Diverse and abundant multi-drug resistant E. coli in Matang mangrove estuaries, Malaysia

Abstract

E.coli, an important vector distributing antimicrobial resistance in the environment, was found to be multi-drug resistant, abundant, and genetically diverse in the Matang mangrove estuaries, Malaysia. One-third (34%) of the estuarine E. coli was multi-drug resistant. The highest antibiotic resistance prevalence was observed for aminoglycosides (83%) and beta-lactams (37%). Phylogenetic groups A and B1, being the most predominant E. coli, demonstrated the highest antibiotic resistant level and prevalence of integrons (integron I, 21%; integron II, 3%). Detection of phylogenetic group B23 downstream of fishing villages indicates human fecal contamination as a source of E. coli pollution. Enteroaggregative E. coli (1%) were also detected immediately downstream of the fishing village. The results indicated multi-drug resistance among E. coli circulating in Matang estuaries, which could be reflective of anthropogenic activities and aggravated by bacterial and antibiotic discharges from village lack of a sewerage system, aquaculture farms and upstream animal husbandry.

Keywords: E. coli; Matang mangrove estuaries; antibiotic resistance; phylogenetic groups.

Figure 1

Locations of eight sampling stations (A–H) along Sepetang, Sangga Besar and Selinsing rivers in Matang Mangrove Forest Reserve, Perak, Malaysia.

Figure 2

Distribution of the E. coli phylogenetic groups in eight different stations located in Sepetang River (A), Sangga Besar River (B–E) and Selinsing River (G and H) and coastal waters (F), (a) distribution of E. coli according to the respective phylogenetic groups (A, B1, B2, D) and (b) according to phylogroup subtyping (A0, A1, B1, B21, B22, D1, D2).

Figure 3

PCA ordination biplot showing the distribution of E. coli phylogenetic groups by sampling stations with respect to their resistance to various antibiotics and the integras genes they carried. The first (PCA1) and second (PCA2) principal components respectively explained 70.7 and 8.6% of the total variance of the explanatory variables. Phylogroups are denoted by various symbols: black circle A, pink square B1, empty square B2 and empty diamond D. Bold letter beside symbol denotes sampling stations located in Sepetang River (A), Sangga Besar River (B–E), Selinsing River (G and H) and adjacent coastal water (F). Black solid arrows indicate isolates resistant to 15 antibiotics: Class I (black box), CN, aminoglycosidase: gentamicin; K, kanamycin; S, streptomycin; N, neomycin; Class II (gray box); AMC, β-lactams: amoxicillin/clavulanic acid; AMP, ampicillin; CRO, ceftriaxone; EFT, ceftiofur; Class III (blue box); ENR, fluoroquinolone: enrofloxacin; CIP, ciprofloxacin; Class IV (yellow box); NA, quinolones: nalidixic acid; OA, oxolinic acid; Class V; TE, tetracycline: tetracycline; Class VI; C, phenicols: chloramphenicol and Class VII; SXT, sulfamethoxazole/trimethoprim. Red dotted arrows indicate E. coli integron gene (s).