Antibiotic resistance profile and phenotypic detection of beta-lactamase-producers among gram-negative bacteria isolated from the gut of household cockroaches in and around University Of Ibadan

Abstract

Background: Cockroaches are carriers of numerous microorganisms. However, there is paucity of information on their role as potential reservoir for beta-lactamase  producers.
Objectives: This research determined the antibiotics susceptibility profile of Beta-lactamase producing Gram-negative bacteria isolated from the gut of  household cockroaches in selected locations in and around University of Ibadan, Oyo state.
Materials and Methods: Thirty Cockroaches from different locations in and around University of Ibadan were collected between June 2015 and March, 2016, and their intestinal homogenates cultured on different selective media for the isolation of  bacteria. The isolates were identified using a combination of biochemical tests and 16S rRNA sequencing. Antibiotic susceptibility testing was done using the  disc-diffusion technique and phenotypic detection of extended-spectrum  beta-lactamase (ESBL), AmpC-beta-lactamase (AmpC) and Metallo- beta-lactamase (MBL) production was done using double-disc synergy,  cefoxitin/cloxacillin and imipenem/EDTA double-disc methods respectively.
Results: A total number of 58 bacteria belonging to nine genera; Pseudomonas, Proteus, Klebsiella, Salmonella, Enterobacter, Escherichia, Serratia, Shigella and Raoultella were isolated. Higher percentage of the isolates exhibited resistance to  erythromycin (90%), azithromycin (87.5%), amoxicillin (84.5%), ampicillin  (74.1%), amoxicillin-clavulanic acid (74.1%), cefoxitin (67.2%) and  chloramphenicol (54%), while lower percentage showed resistance to aztreonam (25%), ertapenem (13%), cefotaxime (8.6%), ceftazidime (10.3%), cefepime (5.2%), ciprofloxacin (3.5%), gentamicin (5.2%) and imipenem (0%). MDR  phenotype was recorded among 82% of the isolates, 17.2% were positive for ESBL, 12% for AmpC and 13.8% for MBL production.
Conclusion: This study identified household cockroaches Periplaneta americana, as a potential reservoir for MDR and beta-lactamase-producing isolates.

Keywords: Susceptibility testing, ESBL, AmpC, MBL, Beta-Lactamase, MDR, Household cockroaches