-level disinfection, despite being approved, have not been tested against Coccidia. In face of the use of these products for the disinfection of endoscopes, it becomes necessary to rediscuss the microorganisms proposed by the RCB 35 for the approval of disinfectants for semi-critical articles with the inclusion of the genus Coccidia, particularly Cryptosporidium. Moreover, it must be considered that producers of high-level disinfectants for use on endoscopes need to specify their effectiveness against Cryptosporidium.
The second aspect concerns the sterilization of endoscopes. A study regarding infection in patients with HIV evidenced a high number of cases among male subjects aged between 20 and 50 years with diarrhea symptoms. The authors infer that the problem of infection may be difficult to control, which would determine, consequently, the need to establish measures aimed at preventing the dissemination of Cryptosporidium(20). Nevertheless, despite the release of the proposals I and II regarding vehicles of broad dissemination in the world, indicating this agent as more resistant than mycobacteria, there were no changes in the recommendations of the guidelines that dictate the aseptic processing of endoscopes. The most probable reasons would be: the low epidemiological expression of the iatrogenic transmission of Cryptosporidium and the limited options for high-level disinfectants capable of eliminating it, which for the time being is hydrogen peroxide at 6% or 7.5%, still unavailable in Brazil.
Currently, there are devices used for the sterilization of endoscopes, such as the System 1®(21), developed by the company Steris®, which uses peracetic acid with a sterilization period of 12 minutes at 50-56 ºC, and a completed cycle of 30 minutes. It is important to highlight that the safety in the use of this system or any other equipment is conditional to the due validations employing the genus Coccidia as a test-microorganism, since an experimental study indicated the ineffectiveness of the peracetic acid 0.2% Steris® at 23-25 ºC for 12 minutes in the inactivation of Cryptosporidium(16).
In addition to the discussion regarding these aspects, there is also the need to identify flaws, to standardize rules and routines for the aseptic processing of endoscopes and to implement the permanent education of the professionals who work in the endoscopy services, aimed at controlling the dissemination of Cryptosporidium and the safety of the provided care(22) , particularly for patients who are immunocompromised.
This theoretical study proposes a reflection on the intrinsic resistance of the subclass Coccidia, particularly the genus Cryptosporidium, considered to be a potential pathogenic agent for immunocompromised patients, and the implications for nursing practice.
It was demonstrated that the subclass Coccidia is more resistant than mycobacteria and that the usual high-level disinfectants are not capable of eliminating it, except for hydrogen peroxide 6% and 7.5%. Although proposal I indicates the subclass Coccidia as being more resistant than bacterial spores, which would require differentiated methods of sterilization, an experimental study showed the sensitivity of Cryptosporidium to a high-level disinfectant, leading to the acceptance of proposal II.
Despite the fact that the literature does not highlight the need to change the current aseptic processing practices for endoscopes, when previously well cleansed, there are contradictions regarding the logic that the presence of a single occyst of Cryptosporidium would be potentially capable of causing the disease in immunocompromised subjects. Therefore, these microorganisms must be included in the list of those indicated for tests to challenge disinfectants on the occasions of their approval for means of registration in national and internationals bodies.
The authors recommend healthcare establishments adopt measures of quality control for the water used, at least in the last rinsing of the endoscopes. The availability of high-level disinfectants against Cryptosporidium is urgent, assuring the use of standard precautions in the processing of colonoscopes.
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