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Revista do Instituto de Medicina Tropical de São Paulo

Print version ISSN 0036-4665On-line version ISSN 1678-9946

Rev. Inst. Med. trop. S. Paulo vol.57 no.6 São Paulo Nov./Dec. 2015 

Brief Communication


Pseudomonas spp. isoladas da cavidade oral de profissionais da saúde de um hospital oncológico do centro-oeste do Brasil

Ana Beatriz Mori LIMA1 

Lara Stefânia Netto de Oliveira LEÃO-VASCONCELOS2 

Dayane de Melo COSTA3 

Larissa Oliveira Rocha VILEFORT3 

Maria Cláudia Dantas Porfírio Borges ANDRÉ2 

Maria Alves BARBOSA3 

Marinésia Aparecida PRADO-PALOS3 

1Secretaria de Estado da Saúde, Seção de Microbiologia, Laboratório Central de Saúde Pública (LACEN), Goiânia, GO, Brazil. E-mail:

2Universidade Federal de Goiás (UFG), Instituto de Patologia Tropical e Saúde Pública, Departamento de Microbiologia, Goiânia, GO, Brazil. E-mails:;

3Universidade Federal de Goiás (UFG),Faculdade de Enfermagem, Goiânia, GO, Brazil. E-mails:;;;


This cross-sectional study, performed in an oncology hospital in Goiania, aimed to characterize the prevalence of oral colonization and antimicrobial susceptibility of Pseudomonas spp. isolated from the saliva of healthcare workers. Microorganisms were subjected to biochemical tests, susceptibility profile, and phenotypic detection. Of 76 participants colonized with Gram negative bacilli, 12 (15.8%) harbored Pseudomonas spp. Of all isolates, P. aeruginosa (75.0%), P. stutzeri (16.7%), and P. fluorescens (8.3%), were resistant to cefoxitin, and therefore likely to be AmpC producers. The results are clinically relevant and emphasize the importance of surveillance to minimize bacterial dissemination and multiresistance.

Key words: Pseudomonas; Oral colonization; Healthcare workers


Este estudo transversal, realizado em um hospital oncológico em Goiânia, objetivou caracterizar a prevalência da colonização oral e suscetibilidade antimicrobiana de Pseudomonas spp. isoladas da saliva de profissionais da saúde. Micro-organismos foram submetidos a testes bioquímicos, perfil de sensibilidade e detecção fenotípica. Dos 76 participantes colonizados por bastonetes Gram negativos, 12 (15,8%) albergavam Pseudomonas spp. Todos os isolados, P. aeruginosa (75,0%), P. stutzeri (16,7%) e P. fluorescens (8,3%), foram resistentes à cefoxitina e, portanto, possíveis produtores de AmpC. Os resultados são clinicamente relevantes e enfatizam a importância da vigilância para minimizar a disseminação e a multirresistência bacteriana.

Pseudomonas spp. is an ubiquitous microorganism frequently isolated in immunocompromised patients. The intrinsic resistance to multiple antimicrobial agents contributes to the opportunistic character of this pathogen. The emergence of healthcare-associated infection (HCAI) is considered a challenge to public health1,5,6,8. The problem increases when AmpC-producing Pseudomonas spp. are isolated from asymptomatic professionals. The enzyme confers resistance to cephalosporins and penicillins. The blaAmpC genes are found in the chromosome of Pseudomonas and CESP group (Citrobacter, Enterobacter, Serratia, and Providencia). Bacteria can eventually present sensitivity to cefoxitin, whereas mutant strains express resistance to it due to the loss of repressor genes7,9,10,13,14. Asymptomatic carriers play a fundamental role in the epidemiology of HAI, since they act as disseminators through droplets of saliva expelled during hospital assistance. The asymptomatic colonization may progress to lower respiratory tract infection (pneumonia) and result in health problems to workers and users attended. It is important to establish control strategies to prevent the spread of nosocomial infections. However, studies of the oropharyngeal colonization of healthcare professionals by Pseudomonas spp. are scant and the relevance of these carriers should be enlightened3,4,11,12. This research aimed to determine the prevalence of oral colonization and the antimicrobial susceptibility of Pseudomonas spp. isolated from the saliva of healthcare workers from an oncology institution located in Goiania, Brazil, reference center in cancer treatment.

This cross-sectional study, carried out from May 2009 to November 2010, involved 294 participants (149 members of the healthcare team and 145 employees from the technical support area) and was approved by the Ethical Committee of the Associação de Combate ao Câncer de Goiás (ACCG/040/08). This research is part of a surveillance projectAlpha developed in a partnership with some academic units of the Universidade Federal de Goiás (UFG). The study population was composed of workers from the following areas: surgical center, infection control, endoscopy, emergency, chemotherapy, rehabilitation and physiotherapy, radiotherapy, intensive care unit, bone marrow transplantation unit, cleaning, and laundry. Interviews and saliva sampling were performed after participants had signed the informed consent. Unstimulated saliva samples were collected in sterile tubes, transported to the laboratory, and streaked on MacConkey agar. Gram-negative bacilli (GNB) isolates were identified by standardized biochemical tests15. Susceptibility tests were performed using the diffusion method with Oxoid disks. Disk-approximation method with cefoxitin was used as a phenotypic marker for the detection of probable AmpC producing Pseudomonas spp. The results were interpreted according to CLSI guidelines2. Pseudomonas aeruginosa ATCC 27853 was used as quality control2.

Of the 294 participants, 76 were colonized with GNB, and among these, 12 (15.8%) harbored cefoxitin-resistant Pseudomonas spp. (100.0%), suggesting AmpC production. Isolates were sensitive to other antimicrobial agents tested (amikacin, aztreonam, cefepime, ceftazidime, ciprofloxacin, imipenem, levofloxacin, meropenem, and piperacillin-tazobactam). Simultaneous colonization by Pseudomonas spp. and Enterobacteriaceae was observed in two professionals. The prevalence of oral colonization with Pseudomonas spp. was higher among cleaning and laundry workers (25.0%), physicians and nurse technicians (16.7%), and radiology technicians (8.3%). Of the workers colonized with cefoxitin-resistant Pseudomonas spp. (n = 12), 66.7% were aware of multiresistance, 25.0% used oral antiseptics and 8.3% practiced self-medication. The isolated species were: P. aeruginosa (75.0%), P. stutzeri (16.7%), and P. fluorescens (8.3%). These results have clinical relevance, since these pathogens do not belong to the normal human oral flora and may cause health problems, such as tonsillitis, esophagitis, pharyngitis, pneumonia, and other systemic diseases.

It is necessary to point out that although the isolates showed sensitivity to ceftazidime in vitro, they can express induced resistance when cephalosporin is administered in vivo. Therefore, the use of beta-lactam agents should be discouraged7,9,10,13,14. As previously stated, this study is one of the few aiming to assess the prevalence of GNB and Pseudomonas spp. isolated from the oral cavity of health professionals. Investigating 100 healthy people, CONTI et al.3 found that 3.2% were colonized with P. aeruginosa on the tongue dorsum and, among these, four showed simultaneous colonization by Pseudomonas spp. and other GNB, confirming our data. The global prevalence of workers colonized with Pseudomonas spp. in the present study was 4.08% (12/294). PRADO-PALOS et al.11 evaluated the prevalence of GNB isolated from the saliva of 278 health workers in a teaching hospital in Goiania. A total of 319 GNB were identified, namely 208 (65.2%) Enterobacteriaceae and 111 (34.8 %) non-fermenters, of which 25 (7.8%) were P. aeruginosa, results that are in accordance with our findings. RAMOS et al.12 carried out a study from 1998 to 2008 in Sao Paulo to survey the prevalence of beta-lactam-resistant enteric bacteria and Pseudomonas spp. isolated from the oral cavity of 250 patients. The authors isolated 154 GNB, encompassing P. aeruginosa (15 isolates) and P. fluorescens (four isolates). Susceptibility tests showed that eight (53.3%) isolates of P. aeruginosa were resistant to cefoxitin and two (13.3%) to carbapenems. Our results are similar to these findings. MORTARI et al.9 reported that P. aeruginosa was isolated from 90 clinical samples in a research developed in Southern Brazil. Phenotypic detection showed that 31 strains (34.4%) were probable AmpC producers.

Surveillance of the oral colonization of workers by Pseudomonas spp. is essential in order to minimize the emergence of HAI. It is important to emphasize that asymptomatic carriers act as disseminators. Strategies are indispensable to determine the prevalence of colonization, monitor the circulating profile, and allow therapeutic interventions. Furthermore, they can ensure excellence in the quality of the service and reduce health hazards to employees, patients, and the community.


The authors thank Fabiana C. Pimenta (Centers for Disease Control and Prevention) for the scientific advice, Nádia F. Gonçalves for the technical assistance, and the Fundação de Amparo à Pesquisa do Estado de Goiás (FAPEG) for the financial support.


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Received: October 12, 2014; Accepted: February 16, 2015

Correspondence to: Ana Beatriz Mori Lima, Secretaria de Estado da Saúde, Laboratório de Saúde Pública (LACEN), Alameda do Contorno 3556, Jardim Bela Vista, 74853-120 Goiânia, GO, Brazil. Phone: 556232019629. E-mail:

CONFLICT OF INTEREST The authors declare that there are no conflicts of interest.

Creative Commons License This is an open-access article distributed under the terms of the Creative Commons Attribution License