There were localised differences in the prevalence of resistance between the centres. The efficacy of the anti-MRSA antimicrobials was very high; however, almost all these antimicrobials showed evidence of creeping MIC.

Aims: Although Staphylococcus haemolyticus is considered as a part of normal skin flora, infections associated with them are increasing. Irrespective of the low virulence profile it poses a severe threat to patients with indwelling devices due to its multidrug-resistant nature. The aim of this study was to determine antibiotic resistance patterns and to detect the genes responsible in clinical isolates of S. haemolyticus. Results: All the 356 S. haemolyticus isolates were susceptible to glycopeptides. 91.3% were resistant to cefoxitin, 85.4% to erythromycin, 57.3% to co-trimoxazole, 52.8% to clindamycin, whereas only 3.7% of isolates were resistant to linezolid. Tetracycline resistance was found in 16.6% of isolates with tetK as the major genetic determinant. Most of the cefoxitin-resistant isolates carried mecA gene (99.4%), whereas dfrG gene was found only in 57.3% of co-trimoxazole-resistant isolates. Macrolides resistance was seen in 85.4% of isolates with cMLS B (constitutive macrolide, lincosamide, and streptogramin B) (42.5%) as the major phenotype with ermC and msrAB genes as the predominant genetic determinants. Among linezolid-resistant isolates all except one showed higher minimum inhibitory concentration (MIC) (>256 mg/mL) with chloramphenicol-florfenicol resistance (cfr) gene as the genetic determinant, whereas one isolate had a lower MIC (16 mg/mL) and was negative for cfr gene. Conclusion: Emerging resistance to linezolid is a cause for concern. Strategies to prevent the spread of antibiotic resistance require continuous surveillance of these multidrug-resistant strains.

Background & objectives:Although there are reports of heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA) across the globe, there is a lack of reliable data on hVISA in India. The present study was undertaken to determine the rate of hVISA among the methicillin-resistant Staphylococcus aureus (MRSA) isolates, and to compare the brain heart infusion agar with vancomycin 4 μg/ml (BHIV4) method with population analysis profile-area under the curve (PAP-AUC) method for the detection of hVISA and to study the distribution of mobile genetic element that carries methicillin-resistance gene SCCmec (Staphylococcal cassette chromosome mec) types among these isolates.Methods:BHIV4 and PAP-AUC methods were employed to detect hVISA among 500 clinical isolates of MRSA. SCCmec typing of these isolates was performed by multiplex polymerase chain reaction. The clinical presentation, treatment with vancomycin and outcome was documented for patients with hVISA.Results:The rate of hVISA was 12.4 per cent by PAP-AUC method. Sensitivity, specificity, PPV, NPV and kappa agreement of BHIV4 with PAP-AUC was 58.06, 93.15, 54.55, 94.01 per cent and 0.498, respectively. The isolation of hVISA was significantly (P<0.01) higher in patients admitted to intensive care units and wards than in patients attending the outpatient departments. Only 38 per cent of the patients received vancomycin as therapy. Majority of the hVISA isolates carried SCCmec type V or IV.Interpretation & conclusions:The rate of hVISA isolation in our study was 12.4 per cent. The sensitivity of the BHIV4 screening test was low, and was in moderate agreement with PAP-AUC test. SCCmec type V was the predominant type seen in half of the isolates. More studies need to be done in different parts of the country on a large number of isolates to confirm our findings.

Objectives: Staphylococcus haemolyticus is associated with device-related infections in immunocompromised individuals and acts as a reservoir for antibiotic resistance genes. It is also the species with the highest antibiotic resistance rates. However, identification is still difficult in most clinical laboratories. Simplified biochemical tests give variable results while newer methods such as MALDI-TOF MS and automated systems may not be readily available. Aim: To compare the performance of the simplified biochemical scheme, BD-Phoenix automated system, and PCR for nuc gene for the identification of S. haemolyticus with MALDI-TOF MS as the gold standard. Methods: This study included 427 coagulase-negative staphylococci (CoNS) isolates of which 356 were identified as S. haemolyticus and 71 as other species by MALDI-TOF MS. These isolates were subjected to a simplified biochemical scheme using tests like the fermentation of maltose, sucrose, trehalose, mannose, urease, xylose, ornithine, and susceptibility to novobiocin. Conventional PCR targeting the nuc gene and BD-Phoenix were also used for identification. The accuracy of these methods was assessed in comparison with MALDI-TOF MS. Results: The sensitivity and specificity of biochemical tests, BD-Phoenix and nuc PCR were 97.5% and 97.2%: 97.8% and 100%: 100% and 100% respectively. Inaccurate identification was observed for some of the isolates (2.2% by BD-Phoenix and 2.5% by biochemical tests). These isolates were identified as S. haemolyticus by the other methods. Conclusion: Identification of S. haemolyticus by biochemical tests and BD-Phoenix had good accuracy comparable to PCR as well as MALDI-TOF MS. This simplified biochemical scheme can be easily implemented even in laboratories with limited resources.

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