ABSTRACT
AIMS: To determine whether therapeutic treatment of pigs with chlortetracycline affects the susceptibility of their Campylobacter isolates for tetracycline, ciprofloxacin and erythromycin. METHODS AND RESULTS: Minimum inhibitory concentrations (MICs) and presence of a tetracycline resistance gene tet(O) were studied in Campylobacter collected before, during and after chlortetracycline treatment. Tetracycline MICs and the presence of tet(O) for additional Campylobacter coli isolates collected previously from seven farrowing farms were also determined. Isolates with ciprofloxacin MICs above the epidemiological cut-off value (ECOFF) were subtyped by flaA restriction fragment length polymorphism (RFLP). Tetracycline MICs of 221 Camp. coli isolates remained under the ECOFF at all sampling stages as well as the MICs for 63 isolates from the other farms. The ciprofloxacin MIC was above the ECOFF for 22% of the isolates, and one Camp. coli isolate had an erythromycin MIC above the ECOFF. None of the studied 300 Campylobacter isolates from nine herds carried tet(O). flaA-RFLP typing revealed the heterogeneity of Camp. coli isolates with high ciprofloxacin MICs. CONCLUSION: Use of chlortetracycline did not increase the MIC values for the antimicrobials studied. SIGNIFICANCE AND IMPACT OF THE STUDY: This study demonstrated that susceptibility of Camp. coli isolates is not affected by chlortetracycline therapy if tet(O) is not present in Camp. coli population.
Subject(s)
Campylobacter Infections/veterinary , Campylobacter coli/drug effects , Chlortetracycline/pharmacology , Sus scrofa/microbiology , Tetracycline Resistance/genetics , Animals , Anti-Bacterial Agents/pharmacology , Anti-Bacterial Agents/therapeutic use , Bacterial Proteins/genetics , Bacterial Typing Techniques , Campylobacter Infections/drug therapy , Campylobacter Infections/microbiology , Campylobacter coli/classification , Campylobacter coli/genetics , Carrier Proteins/genetics , Chlortetracycline/therapeutic use , Ciprofloxacin/pharmacology , Erythromycin/pharmacology , Microbial Sensitivity Tests , Polymorphism, Restriction Fragment Length , Tetracycline/pharmacologyABSTRACT
Limited knowledge is available regarding the dynamics of macrolide resistance under farm conditions with natural Campylobacter populations. We examined the dynamics of antimicrobial resistance in Campylobacter coli at a large pig farm. Faeces were sampled from untreated sows and piglets (n=57), weaned pigs treated with tylosin (n=68) and pigs of the same group 3-5 weeks after withdrawal of tylosin (n=15). Additionally, 48 weaned pigs were sampled after tylosin had not been administered for 7 months at the farm. MICs for seven antimicrobials were determined, isolates were genotyped by PFGE and mutations conferring macrolide resistance were identified. Resistance to at least one antimicrobial agent was higher (P<0.001) in the isolates from the treated pigs (30 of 56) than in those from the untreated animals (2 of 40). Resistance to ciprofloxacin, erythromycin, nalidixic acid and streptomycin was higher (P<0.05) in the isolates from the treated pigs than in those from the untreated animals. All 14 erythromycin-resistant isolates studied (MIC ≥ 512 µg/ml) contained mutation A2075G in 23S rRNA. Resistance against at least one antimicrobial was significantly lower (P<0.05) when tylosin had not been administered for 7 months. Resistance to erythromycin and streptomycin also decreased (P<0.05). PFGE analysis revealed a change of genotypes induced by tylosin treatment. In conclusion, tylosin treatment of pigs selected for a high-level of resistance to erythromycin and resistance to ciprofloxacin, nalidixic acid and streptomycin also increased in C. coli isolates within a few days.
Subject(s)
Anti-Bacterial Agents/therapeutic use , Campylobacter Infections/veterinary , Campylobacter coli/drug effects , Swine Diseases/drug therapy , Tylosin/therapeutic use , Animal Husbandry , Animals , Anti-Bacterial Agents/pharmacology , Campylobacter Infections/drug therapy , Campylobacter coli/genetics , Drug Resistance, Bacterial , Drug Resistance, Multiple, Bacterial , Electrophoresis, Gel, Pulsed-Field/veterinary , Female , Genotype , Microbial Sensitivity Tests/veterinary , RNA, Ribosomal, 23S/genetics , Swine/microbiology , Swine Diseases/microbiology , Tylosin/pharmacologyABSTRACT
We describe a novel application for a microwave on-line sensor to measure the total solids (TS) load entering a municipal wastewater treatment plant (WWTP) from slaughterhouse sewage and some sanitary wastewaters. Measuring this kind of wastewater stream is very challenging, because it contains a high, but varying organic load with nitrogen, phosphorus and microorganisms. The reliability of the measured signal was studied by comparison with laboratory analyses and a correlation is presented of TS-value with other parameters that are typically followed in a wastewater treatment process. The results suggest that on-line microwave sensoring could be used to monitor total solids in wastewater influent. Our results show that the on-line microwave sensor and laboratory reference analyses give similar results with a good correlation between the two techniques. Furthermore, we demonstrate that the total solids values correlate well with conductivity, total nitrogen and BOD(7) values but not with phosphorus, pH and temperature.
