Isolation and identification of Pasteurella species and other bacterial organisms from ovine pneumonic lungs and their antimicrobial susceptibility in Ghana: abattoir-based study

Abstract

Background and aim Pneumonia is the most prevalent respiratory infection in sheep, significantly impacting their health and welfare. This study aimed to isolate Pasteurella spp. and other bacterial organisms from pneumonic sheep lungs and also assess their antibiotic susceptibility. Materials and methods A cross-sectional abattoir-based study was conducted at Tamale and Kumasi abattoirs. Seventy-five ovine pneumonic lungs were randomly sampled to culture and isolate bacterial organisms associated with ovine pneumonia. The Kirby-Bauer disk diffusion method was utilized to evaluate antibiotic susceptibility. Results Among the 75 pneumonic lungs that were cultured, Mannheimia haemolytica was the predominant Pasteurella species, isolated from 54.7% of samples. Other bacteria identified included Staphylococcus aureus (46.7%), E. coli (37.3%), and Klebsiella spp . (19.7%). M. haemolytica was particularly associated with broncho-interstitial pneumonia (29.3%) and interstitial pneumonia (17.3%), while P. multocida was prominent in interstitial cases (13.3%). Both M. haemolytica and P. multocida contributed to 8.0% of bronchopneumonia cases. Seasonal patterns showed M. haemolytica (30%) and P. multocida (16%) were more common in the dry season, whereas Staphylococcus aureus was more prevalent in the wet season. M. haemolytica and P. multocida were most frequently identified in 2–3-year-old sheep from Sahelian breeds. All bacteria were isolated from sheep in poor body condition, but no significant associations were found between breeds, body condition, and pneumonia forms ( p > 0.05). M. haemolytica and P. multocida were highly susceptible to cefotaxime (95%, 100%) and ciprofloxacin (83%, 91%), but exhibited resistance to amoxicillin and doxycycline. Staphylococcus aureus showed sensitivity to gentamicin (94%) and cefoxitin (71%), but resistance to tetracycline (63%). Pseudomonas spp . was completely susceptible to gentamicin, meropenem, and amikacin (all 100%) while resistant to tetracycline (100%) and sulfamethoxazole (75%). Conclusion Mannheimia haemolytica was the most prevalent bacterial pathogen isolated from pneumonic sheep lungs in this study, suggesting its primary role in ovine pneumonia. Staphylococcus aureus, E. coli, Klebsiella spp., Pseudomonas spp., Enterobacter , and Citrobacter spp are also prevalent. These bacteria are mostly effectively inhibited by antibiotics such as cefotaxime, ciprofloxacin, and gentamicin, but they are not susceptible to amoxicillin, tetracycline, and penicillin G.