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Typhoid Fever in Africa: Emerging Flouroquinolone Resistance S KARIUKI1,3, G REVATHI2, J MUYODI1, J MWITURIA1, A MUNYALO1, S MIRZA3, CA HART3 1Centre for Microbiology Research, KEMRI, Kenya, 2Department of Medical Microbiology, Kenyatta National Hospital, Kenya, 3Department of Medical Microbiology and Genito-Urinary Medicine, Liverpool, UK. Introduction • Salmonella Typhi : cause >10 million cases, 600,000 deaths / year, mainly in developing countries. • Comprise 8-10% of all serotype isolations in Kenya. • MDR S. Typhi increasingly reported in Africa; chloramphenicol, ampicillin or cotrimoxazole increasingly ineffective. Salmonella Methods • Between 1999 – 2000: 140 S. Typhi from blood cultures of adults (104) and children (36). • 3 different regions of the country. Methods • Identification by serotype and phage type • Antibiotic susceptibility testing - MIC using Etest method • Plasmid isolation and in-vitro conjugation tests • Genomic DNA characterisation by PFGE Methods PCR • PCR of RepHI1A replicon, present in IncHI plasmids • PCR of gyrA, gyrB, parC and parE genes within QRDR • Digestion with 5 U of Hinf I – determine HinfI mutations in gyrA site RESULTS Antimicrobial susceptibility • Only 19/140 (13.7%) fully susceptible to all drugs tested. • 82.3% were MDR Strains high MICs • Ampicillin,chloramphenicol, tetracycline, (MICs > 256µg/ml), streptomycin (MIC > 1024µg/ml) and cotrimoxazole (MIC> 32µg/ml) RESULTS MICs for Quinolones n=140 MICs (g/mL) Mode Range 2 0.016 1-4 0.016 – 0.032 8 0.25 8-16 0.25 – 0.38 Non-M DR * S . Typhi Nalidixic Acid Ciprofloxacin M DR S . Typhi Nalidixic Acid Ciprofloxacin RESULTS Phenotypes and Genotypes of S. Typhi S. Typhi No. of No. (%) with From raised QMICs isolates XbaI and SpeI PFGE patterns No. (%) isolates Pattern I MDR Sensitive Pattern 2 MDR Sensitive KNH 105 47 (44.7) 42 (40) 13 (12) 47 (44.7) 3 (2.8) Embu 32 16 (50) 20 (64) 0 9 (28.6) 3 (9.3) Nakuru 3 3 (100) 0 0 3 (100) 0 RESULTS PCR of QRDR • No resultant mutations observed after sequencing PCR products of high Quinolone MIC strains. Plasmids • Resistance encoded on a 110-kb selftransferable plasmid of incHI1 incompatibility group. • Increase in MICs of the quinolones had not resulted from any significant mutation Inc groups of S. Typhi 1 2 3 4 5 6 7 8 9 10 11 M 365 bp Genotypes of S. Typhi M 1 2 3 4 5 6 7 Conclusions • Prior to 1991, all S. Typhi were fully susceptible to Abs • Resistance 1st seen 1992, at 25% • 1997 at 68% steadily rising to 76% by 2002. CONCLUSIONS • Two main genotypes in circulation – both S and R strains. • NalR and Cipro high MIC strains (47%) have 10X MIC of sensitive strains • Rx failures already being observed even within sensitive MIC bracket. References 1. Kariuki S, Revathi G, Muyodi J, Mwituria J, Munyalo A, Mirza S, Hart CA. Characterization of multidrug-resistant typhoid outbreaks in Kenya. J Clin Microbiol. 2004 Apr;42(4):1477-82. 2. Kariuki S, Gilks C, Revathi G, Hart CA. Genotypic analysis of multidrug-resistant Salmonella enterica Serovar typhi, Kenya. Emerg Infect Dis. 2000 Nov-Dec;6(6):649-51 3. Kariuki S, Hart CA. Global aspects of antimicrobial-resistant enteric bacteria. Curr Opin Infect Dis. 2001 Oct;14(5):579-86.