Aim: The present study aimed to detect inducible
clindamycin resistance,
vancomycin resistance and mupirocin resistance among MRSA
isolates.
Background: Multidrug and methicillin resistant
Staphylococcus aureus is a
widely spread problem in clinical environment, therefore
current information
regarding antimicrobial susceptibility of the pathogen is
very important for the
treatment of patients and in control and prevention
strategy. S. aureus, a
common pathogen, well known for its multidrug resistance.
Existence of MRSA is
further worsened by inducible clindamycin resistance and
emerging glycopeptide
resistance.
Materials and Methods: The study was conducted for a
period of 6 months from
May to October 2010. A total of 100 non-repetitive S. aureus
isolates from
various clinical specimens were included in the study. A
total of one hundred
non-repetitive isolates were subjected to routine antibiotic
susceptibility testing by
Kirby Bauer’s disc diffusion method including cefoxitin disc
for MRSA. Inducible
clindamycin resistance was detected by D-test, E-test for
vancomycin MIC and
mupirocin resistance by disc diffusion.
Results: Twenty three (85.2%) isolates showed
inducible clindamycin
resistance, one (3.7%) showed constitutive resistance and
three (11.1%) showed
MS phenotypes. Inducible clindamycin resistance (35.7%),
constitutive
resistance (2.3%) and MS phenotype (7.1%) were found to be
higher in MRSA
as compared to MSSA. Only one isolate with vancomycin MIC
4µg/ml by E-test
was considered as VISA. In our study, only one strain, which
had MIC 4µg/ml
has been considered as VISA. VISA may demonstrate
heteroresistance or there
may be subpopulations that are resistant. Screening for
hVISA requires
additional testing to reveal its hetero-variant phenotype
and these methods are
more labor intensive and costly than routine susceptibility
testing. Our study
detected mupirocin resistance in 11(26.1%) MRSA and
30(51.72%)MSSA
isolates, which is a cause for concern. Study showed that
D-test should be
included as a routine disc diffusion test to prevent
therapeutic failure with
clindamycin.
Author (s) Details
G.K. Mangala
Department of Microbiology, JJM Medical College, Davangere,
Karnataka, India.
Ravindra. B
Department of Ophthalmology, JJM Medical College, Davangere,
Karnataka, India.
K. Suresh
Department of Microbiology, JJM Medical College, Davangere,
Karnataka, India.
Please see the link - https://doi.org/10.9734/bpi/rpmab/v3/266
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