Salmonella enterica mcr-1 Positive from Food in Brazil: Detection and Characterization.

The mcr-1 gene has been identified in bacterial isolates obtained from humans, animals, environment, and food, including Salmonella spp., which is one of the major foodborne pathogens worldwide. The aim of this study was to evaluate the presence of mcr-1 gene in Salmonella spp. from food produced in Brazil and to characterize the isolates harboring this gene. A total of 490 Salmonella spp. isolates from the Brazilian National Program for the Control of Foodborne Pathogens were screened for the presence of mcr-1 gene by polymerase chain reaction (PCR). Whole genome sequencing (WGS) was performed in positive isolates to characterize the sequence type (ST), plasmid families and resistance genes. Antimicrobial susceptibility tests were performed by broth microdilution. Selected isolates were submitted to conjugation experiments using the Escherichia coli J53 as a receptor. We detected eight isolates harboring the mcr-1 gene; seven belonged to Salmonella enterica serovar Typhimurium and its monophasic variant 4,[5],12:i:-, and one belonged to serovar Saintpaul. Seven of the mcr-1 positive isolates displayed a high rate of resistance to other antibiotics in addition to colistin. Analysis of the WGS indicated that the ST 19 was the most common ST among the mcr-1 positive isolates. The mcr-1 gene was located in an IncX4 plasmid of ∼33 kb, with no additional resistance genes and with high identity with a plasmid obtained from a clinical isolate of E. coli mcr-1 positive in Brazil. All plasmids harboring the mcr-1 gene were able to conjugate. Our results suggest the spread of a single plasmid type in Brazil harboring the mcr-1 among Salmonella spp. The horizontal transfer of this mobile element has been contributing to the spread of the colistin resistance in the country.

Occurrence of Salmonella spp: in broiler chicken carcasses and their susceptibility to antimicrobial agents / Ocorrência de Salmonella spp: em carcaças de frango e sua suscetibilidade a agentes antimicrobianos

The present study was carried out to evaluate the occurrence of Salmonellae in broiler chicken carcasses and to determine the antimicrobial resistance profile of the isolated strains. Twenty-five out of the 260 broiler chicken carcasses samples (9.6 percent) were positive for Salmonella. S. Enteritidis was the most frequent serovar. Nineteen Salmonella isolates were tested for antimicrobial resistance, and the results indicated that 94.7 percent were resistant to at least one antimicrobial agent. Resistance to streptomycin (73.7 percent), nitrofurantoin (52.3 percent), tetracycline (31.6 percent), and nalidixic acid (21 percent) were the prevalent amongst Salmonella strains tested.

O presente estudo teve como objetivo verificar a ocorrência de Salmonellae em amostras de carcaças de frango e a suscetibilidade dos isolados a agentes antimicrobianos. Das 260 carcaças analisadas, 25 (9,6 por cento) foram positivas para Salmonella. Salmonella Enteritidis foi o sorovar predominante. Com relação à suscetibilidade a agentes antimicrobianos, 94,7 por cento das cepas de Salmonella testadas, apresentaram resistência a um ou mais agentes antimicrobianos. Os perfís de resistência mais comumente observados entre os isolados foram a resistência à estreptomicina (73,7 por cento), nitrofurantoína (52,3 por cento), tetraciclina (31,6 por cento) e ácido nalidíxico (21 por cento).

Occurrence of Salmonella spp. in broiler chicken carcasses and their susceptibility to antimicrobial agents.

The present study was carried out to evaluate the occurrence of Salmonellae in broiler chicken carcasses and to determine the antimicrobial resistance profile of the isolated strains. Twenty-five out of the 260 broiler chicken carcasses samples (9.6%) were positive for Salmonella. S. Enteritidis was the most frequent serovar. Nineteen Salmonella isolates were tested for antimicrobial resistance, and the results indicated that 94.7% were resistant to at least one antimicrobial agent. Resistance to streptomycin (73.7%), nitrofurantoin (52.3%), tetracycline (31.6%), and nalidixic acid (21%) were the prevalent amongst Salmonella strains tested.

Salmonella spp. in raw broiler parts: occurrence, antimicrobial resistance profile and phage typing of the Salmonella Enteritidis isolates

The present study was carried out to evaluate the occurrence of Salmonellae in raw broiler parts and to determine the antimicrobial resistance profile of the isolated strains. Twenty-four (39.3 percent) broiler parts samples were positive for Salmonella and twenty-five Salmonella strains were isolated, since two different serovars were detected in one single positive sample. Salmonella Enteritidis was the most prevalent serovar. Among Salmonella Enteritidis isolates, 95.2 percent belonged to Phage Type 4 (PT4) (20/21) and 4.8 percent to PT7 (1/21). Twenty-two (88 percent) strains of Salmonella were resistant to at least one antimicrobial agent, generating eight different resistance patterns. The S. Typhimurium (n: 1) and S. Hadar (n: 3) isolates presented multiple resistance. Three S. Enteritidis isolates were susceptible to all antimicrobials tested, two were resistant only to tetracycline. The high prevalence of Salmonella in the broiler parts strenghtens the importance of the use of good manufacturing practices (GMP), and HACCP. The results also emphasize the need for the responsible use of antimicrobials in animal production.

Este trabalho foi conduzido para avaliar a ocorrência de Salmonella em cortes de frango e para determinar o perfil de resistência antimicrobiana das cepas isoladas. Vinte e quatro (39,3 por cento) cortes de frango foram positivas para Salmonella, tendo sido isoladas vinte e cinco cepas de Salmonella, uma vez que em uma amostra isolaram-se dois sorovares. Salmonella Enteritidis foi o sorovar prevalente. Entre as Salmonella Enteritidis isoladas, 95,2 por cento pertencem ao Fagotipo 4 (PT4) (20/21) e 4,8 por cento ao PT7 (1/21). Vinte e duas (88 por cento) cepas de Salmonella foram resistentes a pelo menos um agente antimicrobiano e oito diferentes padrões de resistência foram observados. S. Typhimurium (n:1) e S. Hadar (n: 3), apresentaram múltipla resistência. Três cepas de S. Enteritidis foram sensíveis a todos os antimicrobianos e duas resistentes somente a tetraciclina. A elevada ocorrência de Salmonella nos cortes de frango utilizados no presente estudo reforça a importância das normas de boas práticas de fabricação, bem como dos controles de perigos e pontos críticos de controle. No tocante aos níveis de resistência a antimicrobianos, os resultados enfatizam a necessidade do uso responsável dos mesmos na produção animal.

Antibiotic resistance in Salmonella Enteritidis isolated from broiler carcasses

Eighty Salmonella Enteritidis strains isolated from broiler carcasses between May 1995 and April 1996 in the State of Rio Grande do Sul, Brazil, were tested for antibiotic susceptibility using the disk diffusion method. Resistance to colistin, novobiocin, erythromycin and tetracycline was observed in 100 percent of the isolates. The strains showed intermediate resistance at different levels to kanamycin (1.25 percent), enrofloxacin (3.75 percent), neomycin (3.75 percent), fosfomycin (20 percent), sulphonamides (86.25 percent) and nitrofurantoin (90 percent). Resistance to ciprofloxacin, norfloxacin, gentamicin, polymyxin B, sulphametrim and sulphazotrim was not found. Since resistance to antibiotics especially those introduced in the last decades, was detected, it is recommended that their use must be based on the results of resistance tests or minimum inhibitory concentration tests.

Oitenta amostras de Salmonella Enteritidis isoladas de carcaças de frango no período entre maio de 1995 a abril de 1996 no Estado do Rio Grande do Sul, Brasil foram testados para susceptibilidade antimicrobiana pelo método de antibiograma. O antibiograma das amostras apresentou 100 por cento de resistência a colistina, novobiocina, eritromicina e tetraciclina. Tiveram resistência em diferentes níveis a canamicina (1,25 por cento), enrofloxacina (3,75 por cento), neomicina (3,75 por cento), fosfomicina (20 por cento), sulfonamida (86,25 por cento) e nitrofurantoína (90 por cento) e por outro lado não apresentaram resistência a ciprofloxacina, norfloxacina, gentamicina, polimixina B, sulfametrim e sulfazotrim. A constatação de resistência a antibióticos, inclusive àqueles introduzidos na última década, enfatiza a necessidade de uso responsável de antibióticos, e com base em antibiograma ou concentração inibitória mínima.

Identificação de Salmonella enteritidis fagotipo 6A em amostras de alimentos, humanos e materiais de origem avícola / Identification of Salmonella enteritidis fagotipo 6A in samples of sustenances, human and materials of origin poultry

A Salmonella Enteritidis (SE) é um patógeno de importância destacada como causa de toxinfecções alimentares em humanos e prejuízos ao setor produtivo, além de ser um microrganismo de ampla disseminação no ambiente. A caracterização precisa do agente é imprescindível para o sucesso de investigações epidemiológicas e implantação de medidas de prevenção e controle do mesmo. Neste trabalho foram selecionados 238 isolados de SE, dos quais 104 oriundos de carcaças de frango, 106 de alimentos e material biológico de humanos envolvidos em episódios de toxinfecções alimentares e 28 de diferentes materiais de origem avícola. Dentre estes isolados, 111 foram submetidos a fagotipagem. O PT 6ª representou 3,6 por cento (4/111) dos fagotipos de SE deste trabalho, no qual foram identificados também os fagotipos 4 (57,7 por cento; 64/111), 4ª (32,4 por cento; 36/111), 7 (0,90 por cento; 1/111) e RDNC (reagent do not conform 5,4 por cento; 6/111). A identificação do PT 6ª em dois isolados de origem aviária (swab de arrasto e figado de pinto de um dia) e em dois casos de toxinfecção alimentar em humanos (maionese e caso avulso - fezes) indica que este fagotipo poderia estar desenvolvendo uma estratégia semelhante à atribuída ao PT4, ou seja, adaptar-se a um determinado ambiente e apresentar um potencial diferenciado de patogenicidade para humanos. Verificou-se que a fagotipagem é uma ferramenta útil para análise epidemiológica de isolados de SE, estando habilitada para monitorar a manutenção de determinados fagotipos, bem como o aparecimento de novos fagotipos com potencial de patogenicidade.

Phage types of Salmonella enteritidis isolated from clinical and food samples, and from broiler carcasses in southern Brazil.

272 isolates of Salmonella Enteritidis (111 isolated from frozen broiler chicken carcasses, 126 from human food and other biological materials involved in food poisoning outbreaks and 35 from different poultry materials) were selected for phage typing. From these, 111 were phage typed, 57.65% being classified as phage type 4, 32.43% as phage type 4a, 3.60% as phage type 6a and 0.90% as phage type 7, whereas 5.40% samples were not phage typeable. The predominance of phage type 4 is in agreement with the results published worldwide, and reinforces the need for studies related to the epidemiological meaning of these findings.

Phage types of Salmonella enteritidis isolated from clinical and food samples, and from broiler carcasses in Southern Brazil

272 isolates of Salmonella Enteritidis (111 isolated from frozen broiler chicken carcasses, 126 from human food and other biological materials involved in food poisoning outbreaks and 35 from different poultry materials) were selected for phage typing. From these, 111 were phage typed, 57.65 percent being classified as phage type 4, 32.43 percent as phage type 4a, 3.60 percent as phage type 6a and 0.90 percent as phage type 7, whereas 5.40 percent samples were not phage typeable. The predominance of phage type 4 is in agreement with the results published worldwide, and reinforces the need for studies related to the epidemiological meaning of these findings

Utilization of immunomagnetic separation for detection of Salmonella in raw broiler parts

This study was conducted aiming to compare the conventional microbiological method to detect Salmonella in broiler parts with the Immunomagnetic Separation method(IMS) followed by plate isolation and also the IMS associated with Rappaport-Vassiliadis broth (RV). The IMS was performed following a pre-enrichment step in buffered peptone water. Sixty-one samples (raw broiler parts) were tested and the results showed that the use of the IMS method allowed the isolation of Salmonella in 9 of the tested samples, while the association IMS/RV detected the agent in 30 samples. The conventional microbiological method was able to isolate the agent in 25 opportunities. These results allowed to conclude that the IMS/RV association presented an increased sensitivity and permitted a better isolation of Salmonella. The conclusion was that other means of isolation, in particular those which do not interfere with the growth of bead bounded Salmonella, should be searched.

Polymerase chain reaction (PCR) for the detection of Salmonella in artificially inoculated chicken meat

The aim of this study was to develop a polymerase chain reaction (PCR) protocol for the detection of Salmonella in artificially contaminated chicken meat. Tests were performed with different dilutions of Salmonella Typhimurium or Salmonella Enteritidis cells (10-7, 10-8 or 10-9 CFU/mL) inoculated in chicken meat samples, in order to establish the limits of detection, incubation times (0, 6, 8 and 24 hours of pre-enrichment in PBW 1 percent) and three DNA extraction protocols (phenol-chloroform, thermal treatment and thermal treatment and Sephaglass). The assay was able to detect until 10-9 CFU/mL of initial dilution of Salmonella cells inoculated in chicken meat, which allows detection of Salmonella within 48 hours, including 24 hours of pre-enrichment and using the phenol-chloroform DNA extraction protocol. As the results are obtained in a shorter time period than that of microbiological culture, this procedure will be useful in the methodology for detection of Salmonella in chicken

Use of anaerobical cecal microflora, lactose and acetic acid for the protection of broiler chicks against experimental infection with "Salmonella" Typhimurium and "Salmonella" Enteritidis

The effects of treatment with anaerobic cecal microflora (ACM) and/or lactose and/or acetic acid on systemic and digestive tract of broiler chicks infection with "Salmonella" Typhimurium and "S." Enteritidis were studied. ACM was used without previous bacterial identification. Treatment with ACM contributed to the resistance of broiler chicks to infection with "Salmonella" spp. The infections were more persistent in the cecum, rectum and crops in decreasing order of intensity. The infections were also self-limiting since treated and control lots presented similar infection rates at the end of the experiments. Alone or in combination with lactose, ACM reduced the colonization of the digestive tract of broiler chicks by "S." Typhimurium and "S." Enteritidis. The effect of the combination of ACM with lactose or acetic acid was not potentiated in terms of reduction of fecal excretion of "Salmonella" spp. Treatment with ACM reduced the amount of "S." Typhimurium and "S." Enteritidis in feces. Alone or in combination with lactose, ACM reduced the cecal pH in treated birds. "S." Enteritidis was much more invasive than "S." Typhimurium and the use of ACM alone was more effective on the reduction of systemic infection. An explanation for the process of prevention of intestinal colonization with "Salmonella" spp. probably resides in the interrelationship of physiological, microbiological and immunological phenomena, as well as the variation in cecal pH.