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BACKGROUND AND AIMS: Given choice, bacteria prefer a community-based, surface-bound colony to an individual existence. The inclination for bacteria to become surface bound is so ubiquitous in diverse ecosystems that it suggests a strong survival strategy and selective advantage for surface dwellers over their free-ranging counterparts. Virtually any surface, biotic or abiotic (animal, mineral, or vegetable) is suitable for bacterial colonization and biofilm formation. Thus, a biofilm is "a functional consortium of microorganisms organized within an extensive exopolymeric matrix." MATERIALS AND METHODS: The present study was undertaken to detect biofilm production from the repertoire stocks of Acinetobacter baumannii (A. baumannii) and Pseudomonas aeruginosa (P. aeruginosa) obtained from clinical specimens. The tube method was performed to qualitatively detect biofilm production. RESULTS: A total of 109 isolates of both organisms were included in the study, out of which 42% (46/109) isolates showed biofilm detection. Among the biofilm producers, 57% of P. aeruginosa and 73% of A. baumannii showed multidrug resistance (MDR) pattern which was statistically significant in comparison to nonbiofilm producers (P < 0.001). CONCLUSION: To the best of our knowledge, this is the only study to have tested the biofilm production in both P. aeruginosa and A. baumannii in a single study. Biofilm production and MDR pattern were found to be significantly higher in A. baumannii than P. aeruginosa. Antibiotic resistance was significantly higher among biofilm producing P. aeruginosa than non producers. Similarly, antibiotic resistance was significantly higher among biofilm producing A. baumannii than non producers.
RESUMO
INTRODUCTION: Staphylococcus aureus is one of the most common pyogenic bacteria. They are notorious for developing prompt resistance to newer antimicrobials. With increasing incidence of methicillin-resistant S. aureus (MRSA) isolates, the treatment options are also becoming limited. Clindamycin is an excellent drug for skin and soft tissue infections, but resistance mediated by the inducible phenotype (iMLS(B)) leads to in vivo therapeutic failure even though there may be in vitro susceptibility. The double disk approximation test (D-test) can reliably detect the presence of such isolates. This study was aimed to detect and report the prevalence of the iMLS(B) phenotype in NEIGRIHMS, a tertiary care center in Northeast India. METHODOLOGY: A total of 243 consecutive isolates were subjected to routine identification tests followed by antimicrobial sensitivity testing. Erythromycin-resistant isolates were tested for inducible resistance phenotype by the D-test. RESULTS: Among strains tested, 95 (39%) were erythromycin resistant. Twenty-six (10.7%) isolates were D-test positive (iMLS(B) phenotype), 41 (16.88%) were constitutively resistant (cMLS(B) phenotype), and 28 isolates (11.52%) were found to be negative by D-test. The incidence of both inducible and constitutive phenotypes was higher in MRSA isolates compared to methicillin-sensitive S. aureus (MSSA) isolates. CONCLUSIONS: This study revealed a moderate prevalence of the inducible clindamycin phenotype in the staphylococcal isolates tested. Clinical microbiology laboratories in areas of high MRSA prevalence should consider performing the D-test routinely. This will help prevent prescription of drug(s) whose therapeutic efficacy is doubtful.