Laura Beatriz Rodrigues

Behavior of Salmonella heidelberg and Salmonella enteritidis strains following broiler chick inoculation: evaluation of cecal morphometry, liver and cecum bacterial counts and fecal excretion patterns

Over the years, Salmonella Heidelberg (SH) has gained prominence in North America poultry production and in the poultry production of other countries. Salmonella Heidelberg has been isolated and reported from poultry and poultry products in Brazil since 1962, whereas Salmonella Enteritidis (SE) has only emerged as a serious problem in poultry and public health since 1993. These strains of Salmonella can cause intestinal problems in newly hatched chicks, and infection may persist until adulthood. Upon slaughter of chickens, Salmonella can contaminate carcasses, a condition that poses a threat to human health. The aim of this study was to compare the fecal excretion of Salmonella Enteritidis and Salmonella Heidelberg in newly hatched chicks (orally inoculated with 105ufc/mL each) until 20 days of age. In addition, the ratio of cecal villus height:crypt depth (morphometry) and liver and cecum cell counts was analyzed in chicks ranging from 0 to 3 days of age and infected with these two Salmonella strains. One hundred seventeen chicks were separated into one of three experimental groups: a control group, an SE-infected group and an SH-infected group. Eight chicks per group were euthanized at 6, 12 and 72 hours post-inoculation (pi) to allow for Salmonella isolation from the liver and cecum and for the collection of the cecum for villi and crypt analysis. Other birds were allowed to mature to 20 days of age and cloacal swabs were taken at 2, 6, 13 and 20 days pi to compare the fecal excretion of inoculated strains. The Salmonella Enteritidis group had a higher number of cells excreted during the trial. Both strains were isolated from the liver and cecum by 6h pi. At 12h pi the Salmonella Heidelberg group had high cell counts in the cecum. No difference was found in liver cell counts. Both strains showed lower villus height:crypt depth ratio than the control group post-infection.

Antimicrobial resistance in Campylobacter spp isolated from broiler flocks

The aim of this study was to assess the antimicrobial susceptibility of 62 Campylobacter spp. strains obtained from broiler flocks using the agar diffusion method. The Campylobacter spp strains were isolated from 22 flocks aged between 3 and 5 weeks of life, isolated from cloacae swabs, stools and cecal droppings in the farm and from the carcass rinsing in the slaughterhouse. Campylobacter spp strains were tested on Mueller-Hilton (MH) agar (27 samples) and MH plus TTC agar (35 samples). The antimicrobial susceptibility test revealed a 62.5% resistance to at least one drug, especially to enrofloxacin (71%), neomycin (50%), lincomycin (50%), tetracycline (43%), penicillin (42%), ceftiofur (33%) amoxicillin (27%), spiramycin (20%), ampicillin (18%) and norfloxacin (14%), whereas a lower percentage of strains was resistant to erythromycin (10%) and doxycycline (10%). All strains were sensitive to gentamicin and lincomycin-spectinomycin and 80% of them to colistin. These results indicate that it is necessary to reduce the use of antimicrobials in veterinary and human medicine.

Isolamento de Salmonella Heidelberg em diferentes pontos da tecnologia de abate de frangos de corte

Bacteria of the genus Salmonella are part of the normal flora of poultry, and its occurrence in poultry products varies with the production management methods and slaughter technology, representing risks to the consumer and difficulties in exports. S. Heidelberg appears to be more invasive and to cause more severe disease than other non-typhoidal serovars. The objective of the present study was to search for Salmonella at different points of the slaughterhouse and to report on the isolation of S. Heidelberg in a slaughterhouse under federal inspection. S. Heidelberg was isolated in poultry soon after feathering-out and in the chiller water, indicating that, although it was not isolated at another sampled points, the bacteria was present in the environment and could contaminate carcasses ready for consumption, with an impact on public health. This concern is underscored by the fact that S. Heidelberg is a proven causative agent of foodborne infections.

Avaliação in vitro de clorexidina, amônia quaternária e ácido peracético frente a amostras de Salmonella Heidelberg isoladas de abatedouro avícola em 2005 e 2009

The objective of this investigation was to evaluate the in vitro sensibility of Salmonella Heidelberg to three commercially available disinfectants used for sanitization in poultry slaughterhouses. A total of 20 S. Heidelberg were tested (14 isolated in 2005 and six in 2009), and as active ingredients were used chlorhexidine (0.5%), quaternary ammonium (0.5 %) and peracetic acid (1%) at contact intervals of 5, 10, 15 e 20 minutes. All isolates were found to be sensitive to peracetic acid at four specific contact intervals. One hundred percent of S. Heidelberg isolated in 2005 was found to be sensitive to quaternary ammonium, while 33% of 2009 isolates were resistant at a 5-minute contact interval and 16.6% at 10-minutes. With respect to chlorhexidine, 25% of the 2005 isolates were resistant at a 5-minute contact interval, 33% of the 2009 isolates were resistant with the same time, and 17% at a 10-minute contact interval. It can be concluded that the highest disinfectant activity in vitro was found to be with peracetic acid for S. Heidelberg isolates in 2005 and 2009, whereas chlorhexidine and quaternary ammonium had a reduced action against 2009 isolates, indicating the progression of bacterial resistance against these sanitizers and the need for periodic evaluation and rotation of active principles for sanitization.

Lavado traqueobrônquico auxiliado por endoscópio rígido ou por tubo endotraqueal em cães

The present study aimed to evaluate the results of rigid endoscopy and endotracheal tube techniques for collecting tracheobronchic fluid from dogs. Twenty eight erratic or housed dogs, were allocated into to two groups. In group 1, tracheobronchic washing was applied to seven healthy dogs and seven dogs with clinical signs of respiratory disease. In group 2, seven healthy and seven dogs with respiratory disease were submitted to endo-bronchial washing by rigid endoscopy. Using rigid endoscopy, a lower volume was introduced but a higher percentage of washing fluid was recovered. There was no difference regarding the time necessary to perform both techniques. Bacterial counts were higher in samples collected by rigid endoscopy, but there was no difference in total nucleated cell counts from these samples. Thus, the use of rigid endoscopy to collect tracheobronchic fluid was found to be advantageous when compared to the conventional technique using endotracheal tube.

SEROVARS AND ANTIMICROBIAL RESISTANCE OF Salmonella spp. ISOLATED FROM TURKEY AND BROILER CARCASSES IN SOUTHERN BRAZIL BETWEEN 2004 AND 2006

Salmonella spp. causes diseases in fowls, when species-specific serovars (Salmonella Pullorum and S.Gallinarum) are present in flocks, and public health problems, when non-typhoid serovars are isolated, as well as possible bacterial resistance induced by the preventive and therapeutic use of antimicrobials in animal production. This study describes the serovars and bacterial resistance of 280Salmonella spp. strains isolated from turkey and broiler carcasses in Southern Brazil between 2004 and 2006. SalmonellaEnteritidis was the most prevalent serovar (55.7%), followed by Heidelberg (5.0%), Agona (4.3%), Bredeney (3.9%), Hadar (3.2%), and Typhimurium (2.9%). Tennessee and S. Enterica subspecies enterica(O: 4.5) were isolated only in turkeys, and Hadar (18.6%) was the most prevalent serovar in this species. Antimicrobial susceptibility tests were performed in 178 isolates (43 from turkeys and 135 from broilers). All isolates were sensitive to amoxicillin + clavulanic acid, polymyxin B, ciprofloxacin, and norfloxacin, and were resistant to bacitracin and penicillin. Broiler carcass isolates showed resistance to nalidixic acid (48.9%), nitrofurantoin (34.3%), neomycin (9.6%), tetracycline (5.2%), and kanamycin (8.9%); and turkey carcass isolates were resistant to nalidixic acid (62.8%), tetracycline (34.9%), and neomycin (30.2%), with a significant difference in turkeys when compared to broiler carcass isolates. These results indicate the need for judicious use of antimicrobials in livestock production, given that the serovars identified are potential causes of food poisoning.

Campylobacter in broiler slaughter samples assessed by direct count on mCCDA and Campy-Cefex agar

Campylobacter spp. cause foodborne illnesses in humans primarily through the consumption of contaminated chicken. The aim of this study was to evaluate the United States Department of Agricultures (USDA) recommended methodology, protocol MLG 41.02, for the isolation, identification and direct plate counting of Campylobacter jejuni and C. coli samples from the broiler slaughtering process. A plating method using both mCCDA and Campy-Cefex agars is recommended to recover Campylobacter cells. It is also possible to use this method in different matrices (cloacal swabs and water samples). Cloacal swabs, samples from pre-chiller and post-chiller carcasses and samples of pre-chiller, chiller and direct supply water were collected each week for four weeks from the same flock at a slaughterhouse located in an abattoir in southern Brazil. Samples were analyzed to directly count Campylobacter spp., and the results showed a high frequency of Campylobacter spp. on Campy-Cefex agar. For the isolated species, 72% were identified as Campylobacter jejuni and 38% as Campylobacter coli. It was possible to count Campylobacter jejuni and Campylobacter coli from different samples, including the water supply samples, using the two-agar method. These results suggest that slaughterhouses can use direct counting methods with both agars and different matrices as a monitoring tool to assess the presence of Campylobacter bacteria in their products.

Perfil de sensibilidade aos antimicrobianos e eficácia de sanitizantes frente aos isolados de Salmonella spp. oriundos de carcaças suínas no Rio Grande do Sul

The aim of this study was to evaluate the antimicrobial sensitivity and efficacy of three sanitizers against Salmonella spp. isolated from carcasses in swine slaughterhouse. Thirty nine of 120 samples were positive for Salmonella spp. The antimicrobials tested included: penicillin G 10 U, amoxicillin + clavulanic acid 30mcg, ampicillin 10mcg, chloramphenicol 30mcg, tetracycline 30mcg, streptomycin 10mcg, gentamicin 10mcg, neomycin 30mcg, enrofloxacin 5mcg, sulfazotrim 25mcg, sulfonamide 300mcg and trimetropim 5mcg. In the tests with sanitizers were used chlorhexidine, quaternary ammonia and peracetic acid, which were put in contact intervals of 1, 5, 10 and 15 minutes. Antimicrobial resistance was observed using penicillin (100%), tetracycline (94.9%), trimetropim (89.7%), and ampicillin (87.2%). None of the antimicrobials was 100% effective against the samples tested. Amoxicillin + clavulanic acid (86.7%), neomycin (86.7%) and chloramphenicol (64.1%) showed better antimicrobial action. In tests of efficacy of sanitizers, 0.5% peracetic acid was effective at 10 minutes (94.6%) and 15 minutes (97.3%) of contact; 1% quaternary ammonia at 10 minutes (89.2%) and 15 minutes (97.3%) and 0.5% chlorhexidine at 10 minutes (70.3%) and 15 minutes (72.8%). All samples tested were multidrug resistance and six (15.3%) showed resistance to ampicillin, chloramphenicol, streptomycin, sulfonamide and tetracycline (ACSSuT group) indicating the need to monitor the spread of antimicrobial resistance of Salmonella spp. isolated from swine. The most effective sanitizing against the bacteria tested was 0.5% peracetic acid per 15 minutes, reinforcing the need to monitor the effectiveness of products sanitizers against Salmonella spp.

Miniaturized most probable number for the enumeration of Salmonella sp in artificially contaminated chicken meat

Salmonella is traditionally identified by conventional microbiological tests, but the enumeration of this bacterium is not used on a routine basis. Methods such as the most probable number (MPN), which utilize an array of multiple tubes, are time-consuming and expensive, whereas miniaturized most probable number (mMPN) methods, which use microplates, can be adapted for the enumeration of bacteria, saving up time and materials. The aim of the present paper is to assess two mMPN methods for the enumeration of Salmonella sp in artificially-contaminated chicken meat samples. Microplates containing 24 wells (method A) and 96 wells (method B), both with peptone water as pre-enrichment medium and modified semi-solid Rappaport-Vassiliadis (MSRV) as selective enrichment medium, were used. The meat matrix consisted of 25g of autoclaved ground chicken breast contaminated with dilutions of up to 106 of Salmonella Typhimurium (ST) and Escherichia coli (EC). In method A, the dilution 10-5 of Salmonella Typhimurium corresponded to >57 MPN/mL and the dilution 10-6 was equal to 30 MPN/mL. There was a correlation between the counts used for the artificial contamination of the samples and those recovered by mMPN, indicating that the method A was sensitive for the enumeration of different levels of contamination of the meat matrix. In method B, there was no correlation between the inoculated dilutions and the mMPN results.

Antibacterial efficacy of commercial disinfectants on dirt floor used in poultry breeder houses

Dirt floors are used on most Brazilian poultry farms since the construction of concrete floors is very expensive. In vitro tests carried out to verify the effectiveness of disinfectants do not consider the adverse conditions found in poultry farms. Therefore, the present study aimed at evaluating the effect of six commercial disinfectants on the reduction of total and fecal coliforms on the dirt floor of breeder houses. The amount of disinfectant solution to be used per square meter was defined by counting total and fecal coliforms at different soil depths and by analyzing soil physical properties. Coliforms were detected at 0.5 cm, and one liter of disinfectant solution was sufficient for soil saturation at this depth. After that, the efficacy of six commercial products (caustic soda, hydrated lime, phenols 1 and 2, iodine, glutaraldehyde, and quaternary ammonium) in reducing the number of coliforms, after six hours of contact with the dirt floor, was assessed using the most probable number (MPN) method. Escherichia coli specimens isolated from the dirt floor were used to evaluate in vitro effectiveness of disinfectants. Products that yielded the best results in the MPN method were also effective in the in vitro tests. Among the tested disinfectants, hydrated lime was the most efficient, reducing the initial contamination by 2.9 log after six hours of contact with the dirt floor.