ABSTRACT
BACKGROUND & OBJECTIVE: Enterococcus Species are the common cause of nosocomial infections, which are highly resistant to different antibiotics. Therefore, determination of their antibiotic susceptibility patterns and simultaneous resistance to antibiotics is important for better treatment strategies. METHODS: 400 clinical Enterococcus isolates were collected from different hospitals in Tehran, Iran. Standard phenotypic-biochemical tests and PCR were used to identify the Enterococcus species. The antimicrobial susceptibility patterns and simultaneous resistance to selected antibiotics were determined by disk diffusion method according to the CLSI guidelines. All data analysis was performed using Python packages Scipy and Stats models. RESULTS: According to the biochemical and PCR analyses, among 400 Enterococcus species, 72% of samples were Enterococcus faecalis, 10.75% Enterococcus faecium, and 17.25% other Enterococcus species. The results determined antimicrobial resistances of these strains against gentamicin, vancomycin, fosfomycin trometamol, teicoplanin, and quinupristin/dalfopristin. Results confirmed a significant correlation between resistance to vancomycin and resistance to teicoplanin. This correlation remains significant when including only E. faecium or E. faecalis species. We also found a negative correlation between resistance to teicoplanin and quinupristin/dalfopristin. Additionally, Quinupristin/dalfopristin was the least effective antibiotic while vancomycin and teicoplanin were the most effective ones. CONCLUSION: Based on the results and association between simultaneous resistance to some antibiotics such as vancomycin and teicoplanin, in the case of antibiotic resistance, the choice of a second antibiotic can be very important which can lead to good or bad effects.
ABSTRACT
Enterococcus faecalis is one of the most important causative agents of nosocomial infections. Control and prevention of these infections require appropriate epidemiological knowledge. This study investigated the correlation between molecular characteristics and drug resistance of E. faecalis isolates from local hospitals. A total of 125 isolates of Enterococcus faecalis from two hospitals in Tehran were identified by using culture and biochemical method. An antibiotic resistance assay was carried out by a disk diffusion method according to the Clinical and Laboratory Standards Institute guidelines. The genetic diversity of the strains was determined using a repetitive sequence-based polymerase chain reaction (REP-PCR) method. All isolates were typed by REP-PCR, and different PCR amplification products (from 9 to 17 amplified DNA fragments) were detected by gel electrophoresis. There were eight different PCR patterns (A-H), and a significant correlation was detected between the resistance to antibiotics and the obtained PCR patterns. The most relevant cases (28%) belonged to the fourth group (D). All group D isolates were resistant to tetracycline and quinupristin/dalfopristin. A high resistance to certain common antibiotics and clonal propagation were detected among isolates from patients in different wards of the hospitals. This study was the first to investigate E. faecalis isolates from Iranian patients and to describe patterns that showed correlation between infection prevalence and genetic origin/similarity of the isolates.
Subject(s)
Cross Infection/microbiology , Drug Resistance, Microbial , Enterococcus faecalis/isolation & purification , Gram-Positive Bacterial Infections/microbiology , Bacterial Typing Techniques , Cross Infection/drug therapy , Cross Infection/epidemiology , Cross-Sectional Studies , DNA, Bacterial/genetics , Disk Diffusion Antimicrobial Tests , Drug Resistance, Multiple, Bacterial , Enterococcus faecalis/drug effects , Enterococcus faecalis/genetics , Genetic Variation , Genotype , Gram-Positive Bacterial Infections/drug therapy , Gram-Positive Bacterial Infections/epidemiology , Hospitals, Urban , Humans , Iran/epidemiology , PrevalenceABSTRACT
Early detection of antibiotic-resistant enterococci is an important part of patient treatment. Therefore, the aim of the present study was to evaluate the resistance patterns and simultaneously identify and characterise the resistance genes in Enterococcus spp. using a triplex polymerase chain reaction (PCR) method. In all, 150 consecutive Enterococcus spp were collected from several hospitals in Tehran (Iran) from January to December 2015. The Enterococcus species were identified by standard phenotypic/biochemical tests and PCR. The antimicrobial resistance patterns were determined using a disk diffusion method. The triplex PCR method was designed to identify gentamicin and other aminoglycoside resistance genes. Among the 150 Enterococcus specimens, 87 cases (58%) were Enterococcus faecalis, and 63 cases (42%) were Enterococcus faecium. The highest frequency of resistance was observed for tetracycline while the lowest was found for vancomycin. Among the identified samples, 56.9% contained the aac(6')-Ie-aph(2'')-Ia gene, 22.2% contained the aph(3')-IIIa gene, and 38.8% contained the ant(4')-?a gene. Eight percent of the isolates contained the three aminoglycoside resistance genes. Data analysis showed that there was a significant correlation between the phenotypic gentamicin resistance and the presence of the aminoglycoside resistance genes (18.9%, p <0.05), while the correlation between the phenotypic streptomycin resistance and the corresponding genes was not significant (2.8%, p ≥0.5). Nearly half of the identified Enterococcus strains had increased aminoglycoside resistance. The direct correlation between resistance genes, such as the aminoglycoside resistance factor, and phenotypic resistance was not significant (p > 0.05).
