Methicillin Resistant Staphylococcus aureus in Horses and Horse Handlers in Kaduna and Zaria, Nigeria

Methicillin Resistant Staphylococcus aureus in Horses and Horse Handlers in Kaduna and Zaria, Nigeria.

ABSTRACT

Methicillin resistant Staphylococcus aureus (MRSA) is of great public health concern having become resistant to most commonly used antibiotics. They are associated with institutions such as hospitals, but are now increasingly becoming prevalent in community-acquired  infections.

The occurrence of MRSA in horses and horse handlers in Kaduna and Zaria, Nigeria was  studied. Nasal swabs from 240 horses and 65 horse handlers were collected through a one-stage cluster sampling and analysed using standard microbiological tests and genotyping methods.

Structured questionnaires were also administered to 65 horse handlers to assess for risk factors associated with MRSA colonisation. MRSA were found in 10% (24/240) and 6.2% (4/65) of the nasal swab samples collected from the horses and horse handlers respectively.

Of the 44 S. aureus isolates tested for antibiotic susceptibility, 54.6% (24/44) were resistant to penicillin and oxacillin, 47.7% (21/44) to erythromycin, 34.1% (15/44) to tetracycline, 22.7% (10/44) to amikacin and gentamicin, 6.8% (3/44) to sulphamethoxazole+trimethoprim, 2.3% (1/44) to ciprofloxacin, and 2.3% (1/44) were resistant to chloramphenicol.

Multidrug Resistance was found in 74.8% (21/28) of the MRSA isolates. SCCmec types I, III, and IV were found in both the horses and the horse handlers while only one horse was found to carry SCCmec V.

Risk factors identified for the horse handlers included being a Veterinarian, recent exposure to antimicrobial agents, hospital visitation, and personal hygiene.

Risk factors for the horses from this study were allergy and wound management. MRSA-carriage by horses and horse handlers alike as well as MDR (multidrug resistant) strains of S. aureus have been established from this study, which is of public health concern.

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TABLE OF CONTENTS

TITLE PAGE                 i

DECLARATION       –            ii

CERTIFICATION       –           iii

ACKNOWLEDGEMENTS              iv

DEDICATION              vi

TABLE OF CONTENTS             vii

LIST OF TABLES     –         xi

LIST OF FIGURES   –          xiv

ABSTRACT   –          xvi

CHAPTER 1: INTRODUCTION

• Background of Study——— 1
• Statement of Research Problem— 3
• Justification——- 4
• Aim—— 5
• Objectives——— 5

CHAPER 2: LITERATURE REVIEW

• History of Staphylococcus aureus——– 6
• Importance of MRSA— 9
• General Description of aureus———- 10
  • Staphylococcal cell envelope– 11
  • Staphylococcus aureus genome———– 12
• Classification of MRSA———— 13
  • Staphylococcal cassette chromosome mec elements——— 15
• Laboratory Detection and Identification- 18
  • Pathogenesis and virulence factors———- 20
• MRSA in Horses————- 23
• Antibiotic Resistance—- 25
• Emerging Methicillin Resistant Staphylococcus aureus———- 28
  • Mechanism of methicillin resistance——- 29
  • Risk factors associated with nosocomial MRSA———- 31
  • Epidemiology of MRSA in community——- 32
  • Treatment and control of MRSA—- 33
  • The typing of MRSA——- 34
• Mechanism of Genetic Variability of Bacterial Genome—— 34
• Phenotyping Methods——— 36
• Genotyping Methods—- 36
  • Pulsed field gel electrophoresis—- 37
  • Multi-locus sequence typing— 37
  • Staphylococcal protein A sequence typing (spa typing)— 37

CHAPTER 3: MATERIALS AND METHODS

• Study Area—- 40
• Study Design——— 40
• Sample Size Determination——- 41
• Sample Collection——- 42
• Materials Used–42
  • Bacteriological culture media———- 42
  • Sugars and Andrade peptone— 42
  • Antibiotic impregnated discs and their concentrations——- 43
  • Other materials used—– 43
• Isolation of S aureus—- 43
  • Brain heart infusion broth (BHI)— 43
  • Columbia media with 5% sheep blood– 43
  • Baird Parker-egg yolk + tellurite media— 44
• Biochemical Characterization— 44
  • Catalase test— 44
  • Coagulase test— 44
  • Sugar fermentation—- 45
• Antibiotic Sensitivity Testing- 45
• PBP2a Latex Agglutination Test— 47
• Genotyping– 47
  • DNA extraction—– 47
  • Multiplex polymerase chain reaction (M-PCR)—- 48
• Identification of Risk Factors Associated with MRSA in Horses and Horse Handlers—- 49
• Data Analysis—- 49

CHAPTER 4: RESULTS

• Isolation and Identification of MRSA from horses and horse handlers– 51
• Antibiotic Susceptibilities of the MRSA Isolates from the Horses and Horse Handlers—- 54
• PBP2a latex agglutination test to confirm methicillin resistance—- 58
• SCCmec Typing- 60
• Risk Factor Analysis– 62

CHAPTER 5: DISCUSSION

CHAPTER 6: CONCLUSION

6.1 Conclusions– 67

CHAPTER 7: RECOMMENDATIONS

7.1 Recommendations—– 68

References– 69

Appendices      84

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INTRODUCTION 

1.1 Background of study

Staphylococcus; meaning the “golden grape-cluster berry,” and also known as “golden staph” and Oro staphira) is a facultative anaerobic Gram-positive cocci bacterium.

It is frequently part of the skin flora found in the nose and on skin, and in this manner about 20% of the humans are long-term carriers of Staphylococcus. (Kluytmans et al., 1997).

Staphylococcus aureus can cause a range of illnesses from minor skin infections, such as pimples, impetigo, boils (furuncles), cellulitis, folliculitis, carbuncles, scalded skin syndrome, and abscesses, to life-threatening diseases such as pneumonia, meningitis, osteomyelitis, endocarditis, toxic shock syndrome (TSS), bacteremia, and sepsis.

It is still one of the five most common causes of nosocomial infections, often causing postsurgical wound infections. Each year, some 500,000 patients in American hospitals contract a staphylococcal infection. (National Institute of Health, United States, 2007).

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REFERENCES

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Aarestrup F. M., Cavaco L., Hasman H. (2010). Decreased susceptibility to zinc chloride is associated with methicillin resistant Staphylococcus aureus CC398 in Danish swine. Veterinary Microbiology; 142(3-4):455-7.
Abbott Y., Leggett B., Rossney A. S., (2010). Isolation rates of methicillin-resistant Staphylococcus aureus in dogs, cats and horses in Ireland. Veterinary Record. 166:451– 455.
Aires de Sousa M., and de Lencastre H. (2004). Bridges from hospitals to the laboratory: genetic portraits of methicillin-resistant Staphylococcus aureus clones. FEMS Immunology and Medical Microbiology. 40: 101-11.
Ako-Nai A. K., Ogunniyi A. D., Lamikanra A., and Torimiro S. E. (1991). The characterisation of clinical isolates of Staphylococcus aureus in Ile-Ife, Nigeria. Journal of Medical Microbiology. 34109-112.