Introduction The World Health Organization (WHO) estimates 540 cases of Salmonella Typhi infection per 100,000 inhabitants with the majority of deaths attributed to multidrug-resistant strains. The purpose of this study was to determine the antimicrobial resistance profile of Salmonella Typhi isolates from typhoid epidemics and to evaluate multidrug resistance in RRC.
Materials and methods The National Institute for Biomedical Research (INRB) in Kinshasa has, from 2002 to 2014, received Salmonella Typhi isolates from blood and stool cultures from different geographical areas of the DRC for analytical expertise. From INRB, these isolates were shipped to the Kenya Medical Research Institute (KEMRI) in Nairobi, where this work was done. Sorted isolates from the lot were streaked on MacConkey agar (Oxoid, UK) and incubated (Memmert) at 37° C for 24 hours for isolation. Lactosenegative colonies were purified on Mueller-Hinton agar (Oxoid, UK). For confirmation, these isolates were agglutinated on a glass slide with Salmonella Typhi antisera anti O and anti H (Remel, Dartford, UK). Colonies of 95 isolates selected were diluted in NaCl 0.85g/L in accordance with MacFarland Standard 0.5. These isolates were subjected to antibiotic susceptibility testing with 14 common antibiotics (Oxoid), using the Kirby-Bauer diffusion method on Mueller-Hinton agar. The inhibition diameter of each antibiotic was recorded and interpreted.
Results The resistance profile was Sulfamethoxazole 87%, Chloramphenicol 48%, Trimethoprim 46%, Ampicillin 42%, Tetracycline 22%, Nalidixic acid 8%, Amoxicillin
Clavulanic acid 8%, Cefoxitin 4%, Gentamicin 2%, Ciprofloxacin 1 %, Cefotaxime 1%, Ceftazidime 0%, Ceftriaxone 0% and Cefepime 0% of the first-line antimicrobials used in the treatment of typhoid fever, on average, 49% of the isolates were multidrug-resistant.
Conclusion The increase of multidrug resistance in the DRC is a real threat. The judicious use of antimicrobials and the rigorous exploitation of antimicrobial resistance surveillance systems must be the concern of all.
Keywords : Antibiotic resistance profile, Salmonella enterica Typhi isolates, evaluation, multidrug resistance, INRB, Kinshasa DRC, KEMRI, Nairobi.