Increasing Prevalence of Aminoglycoside-Resistant Enterococcus faecalis Isolates Due to the aac(6’)-aph(2”) Gene: A Therapeutic Problem in Kermanshah, Iran (original) (raw)
Related papers
2018
Enterococcus faecium and Enterococcus faecalis are among the predominant species causing hospital-acquired infections, with high mortality and morbidity rates. Enterococci which exhibit high level aminoglycoside (HLAR) and vancomycin resistance (VRE) possess a significant problem in therapeutic treatment. These resistance strains are becoming more widespread in Europe, USA and Asia. Studies have shown that the different distributions of aminoglycoside modifying enzymes (AMEs) among HLAR are based on the geographical regions. In Malaysia, however, data on the prevalence of HLAR and the distribution of AMEs are still limited. Hence, the aims of this study were to determine the antibiotic susceptibility patterns of the clinical isolates E. faecalis and E. faecium and the distribution of HLAR genes among the resistant isolates. Seventy-five clinical enterococci isolates used in this study were originally obtained from a tertiary centre, in the year 2009 and 2010. These isolates were isolated from different sources including pus (50%), blood (32%), urine (11%) and other sources such as CSF and HVS (7%). Reidentification of these isolates was carried out using several methods including sub-culturing on selective medium and Gram staining, followed by confirmatory tests using a commercial biochemical profiling (API20 strep) and 16s rRNA PCR amplification. Antimicrobial susceptibility tests were performed using disc diffusion, E-test and broth microdilution methods. The antibiotics used were aminoglycosides (gentamicin, streptomycin, kanamycin, amikacin, tobramycin) and other antibiotics which are commonly © C O P U P M ii used in the hospital to treat enterococcal infections such as ampicillin, vancomycin, erythromycin, tetracycline, chloramphenicol and linezolid. Detection of HLAR genes was performed on resistance isolates using single PCR amplifications. Out of 25 (33.3%) isolates of E. faecium, 84% and 68% showed high level gentamicin resistance (HLGR) and high level streptomycin resistance (HLSR), respectively. Resistance against erythromycin and tetracycline were 100%, while ampicillin and chloramphenicol showed 84% and 32% resistance rates, respectively. None of the E. faecium isolates showed resistance towards vancomycin and linezolid. On the other hand, all 50 (66.7%) E. faecalis isolates were resistance to all aminoglycosides tested with the following percentages; amikacin (100%), kanamycin (90%), tobramycin (70%), HLGR (36%) and HLSR (46%). These isolates were also resistance to tetracycline (98%), erythromycin (96%), chloramphenicol (46%), ampicillin (24%), linezolid (8%), and vancomycin (4%). Interestingly, the E. faecalis isolates that were resistant to vancomycin were previously reported as susceptible. In this study, E. faecium exhibited higher resistance rates to all antibiotics except vancomycin and linezolid compared to E. faecalis. Additionally, 46% of E. faecalis showed MIC of streptomycin up to 1042 μg/mL while another 36% showed MIC of gentamicin equal to 512 μg/mL. The MIC of aminoglycosides determined in this study showed similar level as observed in other countries, despite the variation of the methods used. The presence of aminoglycoside modifying enzyme (AME) genes [aac(6)-Ie-aph(2)-Ia, aph(2)-Ib, aph(2)-Ic, aph(2)-Id, aph(3)-IIIa] were detected using PCR amplification. The results demonstrated that the HLGR gene, aac(6)-Ie-aph(2)-Ia and the HLSR gene, aph(3)-IIIa were detected in 32% and 40% of E. faecalis and E. faecium resistance isolates, respectively. The spread of these genes were responsible for high level resistance to gentamicin and streptomycin among enterococci isolated in this study. As HLAR genes are highly transferable to not only among the enterococci species but also among various bacterial species, continuous antibiotic surveillance in Malaysian hospitals is warranted in future and preventive measures can be implemented accordingly.
Characterization of High-Level Aminoglycoside-Resistant Enterococci in Kuwait Hospitals
Microbial Drug Resistance, 2004
This study investigated the distribution of genes for aminoglycoside-modifying enzymes (AME) and the genetic relatedness of high-level aminoglycoside-resistant enterococci isolated in Kuwait hospitals. A total of 117 enterococci, consisting of 109 Enterococcus faecalis, seven Enterococcus faecium, and one Enterococcus casseliflavus were studied. The MICs of gentamicin, kanamycin, amikacin, tobramycin, and streptomycin were determined by agar dilution and the genes encoding the AAC(6)-APH(2؆), ANT(4), APH(3), APH (2؆)-Ib, APH (2؆)-Ic, APH (2؆)-Id, and ANT(6) enzymes were amplified by PCR. They were typed by pulsed-field gel electrophoresis (PFGE). Filter mating was used to transfer gentamicin resistance determinants. They were all resistant to kanamycin (MIC Ͼ2000 mg/L). Fifty-five isolates were resistant to gentamicin (MIC Ͼ500 mg/L), 72 were resistant to tobramycin (MIC Ͼ64 mg/L), 115 were resistant to amikacin (MIC Ͼ 64 mg/L), and 97 were resistant to streptomycin (MIC Ͼ 1000 mg/L). The aac(6)-Ie-aph(2؆)-Ia was detected in all isolates with gentamicin MIC Ͼ 500 mg/L and in 15 isolates with gentamicin MIC 256 mg/L. The aph(3)-IIIa gene was detected in 101 isolates, whereas the ant(6)-Ia gene was detected in 85 of the 97 streptomycin-resistant isolates with MIC Ն 1000 mg/L. The aac(6)-Ii gene was detected only in the seven E. faecium isolates. None of them contained ant(4)-Ia, aph(2؆)-Ib, aph(2؆)-Ic and aph(2؆)-Id. PFGE revealed heterogeneous patterns with no dominant clone. The results demonstrated that AME are common in aminoglycoside-resistant enterococci isolated in Kuwait. However, the absence of a dominant clone suggests that they acquired high-level aminoglycoside independently.
Microbial Drug Resistance, 2006
Disks containing 120 g of gentamicin were used to detect high-level gentamicin-resistant phenotype (HLGR) among isolates of Enterococcus faecalis (n ؍ 79) and E. faecium (n ؍ 35). These isolates were collected from three hospitals in Tehran during 2002-2004. The macrobroth dilution assay was then used to determine the minimum inhibitory concentration (MIC) of gentamicin. The susceptibility of isolates against amikacin, netilmicin, tobramycin, and kanamycin were also determined by Kirby-Bauer method. All isolates were subjected to polymerase chain reaction (PCR) assays targeting aminoglycoside modifying enzyme (AMEs) genes including aac(6)-aph(2؆), aph(2؆)-Ib, aph(2؆)-Ic, aph(2؆)-Ia, aph(2؆)-Id, aph(3)-IIIa, and ant(4)-Ia. Fifty-nine isolates (52%) showed HLGR phenotype. All isolates with HLGR phenotype and those showing 64 Ͻ MIC Ͻ 500 g/ml contained aac(6)-aph(2؆). The aph(3)-IIIa was found in 61% of the isolates with HLGR phenotypes and in 65% of isolates with MIC Ͻ 500. Coexistence of aac(6)-aph(2؆) and aph(3)-IIIa gene among HLGR isolates of E. faecalis and E. faecium were 60% and 65%, respectively. The gene aph(2؆)-Ic was amplified in two isolates of E. faecium. The results of PCR for aph(2؆)-Id, ant(4)-Ia and aph(2؆)-Ib genes were negative. The aac(6)-aph(2؆) was the most frequent gene encoding resistance to gentamicin and other aminoglycosides followed by aph(3)-IIIa. Isolates lacking these genes were susceptible to all aminoglyocosides tested in this study.
Iranian journal of microbiology, 2013
High-level gentamicin resistance (HLGR: MIC ≥ 500 µg/ml) in Enterococci is mediated by aminoglycoside modifying enzymes which is mainly encoded by aac(6')-Ie-aph(2″)-Ia gene. The aim of this study was to evaluate the frequency of aac(6')-Ie-aph(2″)-Ia gene in clinical isolates of Enterococcus facium and Enterococcus faecalis collected from hospitals in northwest of Iran. In the present study a total of 111 enterococcus isolates were collected from 4 hospitals during a two year period (July 2009-August 2011). Bacterial identification and species determination were carried out by standard biochemical tests. Antimicrobial susceptibility was evaluated by Kirby Bauer disc diffusion method. MICs were determined by agar dilution method. The frequency of aac(6')-Ie-aph(2″)-Ia gene in the isolates was determined by PCR. The carriage of resistance gene on Tn5281 transposon was identified by long PCR and dot-blot hybridization methods. Antibiotic susceptibility tests revealed that ...
Infection and Drug Resistance, 2019
Background: Enterococcus faecium and Enterococcus faecalis are among the predominant species causing hospital-acquired infections. Currently, enterococcal infections are treated using combination therapy of an aminoglycoside with cell-wall active agents, which led to high level aminoglycoside resistance (HLAR) and vancomycin resistance (VRE) among enterococci. The aim of this study was to determine the prevalence of HLAR and the distribution of the resistance genes among clinical E. faecalis and E. faecium isolates in Malaysia. Materials and methods: Seventy-five enterococci isolates recovered from different clinical sources were re-identified by subculturing on selective medium, Gram staining, biochemical profiling (API 20 Strep), and 16s rRNA sequencing. Antimicrobial susceptibility testing (AST) was performed using Kirby-Bauer disc diffusion, E-test, and broth microdilution methods. PCR amplification was used to detect the presence of aminoglycoside modifying enzyme (AME) genes [aac(6')-Ie-aph(2")-Ia, aph(2")-Ib, aph(2")-Ic, aph(2")-Id, aph (3')-IIIa]. Descriptive data analysis was used to analyze the antibiotic susceptibility profiles and the distribution of HLAR genes. Results: The majority of the isolates recovered from the clinical samples are E. faecalis (66.7%), with the highest recovery from the pus. The prevalence of HLGR (51%) is higher when compared to HLSR (45-49%). Analysis of the resistance genes showed that bifunctional genes aac(6')-Ie-aph(2")-Ia and aph(3')-IIIa contributed to the HLAR E. faecalis and E. faecium. The other AME genes [aph(2")-Ib, aph(2")-Ic, aph(2")-Id] were not detected in this study. Conclusion: This study provides the first prevalence data on HLAR and the distribution of the AME genes among E. faecalis and E. faecium isolates from Malaysia. These highlight the need for continued antibiotic surveillance to minimize its emergence and further dissemination.
The Scientific World Journal, 2014
Enterococci are nosocomial pathogen with multiple-drug resistance by intrinsic and extrinsic mechanisms. Aminoglycosides along with cell wall inhibitors are given clinically for treating enterococcal infections. 178 enterococcal isolates were analyzed in this study.E. faecalisis identified to be the predominantEnterococcusspecies, along withE. faecium,E. avium,E. hirae,E. durans,E. disparandE. gallinarum. High level aminoglycoside resistance (HLAR) by MIC for gentamicin (GM), streptomycin (SM) and both (GM + SM) antibiotics was found to be 42.7%, 29.8%, and 21.9%, respectively. Detection of aminoglycoside modifying enzyme encoding genes (AME) in enterococci was identified by multiplex PCR foraac(6′)-Ie-aph(2′′)-Ia;aph(2′′)-Ib;aph(2′′)-Ic;aph(2′′)-Idandaph(3′)-IIIagenes. 38.2% isolates carriedaac(6′)-Ie-aph(2′′)-Iagene and 40.4% isolates carriedaph(3′)-IIIagene.aph(2′′)-Ib; aph(2′′)-Ic; aph(2′′)-Idwere not detected among our study isolates.aac(6′)-Ie-aph(2′′)-Iaandaph(3′)-IIIagenes w...
Egyptian Journal of Medical Human Genetics, 2019
Background: Enterococci are intrinsically resistant to clinically achievable concentrations of aminoglycosides. However, high-level resistance to aminoglycosides (HLAR) is primarily due to the acquisition of genes encoding aminoglycoside-modifying enzymes (AMEs). Aminoglycosides along with cell wall inhibitors are given clinically for treating enterococcal infections. The current study was conducted to investigate the rate of HLAR and to determine aminoglycoside resistance encoding genes profile in enterococcal isolates from different clinical specimens. Results: From 120 Enterococcus species, 50 (41.7%) enterococcal isolates were proven to have HLAR, 78% (39/50) have high-level gentamicin resistance (HLGR), and 74% (37/50) were high-level streptomycin-resistant (HLSR). HLGR isolates carried aminoglycoside modifying gene aac (6′)-Ie-aph (2′)-Ia in 26/39 (66.7%) of isolates, whereas 32/37 (86.5%) of HLSR carried aph (3′)-IIIa gene and were observed in E. faecalis, E. faecium, E. gallinarum, and E. casseliflavus. The aph (2′)-Ib, aph (2′)-Ic, and aph (2′)-Id that encode HLGR could not be detected. Conclusions: The high detection rate of HLAR among the studied Enterococcus species and the coexistence of HLGR and HLSR strains provide crucial insights to the necessity of routine testing for HLAR in the microbiology lab. The main AME genes among HLGR and HLSR enterococci were aac (6′)-Ie-aph (2″)-Ia and aph (3′)-IIIa, respectively.
Journal of Evolution of Medical and Dental Sciences
BACKGROUND Enterococci are important human pathogens that cause many infections including nosocomial infections. Some important clinical infections caused by Enterococcus species are urinary tract infections, bacterial endocarditis, genital tract infections, surgical wound infections, bacteraemia and meningitis. Around, 80-90% of infections are commonly caused by E. faecalis followed by E. faecium with a contribution of about 10-15% along with emergence of multi-drug resistance (MDR) including to vancomycin. Enterococci have developed both intrinsic and acquired resistance towards many antibiotics including to high level aminoglycosides. This short term project was undertaken to study the prevalence and antibiotic susceptibility (AST) pattern of Enterococcus species isolated from clinical specimen with special reference to high level aminoglycoside resistance (HLAR) in a rural tertiary care hospital. METHODS 100 Enterococci isolated from clinically relevant samples were identified according to standard procedures and AST was carried out according to CLSI guidelines. RESULTS Out of 100 enterococci, 70 E. faecalis, 21 E. faecium and 09 other Enterococcus species were isolated. The results showed that majority of enterococci was isolated from >60 age group (37%), from male patients (59%), from urine samples (59%) and from medicine department (36%). AST showed overall high resistance to Penicillin (98%) Ampicillin (86%), Gentamicin (85%), Ciprofloxacin (60%), Vancomycin (12%) (VRE), high level gentamicin (42%) (HLGR) and high level streptomycin (34%) (HLSR) and 15% isolates showed resistance to HLGR + HLSR. Multi drug resistance was seen in 40 (57.1%) E. faecalis isolates and 11 (52.3%) E. faecium isolates. Minimum resistance was observed with Linezolid (3%). CONCLUSIONS The present study showed high prevalence of antibiotic resistance in Enterococci. Hence, Enterococcus species isolated from samples should be routinely screened for HLAR, MDR and VRE so as to prevent the spread of multi drug resistant Enterococci and for proper selection of antibiotics.
A study of high level aminoglycoside resistant enterococci
African Journal of Microbiology Research, 2016
Enterococci are a common cause of nosocomial infection and prevalence of antibiotic resistance among them is increasing. This study aimed to identify the prevalence of high level aminoglycoside resistant enterococci at Alexandria Main University Hospital. A total of 133 enterococci strains isolated from clinical specimens were all subjected to Bauer Kirby disc diffusion to detect antibiotic susceptibility pattern. High level aminoglycoside resistance (HLAR) and vancomycin resistance were confirmed by minimum inhibitory concentration (MIC). The HLAR enterococci were further identified by API 20 STREP to species level and nitrocefin test was used to detect beta lactamase production. Furthermore, polymerase chain reaction (PCR) for detection of gentamycin resistance was done to all HLGR enterococcal strains and for detection of vancomycin resistance genes. Among the 133 enterococcal isolates, 47 (35.3%) were found to be HLAR (31 Enterococcus faecalis, 13 Enterococcus faecium and 3 Ente...