Prevalence and in vitro susceptibility pattern of MRSA,VRSA, VISA isolates from various clinical samples in tertiary care hospital

Background: Staphylococcus is notorious for its ability to become resistant to antibiotics. MRSA emerged as nosocomial pathogen in the early 1960. Methicillin Resistant Staphylococcus aureus are implicated in serious infections and nosocomial infection outbreaks, thus limiting the treating options to very few agents such as vancomycin and teicoplanin. Vancomycin has been regarded as the first line drug for the treatment for MRSA but its irrational use lead to emergence of vancomycin resistance. The Aim was to determine the prevalence and resistance of MRSA ,VRSA,VISA isolates from various clinical samples in a tertiary care hospital.Material & Methods:This present prospective study was done in the Microbiology department of Government Medical College. The study was conducted for a period of one and half year i.e from January 2019 to June 2020. All the samples (pus, urine, blood, body fluids, sputum etc) were processed as per standard protocols.Results:Out of 26,471 samples, 6578(24.85%) were found to be culture positive. 1583 isolates were identified as Staphylococcus aureus. Among them 1278(80.7%) were MRSA, 21(1.3%) were VISA and 8(0.5%) were VRSA. Maximum number of MRSA isolates were obtained from orthopaedics ward (22.7%) and Intensive Care Unit and most of them were isolated from pus(45%) followed by blood (19.09%)samples. Among them highest resistance were observed against azithromycin (85.6%), followed by ciprofloxacin (63.5%) and least resistance to rifampicin and doxycycline. Majority of the VISA and VRSA strains were isolated from ICU followed by orthopaedics, surgery. Most of them were isolated from pus followed by blood and urine specimen and most were found to be multidrug resistant while they retained their sensitivity to Linezolid and Teicoplanin.Conclusions:As there is high prevalence of MRSA isolates so the treatment options are limited to vancomycin. Overuse of vancomycin can lead to emergence of VRSA strains. So the need for rational use in the infection-control practices to prevent transmission of MRSA as well as VISA strains. Strict implementation of hand hygiene, decolonization of MRSA carriers,and education of healthcare team will be quite helpful.

Application of pulsed field gel electrophoresis for molecular characterization of vancomycin resistant Staphylococcus aureus isolates from hospitals

Aim: The present study was conducted to characterize VRSA isolates on the basis of pulsed field gel electrophoresis (PFGE) and the presence of spa gene, recovered from different Doon Valley Hospitals.Methodology: Six VRSA isolates were analyzed using PFGE and spa typing. spa gene coded Protein A was used as a genetic marker for the characterization of Staphylococcus aureus isolates. Dendrogram were constructed on the basis of unweighted pair group method with arithmetic means (UPGMA method) for clusters analyses.Results: Dendrogram finally showed two major banding patterns at about 85% similarity designated as PFGE type A and PFGE type B exhibiting differences of 4-6 bands. The length of spa gene varied from 1200 to 1500 bp, showing variation in length. The most prevalent length was 1200bp.

Methicillin- and vancomycin-resistant Staphylococcus aureus in health care workers and medical devices / Staphylococcus aureus resistentes a meticilina (MRSA) e vancomicina (VRSA) em profissionais da saúde e artigos médicos

ABSTRACT Introduction: Cross-contamination by Staphylococcus aureus among patients, professionals and medical supplies in health facilities is a constant concern, leading many researchers to study the prevalence of this pathogen in asymptomatic carriers. Objective: We investigated the colonization and the antimicrobial susceptibility profile of Staphylococcus spp. on surfaces of medical articles and in professionals from two basic health units in the city of Rio de Janeiro. Materials and methods: Seventy-nine samples resulted in 49 isolates which underwent phenotypic and molecular characterization by polymerase chain reaction (PCR) of coa, mecA and femA genes. Results: According to the phenotypes, the isolates were identified as S. aureus (n = 35, 71.42%) and coagulase-negative Staphylococcus (CoNS) (n = 14, 28.57%). Among these 14 isolates, 42.85% were methicillin-resistant coagulase negative Staphylococcus (MRCoNS). Among the 35 S. aureus, 31.42% were methicillin resistant (MRSA), and 2.8% were vancomycin resistant, characterized as VRSA. Sixty-eight percent were susceptible to methicillin (MSSA). Genes coa, femA and mecA were amplified from 75.51%, 71.42% and 30.61% of the isolates, respectively. After amplification of the mecA gene, 20.41% were characterized as MRSA, and 10.20% as MRCoNS. The vancomycin-resistant strain was characterized as VRSA after detection of the vanB gene. Conclusion: Our results show a higher frequency of MSSA and MRCoNS among S. aureus and CoNS respectively, colonizing devices and health professionals. However, the already described transfer of the staphylococcal cassette chromosome mec (SSCmec) from MRCoNS to MSSA may alter these results, increasing the frequency of MRSA strains. .

RESUMO Introdução: A contaminação cruzada por Staphylococcus aureus entre pacientes, profissionais e materiais de uso médico em unidades de saúde é uma preocupação constante, o que leva pesquisadores a estudar a prevalência desse patógeno em portadores assintomáticos. Objetivos: Investigamos a colonização e o perfil de suscetibilidade aos antimicrobianos de Staphylococcus spp. em superfícies de artigos médicos e em profissionais de duas unidades básicas de saúde no município do Rio de Janeiro. Materiais e métodos: Foram coletadas 79 amostras que resultaram em 49 isolados, submetidos à caracterização fenotípica e molecular por meio da reação em cadeia da polimerase (PCR) dos genes coa, femA e mecA. Resultados: De acordo com os fenótipos apresentados, os isolados foram identificados como S. aureus (n = 35; 71,42%) e Staphylococcus coagulase negativa (CoNS) (n = 14; 28,57%). Destes 14 isolados, 42,85% foram Staphylococcus coagulase negativa resistentes a meticilina (MRCoNS). Dos 35 S. aureus, 31,42% foram resistentes a meticilina (MRSA). Uma cepa foi resistente a vancomicina e identificada como S. aureus resistente a vancomicina (VRSA) após a detecção do gene vanB. Sessenta e oito por cento foram suscetíveis a meticilina (MSSA). Os genes coa, femA e mecA foram amplificados em 75,51%; 71,42% e 30,61% dos isolados, respectivamente. Após amplificação do gene mecA, 20,41% foram classificados como MRSA e 10,20% como MRCoNS. Conclusão: Nossos resultados mostraram frequência maior de MSSA e MRCoNS entre S. aureus e CoNS, respectivamente, colonizando equipamentos e profissionais de saúde. No entanto, a já descrita transferência do cassete cromossômico estafilocócico mec (SSCmec) de MRCoNS para MSSA poderia alterar esses resultados, aumentando a frequência de cepas MRSA. .

Genetic and Phenotypic Identification of Vancomycin-Resistant Staphylococcus aureus Isolates from Retail Poultry Carcasses in Omu-Aran, North-Central Nigeria.

Staphylococcus aureus is a well-known agent of zoonotic infections. Livestock-associated methicillin-resistant S. aureus (LA-MRSA) had been receiving public health attention for over a decade. Recently, the genomes of some MRSA strains evolved further by enabling acquisition of vanA gene from enterococcus which drives the emergence of vancomycin-resistant S. aureus (VRSA), thus signaling a higher threat to antimicrobial chemotherapy and diagnostic microbiology. This study was designed to examine slaughtered chicken carcasses in Omu-Aran, North-Central Nigeria for the presence of VRSA using vancomycin agar screen (VAS) as recommended by the Clinical and Laboratories Standards Institute (CLSI). To provide independent witness to further support the evidences from VAS, a 235 bp marker for vanA gene was simultaneously detected by PCR. From April 2013 through May 2014, chicken carcasses (n=784) were collected and studied. Among 155 (19.8%) samples which yielded S. aureus, VAS and vanA PCR methods unequivocally identified VRSA in 22 (14.2%). Compared with 46.2% VRSA report from Zaria, North-Western Nigeria, the incidence of VRSA is much less in Omu-Aran chicken carcasses than those of Zaria. Further investigation in other parts of Nigeria is recommended in order to generate nation-wide data on VRSA in this country.

Determination of Vancomycin and Methicillin Resistance in Clinical Isolates of Staphylococcus aureus in Iranian Hospitals.

Aims: The aim of this study was to determine the prevalence of methicillin resistant S. aureus (MRSA), vancomycin resistant or vancomycin intermediate resistant S. aurues (aureus) (VRSA/VISA) among clinical isolates. Study Design: S.aureus isolates used in this study were randomly collected from in-patient and outpatient of several hospitals of 7 cities in Iran (Tehran, Shiraz, Zahedan, Tabriz, Sannandaj, Sari, and Ahvaz) during 2006-2008. Methodology: Antibiotic susceptibility of 250 strains of Staphylococcus aureus isolated from Iranian hospitals were determined by disk diffusion method. Minimum inhibitory concentration (MICs) were determined for oxacillin and vancomycin by E-test. PCRs were used by specific primers (PCR used specific primers) for detection of mecA, vanA, vanB genes. Results: The percentage of resistance by disk diffusion method was as below: methicillin 46%, vancomycin 0%, penicillin 86%, erythromycin 42%, ciprofloxacin 29%, gentamicin 39% and clindamycin 33%. E-test MIC method showed that 43% isolates were resistant to methicillin and 4% isolates were VISA (≤ 8μg/ml). The prevalence of resistance genes in the clinical isolates were: mecA 44%, vanA 0%, vanB 0%. Conclusion: This study revealed that clinical isolates have rather high resistance to methicillin, erythromycin, gentamicin, penicillin and clindamycin We did not observe resistance to vancomycin. In order to avoid a possible outbreak involving VISA), vancomycin should be used carefully as a drug for treatment of S. aureus infections.

Vancomycin resistance among methicillin resistant Staphylococcus aureus isolates from intensive care units of tertiary care hospitals in Hyderabad.

Background & objectives: Multidrug resistant methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of nosocomial and community acquired infections and is on the rise. The glycopeptide vancomycin has been proposed as the drug of choice for treating such infections. The present study aimed at identifying the vancomycin resistance both phenotypically and genotypically among the MRSA isolates from two tertiary care hospitals in Hyderabad, south India. Methods: MRSA were isolated and identified from different clinical samples collected from ICUs of tertiary care hospitals in Hyderabad using conventional methods. Antibiogram of the isolates and vancomycin MIC were determined following CLSI guidelines. vanA was amplified by PCR using standard primers. Results: All vancomycin resistant S. aureus (VRSA) isolates were MRSA. The VRSA isolates were positive for vanA gene, except one which was negative. All VRSA had a vancomycin MIC in the range of 16-64 mg/l. Interpretation & conclusions: The increase in vancomycin resistance among MRSA and excessive use of antimicrobial agents have worsened the sensitivity. Larger studies need to be done in various geographical regions of the country to better define the epidemiology, mechanism of vancomycin resistance in S. aureus and its clinical implications.

Staphylococcus aureus: visitando uma cepa de importância hospitalar / Staphylococcus aureus: visiting a strain of clinical importance

O Staphylococcus aureus é uma bactéria do grupo dos cocos gram-positivos que faz parte da microbiota humana, mas que pode provocar doenças que vão desde uma infecção simples, como espinhas e furúnculos, até as mais graves, como pneumonia, meningite, endocardite, síndrome do choque tóxico e septicemia, entre outras. Essa bactéria foi uma das primeiras a serem controladas com a descoberta dos antibióticos, mas, devido a sua enorme capacidade de adaptação e resistência, tornou-se uma das espécies de maior importância no quadro das infecções hospitalares e comunitárias. Neste artigo faremos uma revisão sobre esse agente infeccioso e as bases dos mecanismos das patologias por ele provocadas, de forma a ressaltar a necessidade de mantê-lo como alvo para o desenho de novos antibióticos.

Staphylococcus aureus is a bacterium from Gram-positive coccus group, which is part of the human microbiota. It may cause diseases that may vary from simple infections (i.e., pimples and furuncles) to severe infections, such as pneumonia, meningitis, endocarditis, toxic shock syndrome and septicemia, among others. This bacterium was one of the first bacteria affected by antibacterial agents, however, its ability of adaptation and resistance turns it into an important hospital and communitarian pathogenic species of great concern. In this article we will discuss some important points related to the S. aureus and the pathologies related to it to reinforce it as a target for the design of new antibiotics.

Detection of methicillin or vancomycin-resistant Staphylococcus aureus from dental hospital / 대한치과보존학회지

The purpose of this study was to obtain the basic information for the improvement of dental environment by investigating the presence of methicillin- or vancomycin-resistant Staphylococcus aureus (MRSA or VRSA) isolated from dental health care workers (DHCWs) and environment of the Chosun University Dental Hospital (CUDH) and a private dental clinic (control group). Staphylococcus aureus (S. aureus) was isolated from anterior nares of 42 DHCWs and 38 sites, unit chairs, x-ray devices, computers, etc., at 10 departments of the CUDH and 20 DHCWs and 11 sites at the private dental clinic. S. aureus was isolated on mannitol salt agar plate and confirmed by PCR with S. aureus species-specific primer. Antimicrobial susceptibility test of clinical isolates of S. aureus against several antibiotics including methicillin (oxacillin) was performed by investigating minimum inhibitory concentration (MIC) using broth microdilution assay. In addition, PCR was performed to detect the methicillin- or vancomycin-resistant gene. The data showed that one strain of S. aureus was isolated from DHCWs of the CUDH and three strains of S. aureus was isolated from 3 samples of the private dental clinic, respectively. All of the isolates from the CUDH and the private dental clinic had resistance to penicillin G, amoxicillin and vancomycin and susceptibility to oxacillin and ciprofloxacin. The S. aureus strains were already obtained the resistance to penicillin G and amoxicillin. These results suggest that two dental clinics were under relatively safe environment.

Combination Effects of Various Beta-Lactam Antibiotics with Vancomycin or Teicoplanin against Staphylococcus aureus with Reduced Susceptibility to Vancomycin / 대한진단검사의학회지

BACKGROUND: Combination effects of various beta-lactam antibiotics with vancomycin or teicoplanin against methicillin-resistant Staphylococcus aureus (MRSA) that were detected as pos-sible hetero-vancomycin resistant Staphylococcus aureus (hetero-VRSA) by the Mu-3 agar method, were evaluated. METHODS: Twenty-four strains of MRSA (possible hetero-VRSA) from 22 inpatients of Dankook University Hospital from July through November 1998, were subjected to the study. Minimum inhibitory concentrations (MICs) of antibiotics, alone or in combination, were tested with the agar dilution method and the fractional inhibitory concentration (FIC) indices were calculated to estimate the combination effects. RESULTS: Six strains of 24 MRSA were estimated as hetero-VRSA by population analysis. The aver-age FIC index of imipenem (I), flomoxef (F), cephalothin (C), cefpirome (E) in combination with van-comycin (V) and teicoplanin (T) were 0.584 for I-V, 0.200 for I-T, 0.747 for F-V, 0.230 for F-T, 0.633 for C-V, 0.374 for C-T, 0.773 for E-V, and 0.386 for E-T, respectively. The presence of synergy and addi-tivity in beta-Lactams were observed as 5.3% (16/304) and 90.1% (274/304) for the combination of van-comycin with I, F, C, or E, respectively, and 29.3% (164/560) and 69.8% (391/560) for the combina-tion of teicoplanin with I, F, C, or E, respectively. CONCLUSIONS: We concluded that the selected beta-lactam antibiotics with vancomycin or teicoplanin showed effective against possible hetero-VRSA, as the combination effects were syner-gistic or additive with the average of the FIC index and the frequency of synergy and additivity in this study.

Prevalence of Staphylococcus aureus with Reduced Susceptibility to Vancomycin in a Tertiary Hospital / 감염

BACKGROUND: Recently isolates of S. aureus with intermediate (VISA) and heterogeneous resistance (hetero-VRSA) to vancomycin, which has been the only effective against MRSA infections, were identified. Several infections due to these isolates did not respond to adequate antibiotic treatments. In Japan, the prevalences of hetero-VRSA ranged from 0 to 48%. The aim of this study was to determine the prevalence of S. aureus heterogenously resistant to vancomycin and VISA. METHODS: The isolates were collected at Seoul National University Hospital from April 1998 to August 1999. To detect S. aureus with reduced susceptibility to vancomycin, brain heart infusion (BHI) agar with 4 mg/L of vancomycin and Mu-3 agar were used. Analysis of resistant subpopulations of bacteria (population analysis) was done. Minimum inhibitory concentration (MIC) for vancomycin was determined by microbroth and agar dilution methods, respectively according to NCCLS and Hiramatsu's recommendation. Coagulase type was determined with type I-VIII antisera. RESULTS: Total 235 MRSA, including 88 isolates from blood and 147 from other specimens, were collected. After 88 blood isolates were inoculated on BHI agar with 4 mg/L of vancomycin, 14 isolates (16 %) grew in variable colonies. But there were no subclones with vancomycin MIC > or =8 mg/L on population analysis and no isolates which grew confluently on Mu-3 agar with beta-lactam disks. In addition, 147 isolates from other specimens did not grow confluently on Mu-3 agar. Among 64 MRSA and 32 MSSA isolates, coagulase type II (49, 77%) and Vll(8, 25%) were respectively the most common types. CONCLUSION: In our tertiary-care hospital, there were no MRSA isolates with reduced susceptibilities to vancomycin.

Vancomycin-resistant Staphylococcus aureus / 대한임상미생물학회지

Clinical isolates of Staphylococcus aureus with reduced susceptibility to vancomycin(VRSA) have been reported from Japan, the United States and France Although the isolates are considered intermediately resistant according to the National Committee for Clinical Laboratory Standards(NCCLS), they are already a cause of a serious concern in the ever worsening antibiotic crisis of today, because they are all methicillin-resistant S. aureus(MRSA) and they are isolated after prolonged and unsuccessful vancomycin therapy. Furthermore, a study in Japan showed a high prevalence of "hetero-VRSA", MRSA strains that are susceptible to vancomycin according to NCCLS, but contain subpopulation of VRSA at the frequency of > or =10-6 and thus can be converted easily to full-blown VRSA upon exposure to the antibiotic. Recent reports from Seoul showed that hetero-VRSA is also prevalent in Korea. This review is to examine the epidemiology, clinical significance, mechanisms and laboratory detection of vancomycin resistance in clinical isolates of S. aureus; and to summerize infection control guidelines recommended by Centers for Disease Control and Prevention and others for this newly emerging nosocomial pathogen.