C N Chaudhari1, K Tandel2, N Grover3, S Sen4, P Bhatt5, A K Sahni6, A K Praharaj7. 1. Professor (Microbiology), INHS Asvini Colaba, Mumbai, India. 2. Medical Officer (Microbiology), Military Hospital Gwalior, India. 3. Associate Professor, Department of Microbiology, Armed Forces Medical College, Pune 411040, India. 4. Senior Advisor (Pathology, Microbiology & Virology) Army Hospital (R&R), Delhi Cantt 10, India. 5. Resident, Department of Microbiology, Armed Forces Medical College, Pune 411040, India. 6. Professor & Head, Department of Microbiology, Armed Forces Medical College, Pune 411040, India. 7. Professor & Head (Microbiology), AIIMS, Bhubaneswar, India.
Abstract
BACKGROUND: Hetero-resistance vancomycin intermediate Staphylococcus aureus (hVISA) is phenotype, which on in-vitro susceptibility test is vancomycin susceptible (VSSA) but has a minority population of vancomycin intermediate (VISA). hVISA is responsible for vancomycin treatment failure. Population Analysis Profile- Area under Curve (PAP-AUC) is a test for detection of hVISA; however, this test is unsuitable for clinical microbiology laboratory. Tests, such as Brain Heart Infusion Agar with 6 μg/ml vancomycin (BHIA6V), E test and Macromethod E Test (MET) are available; however reported to have variable results. METHODS: 58 clinical isolates of Methicillin resistant S aureus (MRSA) having MIC of vancomycin more than 1 μg/ml by E test and agar dilution were analyzed by PAP-AUC, BHIA6V and MET. RESULT: The prevalence of hVISA was 6.9%. hVISA isolates were having vancomycin E test MIC >2 μg/ml. Sensitivity of BHIA6V, MET and E test with MIC >2 μg/ml were 0.75, 0.67 and 1.0 respectively; however, positive predictive values (PPV) were 0.43, 0.4 and 0.27 respectively with PAP-AUC. PAP-AUC ratio correlated with MIC by E test and MET. CONCLUSIONS: There is need for screening MRSA isolates showing in-vitro vancomycin susceptibility ≤2 μg/ml by agar dilution method for detection of hVISA. PAP-AUC test is unsuitable for routine laboratory testing. BHIA6V, MET and E test can be used for screening, however have low PPV.
BACKGROUND: Hetero-resistance vancomycin intermediate Staphylococcus aureus (hVISA) is phenotype, which on in-vitro susceptibility test is vancomycin susceptible (VSSA) but has a minority population of vancomycin intermediate (VISA). hVISA is responsible for vancomycin treatment failure. Population Analysis Profile- Area under Curve (PAP-AUC) is a test for detection of hVISA; however, this test is unsuitable for clinical microbiology laboratory. Tests, such as Brain Heart Infusion Agar with 6 μg/ml vancomycin (BHIA6V), E test and Macromethod E Test (MET) are available; however reported to have variable results. METHODS: 58 clinical isolates of Methicillin resistant S aureus (MRSA) having MIC of vancomycin more than 1 μg/ml by E test and agar dilution were analyzed by PAP-AUC, BHIA6V and MET. RESULT: The prevalence of hVISA was 6.9%. hVISA isolates were having vancomycin E test MIC >2 μg/ml. Sensitivity of BHIA6V, MET and E test with MIC >2 μg/ml were 0.75, 0.67 and 1.0 respectively; however, positive predictive values (PPV) were 0.43, 0.4 and 0.27 respectively with PAP-AUC. PAP-AUC ratio correlated with MIC by E test and MET. CONCLUSIONS: There is need for screening MRSA isolates showing in-vitro vancomycin susceptibility ≤2 μg/ml by agar dilution method for detection of hVISA. PAP-AUC test is unsuitable for routine laboratory testing. BHIA6V, MET and E test can be used for screening, however have low PPV.
Authors: Sebastian J van Hal; Michael C Wehrhahn; Thelma Barbagiannakos; Joanne Mercer; Dehua Chen; David L Paterson; Iain B Gosbell Journal: J Clin Microbiol Date: 2011-01-26 Impact factor: 5.948
Authors: T P Lodise; J Graves; A Evans; E Graffunder; M Helmecke; B M Lomaestro; K Stellrecht Journal: Antimicrob Agents Chemother Date: 2008-06-30 Impact factor: 5.191
Authors: Benjamin P Howden; John K Davies; Paul D R Johnson; Timothy P Stinear; M Lindsay Grayson Journal: Clin Microbiol Rev Date: 2010-01 Impact factor: 26.132
Authors: K C Horne; B P Howden; E A Grabsch; M Graham; P B Ward; S Xie; B C Mayall; P D R Johnson; M L Grayson Journal: Antimicrob Agents Chemother Date: 2009-06-08 Impact factor: 5.191
Authors: Kimberly C Claeys; Abdalhamid M Lagnf; Jessica A Hallesy; Matthew T Compton; Alison L Gravelin; Susan L Davis; Michael J Rybak Journal: Antimicrob Agents Chemother Date: 2016-01-04 Impact factor: 5.191