Introduction:The resistance to antimicrobial agents among Staphylococci is an increasing problem. This has led to renewed interest in the usage of Macrolide-Lincosamide-Streptogramin B (MLSB) antibiotics to treat Staphylococcus aureus (S. aureus) infections. The resistance to macrolide can be mediated by msr A gene coding for efflux mechanism or via erm gene encoding for enzymes that confer inducible or constitutive resistance to MLSBantibiotics. In vitro routine tests for clindamycin susceptibility may fail to detect inducible clindamycin resistance due to erm genes resulting in treatment failure, thus necessitating the need to detect such resistance by a simple D test on a routine basis.Materials and Methods:One hundred and ninety S. aureus isolates were subjected to routine antibiotic susceptibility testing including oxacillin (1 µg) and cefoxitin (30 µg) by modified Kirby Bauer disc diffusion method. Inducible resistance to clindamycin in S. aureus was tested by ‘D test’ as per CLSI guidelines.Results:Twenty (10%) isolates showed inducible clindamycin resistance, 18 (9%) showed constitutive resistance while remaining 16 (8%) showed MS phenotype. Inducible resistance and constitutive resistance were found to be higher in MRSA as compared to MSSA (20%, 16% and 6%, 6%, respectively).Conclusion:Clindamycin is kept as a reserve drug and is usually advocated in severe MRSA infections depending upon the antimicrobial susceptibility results. This study showed that D test should be used as a mandatory method in routine disc diffusion testing to detect inducible clindamycin resistance in Staphylococci for the optimum treatment of patients.

Background / Aims:Septicemia is one of the important causes of mortality and morbidity in neonates and children. Blood culture is the gold standard for the diagnosis. Emergence of multidrug resistant bacterial strains is a major problem in the management of sepsis. Present study was undertaken to identify the common bacterial pathogens associated with pediatric sepsis and to determine their antibiotic susceptibility pattern.Materials and Methods:Blood cultures from 185 suspected cases of sepsis were examined. The growths from the subcultures were identified by conventional biochemical tests. Antibiotic susceptibility testing was performed by modified Kirby-Bauer disk diffusion method and drug resistant strains in primary screening were further processed for extended spectrum beta lactamases (ESBL) and methicillin resistant Staphylococcus aureus (MRSA) status by combination disk method (ESBL) and oxacillin disk diffusion method (MRSA).Results:Out of the 185 cultures obtained from suspected cases, 81 (44%) were culture positive. Fifty-two (35%) of the culture isolates were Gram negative bacilli. Twenty-eight (64%) of the isolates were Gram positive cocci. One case was of mixed infection. The prevalence of MRSA in 41 strains of S. aureus was found to be 29% (12 strains). The overall prevalence of ESBL producers among 28 Gram negative bacterial isolates was found to be 32% (9 strains).Conclusion:This study stresses the need for the continuous screening and surveillance for antibiotic resistance in pediatric care unit.

Background/Aim:Methicillin-resistant Staphylococcus aureus (MRSA) is an important cause of nosocomial infections worldwide. The aim of this study was to determine the prevalence of MRSA and their antimicrobial susceptibility pattern in our hospital located in Mangalore, India.Materials and Methods:The bacterial isolates from various clinical specimens of patients admitted in our hospital were cultured as per standard protocol and all isolates of Staphylococcus aureus obtained were included in the study. The isolates were identified by standard methods like catalase test, slide and tube coagulase tests, and growth on Mannitol salt agar (HiMedia Lab, Mumbai). The antimicrobial susceptibility testing was performed by Kirby–Bauer disc diffusion method. The D-test for inducible clindamycin resistance was performed. The isolates were tested for methicillin resistance by using oxacillin disc by disc diffusion method and confirmed by agar screen test (oxacillin 6 μgm/ml). The results were interpreted according to CLSI criteria.Results:During a period of one year, a total of 237 isolates of S. aureus were studied and 69 (29.1%) were found to be methicillin-resistant. MRSA isolates showed greater resistance to multiple drugs than methicillin sensitive Staphylococcus aureus MSSA isolates. Inducible clindamycin resistance was 18.8% in MRSA as against 3.5% in MSSA. About 40–50% of MRSA were resistant to erythromycin, gentamicin, and chloramphenicol, while less than 30% were resistant to ciprofloxacin and amikacin. However, all strains were sensitive to vancomycin.Conclusion:The regular surveillance of hospital-acquired infections of MRSA may be helpful in formulating and monitoring the antibiotic policy. This may also help in preserving antibiotics like vancomycin, only for life-threatening staphylococcal diseases.

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