Browsing by Author "Mwanga, Irene Frank"

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Virulence attributes and antimicrobial profile of pasteurella multocida isolated from pneumonic goats in Northern Tanzania
(Sokoine University of Agriculture, 2024) Mwanga, Irene Frank
Pneumonic pasteurellosis, stemming from Pasteurella multocida, poses a significant economic threat to small-scale goat farmers in northern Tanzania. This study aimed to assess the prevalence of antimicrobial resistance and virulence genes within Pasteurella multocida isolates collected from goats displaying clinical symptoms of the disease. A total of 200 nasal swab samples were obtained from goats exhibiting signs of pneumonic pasteurellosis. In the laboratory, these samples underwent culture on blood agar enriched with 5% horse blood at 37°C and 5% carbon dioxide for 24-48 hours. Isolates displaying characteristics resembling Pasteurella multocida were subjected to gram staining and biochemical tests, including indole, oxidase, and catalase. Among the presumptive Pasteurella multocida isolates, 10 were initially identified, later confirmed using specific molecular primers, Pm0762 and Pm1231, with only five isolates ultimately confirming the presence of either or both genes. The confirmed isolates were then subjected to susceptibility testing against ten antibiotics. Additionally, screening for the presence of virulence genes, including ptfhA, ptfA, fimA, exbD, and exbB, was conducted. Moreover, antimicrobial resistance genes (sul1, sul2, blaTEM, aac(3)-1, tetA, and acrA) were investigated. Out of the 200 analyzed nasal swab samples, Pasteurella multocida was isolated in only 2.5%. This seemingly low prevalence may be attributed to the larger sample size utilized in this study compared to prior investigations or the influence of geographic and environmental factors. Serogrouping revealed that 20% of the isolates belonged to serogroup A, while a substantial 80% defied classification, posing challenges for surveillance and control efforts. Further analysis uncovered the presence of virulence genes crucial for iron acquisition (exbD found in 100% of isolates) and adhesion (ptfA in 60%), pivotal for bacterial survival and respiratory tract infection. However, despite their significance, all isolates exhibited resistance to a broad spectrum of antimicrobials, including commonly used drugs such as ampicillin, amoxicillin and erythromycin. Resistance extended to cephalosporins (cefotaxime), sulfamethoxazole/trimethoprim, and even macrolides. This widespread resistance underscores the need for judicious antibiotic use in veterinary medicine to curb the emergence of multidrug-resistant strains. Notably, susceptibility was retained against gentamicin and ciprofloxacin, suggesting potential alternative treatment options. Nevertheless, the prevalence of multidrug resistance across all isolates (100%) emphasizes the urgency for innovative strategies to combat pneumonic pasteurellosis. Additionally, the identification of antimicrobial resistance genes like blaTEM and sul1 in some isolates further accentuates the evolving threat of resistance. Moreover, the prevalence of untypable strains underscores the necessity for further research to understand their implications and devise alternative typing methodologies for effective control. In summary, this study reveals a concerning landscape of antimicrobial resistance and virulence in Pasteurella multocida among goats in northern Tanzania. Addressing challenges such as low isolation rates, untypable strains, and widespread resistance necessitates a multifaceted approach involving prudent antibiotic use, exploration of novel treatment modalities and diagnostics, and collaboration among public health authorities, veterinarians, and livestock producers. Only through concerted efforts can we effectively combat pneumonic pasteurellosis and safeguard the health and livelihoods of small-scale goat farmers in the region.