High Prevalence of Multidrug-Resistant Nontyphoidal Salmonella Recovered from Broiler Chickens and Chicken Carcasses in Brazil

High frequency of non-susceptibility to ciprofloxacin in nontyphoid Salmonella recovered from Brazilian broiler chicken

1. This study evaluated the minimal inhibitory concentration (MIC) of ciprofloxacin and the presence of plasmid-mediated quinolone resistance (PMQR) mechanisms in 97 nontyphoidal Salmonella spp. isolated from broilers and carcases from three different regions in Brazil. The presence of mutations in quinolone resistance determination regions (QRDRS) was investigated in the ciprofloxacin-resistant strain by DNA sequencing.2. Most of the Salmonella spp. (85.6%) had intermediate resistance to ciprofloxacin and only one isolate was resistant. MIC breakpoints ranged from ≤0.03 to 1 µg/ml and 67.0% of the strains had a MIC of 0.25 µg/ml (n=65). Thirteen strains (13.4%) were susceptible to ciprofloxacin with MIC ≤0.06 µg/ml. The qnrB gene was detected in eight isolates with intermediate resistance and in two susceptible strains. The other PMQR genes, qnrA, qnrC, qnrD, qnrS, qnrVC, aac(6')-Ib, qepA, oqxAB and mutations in QRDR were not detected in any strain.3. There was a high frequency of ciprofloxacin intermediate resistant Salmonella from broiler and broiler carcases from Brazil. The presence of these strains in poultry and derived products poses a risk to public health.

Emergence, Dissemination and Antimicrobial Resistance of the Main Poultry-Associated Salmonella Serovars in Brazil

Salmonella infects poultry, and it is also a human foodborne pathogen. This bacterial genus is classified into several serovars/lineages, some of them showing high antimicrobial resistance (AMR). The ease of Salmonella transmission in farms, slaughterhouses, and eggs industries has made controlling it a real challenge in the poultry-production chains. This review describes the emergence, dissemination, and AMR of the main Salmonella serovars and lineages detected in Brazilian poultry. It is reported that few serovars emerged and have been more widely disseminated in breeders, broilers, and layers in the last 70 years. Salmonella Gallinarum was the first to spread on the farms, remaining as a concerning poultry pathogen. Salmonella Typhimurium and Enteritidis were also largely detected in poultry and foods (eggs, chicken, turkey), being associated with several human foodborne outbreaks. Salmonella Heidelberg and Minnesota have been more widely spread in recent years, resulting in frequent chicken/turkey meat contamination. A few more serovars (Infantis, Newport, Hadar, Senftenberg, Schwarzengrund, and Mbandaka, among others) were also detected, but less frequently and usually in specific poultry-production regions. AMR has been identified in most isolates, highlighting multi-drug resistance in specific poultry lineages from the serovars Typhimurium, Heidelberg, and Minnesota. Epidemiological studies are necessary to trace and control this pathogen in Brazilian commercial poultry production chains.

Assessment of maternal immunity against Salmonella enterica serovar Heidelberg in progeny of broiler breeders vaccinated with different formulations of bacterins

Salmonella Heidelberg (SH) has been reported in broiler flocks of many countries. The ability of some SH strains from poultry origin to cause foodborne infections in humans is a concern. Usually infection of broiler flocks by SH occurs in the first days of life. Therefore, control measures should start early post-hatch. One of the strategies is to generate high titers of anti-Salmonella IgY in breeders by using bacterins to provide passive immunity to their progeny. In this study three broiler breeder flocks were submitted to three Salmonella vaccination regimes (two doses of vaccine 1, two doses of vaccine 2 and non-vaccinated). When breeders were 30 and 55 weeks-old, part of their offspring were separated and challenged with a SH strain at three days of age. Dissemination to organs, caecal colonization and faecal excretion of SH were evaluated over 20 days. Chicks from vaccinated 30 week-old breeders presented lower amounts of SH in caecal content at 1, 3 and 6 days-post infection, correlating with high titers of maternal anti-Salmonella IgY in their yolk. In contrast, there were no differences in counts of SH in caecal content of chicks when their parents were 55 weeks-old and titers of IgY were reduced. Amounts of SH in liver and spleen were low and there were no differences among birds over the experiment. Progeny from 30 week-old flock vaccinated with vaccine 1 also showed lower SH faecal shedding than the remaining birds. Apparently, the maternal IgY was associated with reductions in intestinal infection by SH.

Comparison of antimicrobial resistance in thermophilic Campylobacter strains isolated from conventional production and backyard poultry flocks

1. The aim of this study was to compare the resistance pattern of thermophilic Campylobacter spp. isolated from conventional production (n = 34) and backyard poultry flocks (n = 36) from Rio de Janeiro State, Brazil. The disc diffusion method and statistical tests were used for investigation and analysis of the resistance pattern of Campylobacter spp. isolated from different rearing systems.2. Antimicrobial resistance percentages to amoxycillin with clavulanic acid (AMC), ampicillin (AMP), ceftiofur (CTF), ciprofloxacin (CIP), enrofloxacin (ENO), erythromycin (ERI), gentamicin (GEN) and tetracycline (TET) were 32.4%, 44.1%, 67.6%, 97.1%, 82.4%, 26.5%, 5.9% and 38.2% in conventional production flocks respectively, while the backyard flock's resistance levels were 0.0%, 13.9%, 69.4%, 100.0%, 91.7%, 5.6%, 0.0% and 16.7%, respectively.3. Campylobacter spp. from conventional poultry production was more resistant to AMC, AMO, ERI and TET (P > 0.05) when compared to strains from backyard poultry. A higher frequency of resistance to fluoroquinolones (FLQ), CIP and ENO, was observed in strains from both systems, demonstrating the spread of resistant strains among poultry production environments.