title: Increasing Trend of Heterogeneous Vancomycin Intermediate Staphylococcus aureus in a Tertiary Care Center of Northern India.
abstract: Heterogeneous vancomycin intermediate Staphylococcus aureus (hVISA) strains are increasingly reported, and their association with vancomycin treatment failure is a well-known problem worldwide. A total of 500 clinical isolates of methicillin-resistant S. aureus were screened for hVISA by four different methods from May 2011 to May 2014. The number of strains screened for hVISA from May to April in 2011-2012, 2012-2013, and 2013-2014 were 198, 123, and 179, respectively. hVISA strains were studied by transmission electron microscopy (TEM) for cell wall thickness and also for their ability to form biofilm on a polystyrene microtiter plate. hVISA strains detected by four different methods-brain heart infusion agar with vancomycin with 4 mg/L/gradient plate/macro E-test/and glycopeptide resistance detection (GRD) E test-were as follows: 11.6%/10%/9%, and 9.5% in 2011-2012, 12.1%/9.7%/8.9%, and 10.5% in 2012-2013, and 13.9%/11.7%/11.1%, and 12.8% in 2013-2014, respectively. Population analysis profile-area under curve analysis confirmed hVISA in 4.5% (9/198), 6.5% (8/123), and 6.7% (12/179) in respective years; 24% (7/29) of hVISA isolates were nonsusceptible to daptomycin. TEM showed a significant increase in cell wall thickness of hVISA isolates (p<0.001) with a distinct reduction in their biofilm formation ability.
authors.affiliation: 1 Department of Microbiology, Sanjay Gandhi Postgraduate Institute of Medical Sciences , Lucknow, Uttar Pradesh, India .|2 Amity Institute of Biotechnology, Amity University Uttar Pradesh , Lucknow, Uttar Pradesh, India .
authors.forename: Avinash
authors.initials: A
authors.lastname: Singh
authors.affiliation: 1 Department of Microbiology, Sanjay Gandhi Postgraduate Institute of Medical Sciences , Lucknow, Uttar Pradesh, India .
authors.forename: Kashi Nath
authors.initials: KN
authors.lastname: Prasad
authors.affiliation: 1 Department of Microbiology, Sanjay Gandhi Postgraduate Institute of Medical Sciences , Lucknow, Uttar Pradesh, India .
authors.forename: Richa
authors.initials: R
authors.lastname: Misra
authors.affiliation: 1 Department of Microbiology, Sanjay Gandhi Postgraduate Institute of Medical Sciences , Lucknow, Uttar Pradesh, India .
authors.forename: Mohibur
authors.initials: M
authors.lastname: Rahman
authors.affiliation: 1 Department of Microbiology, Sanjay Gandhi Postgraduate Institute of Medical Sciences , Lucknow, Uttar Pradesh, India .
authors.forename: Satyendra Kumar
authors.initials: SK
authors.lastname: Singh
authors.affiliation: 1 Department of Microbiology, Sanjay Gandhi Postgraduate Institute of Medical Sciences , Lucknow, Uttar Pradesh, India .
authors.forename: Ravi Prakash
authors.initials: RP
authors.lastname: Rai
authors.affiliation: 1 Department of Microbiology, Sanjay Gandhi Postgraduate Institute of Medical Sciences , Lucknow, Uttar Pradesh, India .
authors.forename: Aparna
authors.initials: A
authors.lastname: Tripathi
authors.affiliation: 2 Amity Institute of Biotechnology, Amity University Uttar Pradesh , Lucknow, Uttar Pradesh, India .
authors.forename: Janmejai Kumar
authors.initials: JK
authors.lastname: Srivastava
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D019540:Area Under Curve; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D002473:Cell Wall / Q000187:drug effects / Q000648:ultrastructure; D017576:Daptomycin / Q000494:pharmacology*; D006801:Humans; D007194:India; D008826:Microbial Sensitivity Tests; D046529:Microscopy, Electron, Transmission; D012189:Retrospective Studies; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000382:microbiology; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000254:growth & development / Q000302:isolation & purification / Q000648:ultrastructure; D062606:Tertiary Care Centers; D014640:Vancomycin / Q000494:pharmacology*; D020713:Vancomycin Resistance
chemical_list: D000900:Anti-Bacterial Agents; D014640:Vancomycin; D017576:Daptomycin