Prevalence of tetracycline resistance genes among multi-drug resistant bacteria from selected water distribution systems in southwestern Nigeria

Abstract

BackgroundAntibiotic resistance genes [ARGs] in aquatic systems have drawn increasing attention they could be transferred horizontally to pathogenic bacteria. Water treatment plants (WTPs) are intended to provide quality and widely available water to the local populace they serve. However, WTPs in developing countries may not be dependable for clean water and they could serve as points of dissemination for antibiotic resistant bacteria. Only a few studies have investigated the occurrence of ARGs among these bacteria including tetracycline resistance genes in water distribution systems in Nigeria.MethodologyMulti-drug resistant (MDR) bacteria, including resistance to tetracycline, were isolated from treated and untreated water distribution systems in southwest Nigeria. MDR bacteria were resistant to >3 classes of antibiotics based on break-point assays. Isolates were characterized using partial 16S rDNA sequencing and PCR assays for six tetracycline-resistance genes. Plasmid conjugation was evaluated using E. coli strain DH5α as the recipient strain.ResultsOut of the 105 bacteria, 85 (81 %) and 20 (19 %) were Gram- negative or Gram- positive, respectively. Twenty-nine isolates carried at least one of the targeted tetracycline resistance genes including strains of Aeromonas, Alcaligenes, Bacillus, Klebsiella, Leucobacter, Morganella, Proteus and a sequence matching a previously uncultured bacteria. Tet(A) was the most prevalent (16/29) followed by tet(E) (4/29) and tet30 (2/29). Tet(O) was not detected in any of the isolates. Tet(A) was mostly found with Alcaligenes strains (9/10) and a combination of more than one resistance gene was observed only amongst Alcaligenes strains [tet(A) + tet30 (2/10), tet(A) + tet(E) (3/10), tet(E) + tet(M) (1/10), tet(E) + tet30 (1/10)]. Tet(A) was transferred by conjugation for five Alcaligenes and two E. coli isolates.ConclusionsThis study found a high prevalence of plasmid-encoded tet(A) among Alcaligenes isolates, raising the possibility that this strain could shuttle resistance plasmids to pathogenic bacteria.

Molecular characterization of selected multidrug resistant Pseudomonas from water distribution systems in southwestern Nigeria

“…Similarly, tetracycline resistance gene has also not been described in among Pseudomonads from Nigeria. Although our recent report [ 28 ] stated the occurrence of tet (E), tet (M), tet (30) among Alcaligenes , tet (E) in Aeromonas and Klebsiella , tet (B) in Bacillus and Leucobacter from these water distribution systems. Absence of tet (B) but highest occurrence of tet (A) which are both efflux pump genes in these pseudomonads is contrary to the report of Shababi et al [ 29 ] who reported more prevalence of tet (B) than tet (A) in their studies among MDR P. aeruginosa from municipal sewage.…”

Antimicrobial susceptibility, phylotypes, and virulence genes of Escherichia coli from clinical bovine mastitis in five provinces of China

“…Therefore, it can be speculated that the E. coli strains showed a high resistance to amoxicillin. Resistance rates towards tetracycline were 9.0% in the European Union (Thomas et al, 2015), 14.3% in Canada (Saini et al, 2012), and 55.1% in Southwestern Nigeria (Adesoji, Ogunjobi, Olatoye, & Douglas, 2015). Moreover, 34.8% isolates had MDR (Figure 1).…”

Detection of Extended Spectrum Beta-Lactamases Resistance Genes among Bacteria Isolated from Selected Drinking Water Distribution Channels in Southwestern Nigeria

“…These were subsequently transferred to Nutrient agar slants and also stored in phosphate buffer glycerol at −80°C [ 3 – 5 ]. Molecular characterization of bacteria using 16S rDNA sequencing was determined as described in Adesoji et al [ 11 ].…”

“…Antibiotics concentrations used for Gram-positive bacteria include sulfamethoxazole (512 μ g/mL), ampicillin (0.5 μ g/mL), tetracycline (16 μ g/mL), sulfamethoxazole/trimethoprim (76/4 μ g/mL), gentamycin (16 μ g/mL), erythromycin (8 μ g/mL), rifampin (4 μ g/mL), lincomycin (4 μ g/mL), and ciprofloxacin (4 μ g/mL). Negative and positive controls used were E. coli strain K12 and E. coli strain H4H, respectively, as we described in our previous studies [ 3 – 5 , 11 ].…”