Assessment of the quality indices and prevalence of Escherichia coli pathotypes in selected rivers of Osun state, Southwestern Nigeria
- Authors: Titilawo, Osuolale Yinka
- Date: 2015
- Language: English
- Type: Thesis , Doctoral , PhD (Microbiology)
- Identifier: vital:11295 , http://hdl.handle.net/10353/d1021274
- Description: Surface waters are important freshwater sources used for domestic, industrial, agricultural and recreational activities, and the availability of good quality freshwater is indispensable for preventing water-borne diseases and improving quality of life especially in communities that lack pipe-borne water. Water samples were collected from ten rivers at different locations in Osun State, Southwestern Nigeria. A total of 12 physicochemical parameters, counts of total coliforms (TC) and Escherichia coli isolates were determined using standard analytical procedures. Confirmed Escherichia coli isolates (n=300) were assessed for the presence of 10 virulence genes (VGs) associated with Escherichia coli strains causing intestinal and extra-intestinal infections. The recovered Escherichia coli isolates were elucidated for their antibiogram profiling by disk diffusion method and the resistant isolates were further profiled for their genotypic antimicrobial resistance by polymerase chain reaction technique. The physicochemical qualities ranged as follows: pH (6.9 - 7.6), temperature (26 – 29 ºC), turbidity (2.28 – 9.46 NTU), electrical conductivity (229 – 581 μS/cm), nitrate (0.03 – 0.05 mg/L), nitrite (0.00 – 0.01 mg/L), sulphate (3.33 – 20.33 mg/L), chloride ions (7.83 – 27.33 mg/L), dissolved oxygen (4.23 – 5.57 mg/L), total dissolved solids (56 – 184 mg/L), total hardness (78 – 519 mg/L) and alkalinity (50.67 – 146.67 mg/L). Statistical analysis showed that pH, temperature, electrical conductivities, nitrates, nitrites, chloride, dissolved oxygen, total dissolved solid, total hardness and alkalinity were significantly different (P < 0.05), whereas turbidity and sulphate were not significantly different (P ˃ 0.05) from each parameter with respect to sampling sites. While the VG lt for enterotoxigenic E. coli had the highest prevalence of 45%, the enteropathogenic E. coli genes eae and bfp were detected in 6% and 4% of the isolates respectively. The VGs stx1 and stx2 specific for the enterohemorrhagic E. coli pathotypes were equally detected in 7% and 1% of the isolates respectively. Also, the VG eagg harboured by enteroaggregative pathotype and diffusely-adherent E. coli VG daaE were detected in 2% and 4% of the isolates respectively and enteroinvasive E. coli VG ipaH was not detected. In addition, the VGs papC for uropathogenic and ibeA for neonatal meningitis were frequently detected in 19% and 3% of isolates respectively. While all the isolates tested were susceptible to imipenem, meropenem, amikacin and gatilofloxacin, others were variously susceptible, and resistant as follows; ciprofloxacin (96%), kanamycin (95%), neomycin (92%), streptomycin (84%), chloramphenicol (73%), nalidixic acid (66%), nitrofuratoin (64%), gentamycin (63%), doxycycline (58%), cefepime (57%), tetracycline (49%) and cephalothin (42%). Conversely, all the isolates were resistant to sulphamethoxazole, and high levels of resistance were equally observed against amoxycillin (59%), ampicilin (57%) and cefuroxime (40%). Cefepime, cephalothin, cefuroxime, nalidixic acid, nitrofuratoin, chloramphenicol and tetracycline were not significantly different in their effect against the isolates from all locations (P > 0.05), whereas the resistance profile of the isolates against gentamycin, ciprofloxacin, sulphamethoxazole, ampicillin and amoxicillin were significantly different (P < 0.05). Amikacin, kanamycin, streptomycin, meropenem, imipenem and gatilofloxacin were statistically excluded from the analysis since all tested isolates showed total susceptibility to these antimicrobials. The multiple antibiotic resistance indexing ranged from 0.50 to 0.80 for all the sampling locations and exceeded the threshold value of 0.2. Prevalence and distributions of the 19 resistance determinants assessed were obtained as follows; [sulfonamides (sulI (8%), sulII (41%)], [beta-lactams; (ampC 22%; blaTEM, (21%), blaZ (18%),], [tetracyclines (tetA (24%), tetB (23%), tetC (18%), tetD (78%), tetK (15%), tetM, (10%)], [phenicols; (catI (37%), catII (28%), cmlA1 (19%)] and [aminoglycosides; (aacC2 (8%), aphA1 (80%), aphA2 (80%), aadA (79%) and strA (38%)]. The Pearson chi square exact test revealed many strong significant associations among ampC, blaTEM, blaZ and tetA genes with some determinants screened. In the same vein, a grand total of 366 resistance gene fingerprints were spotted across the sampling locations and among the resistant pathotypes, the modal prevalent gene prints were found among the ETEC strains in 148 (40%), being the predominant pathotype observed, followed by UPEC strains 80 (22%) while the lowest was the least occurring EAEC pathotype 14 (4%). While some physicochemical parameters exceeded prescribed standards for drinking water, some fell within. The total coliforms obtained in all the sampling sites were above the acceptable limits. Findings reveal the presence of diarrhoeagenic and non-diarrhoeagenic E. coli in the selected rivers and suggest a potential public health risk as the rivers are important resources for domestic, recreational and livelihood usage by their host communities. The multiple drug resistance indexing signifies isolates and pathotypes of high antimicrobial usage origin. An increase in the antimicrobial resistance signatures towards conventionally used antibiotics as observed in this study necessitates for safe water supply, adequate sanitation facilities and proper surveillance programs towards the monitoring of antimicrobial resistance determinants in water-bodies. Generally, results from this study indicate that the river waters are not suitable for consumption, domestic or recreational use and re-echo the importance of safeguarding the freshwater resources of Southwestern Nigeria.
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Evaluation of the quality indices of the final effluents of two wastewater treatment plants in buffalo City Metropolitan Municipality in the Eastern Cape Province
- Authors: Osuolale, Olayinka O
- Date: 2015
- Language: English
- Type: Thesis , Doctoral , PhD (Microbiology)
- Identifier: vital:11292 , http://hdl.handle.net/10353/d1021079
- Description: Waste waters can be sources of pollution to surface water and the environment with severe implications for public health. Most treatment plants in the Buffalo City Municipality in the Eastern Cape Province discharge their treated effluent into the surface waters which directly and indirectly impacts on the quality of surface waters in the region. The objective of this study was to determine the microbiological and physicochemical qualities of the final effluents of two wastewater treatment plants in the Buffalo City Municipality in the Eastern Cape Province of South Africa over a period of 12 months (September 2012 to August 2013). The qualities of the final effluents of WW-Ama Wastewater Treatment Plant with respect to phosphate (3.9 mg/l - 20.6 mg/l), free chlorine (0.05 mg/l - 0.71 mg/l), chemical oxygen demand (COD) (4.7 mg/l - 211 mg/l), and faecal coliform (0 - 2.92 × 104 CFU/100 ml) were not in compliance with the permissible limits set for effluent discharged to surface water by South Africa guidelines for effluent discharge. Other physicochemical parameters like biological oxygen demand (BOD) (2.2 mg/l - 9.0 mg/l), total dissolve solid (TDS) (253 mg/l - 336.3 mg/l) and turbidity (4.8 NTU - 43.20 NTU) with no SA regulatory set limits were compared to other regulatory standards and they do not comply with the limits. Also, at the second WWTP’s, the WW-Dim Treatment Plant effluent quality for free chlorine (0.06 mg/l - 7.2 mg/l), BOD (0.1 mg/l - 7.4 mg/l), and turbidity (4.02 NTU - 24.3 NTU) also did not comply. For microbiological qualities, counts of presumptive E. coli and Vibrio ranged between 0 - 2.92 × PROFESSOR ANTHONY I. OKOHAntibiogram of the bacterial isolates were determined using the disk diffusion method. A total of 107 confirmed E. coli and 100 confirmed Vibrio spp. were used for this assay. Results of antibiotic sensitivity test revealed that 63.6% of the E. coli isolates were resistance to ampicillin while 49.5% were resistant to tetracycline and cephalothin. The least resistances were observed against gentamicin (3.7%) and cefotaxime (1.9%). No resistance was observed against meropenem. For the Vibrio spp, resistance was most frequently observed against tetracycline (38%) ampicillin (26%), chloramphenicol (16%), cefotaxime (14%), trimethoprim-sulfamethoxazole (13%) and the least resistance observed was against ciprofloxacin (1%). This study demonstrates that poorly treated wastewater effluent can be a source of eutrophic water with high nutrient levels and pathogenic bacteria and enteric viruses as well as antibiotic resistance determinants that could impact negatively on human health. The finding of this study also suggests that WWTPs have to be properly monitored and controlled to ensure compliance to set guidelines. This could be attained through the application of appropriate treatment processes, which will help to minimize possible dangers to public environment health.
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