RESUMEN
OBJECTIVES: Enterococci have gained attention during the past decade as important nosocomial pathogens. Their increasing prevalence has been paralleled by the occurrence of multidrug-resistant and high-level aminoglycoside-resistant strains. This study isolated Enterococcus spp. from hospital samples and determined their antibiotic resistance profile, focusing on aminoglycosides, and associated resistance mechanisms. METHODS: A total of 195 enterococci from hospital samples in Tehran were studied. Isolates were identified by biochemical reactions. Antimicrobial resistance was determined by disk diffusion. The vancomycin MIC for vancomycin-resistant isolates was determined by agar dilution. Detection of aminoglycoside resistance genes and intI1 and intI2 gene was performed by PCR. RESULTS: The majority of isolates were Enterococcus faecalis (65.1%), followed by Enterococcus faecium (31.8%), Enterococcus gallinarum (2.6%) and Enterococcus solitarius (0.5%). According to antibiogram results, 42.1% of isolates were high-level gentamicin-resistant (HLGR) and 40.5% were high-level streptomycin-resistant (HLSR). There was a high prevalence of aac(6')-Ie-aph(2")-Ia (96.3%) among HLGR isolates. ant(6)-Ia and aadA were identified in 93.7% and 64.6% of HLSR isolates, respectively. aph(2'')-Ic was detected in 7 isolates (3.6%) and aph(2'')-Ib in only 4 isolates (2.1%); no isolates harboured aph(2'')-Id, intI1 or intI2. CONCLUSION: Multidrug resistance was higher among HLGR and HLSR isolates compared with non-HLGR and non-HLSR isolates, which may result in limited treatment options. More than 50% of isolates were susceptible to aminoglycosides, thus correct identification in clinical laboratories and administration of these antibiotics can result in decreased used of antibiotics such as vancomycin and linezolid and help to reduce the emergence of resistance to these drugs.
Asunto(s)
Aminoglicósidos/farmacología , Proteínas Bacterianas/genética , Farmacorresistencia Bacteriana Múltiple , Enterococcus/clasificación , Infecciones Urinarias/microbiología , Pruebas Antimicrobianas de Difusión por Disco , Enterococcus/efectos de los fármacos , Enterococcus/aislamiento & purificación , Gentamicinas/farmacología , Humanos , Irán/epidemiología , Filogenia , Prevalencia , Estreptomicina/farmacología , Infecciones Urinarias/tratamiento farmacológico , Resistencia a la VancomicinaRESUMEN
BACKGROUND: Vancomycin-resistant enterococci pose an emerging health risk. The limitation in therapeutic options has resulted in the development of new drugs such as quinupristin/ dalfopristin and linezolid. AIM, SETTING AND DESIGN: This study investigated the species prevalence and antibacterial resistance among enterococci isolated in selected Tehran hospitals. MATERIALS AND METHODS: Between March 2006 and August 2007, 200 enterococcal isolates from urine, blood, stool and wound were recovered in 2 teaching hospitals of Tehran province. Susceptibility of all isolates was tested against vancomycin, teicoplanin and linezolid antibiotics by disk diffusion and agar dilution method. RESULTS AND CONCLUSION: Seventeen (8.5%), 6 (3%) and 4 (2%) of the isolates were resistant to vancomycin, teicoplanin and linezolid, respectively. Within the vancomycin-resistant isolates, 6 (35.2%), 4 (25%) and 1 (5.88%) showed vanA, vanB and vanC genotype patterns, respectively. Four (23.5%) of VRE isolates were resistant to linezolid with minimum inhibitory concentrations between 16 and 32 microg/mL. Two linezolid vancomycin resistant enterococci were E. faecium.