Multidrug resistance in Salmonella enterica serovar typhi isolated from patients with typhoid fever complications in Lagos, Nigeria

• Published in: Public health (London) Vol. 119; no. 4; pp. 321 - 327
• Main Authors: Akinyemi, K.O., Smith, S.I., Bola Oyefolu, A.O., Coker, A.O.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Ltd 01-04-2005
• Subjects: Anti-Bacterial Agents - pharmacology; Antimicrobial; Drug Resistance, Multiple, Bacterial; Electrophoresis, Agar Gel; Female; Fever of Unknown Origin - epidemiology; Fever of Unknown Origin - microbiology; Hepatosplenomegaly; Humans; Male; Microbial Sensitivity Tests; Multidrug resistant; Nigeria - epidemiology; Plasmid; Plasmids; Psychosis; Salmonella enterica serovar typhi; Salmonella typhi - genetics; Salmonella typhi - isolation & purification; Typhoid fever; Typhoid Fever - blood; Typhoid Fever - epidemiology; Typhoid Fever - microbiology; Nigeria; Plasmid; Antimicrobial; Psychosis; Hepatosplenomegaly; Salmonella enterica serovar typhi; Multidrug resistant; Typhoid fever
• ISSN: 0033-3506; 1476-5616
• DOI: 10.1016/j.puhe.2004.04.009

Objective. The aim of this study was to determine the prevalence of
Salmonella enterica serovar typhi in patients with pyrexia of unknown origin (PUO), and antimicrobial resistance in strains isolated from patients with
S. typhi in Lagos, Nigeria.
Study design. In total, 103 patients were included in this study, subdivided into two categories. Category A comprised 74 patients presenting with PUO, and Category B comprised 29 patients harbouring
S. typhi who did not respond to initial treatment.
Methods. Blood samples were cultured for bacterial isolates and identified by standard procedures. Susceptibility testing was performed according to the National Committee for Clinical Laboratory Standards. Plasmid DNA extraction was performed using the alkaline lysis method with
Escherichia coli v517 used as the standard. Conjugation and transformation experiments were performed using standard methods. For the latter,
E. coli K12 HB 101 (ara-14, galK2, hsd 520, lacyl, leu, mtl-1, Pro A2, rec A13, rps L20, sup E44, thii xyl-5) was used as the recipient and plasmid PBR 322 was used as the positive control.
Results. The prevalence of
S. typhi in PUO was 16.2% (12/74). In all, 25 of 41 (61.0%) cases were multidrug resistant (MDR) with phenotypic-resistant patterns: ACoCT, ACTCeS, ACTCoCe and ACTS were commonly encountered among the strains. Interestingly, four of the strains harbouring similar plasmid DNA were isolated from patients with hepatosplenomegaly, and a strain harbouring a large transferable plasmid of 81.2
MDa was isolated from a psychosis patient.
Conclusions. Our study confirmed the circulation of MDR
S. typhi in Lagos, Nigeria. Periodic review of antibiotics used in hospitals is essential as the efficacies of chloramphenicol, ampicillin and cotrimoxazole are now doubtful. Ciprofloxacin and ofloxacin are effective drugs for treatment of typhoid fever, but with current trends of drug abuse in Nigeria, resistance is likely to develop. These results, therefore, provide an early warning signal for the prudent use of fluoroquinolone antimicrobials to preserve their usefulness.