Article

Phenotypic characteristics and population genetics of Enterococcus faecalis cultured from patients in Tehran during 2000-2001.

Department of Microbiology, Alzahra University, Vanak, Tehran, Iran.
Canadian Journal of Microbiology (Impact Factor: 1.2). 11/2003; 49(10):645-9. DOI: 10.1139/w03-082
Source: PubMed

ABSTRACT Conventional bacteriology techniques were used to identify enterococci isolates cultured from patients at different hospitals in Tehran during 2000-2001. The identification was confirmed using species-specific PCR targeting the D-alanyl-D-alanine ligase gene. A total of 59 isolates of Enterococcus faecalis were identified. The rates of resistance to different antibiotics were in the following order: penicillin 84%, ciprofloxacin 42%, high-level gentamicin 30%, nitrofurantoin 14%, imipenem 4%, and chloramphenicol 2%. Resistance to ampicillin was found to be rare among the Iranian isolates of E. faecalis. Multi-locus enzyme electrophoresis was then used to analyze the strains. Forty-five electrophoretic types were obtained when 10 enzyme loci were screened. Although the collection of bacterial isolates was limited in time and location, considerable heterogeneity was found. Analysis of strains for linkage disequilibrium demonstrated that the studied population is not clonal, since the index of association was not significantly different from zero (Ia = 0.0296). Enterococcus faecalis isolates recovered from patients in Tehran were genetically diverse and seemed to possess a high potential for genetic recombinations, though none were resistant to vancomycin.

0 Bookmarks
 · 
71 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Vancomycin (glycopeptide)-resistant enterococci (VRE or GRE) can cause serious problems for hospitalized patients due to the limited options for treatment of VRE infections. As infection with VRE increases in hospitals, further knowledge about vancomycin resistant genes is needed. Isolates of Enterococcus spp. were collected from hospitalized patients in Tehran (Iran) during 2006. Detailed molecular analysis was performed for vancomycin resistance genotype and vanHAX using conventional PCR and PCR- RFLP (restriction fragment length polymorphism), respectively. out of 830 enterococci spp., 48 VRE isolates (5.8 percent) were obtained. All of VRE isolates carried vanA gene. DdeI digestion of vanHAX element showed the presence of point mutation at 8234 position. This study indicates that vanA is a predominant genotype in Iranian isolates. In addition, PCR-RFLP analysis revealed the presence of two types of vanHAX element in vanA harboring transposons.
    Iranian biomedical journal 11/2008; 12(4):223-8.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Background: Enterococci faecalis are predominating species of Enterococci causing nosocomial infections. Acquisition of resistance to antibacterial agents, and ability to transfer the re- sistant genes made them clinically important. This study was performed to determine the frequency of isolation of different species of Enterococci, and the antibacterial resistance pattern of the isolated species. Methods: Enterococcal species were isolated from clinical samples. In vitro susceptibility of the isolates to 10 antibacterial agents was tested by standard methods and β-lactamase produc- tion was detected using starch-iodide method. Results: 100 Enterococci were isolated from 585 different clinical samples. 73% of the isolates were E. faecalis, 13% E. faecium and 14% which were not identified as either one, were regarded as other enterococcal species. Highest rate of resistance (98% or more) was found for oxacillin and penicil- lin while vancomycin and chloramphenicol were among the most active agents. Resistance to antibacterial agents was more common for E. faecium and β-lactamase production was found in 81% of the isolates. Conclusion: E. faecalis was the dominant species, with the higher rate of β-lactamase production. E. faecium was more resistant to antibacterial agents as compared to other isolates. 80% of the isolates had multiple drug resistance phenotypes (MDR). Low−level resistance to vancomycin (intermediate reaction in disk diffusion method, minimum inhibitory con- centrations range ≥4−16 µg/ml) and presence of MDR isolates is very important and should be considered as an danger alarm for serious enterococcal infections. Iran J Med Sci 2005; 30(2): 68-72.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Infections with high levels of gentamicin-resistant (HLGR) isolates of Enterococcus faecalis are common in Tehran hospitals. Genes encoding such resistance are transmissible by conjugation at high frequency. The purpose of this study was to determine the existence of Tn5281 and its flanking aminoglycoside modifying enzyme gene aac(6')-aph(2") among 102 HLGR isolates of E. faecalis cultured from patients at three hospitals in Tehran, Iran. These isolates were detected by disks containing 120 microg of gentamicin and made 65% of all E. faecalis during the study period. DNA was extracted from HLGR isolates and subjected to PCR assays targeting aac(6')-aph(2") and conjugative transposon Tn5281. The amplified aac(6')-aph(2") gene was labeled with digoxigenin and probed with Tn5281 amplicons in dot blot hybridization assays. The aac(6')-aph(2") gene was detected in 91%-92% (n = 93) of the HLGR isolates. All isolates containing aac(6')-aph(2") were positive in long-PCR targeting Tn5281 and the probe hybridized with Tn5281 amplicons. The number of HLGR isolates of E. faecalis has increased considerably in Tehran hospitals. Tn5281 is the main cause of transmission of aac(6')-aph(2") to different isolates of E. faecalis in the hospitals studied.
    Canadian Journal of Microbiology 10/2008; 54(10):887-90. · 1.20 Impact Factor