Simple, rapid, and cost-effective modified Carba NP test for carbapenemase detection among Gram-negative bacteria.

PURPOSE: Detection of carbapenemases among Gram-negative bacteria (GNB) is important for both clinicians and infection control practitioners. The Clinical and Laboratory Standards Institute recommends Carba NP (CNP) as confirmatory test for carbapenemase production. The reagents required for CNP test are costly and hence the test cannot be performed on a routine basis. The present study evaluates modifications of CNP test for rapid detection of carbapenemases among GNB. MATERIALS AND METHODS: The GNB were screened for carbapenemase production using CNP, CarbAcineto NP (CANP), and modified CNP (mCNP) test. A multiplex polymerase chain reaction (PCR) was performed on all the carbapenem-resistant bacteria for carbapenemase genes. The results of three phenotypic tests were compared with PCR. RESULTS: A total of 765 gram negative bacteria were screened for carbapenem resistance. Carbapenem resistance was found in 144 GNB. The metallo-ß-lactamases were most common carbapenemases followed by OXA-48-like enzymes. The CANP test was most sensitive (80.6%) for carbapenemases detection. The mCNP test was 62.1% sensitive for detection of carbapenemases. The mCNP, CNP, and CANP tests were equally sensitive (95%) for detection of NDM enzymes among Enterobacteriaceae. The mCNP test had poor sensitivity for detection of OXA-48-like enzymes. CONCLUSION: The mCNP test was rapid, cost-effective, and easily adoptable on routine basis. The early detection of carbapenemases using mCNP test will help in preventing the spread of multidrug-resistant organisms in the hospital settings.

Prevalence of Mupirocin Resistance Among Staphylococci, its Clinical Significance and Relationship to Clinical Use.

INTRODUCTION: Mupirocin competitively inhibits bacterial isoleucyl transfer-RNA synthetase and inhibit bacterial protein synthesis. Widespread usage and over the counter availability of the drug has resulted in resistance among Staphylococcus species. OBJECTIVES: This study aimed to determine the overall prevalence of mupirocin resistance among staphylococci. Correlate clinical significance of mupirocin resistance and its relationship to clinical use. METHODS: Consecutive, nonrepetitive, clinical isolates of Staphylococcus aureus (n = 98), and coagulase-negative staphylococci (CoNS) (n = 45) from skin and soft-tissue infections between January 2014 and June 2014 were studied. Antibiotic susceptibility testing was done according to Clinical and Laboratory Standards Institute guidelines. Low- and high-level mupirocin resistance was screened by using 5 µg and 200 µg discs respectively and confirmed by agar dilution. Annual consumption of mupirocin was studied and correlated with resistance. RESULTS: High-level mupirocin resistance was found in 8.2% S. aureus and 15.6% of CoNS, while low-level mupirocin resistance was found in 17% S. aureus and 8.9% CoNS. High-level mupirocin resistance was more common in methicillin-sensitive S. aureus isolates when compared with methicillin-resistant S. aureus isolates (P < 0.05). Mupirocin resistant S. epidermidis were associated with methicillin resistance and constitutive clindamycin resistance. CONCLUSION: High prevalence of mupirocin resistance was found in the present study. Increased prevalence of mupirocin resistance among community-acquired staphylococci demands the judicious use of the drug in the community.