Occurence of Beta-Lactamases in Escherichia Coli and Klebsiella Species isolated from Environmental Sources and Hospital Patients in Nsukka, Enugu State

Abstract

The increase in β-lactamase producing Enterobacteriaceae particularly Escherichia coli and Klebsiella species is currently posing a serious public health problem. A total of 179 isolates of Escherichia coli and Klebsiella species from various environmental and hospital samples were screened in this study. Antimicrobial drug susceptibility testing was carried out in all the isolates by disc diffusion method. High level of antimicrobial resistance was noticed in test organisms against some of the antimicrobial drugs: Ampicillin (83.3% and 83.4%), Augumentin (77.3% and76.1%), and low level of resistance was observed against imipenem (1.5% and 6.2%), Ofloxacin (42.4% and48.1%) and Nitrofuration (45.5% and45.1%) from environmental and clinical isolates respectively. None of the isolates were susceptible to any of the antimicrobial drugs used. The multiple antibiotics resistance (MAR) indexing was found to be very high, indicating that the organisms originated from high risk sources of drug resistant organisms. Beta-lactamase (β-lactamase), Extended spectrum beta-lactamases (ESBLs) and Metallo beta-lactamases (MBLs) were detected by Nitrocefin test, Double disc synergy test and EDTA Double Disc Synergy test respectively. The overall prevalence rate of β-lactamase, ESBLs and MBLs was 36.4% and 45.1%, 18.2% and 29.2%, 1.5% and 6.2% from environmental and clinical isolates respectively. The prevalence of β-lactamase and ESBLs was high in Escherichia coli (39.5% and 18.4%), (47.1% and 30.3%) from environmental and clinical isolates respectively, while MBLs producers were detected more in clinical isolates of Klebsiella species (10.6%). Only one (1.5%) environmental isolate of Escherichia coli was MBL producer. Distribution of β-lactamase producers varied among Escherichia coli and Klebsiella species, but was more prevalent in sewage (89.5%) and urine (86.7%) in environmental and clinical samples respectively. Furthermore, high prevalence (55.3% and 36.8%) of β-lactamase and ESBLs was recorded in male patients when compared to their female counterparts (40% and 25.3%). MBLs recorded higher in females (6.7%) than in males (5.2%). Distribution of β-lactamase producers among patients of different age groups showed the highest prevalence (68.4%) among 41-50 year age group while ESBLs and MBLs showed high prevalence (50.0% and 33.3%) in organisms isolated from individuals 51 years and above. Some of the isolates were also subjected to plasmid DNA profiling using agarose gel electrophoresis (AGE), and the presence of plasmid which molecular weight clustered around 24.7kb for Escherichia coli and 23.1-50.2kb for Klebsiella species were observed in isolates from environmental sources while 24.7- 29.5kb for Escherichia coli and 23.2- 32.5 kb for Klebsiella species were noticed in isolates from clinical samples. No significant (p>0.05) difference among the isolates from environmental and clinical sources was observed regarding the prevalence rate of β-lactamases. The results of this study show that both hospital and community environments harbour β- lactamase producing strains of Escherichia coli and Klebsiella species. This has obvious public health implication.