Breast abscess caused by penicillin resistant Pneumococci.

Breast abscess is mostly caused by Staphylococcus aureus. A 26-year-old immunocompetent lady was admitted with breast abscess. Incision and drainage (I/D) was done and Pneumococci were isolated from the drained pus. The patient was earlier treated with Augmentin which was later changed to linezolid after testing for antibiotic susceptibility. This strain showed a high level of resistance to penicillin. It had been noticed that there was a slow increase in the number of penicillin resistant Pneumococci isolated in our hospitals. The increase in penicillin-resistant Pneumococci correlates with the intensive use of beta-lactam antibiotics. Hence, antibiotics should be used judiciously, avoiding their use particularly in mild self-limiting upper respiratory infections. Attention therefore, should focus on monitoring resistance in Pneumococci to prevent mortality and morbidity associated with this organism, which continues to take a heavy toll on children and the elderly.

Evaluation and comparison of tests to detect methicillin resistant S. aureus.

BACKGROUND AND OBJECTIVES: Phenotypic methods for detection of methicillin resistant Staphylococcus aureus (MRSA) have been compared with the gold standard which, as of now, is by the detection of mecA gene and femA gene by polymerase chain reaction (PCR). Discrepancies in detection have an adverse effect on patient management, thereby highlighting the importance of accuracy in detection. Our study aims to evaluate the efficacy of cefoxitin disk diffusion test to detect MRSA and compare it with other phenotypic and molecular methods. METHODOLOGY: The study was conducted from June 2006 to December 2007 and included 610 Staphylococcus aureus (S. aureus) isolates obtained from clinical samples. All isolates were tested for MRSA using oxacillin screen agar plates with 6 microg/ml of oxacillin, cefoxitin disk diffusion using 30 microg disk and MIC of oxacillin. Selected isolates (55) were tested for presence of mecA gene and Fem A gene by PCR. RESULTS: Out of 610 isolates, MRSA was identified in 34.09% by cefoxitin disk diffusion, 34.9% by oxacillin screen agar, 34.4% by MIC and 37.3% by oxacillin disk diffusion. When selected isolates were tested with molecular methods, the cefoxitin disk diffusion and PCR tests were comparable. DISCUSSION: Prevalence of MRSA (34.09%) is quite high as in other studies. The oxacillin disk diffusion test which was used routinely earlier is showing low specificity (56%). Among all phenotypic methods, cefoxitin disk diffusion and PCR alone have similar sensitivity and specificity. CONCLUSION: Results of cefoxitin disk diffusion test are in concordance with the PCR for mecA gene. Thus, the test can be an alternative to PCR for detection of MRSA in resource constraint settings.

Prevalence of community acquired MRSA in a tertiary care facility.

Traditionally, methicillin resistant Staphylococcus aureus (MRSA) is considered as a nosocomial pathogen, but an increasing prevalence of community acquired MRSA is being reported worldwide including India, which implies a strategic change in the antibiotic of choice for treatment of community acquired Staphylococcal infections, which till now is cloxacillin. This study is aimed at identifying the prevalence and susceptibility characteristics of community acquired MRSA in our hospital. The study group consisted of 208 consecutive MRSA identified on the basis of their resistance to cefoxitin disk (30 microg) by the disc diffusion method and mecA gene detection by polymerase chain reaction (PCR). Isolates were categorized as community acquired MRSA based on criteria for inclusion and their antibiotic susceptibility was compared with that of the hospital acquired MRSA isolates. Among the 208 MRSA analyzed, 18% (n = 37) were community acquired and were from infections such as cellulitis and superficial injuries. The isolates were significantly more sensitive to ciprofloxacin than the hospital acquired MRSA isolates. The prevalence of community acquired MRSA in this study (18%) is comparable to its prevalence in other studies across India. Susceptibility to antibiotics other than glycopeptides was an important characteristic of community acquired MRSA. In the absence of other reliable phenotypic test for its identification, susceptibility to ciprofloxacin is suggested as an alternative. A prudent clinician should be aware that, cloxacillin, the drug of choice for skin infections such as carbuncle and cellulitis, will not be effective in these cases and that community acquired MRSA has a range of antibiotics to choose from, other than the glycopeptides, when compared with that of hospital acquired MRSA.