Investigation of the virulence markers and drivers enabling Escherichia Coli to cause neonatal and postweaning piglet diarrhea in Mukono and Masaka Districts, Uganda

Abstract

Piggery production is highly constrained by diseases with diarrhea in piglets being a major condition resulting in economic losses and piglet mortalities to smallholder farmers in Uganda. This cross-sectional study was carried out in Mukono and Masaka districts which are high pig producing districts of Uganda between December 2021- June 2022. The overall aim was to determine the pathogenic determinants that enable Escherichia coli to cause piglet diarrhea in the smallholder pig farms. A total of 80 households in equal proportion were visited in each district for questionnaire survey and fecal sample collection. Fecal samples were enriched in bufferd peptone water under aerobic conditions overnight at 37ºC. Culture and isolation was done on MacConkey agar. Demographic information and risk factors associated with pathogenic Escherichia coli infection were obtained from the questionnaire while antimicrobial resistance (AMR) against 9 selected antimicrobials using Kirby- Bauer disc diffusion method and virulence gene marker characterization using a multiplex polymerase chain reaction were done on the Escherichia coli isolates obtained from the fecal samples collected from piglets. Data analaysis was data using Microsoft Excel for entry, cleaning, summary statistics and graphical presentations and analysis of the drivers was done using SPPS Version 23. Out of the 215 fecal samples collected, 175 (81.4%) Escherichia coli isolates were obtained. All the isolates were resistant to Erythromycin, and they also showed a high resistance to some of the commonly used antimicrobials Ampicillin, Tetracycline, and Sulphamethoxazole Trimethoprim. Some isolates showed resistance against drugs commonly used in human than veterinary medicine e.g Nalidixic Acid, Chloramphenicol, Gentamicin and Ciprofloxacin. More than half of the isolates (58.3%), carried atleast one of the eleven virulence gene markers screened. The EAST1 was the most prevalent followed by STa. There was expression of more than one virulence gene markers in 6.2% of the isolates with EAST1/STa being expressed more frequently. Three adhesins (F17, F18 and AIDA-I) were detected with F18 being the most detected adhesin. There was a significant association between the observed diarrhea and presence of AIDA-I or EAST1. From the multivariate logistic regression model, none of the studied risk factors was significantly associated with the presence of virulence gene marker. Since majority of the isolates expressed a virulence gene marker, this combined with the high rates of AMR, calls for a need to invest in a more sustainable control strategy such as vaccination to curb the impacts of the disease and reduce on antimicrobial use as a way of tackling AMR.