Aldemir Reginato Ribeiro

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% of the isolates. The strains showed intermediate resistance at different levels to kanamycin (1.25%), enrofloxacin (3.75%), neomycin (3.75%), fosfomycin (20%), sulphonamides (86.25%) and nitrofurantoin (90%). 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.

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%) 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% belonged to Phage Type 4 (PT4) (20/21) and 4.8% to PT7 (1/21). Twenty-two (88%) 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.

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.

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%) 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.

Resistência antimicrobiana em Salmonella Enteritidis isoladas de amostras clínicas e ambientais de frangos de corte e matrizes pesadas

The antimicrobial resistance of Salmonella Enteritidis strains isolated from clinical and environmental poultry samples in the Southern Brazil during the years of 1999, 2000 and 2001 was evaluated. Among the 79 isolated samples, 64 (81%) were resistant to at least one of the antimicrobial agents tested, showing 22 different resistance patterns. Tetracycline showed the highest percentage (64,5%) of resistance among the antimicrobial agents used. Resistance to drugs at different levels was found as the following: ampicillin (1.2%), kanamycin (1.2%), ciprofloxacin (2.5%), enrofloxacin (8.8%), gentamicin (21.5%), streptomycin (20.2%), nitrofurantoin (26.6%), and nalidixic acid (30.4%). None of the S. Enteritidis strains were resistant to chloramphenicol, norfloxacin, and polimycin B. Among the 64 S. Enteritidis strains that showed resistance, 43 (67.2%) were resistant to two or more antimicrobial agents. Twenty-one (32.8%) strains were resistant to only one of the antimicrobial agents, 14 to tetracycline, three to nalidixic acid, three to nitrofurantoin, and one to gentamycin. These antimicrobial resistance levels suggest a high occurrence of tetracycline resistant S. Enteritidis strains and resistance to two or more antimicrobial agents.

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 alone 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.

In vitro efficiency of disinfectants against salmonella enteritidis samples isolated from broiler carcasses

The threat to public health represented by Salmonella is at least partially a consequence of its ecology in poultry hosts. Good manufacturing practices in the processing plant can reduce the contamination of poultry products, and critical control point principles are essential throughout the chain production. One procedure adopted in critical points control to prevent and to reduce Salmonella in farms and poultry products is the use of disinfectants. This study aimed at evaluating disinfectant efficiency against Salmonella enteritidis samples isolated from broiler carcasses in Rio Grande do Sul State between 1995 and 1996. The tested disinfectants were: phenol 1:256, quaternary ammonium 1:2500, glutaraldehyde 1:200, and iodine 1:500, with contact times of 5, 10, 15, and 20 in an in vitro test. .Phenolic compounds showed better results, iodine and glutaraldehyde showed intermediary results, and quaternary ammonium presented efficiency at all contact times evaluated in the in vitro test.