Comparative effectiveness of antimicrobials in experimental infection of chicks with salmonella infantis

Abstract

Salmonellosis is one of the most widespread zoonoses. Control of salmonellosis is becoming a matter of great importance as the number of cases of Salmonella infection increases, new Salmonella serovars emerge and the bacteria contaminate food products and environment easily. Salmonella infantis is one of the most common serovars among those isolated recently from poultry products and meat products and that translates into need to develop new and effective treatment methods concerning infection caused by this serovar. In the present publication we study the comparative effectiveness of different antimicrobials selected for therapy of chicks, which have been experimentally infected with Salmonella infantis. For the experiment we employed as many as 275 Hisex Brown chicks which we had divided into 11 groups (n = 25 in each group). We administered the drugs via drinking water at a concentration 200 mg/L for 5 days. The treatment began 24 hours before the challenge. On the second day of life the chicks were challenged by intraperitoneal injection with 1.5 x 10^8 CFUs of one-day old agar culture of S. infantis in 0.5 mL isotonic saline (1 McFarland). The observation period in the experiment was 15 days following the drug withdrawal. The study of comparative effectiveness of aforementioned drugs for treatment of chicks, infected with S. infantis, demonstrated the highest therapeutic effectiveness of fluoroquinolone class of antimicrobials. The survival rate for the chicks, receiving enrofloxacin and ciprofloxacin, was 96 %. The survival rate for the chicks, receiving ofloxacin per os, was 92 %. Tilmicosin and chloramphenicol showed lower therapeutic effectiveness, 44 % and 36 % respectively. When we used tylosin, amoxycillin, doxycycline or apramycin, the results were at their worst as the mortality rate of the chicks was 80-96 %.