Multidrug-Resistant Listeria Species Shows Abundance in Environmental Waters of a Key District Municipality in South Africa.

Liyabona Mpondo,Anthony Ifeanyi Okoh,Kingsley Ehi Ebomah

doi:10.3390/ijerph18020481

Abstract

The prevalence of bacteria with multidrug-resistance (MDR) is a significant threat to public health globally. Listeria spp. are naturally ubiquitous, with L. monocytogenes particularly being ranked as important foodborne disease-causing microorganisms. This study aimed to evaluate the incidence and determine the antimicrobial resistance (AMR) profiles of multidrug-resistant Listeria spp. (MDRL) isolated from different environmental samples (river and irrigation water) in the Sarah Baartman District Municipality (SBDM), Eastern Cape Province (ECP), South Africa. Molecular identification and characterization were carried out using polymerase chain reaction (PCR) and isolates that exhibited phenotypic resistance were further screened for relevant antimicrobial-resistant genes (ARGs). Findings revealed a total of 124 presumptive Listeria isolates; 69 were molecularly confirmed Listeria species. Out of the confirmed species, 41 isolates (59%) were classified as L. monocytogenes while 9 (13%) were classified as L. welshimeri. All Listeria spp. exhibited phenotypic resistance against ampicillin, penicillin, and trimethoprim-sulphamethoxazole and further screening revealed ARGs in the following proportions: sulI (71%), blaTEM (66%), tetA (63%), and blaCIT (33%). Results confirmed the occurrence of ARGs among Listeria inhabiting surface waters of ECP. The present study indicates that the river water samples collected from SBDM are highly contaminated with MDRL, hence, constituting a potential health risk.

Highlights

Accepted: 3 January 2021Genus Listeria is made up of a group of small rod-shaped, non-spore-forming, facultative anaerobic microorganisms that belong to the family Listeriaceae
The results showed that the standard plate count for Listeria spp. obtained from the river samples collected from Bloukrans River access point one (BRT) and Bloukrans River access point two (BRD) ranged from 3.49–3.88 log10 CFU/100mL
extended-spectrum beta-lactamases (ESBL) encoding genes harbored by Listeria spp. recovered from the aquatic environment in South Africa. The findings of this current study revealed the presence of Listeria spp. in river water and irrigation water samples

Summary

Introduction

Genus Listeria is made up of a group of small rod-shaped, non-spore-forming, facultative anaerobic microorganisms that belong to the family Listeriaceae. These bacterial species are motile and capable of thriving at low temperatures and in harsh conditions [1,2]. The genus Listeria contains 20 major species including L. welshimeri, L. grayi, L. marthii, L. seeligeri, L. ivanovii, L. innocua, and L. monocytogenes and these microbes are present within various environmental niches including soil, vegetables, water, wastewater, and animal feces [3]. Among the common Listeria spp., L. ivanovii and L. monocytogenes are both considered as relevant animal and human pathogens. L. monocytogenes is regarded as the third most common foodborne pathogen causing infections in individuals with higher risk, for instance, elderly and immune-compromised people, as well as pregnant women [16]

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