Infections with Campylobacter spp. and Salmonella spp. are the most frequently reported causes of human bacterial enteritis. Warm-blooded animals, including livestock, pets, and wildlife, can be carriers of the bacteria and may contaminate the environment and food products. The present study investigated the occurrence of Campylobacter spp. and Salmonella spp. in fecal pat samples from free-ranging toque macaques (Macaca sinica) and tufted gray langurs (Semnopithecus priam) collected in March-May 2015 in Sri Lanka. In 58 samples from toque macaques, Campylobacter jejuni was isolated in 10 (17%), Campylobacter coli in four (7%), and Salmonella enterica subsp. enterica serovar Virchow in two (3%). None of the bacteria were isolated in the 40 samples from tufted gray langurs. Pulse-field gel electrophoresis and multilocus sequence typing identified six profiles and four clonal complexes of C. jejuni. The isolated Campylobacter spp. showed varying susceptibility to antimicrobial substances. All Campylobacter spp. isolates were susceptible to chloramphenicol, erythromycin, florfenicol, gentamicin, and streptomycin. Four of the C. jejuni were resistant to at least one of the following: ampicillin, ciprofloxacin, nalidixic acid, and tetracycline, and one of the isolates was multidrug resistant. All four C. coli were resistant to ampicillin, whereas the two Salmonella Virchow strains were susceptible to all antibiotics tested. The presence of Campylobacter spp. and Salmonella spp. in toque macaques may have an impact on the conservation of endangered primates and public health in Sri Lanka.

Background: Multidrug-resistant (MDR) Salmonella enterica serovar Typhimurium (S. Typhimurium) is a serious public health threat as infections caused by these strains are more difficult and expensive to treat. Livestock serve as a reservoir for MDR Salmonella, and the antibiotics chlortetracycline and florfenicol are frequently administrated to food-producing animals to treat and prevent various diseases. Therefore, we evaluated the response of MDR S. Typhimurium after exposure to these two antibiotics. Results: We exposed four MDR S. Typhimurium isolates to sub-inhibitory concentrations of chlortetracycline (16 and 32 mu g/ml) or florfenicol (16 mu g/ml) for 30 min during early-log phase. Differentially expressed genes following antibiotic treatment were identified using RNA-seq, and genes associated with attachment and those located within the Salmonella pathogenicity islands were significantly up-regulated following exposure to either antibiotic. The effect of antibiotic exposure on cellular invasion and motility was also assessed. Swimming and swarming motility were decreased due to antibiotic exposure. However, we observed chlortetracycline enhanced cellular invasion in two strains and florfenicol enhanced invasion in a third isolate. Conclusions: Chlortetracycline and florfenicol exposure during early-log growth altered the expression of nearly half of the genes in the S. Typhimurium genome, including a large number of genes associated with virulence and pathogenesis; this transcriptional alteration was not due to the SOS response. The results suggest that exposure to either of these two antibiotics may lead to the expression of virulence genes that are typically only transcribed in vivo, as well as only during late-log or stationary phase in vitro.