ISOLATION, CHARACTERIZATION AND ANTIBIOGRAM OF SOME ENTERIC PATHOGENIC BACTERIA FROM WASTE DUMPS IN ZARIA METROPOLIS, NIGERIA
ISOLATION, CHARACTERIZATION AND ANTIBIOGRAM OF SOME ENTERIC PATHOGENIC BACTERIA FROM WASTE DUMPS IN ZARIA METROPOLIS, NIGERIA
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Date
2017-05
Authors
NYANDJOU, YOMI MARIE CAROLE
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Abstract
Refuse dumpsites are found littered both within and on the outskirts of cities in Nigeria; due to poor and ineffective waste management, poised public health concerns and add strain on diminishing land space as well as harboring enteric pathogenic bacteria. This study is aimed at assessing the Temperature and pH conditions of the waste dump sites, estimation of the total aerobic bacterial counts, isolation and characterization of Gram negative aerobic enteric pathogenic bacteria. Five hundred and twenty (520) soil samples were collected from sixteen waste dumps in four locations and a control site in Zaria metropolis. The locations were Tudun-Wada, Zaria city, Sabon-Gari, Samaru and Kabama in the dry and in the wet seasons. Pathogenic bacteria were isolated from the waste dump soil samples on selective culture media. Pure isolates were identified by Gram staining and characterized using both conventional biochemical and Microgen identification, and molecular techniques. Bacterial isolates were subjected to antibiotic susceptibility testing using agar disc diffusion method. Target isolates were molecularly characterized by PCR amplification of the virulence and antibiotic resistance genes, and the closest match of the 16S rRNA genes were determined by similarity searches on the Genbank database. The data for refuse dumps conditions which included temperature and pH were analysed using descriptive statistics. Statistical Analysis System (SAS) version 9.2 package was used in the analysis of data on the bacterial counts at p = 0.05. Zaria City had the highest mean temperature (34.1oC), pH (8.3) and plate counts (3.3x108±1.3x107cfu/g). Bacteriological analysis of the soil samples gave a total of 189 (36.3%) isolates among which 65(12.5%) were identified target isolates. Of these 65 target isolates, 36(6.9%) were Salmonella enterica, 22(4.2%) Escherichia coli O157:H7 and 7(1.4%) Vibrio cholerae non-O1 isolates. Dry season had the highest occurrence of the isolates 37 (14.2%) while the wet season has the least 29 (11. 2%). Escherichia coli O157:H7 and Salmonella enterica were 100% susceptible to Gentamicin (30μg) and Chloramphenicol (30μg) respectively. Vibrio cholerae non-O1 isolates were 85.7% susceptible to Ofloxacin (10μg). Most isolates were resistant to Ampicillin (10μg), Amoxycillin-clavulanic acid (30μg) and Tetracycline (30μg). The Vibrio cholerae non-O1 were 100% resistant to both Ampicillin (10μg) and Cotrimoxazole (25μg). Virulence genes, InvA and Stn was demonstrated in 6(100%) and 5(83.33%) respectively in Salmonella enterica, Stx and hlyA in 5(71.43%) and 4(57.14%) respectively of E. coli O157:H7 and toxR in 6(100%) of Vibrio cholerae non-O1 by PCR. Similarly antibiotic resistant genes tetA, tetB and blaTEM1 was demonstrated in 2(33.33%), 1(16.66%) and 2(33.33%) respectively of Salmonella enterica, tetA
and blaTEM1 in 4(66.66%) and 1(16.66%) of E. coli O157:H7. The BLAST search yielded 13.3% each of the isolates having 98% and 97% homology with Salmonella enterica and E. coli O157:H7 respectively. Five isolates (33.3%) had 96% identity, 4 had 95% and 2 had 94% identity with the organisms in the GenBank. A total of 6 Salmonella serovars and 7 enterohaemorrhagic E. coli were identified among which 5 Salmonella enterica subsp. enterica serovar Typhi, one Salmonella enterica subsp. enterica serovar Typhimurium, 6 enterohaemorrhagic E. coli serogroup O157:H7 and one E. coli serogroup O83:H1. The predominant Salmonella serovars were the typhoidal Salmonellae and the predominant E. coli seroroup were the enterohaemorrhagic E. coli serogroup O157:H7. The most potent antibiotics against the enteric pathogenic bacteria isolates were Gentamicin (30μg) and Chloramphenicol (30μg) followed by Nitrofurantoin (30μg) and Ofloxacin (10μg). Ampicillin (10μg) was the least effective against the isolates. Zaria city was the location with the highest prevalence 26 (25.0%) and multidrug resistant isolates. The presence of multidrug resistant enteric bacterial pathogens suggests that the waste dump soil environment were contaminated with faecal matters and that antibiotics were disposed off indiscriminate. Proper policy should be put in place for waste handlers and those who live in the vicinity of the dumps to safeguard their lives
Description
A DISSERTATION SUBMITTED TO THE SCHOOL OF POSTGRADUATE STUDIES, AHMADU BELLO UNIVERSITY, ZARIA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD OF THE DOCTOR OF PHILOSOPHY DEGREE IN MICROBIOLOGY DEPARTMENT OF MICROBIOLOGY, FACULTY OF LIFE SCIENCES, AHMADU BELLO UNIVERSITY, ZARIA, NIGERIA
Keywords
ISOLATION,, CHARACTERIZATION,, ANTIBIOGRAM,, ENTERIC PATHOGENIC BACTERIA,, WASTE DUMPS,, ZARIA METROPOLIS,, NIGERIA