Abstract
The aim of the present study was to study the bacterial investigation of pneumonic calves, antibiotic susceptibility testing and analysis of some virulence and antibiotic resistance genes for the recovered isolates and evaluation of the changes of haematological indices and selected serum biochemistry variables. Bacteriological examination of nasal swabs of 40 apparently healthy and 90 pneumonic calves revealed that E. coli was the prominent pathogen (34.6%) followed by S. aureus (28.5%) and Past. Multicoda (13.1%). Antibiotic sensitivity testing exhibited high resistance rates of E. coli and S. Aureus isolates against the most used antibiotics. Past. Multocida isolates were of high sensitivity rate against most antibiotics except some resistance for tetracycline, enerofloxacin and norofloxacin. Both iss and pap C virulence genes of E. coli were detected in 80% and 60% of the examined isolates, respectively. High prevalence rate of virulence genes (spa, clfA) and (Tox A and kmt1) of S. aureus and Past. multocida recovered isolates was recorded. Genotypic detection of antibiotic resistant genes of the most yielded isolates was discussed in details. In pneumonic calves, there were significant decreases in RBCs, Hb and PCV than that of healthy one. The significant increase in WBCs with neutrophilia was detected as well as significant decrease in lymphocyte count. Serum biochemical parameters revealed significant increase in globulin, AST, ALT, urea, creatinine, P and K, while albumin, glucose, Fe, Mg and Ca were significantly decreased.
Highlights
Respiratory infections are responsible for 3752% losses in cattle
Bacteriological examination of bacterial pathogens in calves: The present study recognized that E. coli (34.6%), S. aureus (28.5%) and Pasterella multocida (13.1%) were that most predominant isolated pneumonic bacterial pathogens among 40 apparently healthy and 90 pneumonic calves showing pneumonia and respiratory disorders (Table 4)
Serotyping of the recovered E. coli isolates in this study revealed different serotypes (O143: H4, O1: H2, O63: H5, O157:H7, O158: H10, O119:H4, O86:H9 and O18:H6) (Table 5)
Summary
Respiratory infections are responsible for 3752% losses in cattle. Calves experienced pneumonia at early age might have severe depression in the future in the production capabilities causing severe economic costs (Sayed and Zaitoun, 2009 and Griffin et al, 2010).Bacteria and viruses in combination with stress factors are the key in triggering acute respiratory infections usually bacteria act as the second invaders to worsen the ill-animal's condition (Yousef et al, 2013). Respiratory infections are responsible for 3752% losses in cattle. Calves experienced pneumonia at early age might have severe depression in the future in the production capabilities causing severe economic costs (Sayed and Zaitoun, 2009 and Griffin et al, 2010). Bacteria and viruses in combination with stress factors are the key in triggering acute respiratory infections usually bacteria act as the second invaders to worsen the ill-animal's condition (Yousef et al, 2013). The most bacterial causes include: Staphelococcus aureus, Staphelococcus Pneumonae, Escherichia coli, pseudomonas spp., Klebsiella spp, Mycoplasma haemolytica and Pasterella multocida. The presence of resistant bacteria poses a risk to humans as they may act as resistance reservoirs, contributing to the maintenance and spread of antibiotic resistance genes (Goni-Urizza et al, 2000)
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