PREVALENCE OF MULTIDRUG RESISTANT LIVESTOCK ASSOCIATED STAPHYLOCOCCUS 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
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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 well being
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
1.4 Research Questions
- Can S. aureus be isolated and identified from nasal passage of healthy cattle?
- 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? - How is the minimum inhibitory concentration (μg/disc) of S. aureus determined?
- How is the minimum inhibitory concentration (μg/ml) of S. aureus isolated from nasal passage of healthy cattle
to flucloxacillin and vancomycin determined? - 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.
PREVALENCE OF MULTIDRUG RESISTANT LIVESTOCK ASSOCIATED STAPHYLOCOCCUS AUREUS