Detection of Mutation in gyrA and parC Gene on Resistant Salmonella enterica Serovars. Isolated from Two Hospitals in South East Nigeria

Aim: To detect the resistant pattern and existence of the genes responsible for floroquinolone-resistant in the quinolone-resistant determining regions (QRDR’s) of S. enterica serovars.Typhi.
Study Design: The Stool samples from Patients with symptoms of enteric fever, from different units and wards from two hospitals in Southeast region of Nigeria, were used for the surveillance.
Place and Duration of Study: The study was carried out in the Department of Microbiology and Biotechnology, Nigerian Institute for Medical Research, Lagos, between July and December, 2011.
Methodology: 50 isolates of Salmonella enterica serovar.Typhi were screened for the antibiotics susceptibility pattern, using multidisc agar diffusion and E-test. Double disc synergy Test (DDST) reported the presence of ESBL’s strains. The DNA amplification was performed by PCR using HOT FIREPol ® DNA polymerase with 25mMMgcl2. DNA –sequencing of the (QRDR’S) of gyrA (n= 32) and parC (n=3), was performed using sanger sequencing ABI 3730 x l, Applied Biosystems.
Results: A total of 39(78%) of the S. enterica produced β-lactamase. ESBL’s positive strains were 17(34%) and 46(92%) isolates were Multi-Drug Resistant S. typhi (MDRST). Sequencing of the mutations in gyrA gene of the (QRDR’s) was at Asp-87- Gly and Asp-87- Asn or at Ser-83- Tyr, while mutations in parC 3(6%), were at Asp-87- Gly.
Conclusion: Chromosomal encoded ESBL’s and mutations were found to be responsible for the MDRST. Ceftriazone and levofloxacine were found to be significant alternatives in treating S. enterica serovar.Typhi. This is the first report of mutation in both gyrA and parC genes in S. enterica serovar.Typhi in Southeast Nigeria.