TITLE:
High Prevalence of Ciprofloxacin Resistance in Community Associated Staphylococcus aureus in a Tertiary Care Indian Hospital
AUTHORS:
Bhavya Chakrakodi, Sushma Prabhakara, Savitha Nagaraj, Jerome Etienne, Gayathri Arakere
KEYWORDS:
Ciprofloxacin Resistance; Indian ST772 Staphylococcus Aureus; gyrA Mutations
JOURNAL NAME:
Advances in Microbiology,
Vol.4 No.2,
January
23,
2014
ABSTRACT: We have studied the nature of ciprofloxacin resistance
in methicillin sensitive and resistant Staphylococcus aureus among
patients in a tertiary care hospital in Bengaluru, South India. All the
isolates were highly resistant to ciprofloxacin. Molecular characterization of
these samples performed using Staphylococcal Cassette Chromosome typing and
multilocus sequence typing showed that 37.5% of total isolates and 59% of MRSA
were sequence type (ST)772 and the rest were other STs. This indicates high
prevalence of CA-MRSA in this tertiary care hospital serving the Indian
community. Mutations responsible for ciprofloxacin resistance among these isolates
in DNA gyrase (gyrA and gyrB) and topoisomerase IV (grlA and grlB) were analyzed by PCR amplification of specific fragments and
sequencing. We found that for ST772 and five other STs present in this
collection, single mutation in the gyrA gene, Ser-84→Leu, was sufficient
for the high resistance. In vitro generation of ciprofloxacin resistance
in two sensitive ST772 isolates by exposure to increasing antibiotic
concentrations also resulted in the same single mutation of gyrA. The
factors responsible for high ciprofloxacin resistance are varied and are
dependent on the genetic background of the isolates and the environment. This
is the first report on the mechanism of ciprofloxacin resistance among the most
prevalent Indian CA-MRSA.