Bacteriological analysis of the water samples such as heterotrophic counts, coliform counts, Faecal Coliform/Faecal Streptococci (FC/FS) ratio were carried out following standard procedures. Gram-negative bacteria and Gram-positive Staphylococcal species were identified using ID 32E and Microbact 12S kits respectively. Susceptibility of the isolates to ceftazidime, ceftriaxone, cefuroxime, erythromycin, gentamicin, amoxycillin/clavulinate, cloxacillin, ampicillin, ciprofloxacin, ofloxacin and nitrofurantoin were carried out using the agar diffusion method. Susceptibility of the isolates to Dettol®, Savlon® and Izal®was also determined using agar dilution method. Resistant bacteria were subjected to molecular analysis to further ascertain their status.Physicochemical properties of the river water such as pH, temperature, electrical conductivity, dissolved oxygen (DO), biochemical oxygen demand (BOD), chemical oxygen demand (COD), total solids (TS), total suspended solids (TSS), hardness, sulphate, chloride, nitrates and alkalinity were analysed using standard methods. Elemental analyses of water samples and bottom soil sediments were carried out using Atomic Absorption Spectrometer (AAS). Analysis of variance (ANOVA) was carried out on the elemental data to determine the level of impact of the wastes on the river water quality. The study revealed generally high levels of heterotrophic and coliform counts throughout the year with sampling point P1 around farmland having the highest counts and P4 on the stream that carried effluents from Sokoto Cement Factory, having the least. FC/FS ratios were generally very high (above 4.0). Of the 434 bacteria isolated, E. coli among the Enterobacteriaceae was highest (11.98%).Pseudomonas aeruginosa(7.37%) constituted the majority of non-EnterobacteriaceaeGram-negative organisms whileStaphylococcus aureus(6.91%) was the highest among the Gram-positive organisms. The antibiotic susceptibility profiles showed that most of the Enterobacteriaceae isolates (˃60%) were sensitive to ceftazidime, gentamicin, amoxycillin/clavulinate, the quinolones (ofloxacin, cloxacillin, ciprofloxacin) and nitrofurantoin. Among the non-fermenting Gram negative isolates, Elizabethkingia meningoseptica were most susceptible to the various test antibiotics, ranging from 68.5% to 100% except with erythromycin, having 50% efficacy. Staphylococcus cohnii, among the Gram-positive isolates were the most susceptible to the various test antibiotics, ranging from 75% to 100% except with cefuroxime, cloxacillin, ciprofloxacin and ampicillin, having 50% efficacy. Multiple antibiotic resistance was shown by 91.30% of Shigella flexneri, 37.50% of Pseudomonas aeruginosaand 50% of Staphylococcus cohnii. The MIC values of the test disinfectants (Dettol®, Savlon® and Izal®) against the isolates showed that the mean MICs of Dettol® and Savlon® were higher for Enterobacteriaceae compare with other Gram-negative organisms with Enterobacter aerogenes having the highest values of 2.50 and 3.00 respectively. The β-lactam (blaTEM), virulence (spvC) and quinolones (qnrS) resistance genes were detected in Pseudomonas aeruginosa while aminoglycosides and quinolone resistance genes (aacC3 and qnrS) were detected in Klebsiella pneumoneae.Physicochemical parameters show varying with changes in the season. Sampling point P1 hadthe highest values for DO, BOD, COD, TDS and TSS in the dry and rainy seasons while P4 had the highest electrical conductivity value in the rainy season. Concentration of nitrate, ammonia and chloride in the water samples increased and decreased for sulphate and phosphate in the rainy season.AAS analyses of water and bottom soil sediment samples showed that 18 elements were detected, of which five namely Fe, Ag, Cd, Hg and Pb had concentrations above WHO limits. One way ANOVA test of the elemental concentrations of water samples and bottom soil sediments showed that concentrations of Zn, Ag, Cd, Cr, Mn, Fe, Co and Pb were more in sediment than in water. Generally, water of River Sokoto failed both bacteriological and physicochemical tests and therefore not fit for domestic, industrial and agricultural purposes.
BACTERIOLOGICAL AND PHYSICOCHEMICAL IMPACT ASSESSMENT OF INDUSTRIAL AND DOMESTIC WASTES ON RIVER SOKOTO