Enterococcus ssp. de origem clínica e ambiental: perfil de sensibilidade aos antimicrobianos, fatores de virulência e caracterização molecular

Abstract

Enterococci are found in the intestinal microbiota of humans and other animals, in soil, water, plants, vegetables and food. However, in recent decades these microorganisms have been highlighted as agents of nosocomial infections due to their intrinsic and acquired resistance to various antimicrobials. Inadequate use of antimicrobials in agriculture contributes to the emergence of multiresistant isolates in the environment that can be transmitted to humans. The aim of the present study was to investigate the presence of enterococci species in different nonclinical samples (food, animals, water and sewage) and to characterize them for antimicrobial susceptibility profile and virulence factors. It was also investigated whether isolates of penicillin-resistant /ampicillin-sensitive Enterococcus faecalis (PRASEF), which were previously obtained from humans, are widespread in the environment and whether they would be genetically similar. Samples from a variety of nonclinical sources (food, water, animal feces, sewage) were grown for enterococcal isolation. Isolates were phenotypically identified in species and subjected to antimicrobial susceptibility testing (broth dilution and disc diffusion) according to the CLSI (Clinical and Laboratory Standards Institute). Research was made into the production of gelatinase and hemolysins. Isolates of the E. faecalis species were further compared genetically by the PFGE technique (pulsed field electrophoresis) with clinical isolates previously obtained from patients of the UFTM clinic hospital. The aac(6’)-Ie/aph(2”)- Ia gene that confers high-level resistance to gentamicin (HLRG) was detected by PCR. The most prevalent species in non-clinical samples of plant origin were E. casseliflavus (28.6%) and E. faecalis (19.0%), but among those of animal origin were E. faecalis (26.2%) and E. faecium (23.8%). It was observed high prevalence of resistance to erythromycin, tetracycline, ciprofloxacin and norfloxacin. Among the non-clinical isolates of E. faecalis, 3 (2.9%) were PRASEF; all of them were recovered from the hospital sewage and presented HLGR. The prevalence of non-clinical (50.5%) and clinical (55.8%) gelatinase-producing E. faecalis was similar, but hemolysin production was higher among non-clinical (63.5%). than among those of clinical origin (2.8%). E. faecalis submitted to PFGE (n = 31) were classified into 19 pulsotypes (A-S). The tested PRASEF isolates obtained from sewage (n = 3) and from patients (n = 4) were classified in the same pulsotype. One PRASEF isolate recovered from the hospital sewage was submitted to MLST (multilocus sequencing typing) and was encompassed into the CC9 (clonal complex), which is common among in isolates from hospitals. Despite the diversity of species of the genus Enterococcus, the most prevalent species in clinical samples, E. faecalis and E. faecium, were also the predominant species in non-clinical samples. Many E. faecalis isolates of nonclinical origin showed resistance to different antimicrobials; however, isolates presenting the unusual phenotype of penicillin resistance appear to be restricted to the hospital environment. The results of the present study highlight the need for treatment of hospital sewage in order to prevent multidrug resistant microorganisms of hospital origin from spreading to the environment.