Microbes and Infectious Diseases 2022; Article-In-Press, DOI: 10.21608/mid.2022.122411.1249 Microbes and Infectious Diseases Journal homepage: https://mid.journals.ekb.eg/ DOI: 10.21608/MID.2022.122411.1249 * Corresponding author: Moses Njutain Ngemenya E-mail address: njutain.moses@ubuea.cm © 2020 The author (s). Published by Zagazig University. This is an open access article under the CC BY 4.0 license https://creativecommons.org/licenses/by/4.0/. Original article Isolation and molecular identification of Salmonella with high multidrug resistance to first line typhoid antibiotics in Southwest Cameroon Rita Ayuk Ndip 1 , Laupy Anne Awah 1 , Stephen Mbigha Ghogomu 1 , Fidelis Cho-Ngwa 1,2 , Moses Njutain Ngemenya *1,3 1- Department of Biochemistry and Molecular Biology, Faculty of Science, University of Buea, P.O. Box 63, Buea, Cameroon. 2- National Higher Polytechnic Institute, University of Bamenda, Cameroon. 3- Department of Medical Laboratory Sciences, Faculty of Health Sciences, University of Buea, P.O. Box, 63 Buea, South West Region, Cameroon. Introduction Salmonella enterica causes gastroenteritis, enteric (typhoid and paratyphoid) fevers in humans and animals [1]. Salmonella infections were initially treated with first line drugs ampicillin, sulphamethoxazole-trimethoprim, and chloramphenicol. Due to emergence of multidrug resistant (MDR) Salmonella strains, these drugs have become less effective [2]. This led to a shift to third generation cephalosporins (ceftriaxone) and fluoroquinolones (ciprofloxacin). However, resistance to ciprofloxacin has also emerged with reported decreased susceptibility to the drug [3]. The World Health Organisation recommends use of fluoroquinolones as optimal treatment choice in areas showing resistance to first line drugs and use of third generation cephalosporins in severe MDR cases [4,5]. The prevalence of MDR bacteria continues to rise worldwide leading to increased incidence of treatment A R T I C L E I N F O Article history: Received 17 February 2022 Received in revised form 19 March 2022 Accepted 20 March 2022 Keywords: Salmonella Antibiotics Susceptibility Multidrug resistant Genes A B S T R A C T Background: The prevalence of typhoid fever in Cameroon is high. However, studies on susceptibility of Salmonella to the recommended antibiotics are few and not extensive. This study investigated the susceptibility of Salmonella isolated from clinical specimens in the South West region of Cameroon and the genes responsible for their antibiotic resistance. Methods: Salmonella was isolated from clinical specimens collected from some medical laboratories in the study area by culture on Salmonella Shigella agar. Identification and resistance genes analysis were done using biochemical tests, PCR and gene sequencing. Disc diffusion test was done using 11 commercial antibiotics and minimum inhibitory concentrations determined by microdilution test to assess antibiotic susceptibility profile. The Multi- Antibiotic Resistance (MAR) index values were calculated. Results: Salmonella was isolated from 50 out of 115 specimens, of which 46 (92 %) were multidrug resistant (MDR) with MAR indices > 0.2. The MDR isolates showed high resistance to penicillins and low resistance to ciprofloxacin. PCR revealed that antibiotic resistance was largely due to the tem-1, Sul 1, dfrA1, floR genes. Sequencing revealed double mutations at codons 83 (Ser83-Phe) and 87 (Asp87-Gly) and one mutation at codon 83 (Ser83-Trp) in the quinolone resistance determining regions of the gyrA gene in two isolates. Conclusion: This study has revealed presence of MDR Salmonella enterica isolates in Southwest Cameroon with several resistance genes. This finding will guide use of antibiotics in treatment of Salmonella infections in the study area and justifies the search for new efficacious antibacterials against the MDR strains.