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
 · 
84 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: High-level gentamicin resistance (HLGR) in enterococci eliminates the synergistic bactericidal effect of combined exposure to cell wall-active agent and gentamicin. In such instance, controlling the spread of these organisms becomes of paramount importance. With the recent emergence of HLGR enterococci, 147 enterococcal urinary tract infection isolates from 7 medical care units in Tehran during 1 year (2005-2006) were collected. Speciation was based on using conventional biochemical tests and confirmed by polymerase chain reaction technique. Antimicrobial susceptibility tests were assayed for 10 antibiotics with the disk diffusion method. Enterococcus faecalis (70%) and Enterococcus faecium (30%) were the most important species. The results obtained from polymerase chain reaction showed a high rate of agreement with phenotypic assays for both species. High-level gentamicin resistance phenotype was detected in 61.5% of E. faecalis and 79% of E. faecium strains. Susceptibility to different antimicrobial agents between 2 species was different. All HLGR isolates contained the aac(6′)-Ie-aph(2″)-Ia gene. The high prevalence of HLGR enterococcal strains shown by the present study revealed the emergence of effective antibiotic therapy for enterococcal infections that should be based on accurate antimicrobial susceptibility tests and species identification.
    Infectious Disease in Clinical Practice 12/2007; 16(1):41-45.
  • 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.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Enterococci are pathogens that can cause nosocomial infections and acquire resistance properties via several molecular mechanisms. The aac (6')Ie-aph(2″)Ia gene plays a significant role in the emergence of high-level gentamicin-resistant (HLGR) strains. The screening of resistant strains and the provision of appropriate antibiotic therapy can decide the outcome of serious nosocomial infections. In the present study, 142 enterococci were isolated from patients, and the species were identified using standard methods. An antimicrobial susceptibility test was performed using the disc diffusion method, and the minimum inhibition concentration (MIC) of gentamicin was determined according to the broth micro-dilution method. Additionally, PCR was utilized to detect the aac(6')Ie-aph(2″)Ia gene, the presence of which was confirmed by digestion with Sca1 and sequencing. Of the 142 isolates, 62 (43.7%) were found to exhibit the HLGR phenotype. All except one of the HLGR isolates contained the aac(6')Ie-aph(2″)Ia gene. The prevalence of resistance to other antibiotics and multi-drug resistance (MDR) was higher among the HLGR isolates compared to the non-HLGR isolates. Our results indicate that high prevalence rates of MDR and HLGR enterococci are an important problem associated with medical treatment. Furthermore, the presence of the aac(6')Ie-aph(2″)Ia gene was shown to correspond to the presence of the HLGR phenotype among enterococci.
    Journal of infection and public health. 06/2013; 6(3):202-8.