*1Adenugba, I. T., 2Umoh, J. U., 2Bassey, M., 2Uyanga, F. Z., and 1Ntekpere, E. I.
*1Department of Biological Sciences, Akwa Ibom State Polytechnic, Ikot Osurua, Ikot Ekpene, Nigeria
2Department of Microbiology, Faculty of Biological Sciences, Akwa Ibom State University, Nigeria
*Correspondence to: adenugba.imaobong@akwaibompoly.edu.ng; Phone: +234 (0) 8121902332
Abstract:
Background: Infection caused by antibiotic resistant Enterobacter spp. is a growing public health challenge as this significantly contributes to disease burden and high mortality in resource-limited settings. This study aimed to determine multidrug and colistin resistance patterns of Enterobacter isolates from water, human and animal samples in six rural communities in Akwa Ibom State, Nigeria.
Methodology: This was a laboratory-based study of 124 non-duplicate Enterobacter species isolated from water (n=43), human (n=46), goat (n=22) and dog (n=13) faecal samples in six local government areas (LGAs) of Akwa Ibom State. Enterobacter species were isolated from the samples following aerobic culture on Violet Red Bile Glucose agar after preliminary incubation in Enterobacteriaceae Enrichment broth at 37°C for 18 hours. Identification of Enterobacter isolates to species level was done using VITEK®2 compact system. Antibiotic susceptibility testing (AST) of isolates to selected antibiotics was performed using the Kirby-Bauer disc diffusion method, while colistin susceptibility testing (CST) was performed using disk elution MIC method. Multidrug resistance (MDR) was defined as resistance of an isolate to antibiotics in three or more classes. Multiple antibiotic resistance (MAR) index was determined as the number of antibiotics to which an isolate was resistant to, divided by the number of antibiotics to which the isolate was tested.
Results: Of the 124 non-duplicate Enterobacter isolates, 8 species were identified; E. cloacae (n=42), E. aero- genes (n=41), E. cloacae subsp dissolvens (n=17), E. gergoviae (n=11), E. quasiroggenkampii (n=4), E. mori (n=3), E. hormaechei (n=3), and E. bugandensis (n=3). Enterobacter spp from water samples were 95.3% and 90.7% sensitive to ciprofloxacin and ceftazidime respectively; those from humans were 95.7% sensitive to amoxicillin-clavulanate, those from goats were 86.4% sensitive to ceftazidime while those from dogs were 92.3% sensitive to amoxicillin-clavulanate and 84.6% sensitive to doxycycline and ceftazidime. The isolates exhibited varying resistance to imipenem, cefoxitin, and streptomycin. Enterobacter isolates from water, human, goat and dog samples had MARI of > 2 in 34.9%, 60.9%, 27.3% and 46.2% respectively, with resistance to 2-6 antibiotics. The MDR rate among Enterobacter isolates was 34.7% (n=43), with 30.2%, 41.3%, 27.3% and 38.5% in isolates from water, human, goat and dog samples respectively. Colistin-resistant rates in Enterobacter isolates from water, human, goat and dog samples were 25.6%, 28.3%, 27.3% and 38.5%, respectively, with E. cloacae, E. aerogenes and E. dissolvens being the most colistin-resistant isolates. Mcr-1 gene was detected in colistin-resistant isolates from samples in two of the six rural communities (Ikot Abasi and Uruan) in the State.
Conclusion: The findings of this study underscore the need for continuous surveillance to monitor resistance patterns and implementation of antibiotic stewardship and infection control policies to prevent the emergence and spread of resistant strains in the community.
Keywords: Colistin resistance, Enterobacter spp., Multidrug-resistance, water, faecal, samples
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