Growing Resistance to Vancomycin among Methicillin Resistant Staphylococcus Aureus Isolates from Different Clinical Samples (original) (raw)
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https://www.ijrrjournal.com/IJRR\_Vol.5\_Issue.9\_Sep2018/Abstract\_IJRR0020.html, 2018
Introduction: Resistance to methicillin and other β-lactamase resistant penicillins was first observed in Staphylococcus aureus soon after methicillin was introduced into clinical use in Britain in 1961. Methicillin resistant S. aureus (MRSA) is responsible for around 30% or more of all S. aureus infections. MRSA is a multidrug resistant organism that threatens the continued effectiveness of antibiotics worldwide and causes a threat in hospitals and long-term care settings. Vancomycin has been the treatment of choice for serious infections caused by MRSA. But there has been uncertainty regarding the method for detection of minimum inhibitory concentration of vancomycin, clinical relevance of reduced vancomycin susceptibility in S. aureus & increasing concern regarding the efficacy of vancomycin for treatment of MRSA infections. Materials and Methods: A study was planned to determine the prevalence of methicillin resistance in clinical isolates of S. aureus isolated from samples of patients attending OPDs & IPDs of Career Institute of Medical Sciences, Lucknow. Antimicrobial susceptibility testing was performed by Kirby Bauer disc diffusion method. The isolates were tested for methicillin resistance by using cefoxitin disc (30µg) by disc diffusion method. The results were interpreted according to CLSI criteria. Vancomycin MICs were compared by two methods viz. E TEST & VITEK 2. Results: A total of 163 isolates were studied and 66(40.4%) were found to be methicillin resistant. MRSA isolates showed greater resistance to multiple drugs as compared to methicillin sensitive S. aureus (MSSA) isolates. 48.48%, 86.36%, and 42.42% of MRSA were resistant to chloramphenicol, cotrimoxazole & doxycycline as compared to 4.12%, 15.46% & 12.37% of MSSA respectively. On determination of MICs for vancomycin for the MRSA isolates, all were identified as VSSA by E Test & Vitek 2 methods but the MIC values were variable on testing with both methods. Out of 66 isolates, 51 isolates had MIC=1.5µg/mL & 15 isolates had MIC = 2 µg/mL by E Test method. When these isolates were tested with Vitek 2, only 20 had MIC=1.5µg/mL while 46 had MIC=2µg/mL. Conclusion: An ever rising isolation of MRSA from various infections was observed. These isolates were also associated with high level of co-resistance to other group of antibiotics. There is a need to study the epidemiology of such infections. Robust antimicrobial stewardship and strengthened infection control measures are required to prevent spread and reduce emergence of resistance.
Journal of Evolution of Medical and Dental Sciences, 2017
BACKGROUND Staphylococcus aureus is notorious for its ability to become resistant to antibiotics. MRSA emerged as nosocomial pathogen in the early 1960s. Methicillin Resistant Staphylococcus aureus (MRSA) are implicated in serious infections and nosocomial infection outbreaks. These strains show resistance to a wide range of antibiotics, thus limiting the treating options to very few agent s such as vancomycin and teicoplanin. Vancomycin has been regarded as the first-line drug for treatment of MRSA. At the same time, there has been an increase in the use of this antibiotic for other infections as well. This has further lead to an increase in the number of both Vancomycin Intermediate Staphylococcus aureus (VISA) and Vancomycin Resistant Staphylococcus aureus (VRSA). Aims-To determine the presence of MRSA and VRSA among staphylococcal isolates in Eastern Bihar. MATERIALS AND METHODS A total of 10806 samples from patients attending inpatient and outpatient departments from January 2011 to April 2013 were included in the study. Samples were processed as per standard protocol and antibiotic susceptibility testing was done by modified Kirby-Bauer method. Isolates were tested by disc diffusion using oxacillin disc 1 µg, cefoxitin disc 30 µg and by agar dilution for MRSA. VRSA isolates were tested using 30 µg vancomycin disc. MIC of vancomycin to Staphylococcus aureus was determined by agar dilution method. RESULTS Out of a total of 633 Staphylococcus aureus isolates, 22.4% were found to be methicillin resistant, 9.95% were VISA and 3.79% were VRSA. Results of oxacillin agar dilution method were in concordance with the cefoxitin disc diffusion method in detecting MRSA strains. All VISA strains were sensitive to linezolid and all VRSA were sensitive to imipenem. 88.7% and 87.3% of all MRSA isolates were sensitive to imipenem and linezolid respectively. CONCLUSION The present shows that antibiotic resistance is steadily on the rise. It is also quite clear that MRSA is acquiring resistance to drugs like rifampicin, teicoplanin, amikacin, netilmicin and imipenem which were at one time used as an alternative to vancomycin. It is therefore imperative for the medical community to work together to fight against this man-made phenomenon called antibiotic resistance.
Journal of Basic Research in Medical Sciences, 2016
Introduction: In this study, using the phenotypic and genotypic methods, oxacillin susceptibility in Staphylococcus aureus (S. aureus) strains isolated from patients at two government hospitals in Ilam, Iran was tested. Materials and methods: Out of 200 S. aureus isolates from different human clinical specimens consisting of blood (31%), wound (20%), urine (21%), catheters (7%), sputum (12%), others (9%) were collected. The methicillin resistant S. aureus isolates were investigated using disk diffusion methods and oxacillin (1μg) and cefoxitin (30μg), on Mueller-Hinton agar were used, and MecA and vanA genes were detected by PCR. In addition, the isolates were tested for their antibiogram profiles. Results: Among 200 S. aureus strains included in this study, 35.96% were MRSA. The percentage of resistance by disk diffusion method was as below: penicillin 85.96%, vancomycin 0%, ampicillin 87.71%, gentamicin 48.25% erythromycin 54.25%, clindamycin 32.45%, amikacin 21.05%, ciprofloxacin 42.10%, tetracycline 51.75% and co-trimoxazole 42.10%. Phenotyping method by disk diffusion method using oxacillin and cefoxitin for detecting of MRSA showed sensitivity and specificity of about 33.33% and 35.96%, respectively. Presence of MecA and vanA genes in MRSA isolates by PCR were 35.96% and 0%, respectively. The oxacillin and cefoxitin disk diffusion methods showed 92.68% and 100% sensitivity, respectively, and 98.8% specificity. Conclusion: Our finding showed that, the cefoxitin disk diffusion method is better in compared to the oxacillin disk diffusion similar to results from detecting of MecA gene in PCR as a golden test.
Background Staphylococci are Gram-positive cocci arranged in clusters. They are colonized in humans and animals. Also, Staphylococcus aureus (S. aureus) is frequently associated with various superficial to deep-seated infections in humans. Due to the potential for easy transmission, Staphylococci are associated with both hospital-acquired and community-associated infections. Strains of S. aureus resistant to methicillin (MRSA) pose treatment challenges. In such cases, vancomycin is the treatment of choice. Due to the indiscriminate use of vancomycin, recently, we are seeing the emergence of vancomycin-intermediate sensitive S. aureus (VISA) and vancomycinresistant S. aureus (VRSA). The present study aims to evaluate the minimum inhibitory concentrations (MICs) of vancomycin and daptomycin among MRSA strains isolated from human clinical specimens Methods The study included 115 MRSA isolates collected over 26 months from July 2010 to September 2012. The strains were isolated from pus, urine, wound swabs, catheters, blood, and sputum. The bacteria were acquired from different inpatient and outpatient departments of Prathima Institute of Medical Sciences, Karimnagar, Telangana, India. Kirby-Bauer disk diffusion method using cefoxitin was used to confirm the MRSA isolates. The agar dilution and the Epsilometer method (E-test) were used to test the MICs of MRSA isolates against vancomycin and daptomycin, respectively, by the standard procedures recommended by the clinical laboratory standards institute (CLSI). Results Of the 115 S. aureus isolates, seven (6.08%) strains were resistant to vancomycin (VRSA) and 53 (46.08%) were found to be VISA using the new CLSI breakpoints. The MIC of the daptomycin was found to be ≤1 µg/ml for all the MRSA isolates. Conclusion The study results depicted an increasing trend in the vancomycin MICs among the MRSA isolates. Several tested strains show MICs in the intermediate sensitive range (VISA). The 1 2 3
Scholars Journal of Applied Medical Sciences, 2016
Staphylococcus aureus is one of the important causes of community acquired and hospital acquired infections worldwide. Methicillin resistant Staphylococcus aureus is one of the major antibiotic resistant organisms. The present study was undertaken to determine the antibiotic sensitivity of Staphylococcus aureus isolates from various clinical samples and to evaluate the possible presence of MRSA, VISA (vancomycin intermediate Staphylococcus aureus) and VRSA (vancomycin resistant Staphylococcus aureus). A total of 120 isolates of S. aureus which were isolated from various clinical samples were tested for methicillin resistance using the oxacillin disc diffusion test (1µg) and cefoxitin disc diffusion test (30µg). All isolates were subjected to minimum inhibitory concentration (MIC) testing with agar dilution method according to the CLSI (Clinical Laboratory Standards Institutes) guidelines. Disc diffusion method was also used to determine the susceptibility of strains to common antibiotics. 64(53.3%) isolates were found to be MRSA by the cefoxitin disc diffusion method and 63(52.5%) isolates were found to be MRSA by oxacillin disc diffusion method. No VISA&VRSA isolates were detected by using the MIC agar dilution method. MRSA isolates were also highly resistant to other antibiotics that were tested.
https://www.ijhsr.org/IJHSR\_Vol.7\_Issue.1\_Jan2017/IJHSR\_Abstract.010.html, 2017
Background: Staphylococcus aureus is one of the most common causes of nosocomial infections. Vancomycin is the drug of choice to treat infections caused by MRSA. Objectives: The study determines Vancomycin MIC of MRSA strains by both agar dilution and Vitek methods. Presence of VAN a gene was also determined. Materials and Methods: Study was conducted from April 2015-March 2016.A total 70 Staphylococcus aureus strains were included. Methicillin resistance was determined by using Cefoxitin disc (30ug) as per CLSI guidelines. Vancomycin resistance was detected by both agar dilution and Vitek methods. PCR was done to determine presence of VAN A gene among VISA strains. Results: Among 70 S.aureus strains, 40 (57%) strains were methicillin resistant. Maximum MRSA strains (55%) were isolated from pus samples. 6 VISA (Vancomycin intermediate S. aureus strains) strains were detected by agar dilution method. Vitek was able to detect 3 VISA strains. All VISA strains were sensitive to Rifampicin and Linezolid by disc diffusion method. All VISA strains were negative for VAN A gene by PCR. Conclusion: Disc diffusion method misclassifies vancomycin intermediate isolates as fully susceptible strains. Clinical laboratories must perform MIC method to correctly identify VISA strains and avoid treatment failure.
Der Pharmacia Lettre, 2013
Methicillin-resistant Staphylococcus aureus (MRSA) causing nosocomial infection posed a serious therapeutic challenge. We report the prevalence, antibiotic susceptibility pattern and MIC value of vancomycin of MRSA isolates from Doon valley hospitals, Uttarakhand. Clinical specimens were collected from different hospitals were subjected to MRSA screening using conventional microbiological methods. Subsequently the antibiotic sensitivity test was performed for the confirmed MRSA isolates and interpreted as per standard guidelines. The isolates were then checked for minimum inhibitory concentration (MIC) of vancomycin through broth macrodilution method. All MRSA strains were found to be multi-drug resistant including six isolates (15.7%) which showed resistance against vancomycin (VRSA) apart from resistant to other antibiotics. MIC detection of vancomycin further revealed six strains (15.8%) showed a high level of resistance (>32 µg /ml). Regular surveillance of hospital acquired infection excessive use of antimicrobial agents and monitoring of antibiotic susceptibility pattern is required to reduce the prevalence of MRSA.
Journal of Pure and Applied Microbiology, 2019
Staphylococcus aureus (S.aureus) and coagulase negative Staphylococci (CONS) are the commonest pathogens that lead to severe bacterial infections. It is a bacterium with consistent resistance development against commonly used antibiotics, with emergence of Methicillin resistant staphylococcus aureus (MRSA) causing several infections in patients following hospitalization. Glycopeptides like vancomycin is used as primary drug for treating infectious diseases caused by MRSA. Due to indiscriminate use of vancomycin to treat MRSA, several strains with variable susceptibility to the same have emerged. Evaluation of Vancomycin Minimum Inhibitory Concentration (MIC) in the MRSA isolates obtained from clinical samples received in the diagnostic microbiology laboratory. About 120 Staphylococci obtained from different clinical samples in the diagnostic Microbiology laboratory, at tertiary health care center, South India, were included in the study. The isolates were identified and susceptibility to the relevant antibiotics was done by Vitek 2 an automated system. Vancomycin MIC was detected by Vitek 2 and E-test strip technique. Out of 120 Staphylococcal strains, 79(65.8%) S. aureus and 41(34.1%) CONS were isolated. Methicillin resistance was observed in 38 (48.1%) strains of S. aureus. Almost all 38 MRSA isolates were vancomycin sensitive with MIC range of 0.5-2µg/ml. Maximum isolates had MIC of 1 µg/ml i.e. 65.78% and 71% by E-Test and Vitek 2 respectively. The reported increased MIC of Vancomycin, though within the susceptible range, might experience poor clinical outcomes. Emergence and spread of resistance to glycopeptides like vancomycin needs to be kept in check by rapidly detecting the strains for resistance and strictly obeying the infection control practices.
Journal of the Medical Association of Thailand = Chotmaihet thangphaet, 2014
Staphylococcus aureus is a species of bacteria that causes a number of diseases and more than 60% of it is presently resistant to methicillin. Vancomycin is the drug of choice for the eradication of methicillin-resistant S. aureus (MRSA). This study aimed to investigate the susceptibility of heterogeneous vancomycin intermediate S. aureus (hVISA) and vancomycin intermediate S. aureus (VISA) to vancomycin by standard disk diffusion, microbroth dilution, a one-point population assay, and a population analysis profile. Sixty-eight MRSA isolates from patients admitted to Sanprasitthiprasong Hospital between November 2010 and November 2011 were tested. Standard disk diffusion showed that all the MRSA isolates were susceptible to vancomycin. Vancomycin MICs for all isolates were 1-2 microg/mL. Only two MRSA isolates (2.9%) were able to grow on brain heart infusion agar supplemented with vancomycin 4 microg/mL and were confirmed by a population analysis as hVISA. This study showed the effe...
2018
DOI: 10.21276/sjpm.2018.3.10.16 Abstract: Staphylococcus aureus is one of the most common causes of Blood Stream infections (BSI), skin and wound infections, osteomyelitis, endocarditis, and nosocomial infections, especially pneumonia, surgical site infections (SSI), and continue to be a major cause of community-acquired infections. Methicillin Resistant Staphylococcus aureus (MRSA) is an important cause of community and hospital acquired infections. MRSA are mainly nosocomial and are increasingly reported from many countries worldwide. The purpose of present study was to determine the sensitivity of S. aureus isolated from infected patients to methicillin and to evaluate the possible presence of VRSA in our tertiary care hospital. Staphylococci were isolated and identified by standard microbiological procedures. Methicillin resistance was detected by using cefoxitin (30 μgm) by disc diffusion method. MRSA strains detected were then subjected to vancomycin agar screen test and E tes...