Detection of ESBL, AmpC, and MBL-Producing Chryseobacterium indologenes Isolates Recovered from Hospital Environment in a Tertiary Health Care Facility

Abstract

Objective: Chryseobacterium indologenes are aerobic, Gram negative, non-fermentative rods that are intrinsically multidrug-resistant. Although an uncommon environmental pathogen, C. indologenes has been implicated recently in nosocomial infections and very resistant to plethora of antibiotics. The aim of this study is to phenotypically determine the occurrence of extended spectrum beta-lactamase (ESBL), cephalosporinase (AmpC) and metallo-beta-lactamase (MBL) production in isolates of Chryseobacterium indologenes recovered from hospital environment. Material and Methods: Hundred and eight (104) environmental samples were collected from different inanimate sources from hospital wards out of which fourteen (14) of them were from the floors and sixteen (16) of them from sinks. The isolates were identified and characterized using a commercial test kit, API 20NE® BioMerieux, France following preliminary isolation and identification on three culture media. The identified bacteria subsequently were subjected to Antimicrobial Susceptibility Testing using Kirby Bauer agar disk diffusion method according to CLSI standard. Extended spectrum β-lactamase production was determined phenotypically by Double Disc Synergy Test (DDST) using Ceftazidime and Cefotaxime alone and in combination with Clavulanic acid. AmpC production was also determined using Cefoxitin and Ceftazidime – Double Disk Synergy Test (CC-DDST) and Ceftazidime-Imipenem antagonistic test (CIAT) methods so as to detect both inducible and constitutive AmpC production, whereas MBL detection was done by Imipenem EDTA Combined Disc Diffusion Test and using Modified Hodges Test (MHT). Results: Of the twenty isolates recovered, two (47.8%) of the bacteria isolated were C. indologenes. The two non-duplicate isolates were recovered from the floor and a sink in Paediatrics Ward and Male Surgical Ward respectively. On Mueller Hinton Agar (MHA), the bacteria produced a characteristic yellowish pigmentation. Antimicrobial susceptibility testing (AST) revealed both bacteria as multidrug-resistant to different classes of antimicrobials used against them. The organisms were resistant to Amoxiclav (100%), third generation-cephalosporins (3GC) (100%), monobactam (100%), carbapenems (100%), aminoglycosides (100%), lipopeptides (100%), and glyclycycline (100%) used. However, they were completely susceptible to piperacillin, piperacillin-tazobactam and ciprofloxacin (100%). The isolates also showed a multiple resistance index of 0.8. C. indologenes isolates recovered from hospital environment were found to phenotypically produce β-lactamases including ESBL, AmpC and MBL. Conclusion: The isolation of C. indologenes from hospital environment in this study should be a concern to us as its route into humans may be very lethal considering its multidrug-resistant nature. This study therefore encourages proper infection control measures to be advocated in health facilities, need to maintain good hygiene in hospital environment, as well as regular handwashing so as to minimize or prevent the cross transmission of this pathogen to patients as the resultant effect may be unprecedented. There may also be need for Clinical Microbiologists, Laboratory Scientists and Pathologist to routinely include the isolation and identification of these less reported non-fermenting Gram-negative bacteria in their laboratories.