ABSTRACT
Staphylococcus aureus,
‘one of the most adaptable and virulent pathogens in modern times’ is a
facultative anaerobic Gram-positive coccal bacterium able to infect any tissue
of the human body to cause ailments ranging from minor skin infections to
life-threatening diseases. The bacterium is also known to colonize and infect
both pets and livestock, including dogs, cats, rabbits, horses, cattle and pigs
to result in zoonosis. A major concern is the prevalence of irrepressible
multidrug resistant S. aureus in pets and livestock, as these may serve
as reservoirs for human colonization and compound the problem of emergence
and/or re-emergence of global diseases. This project was designed to assess the
prevalence of multidrug resistant livestock associated S. aureus isolated from nasal passage of healthy cattle in Kara
Market, Ogun state, Nigeria.
A total of 500 nasal samples were collected from
healthy adult cattle (250 from male and 250 from female cattle) but 409 S. aureus isolates were identified(218
from male and 191 from female cattle) by Gram staining and specific biochemical
tests.
The antibiogram of the S. aureus isolates revealed that all the isolates exhibited
multidrugresistance (8/12) to ceftriaxone, gentamicin, cotrimoxazole,
erythromycin, amoxicillin, streptomycin, chloramphenicol and ampicillin, fairly
resistant(3/12) to quinolones but weakly resistant (1/12) to vancomycin. High
minimum inhibitory concentration greater than 128 μg/ml was exhibited by 63.3%
of the isolates against flucloxacillin (methicillin) but 28% of the isolates
were equally resistant (>128 μg/ml) to vancomycin (glycosidic). The in-vitro
combination effect of flucloxacillin and ampicillin on the isolates resulted in
86.3% additive to imply the unsuitability of the combination to effectively
control staphylococcal infections.
Vancomycin was observed to be bactericidal to
livestock associated multidrug and/or methicillin resistant S. aureus in this study. The quinolones
antibiotics (ciprofloxacin, pefloxacin and ofloxacin) are fairly effective
(known to be relatively non-toxic) may be used to complement and/or substitute
toxic antibiotics in curtailing ailment resulting from multidrug resistant S. aureus.
CHAPTER
ONE
INTRODUCTION
1.1
Background to the Study
Cattle are large bodied ruminants that feed on
pastures and forages or fodder. In Nigeria, cattle are reared primarily for
meat which is a veritable source of protein for humans, and for milk (Arowolo et al., 2013). Cattle rearing in Nigeria
is an old occupation which is traditionally practiced by Fulanis and Shuwa
Arabs in northern Nigeria with an extremely few local villages in the southern
Nigeria (Erebor, 2003).
Staphylococcus aureus is
a facultative anaerobic gram-positive coccal bacterium and due to a combination
of numerous bacteria immune-evasive strategies which it uses, it is considered
a successful pathogen. The nasal
passages is considered to be the major habitat (Kluytmans et al., 1997; Lowy, 1998; Lowy, 2003) and the biggest supply of S. aureus in people, yet numerous body
locales can harbor this bacterium (Vandenbergh & Verbrugh, 1999). S. aureus is a typical tenant of the
skin (Lowy, 2003; Williams, 1963), perineum and can likewise be found in the
axillae (Ridley, 1959), vagina (Guinan et
al., 1982) and the gastrointestinal tract (Williams, 1963). S. aureus strains are noteworthy human
pathogens and are conceivably ready in contaminating any human body tissue,
bringing on everything from skin contaminations to life-debilitating
sicknesses. In people, the diseases brought on by S. aureus can be partitioned into these three sorts in general;
shallow sores, (for example, surgical site and wound contaminations), life and
systemic undermining factors, (for example, osteomyelitis, endocarditis,
pneumonia, mind abscesses/wounds, bacteraemia and meningitis), then toxinoses,
(for example, poisonous stun disorder, sustenance harming and singed skin
disorder (Alo et al., 2013; Aires de
Sousa et al., 2004; Lowy, 2003). The
sign of staphylococcal contamination are the boils that contain discharge which
is made up of dead neutrophils, dead and living microbes, tissue (necrotic),
the lysed host substance and bacterial cells. The immunocompetent hosts, as a
rule, effectively clear the disease and deplete the ulcer, though for the
immunocompromised and sporadically for a sound individual, the contamination
might advance to a more profound tissues and turn into a conceivably lethal
intrusive contamination (Norvick, 2006). It is still one of the five most common causes of nososcomial
infections, often causing postsurgical wound infections (Bowersox, 1999). S. aureus is likewise known to colonize
and contaminate both pets and animals, including pooches, felines, rabbits,
stallions, steers and pigs (Morgan, 2008). A noteworthy concern is the nearness
of methicillin safe S. aureus (MRSA)
in pets and domesticated animals, as these may fill in as repositories for
human colonization, an illustration is MRSA ST398 from pigs (Weese, 2010).
The unnecessary
utilization of antibiotics has prompted to the rise of different medication
safe strains of S.aureus (Lowy,
1998). The Penicillin was presented for curing infections caused by S.
aureus in the 1940s, and adequately diminished mortality and
bleakness. Be that as it may, in late 1940s, its resistance because of the
nearness of penicillinase developed (Eickhoff, 1972). The staphylococci are
extremely fit for advancing imperviousness to the regularly utilized
antimicrobials, for example, erythromycin (Walmark & Finland, 1961),
ampicillin (Klein and Finland, 1963), and antibiotic medication (Eickhoff,
1972). Much of the time, imperviousness to antimicrobial agents is coded for by
qualities carried on plasmids, representing the quick spread of resistant
microscopic organisms (Morris et al.,
1998). One purpose behind the proceeding with essential part of S. aureus in illness is its inclination
and propensity to wind up distinctly impervious to antimicrobial (Waldvogel,
2000). S. aureus is presently the
main general reason for nosocomial diseases and, as more patients are dealt
with outside the healing center setting, is an expanding worry in the group
(CDC NNIS System, 2001; Diekema, 2001).
The time of medication development and its execution in human and
creature wellbeing and horticulture was started by the revelation of
anti-infection agents over 70 years prior. These disclosures were powerful
against organisms consequently were viewed as effective against pathogenic
microorganisms however this achievement was fleeting as they were tempered with
in all cases by the rise of resistant microorganisms (D'Costa et al., 2011). A standout amongst the
most relentless issues confronted by human services benefits far and wide is
the expanding pervasiveness of antimicrobial resistance. This resistance is
broadly perceived as a noteworthy general wellbeing danger and this issue is
aggravated by a consistent reducing of the quantity of new specialists
(antimicrobials) entering the clinical practice (D.H, 2000). There is an
expanding worry that some less-alarming infections which were effortlessly
treated are currently turning out to be progressively hard to treat and
ailments created by microscopic organisms which are impervious to antimicrobial
agents may set aside a more drawn out time of opportunity to treat successfully
(Butler et al., 2006). In spite of
the fact that the issue of multidrug resistance has pulled in the consideration
of medicinal services administrations and the overall population, rates of
antimicrobial resistance among healing center and group pathogens have expanded
alarmingly amid the previous decade (NNIS, 2001).
1.2
Statement of the Problem
In Nigeria, cattle are reared
primarily as a source of meat. According
to Kuehnert et al. (2006), Lowy
(1998, 2003), Onanuga & Temedie (2011), Vandenbergh & Verbrugh (1999), Williams (1963), the
nares and the skin of humans and animals may be considered as ecological niche
for S.
aureus colonization but this colonization does
not frequently result into infection thereby tagging the bacterium a normal
flora of these body parts. S. aureus colonizes
the nares and the skin but if there is an abrasion, lesion or wound in these
parts, S. aureus may migrate into the
body or blood and cause infections. These infections are called opportunistic
(staphylococcal) infections. Compared to other pathogens, S. aureus has a high tendency and proneness to become resistant to
antimicrobials (Weese, 2010). This fact, coupled with the constant abuse of
drugs and lack of control in the sales of antibiotics contributes to the
increasing problem in multidrug resistance of S. aureus including methicillin and vancomycin which is considered
as the first line of treatment against methicillin resistant Staphylococcus aureus (MRSA). Cuny et
al. (2015), Fluit (2012), Johnson (2011) and Morgan (2008) established that
methicillin resistant S. aureus (a
multidrug resistant organism) may not only be a nosocomial and community
acquired infection but it could also be a zoonotic infection as it can be
transmitted from animal to human. The presence of multidrug resistant S. aureus in the nares of cattle poses a
threat to cattle herders, butchers, beef retailers/handlers and consumers as
these cattle are frequently asymptomatic carriers hence are considered
‘healthy’. This study may evaluate the prevalence of multiple antibiotic
resistant livestock associated S. aureus and
suggest possible control to diseases caused by multiple antibiotic resistant
livestock associated S. aureus.
1.3
Objective of the Study
The general objectives of the study
were to evaluate the prevalence of multidrug resistant livestock associated S. aureus and suggest possible control
to staphylococcal infections in humans caused by livestock associated S. aureus using the antibiogram of the
isolates. The specific objectives are to:
- isolate
and identify S. aureus from
nasal passage of healthy cattle by Gram staining and biochemical tests (catalase test, slide
coagulase test and fermentation of mannitol);
- determine
the antibiogram of the isolates and calculate the Multiple Antibiotic
Resistance Index (M.A.R.I) using the antibiogram of the isolates;
- determine
the minimum inhibitory concentration (μg/disc) of the S. aureus isolates to vancomycin;
- determine
the minimum inhibitory concentration (μg/ml) of the isolates to
flucloxacillin as a test for methicillin resistant S. aureus (MRSA) and vancomycin and
- determine
the synergistic, antagonistic or additive effect of two antibiotics to
suggest possible control of staphylococcal infections in human caused by
multidrug resistant livestock associated S. aureus.
1.4
Research Questions
1. Can S. aureus beisolated and identified
from nasal passage of healthy cattle?
2. How
is the antibibiogram of S. aureus
isolates determined and how are the Multiple Antibiotic Resistance Index of the
isolates calculated using the antibiogram of the isolates?
3. How
is the minimum inhibitory concentration (μg/disc) of S. aureus determined?
4. How
is the minimum inhibitory concentration (μg/ml) of S. aureus isolated from nasal passage of healthy cattle to
flucloxacillin and vancomycin determined?
5. Are
the effects of the combined antibiotics synergistic, additive or antagonistic?
1.5
Significance of the Study
- This
result may create more awareness on the danger of multidrug resistant S. aureus in ruminant flocks.
- This
result may educate the general public on the effect of negligence of
multidrug resistant S. aureus in
cattle and its effect in the consumption of undercooked beef.
- The
result may suggest possible control of staphylococcal infections in humans
caused by livestock associated S.
aureus.
1.6
Justification for the Study
The study may provide a more recent
data on multiple antibiotic resistant S.
aureus and suggest possible control of livestock associated staphylococcal
infections in human.
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