Occurrence of antibiotic resistant bacteria in waste site of Ede south west Nigeria
Institute of Ecology and Environmental Studies, Obafemi Awolowo University, Ile-Ife, Nigeria
(Received: June 19, 2007; Revised received: November 30, 2007; Accepted: December 05, 2007)
Abstract: Analysis of antibiotic resistant bacteria from composted waste site soil samples for two seasons were done, using prepareddiagnostic test agar and direct sensitivity tests. All major isolated bacteria were subjected to various antibiotics. Concurrent positive andnegative tests were simultaneously studied. Results show relatively high resistant and sensitive bacteria in both seasons. In wet seasons,the Bacillus cereus concentrations are considerably reduced than in the dry. In the dry seasons, Bacillus cereus was sensitive toErythromycin (ERY) and Tetracycline (TET) and slightly resistant to Ampicillin (AMP), Chloramphenicol (CHL), Cloxacillin (CXC) andwater (CNT). In the wet season, identified Pseudomonas aeruginosa was moderately resistant to Streptomycin (STR) and Tetracycline andremained resistant to Ampicillin, Cotrimoxazole (COT), Nitrofurantion (NIT) and water (CNT). The implications for human health arediscussed.
Key words: Antibiotic, Resistance, Heterotrophic, Sensitivity, BacteriaPDF of full length paper is available with author (*[email protected])
The proportion of time spend in-doors is greater for children
Study area: The study area Ede in south west Nigeria was
and healthy mothers (Simecox et al., 1995; Whitmore et al., 1994),
chosen because of its relative by high population of about 145,000.
but in Nigeria it is contrary because of self employment. People
The population figure has direct relationship with the volume of
spread their wares on the common public sites. As a result children
solid wastes generated (NEST, 1991) as a medium town with
and adults get infected via air borne bacteria, food, dermal contact
same characteristics as other medium cities in Nigeria. The
geography and topography are described in Fig. 1. Compostedmunicipal soil, samples were collected in dry (Nov. 2004 - Feb.
The burden of improper disposal method has not been
2005) and wet seasons (June-Sept. 2005) from the general
rigorously assessed in terms of mutagenicity, otherwise proper method
common site located along “Awo Town junction” from four different
of waste management might be altered if risks were adequately
locations. Three of the sites were chosen as the relatively high-
addressed and analyzed. Nigeria is a typical developing nation at a
use study site while the fourth was chosen as the low-use site.
cross road because of growing population and consumption patternswhich invariably compound the problem of waste collection and disposal.
Total heterotrophic bacteria (TAB) count: Multiple portions of
The magnitude of solid waste problem is worsening and the government
soil samples were suspended in distilled deionized water. A 100
at various levels failed to address and seek modern waste management
fold serial dilution of the mixture (1 ml) was plated in duplicate in a
study that will correctly analyze the waste composition characteristics
sterile nutrient agar medium. The culture plates were incubated
and generation rate is lacking (Nwankwo, 1991).
aerobically at room temperature for 48 hr for isolation of aerobesand causative heterotrophic bacterial present in the samples (Kelly
Indiscriminate dumping of wastes causes traffic obstruction,
intrusion of microbes into the immediate environment and a numberof hazardous diseases. (Achudume and Olawale, 2007). Overall
Antibiotics sensitivity assay: The incubation assay was used to
prevalence and severity of exposure to mutagens may represent a
measure antibiotic sensitivity of the isolated organisms. In general,
risk index for public health Atasoylu et al. (2007). The used antibiotics
100µl of the isolated bacterial suspension (1x108) cells was placed
syringes from various origins (agricultural, hospitals/clinics and
in glass reaction tube. Using prepared diagnostic test (DST) agar,
pharmaceutical industries) are dumped on waste sites and this has
the selected bacteria were subjected to various antibiotics, Ampicilin
implication for public health etc. This has implication for public health
(AMP), Chloramphenicol (CHC), Cloxacillin (CXC), Erythromycin
specifically mothers and children who holds potential health risk
(ERY), Streptomycin (STR), Tetracycline (TET), Cotrimoxazole
(Achudume and Olawale, 2007). The health implication of bacterial
(COT) and Nitrofurantion (NIT) at recommended concentrations of
sensitivity in waste sites is for sole purpose of hygienic assessment of
100 µl, 250 µl, 50 µl, 100 µl, 250 µl, 100 µl, 250 µl, 250 µl and 400 µl
the local environment from a socio-demographic perspective.
respectively (Stern et al., 1989; Silkowski et al., 1992). For direct
Therefore the primary objective of the present study was to assess
sensitivity tests, the total volume of the reaction tube was brought up
the occurrence of antibiotic resistance bacteria in waste site located
to 600 µl with potassium phosphate buffer. The required numbers of
wells were filled up with appropriate previously prepared antibacterial
Journal of Environmental Biology March, 2009
Table - 1: Mean and standard deviation of antibiotic patterns of isolated and type culture of heterotrophic bacteria (HTB) in dry season
All experiments were in triplicate. NCIB - National collection of industrial bacteria, R - Resistant, S - Sensitive, SR - Slightly resistant
Table - 2: Mean and standard deviation of antibiotic sensitivity patterns of isolated and type culture of heterotrophic bacteria (HTB) in wet season
All experiments were in triplicate. NCIB - National collection of industrial bacteria, R - Resistant, S - Sensitive, SR - Slightly resistant
solution. Concurrent positive controls consisted of potassium
to Erythromycin (ERY), moderately resistant to Streptomycin (STR)
phosphate buffer in nutrient agar medium. While concurrent negative
and resistant to Ampicilin (AMP), Chloramphenicol (CHL),
test consisted of dimehyl sulfoxide (DMSO) as solvent or isolates
Cloxacillin (CXC) and water (CNT), while its typed culture NCIB
mixed with the solvent in a range of microlitre amounts. All broth
4349 was sensitive Erythromycin (ERY), moderately resistant to
culture of each test organism was done in triplicate.
Streptomycin (STR) and Tetracyclin (TET) and showed resistance toAmpicillin (AMP), Choramphenicol (CHL), Cloxacillin (CXC) and water
The culture media efficiency test was carried out with standard
(CNT). Klebsiella penumoniae was sensitive to Ampicillin, Tetracyclin
strains of Pseudomonas aeruginosa NCIB 950, Bacillus cereus NCIB
and Nitrofurantoin, moderately resistant to Streptomycin and resistant
6349, and Klebsiella pneumoniae NCIB 418. These components
to Cotrimoxazole and water. The type culture NCIB 418 was moderately
were incubated at 37oC for 48 hr. The relative susceptibility of test
resistant to Ampicillin, Streptomycin, sensitive to Tetracyclin and
organism was recorded. The means and their SD in the results were
Nitrofurantoin and resistant to Cotrimoxazole and water (Table1).
subjected to the test of significance by student’s t-test.
Composted waste soil contained large fraction of detectable
level of antibiotic resistant bacteria particularly in wet season.
Summary statistics for two groups of isolated heterotrophic
Antibiotic products, and other toxic wastes are discharged in various
bacteria for dry and wet seasons are given in Table 1 and 2
amount in the environment as a result of the increasing and often
respectively. Soils from high-use and low-use dumping sites were
indiscriminate use of antibiotics in homes, animals farming and clinics
analysed for antibiotic resistance bacteria using standard culture
(Karlowsky et al., 2003). The main receptacles for these pollutants
techniques. Analyses of the samples show relatively high number of
are the waste dumps and the common sites.
resistant bacteria in both seasons. The concentrations of bacteriarecovered in wet season samples were more than in dry season
Table 1 and 2 show different species of specific resistant
samples. The results indicate both antibiotic sensitive and resistant
bacteria. Generally these bacteria are normally found below infection
patterns of isolated and type culture of heterotrophic bacteria in
levels in the environment, but when their concentration increases
varying seasons. Besides, the sensitivity ranking and significant
they can infect innocent persons working in nearby areas. These
interspecies were found in the type culture.
bacteria from garbage and trash causes several problems in humanbeings like of respiratory, cardiovascular and immune systems
A chart consistent for screening sensitivity, resistance and
disorders and cancer in lungs liver and other vital organs of
monitoring phase of the study guides each assessment. In dry season
vulnerable persons (Kelly et al., 1999).
Bacillus cereus was sensitive to Erythromycin (ERY) and Tetracyclin(TET), moderately resistance to Streptomycin (STR) and resistant
Most investigations on antibiotic resistance in the ecological
to Ampicillin (AMP), Chloramphenicol (CHL), Cloxacillin (CXC)
habitat are concerned with bacteria of fecal origin, because they are
and water (CNT), while its typed culture NCIB 6349 was sensitive
used as pollution indicators and may be associated with infectious
Journal of Environmental Biology March, 2009
Antibiotic resistant bacteria in waste site
diseases. However, in many dumping sites, fecal bacteria are of little
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Journal of Environmental Biology March, 2009
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