In vitro susceptibility of Czech porcine isolates of C. perfringens Type A cpb2+ to amoxicillin, ampicillin and amoxicillin-clavulanic acid

Clostridium perfringens type A enteritis is a frequent disease of the newborn piglets with a major economic impact in the Czech Republic and important swine producing countries as well. Different antimicrobials may be used for treatment of piglets affected by clostridial enteritis. There are only a few reports on antimicrobial susceptibility of C. perfringens from pigs. Overall, the most common resistance in C. perfringens is to tetracyclines. The aim of the study was evaluate sensitivity pattern for aminopenicillins as important group of antibiotics for control of clinical infection in piglets.

For the trial purposes 56 isolates of C. perfringens cpb2- positive from clinical cases of neonatal enteritis from period 2007 - 2015 from farm in Czech Republic were chosen. Each isolate represented one piglet (1 – 14 days) and one different farm per year. Identification of C. perfringens was performed based on the demonstration of the characteristic morphology after 24-48 hour anaerobic cultivation on Wilkins-Chalgren agar (WCA).

Definitive identification was performed by Matrix-Assisted Laser Desorption Ionization Time-Of-Flight Mass Spectrometry (MALDI-TOF MS), (Bruker Daltonics, Germany). Genetic characterization of isolates was finalized by the determination of species-specific gene (cpa) and cpb2 by specific PCR . MIC testing was performed according to CLSI guidelines by agar dilution method (CLSI, 2013). Data in the final report are presented as MIC range and MIC₅₀, MIC₉₀.

Range of MICs to ampicillin in 56 C. perfringens Type A cpb2+ isolates was from < 0, 01 to 4 mg/l, MIC₅₀ was 0,125 mg/l and MIC₉₀ 2 mg/l. Range of MICs for amoxicillin was same like in case of ampicillin (from < 0, 01 to 4 mg/l), but MIC₅₀ achieved 3 times lower value: 0, 03 mg/l, MIC₉₀ for amoxicillin was 2 mg/l. Range of MICs values to amoxicillin-clavulanate was established from < 0, 01 to 8 mg/l, MIC₅₀ was < 0, 01 and MIC₉₀ was 2 mg/l.

Based on results we can conclude that aminopenicillins are very good option for the treatment of C. perfringens type A infection of piglets. According currently available interpretive criteria we haven’t found isolates resistant to aminopenicillins. We have confirmed that prevalence of strains producing beta- lactamases is very low. According rational use of antimicrobials we consider amoxicillin as optimal choice for treatment clinical cases. Major differences between amoxicillin and ampicillin were not observed but amoxicillin showed better MIC₅₀ parameter and distribution of MICs.

Disclosure of Interest: None Declared.