Detection and risk factor analysis of avian colibacillosis associated with colistin-resistant Escherichia coli and Klebsiella pneumoniae

Muhammad Adnan Saeed^1*Haseeb Asif¹Syed Ehtisham-ul-Haque¹Aman Ullah Khan¹Aziz Ur Rehman¹Aiman Rehman¹Muhammad Kamran Rafique¹Ishtiaq Ahmed¹Muhammad Fiaz Qamar¹Herbert Tomaso²Hosny El-Adawy^2*

• ¹University of Veterinary and Animal Sciences, Lahore, Punjab, Pakistan
• ²Institut für bakterielle Infektionen und Zoonosen, Friedrich Loeffler Institut, Jena, Germany

Colibacillosis associated with colistin-resistant avian pathogenic Escherichia coli poses a threat to both food security and public health. The potential horizontal transmission of mobilized colistin-resistant (mcr) genes facilitates the co-emergence of Klebsiella pneumoniae. This study aimed to determine the prevalence, molecular detection, analyze the antibiogram and identify associated risk factors for colistin-resistant Escherichia coli and Klebsiella pneumoniae isolated from broiler chicken in three districts of Punjab province, Pakistan.In total, 230 visceral organ samples were collected from 13 different chicken farms located in Sargodha, Jhang and Toba Tek Singh in Pakistan. Following isolation, broth microdilution test was used to confirm phenotypic colistin resistance. Polymerase chain reaction was used to detect mcr-1 and mcr-2 genes associated with colistin resistance. Antimicrobial susceptibility test against 11 antibiotics was performed by using Kirby-Bauer disk diffusion method. Risk factors associated with colistinresistant bacteria, including host attributes, farm management practices, environmental and agent characteristics were analyzed.The prevalence of colistin-resistant E. coli and K. pneumoniae was 24.78% (95% CI, 19.6%-30.7%) and 3.04% (95% CI, 1.5%-6.1%), respectively. The prevalence of colistin-resistant E. coli varied between cities as 42%, 23.61% and 5.55% for Jhang, Sargodha and Toba Tek Singh, respectively. The detection frequency of mcr-1 gene 42.1% (24/57) was significantly (p < 0.01) higher than mcr-2 gene, 14.03% (8/57). Phylogenetic analysis of lipid A phosphoethanolamine transferase sequences revealed greater similarity with mcr-1.5 variant. Isolates were found resistant to amoxycillin-clavulanic acid (84.21%), cefotaxime (70.17%) and trimethoprim-sulfamethoxazole (73.68%). The multivariate logistic regression predicted preceding viral infection of respiratory tract as a significant association (OR = 4.808, p < 0.01), whereas daily removal/culling of dead/diseased chicken (OR = 0.308, p = 0.01) as a protective factor against the emergence of colistin-resistant strains.These findings indicate that emergence of the colistin-resistant strains deteriorates colibacillosis control efforts in poultry and serve as a possible reservoir for zoonotic infections.