José Renaldi Feitosa Brito

Qualidade microbiológica do leite refrigerado nas fazendas

Avaliaram-se a qualidade microbiologica do leite obtido mecanicamente e refrigerado durante 48 horas, em 24 rebanhos, e a associacao entre a contaminacao microbiana e os procedimentos de higienizacao dos equipamentos de ordenha e armazenamento do leite. Os procedimentos de higiene foram avaliados in loco com auxilio de questionarios. Foram realizadas a contagem padrao em placas, a contagem de coliformes totais e a pesquisa de Staphylococcus aureus e Streptococcus agalactiae. No leite de 14 rebanhos, foram pesquisadas Salmonella spp. e Listeria monocytogenes. As medias geometricas da contagem padrao foram 103 UFC/ml foram verificadas em sete rebanhos. S. aureus e S. agalactiae foram isolados em 22 e 12 dos 24 rebanhos, respectivamente, e nao foram encontradas Salmonella spp. e L. monocytogenes. O uso de detergentes alcalino e acido, mais o de sanitizante foi associado (P 5×105 UFC/ml.

Diversity of virulence profiles of Shiga toxin-producing Escherichia coli serotypes in food-producing animals in Brazil

The prevalence, serotypes and virulence profiles of Shiga toxin-producing Escherichia coli (STEC) were investigated in 205 healthy beef and dairy cattle, and 106 goats reared in the southeastern region of Minas Gerais State, Brazil. The prevalence of STEC was 57.5% (61/106) in goats, 39.2%, (40/102) in beef cattle and 17.5% (18/103) in dairy cattle. Among the 514 STEC isolates, 40 different serotypes were found and some of them were identified in a specific host. STEC isolates harboring stx1 corresponded to 15.6% (28/180), 26.7% (16/60) and 24.1% (66/274) in beef cattle, dairy cattle and goats, respectively. stx2 was found in 30% (54/180), 53.3% (32/60) and 34.7% (95/274) of beef and dairy cattle, and goats. stx1 plus stx2 sequences were harbored by 54.4% (98/180), 20% (12/60) and 41.2% (113/274) of beef cattle, dairy cattle and goats, respectively. The eae sequence was found in 15% (9/60) and 0.6% (1/180) of STEC isolates from dairy and beef cattle, respectively, and the toxB gene was found only in one O157:H7 strain isolated from beef cattle. Strains with the genetic profiles stx2 ehxA iha saa and stx1 stx2 ehxA iha saa were the most prevalent among STEC isolates from cattle. Profiles stx1 stx2 ehxA iha, stx2, and stx1 iha accounted for 75.5% (207 /274) of the STEC isolates from goats. While STEC strains carrying either stx2 alone or associated with stx1 were found more frequently in cattle, those harboring sequences stx1c and stx2d alone or associated with stx1c predominated in goats. Our data show a diversity of STEC strains in food-producing animals, most of them carrying genes linked to severe forms of human diseases.

Sensibilidade e especificidade do "California Mastitis Test" como recurso diagnóstico da mastite subclínica em relação à contagem de células somáticas

The California Mastitis Test (CMT) is a simple and widely used diagnostic tool for subclinical mastitis. It is used even in areas where laboratory facilities are available for diagnosis and monitoring program purposes. CMT usually score 1-5, where 1 indicates a completely negative reaction and 2-5 increasing degrees of inflammatory reaction of the udder. The reactions 2-5, 3-5 or 4-5 may be considered as indicative of subclinical mastitis, bever, may produce either false-positive or false-negative results. The aim of this study waecause they are related to an increase of the somatic cell count (SCC) in the milk. This variation, hows to assess the sensitivity and specificity of the CMT in comparison with SCC. A total of 3,012 quarter milk samples from 760 lactating cows were examined. CMT was evaluated at the moment of sampling at cow side and SCC in the laboratory, with a fluoro-opto-electronic method (Fossomatic 90). The average CCS (x 1,000 cells/ml) for CMT scores were: 1 (79.9), 2 (333.5), 3 (670.3), 4 (1,354.0) and 5 (4,455.6). Three options for CMT interpretation were evaluated in relation to a range of CCS, starting from 100,000 cells/ml: (a) 1 versus 2, 3, 4, and 5; (b) 1 and 2 versus 3, 4 and 5; and (c) 1, 2 and 3 versus 4 and 5. The sensitivities of CMT scoring to detect quarters with SCC >200,000/ml were 79%, 61% e 34% for options a, b and c, respectively. The sensitivities of CMT scores for SCC >500,000/ml for options a, b and c, were, respectively, 93%, 82% e 54%. The sensitivity of CMT scores to identify subclinical mastitis was satisfactory (above 80%) when options b and c were used. The interpretation of CMT score 3 as negative for subclinical mastitis was considered as adequate (sensitivity around 80%) only when CCS ranged between 1,200,000 and 1,400,000 cells/ml. The specificities of CMT scoring for CCS of 200,000 and 500,000 were, respectively, 90% and 80% (option a), 97% and 90% (option b) and 99% and 97% (option c).

Concentração mínima inibitória de dez antimicrobianos para amostras de Staphylococcus aureus isoladas de infecção intramamária bovina

The minimum inhibitory concentrations (MIC) for ampicillin, cephalothin, erythromycin, gentamicin, neomycin, norfloxacin, oxacillin, penicillin G, tetracycline and tylosin against 112 Staphylococcus aureus strains isolated from bovine intramammary infections were determined. The strains were originated from 33 dairy herds located in the Zona da Mata, Minas Gerais State. Twenty-four strains were isolated from clinical cases of mastitis, 66 from subclinical infections and 22 from chronic infections. The chronic infection strains were isolated from the same mammary quarters of nine cows of one herd over a period of 13 months. The MIC was performed on Mueller Hinton agar and concentrations, ranging from 0.015 to 128µgml-1, were evaluated for each antimicrobial agent. The American Type Culture Collection (ATCC) recommended quality control strains, S. aureus ATCC 29213, Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853, were included on each batch of test. All strains were susceptible to cephalothin, erythromycin, gentamicin, norfloxacin and oxacillin, 91% were susceptible to tetracycline (MIC50: 0.5µgml-1) and tylosin (MIC50: 2.0µgml-1), 65% to ampicillin (MIC50: 0.125µgml-1) and penicillin G (MIC50: 0.06µgml-1). All strains but one in the intermediate pattern, were susceptible to neomycin (MIC50: 0.5µgml-1). The resistance levels to ampicillin and penicillin were higher in strains isolated from clinical and subclinical (positive scores on CMT) cases (P<0.02). The resistance level to tylosin was also higher among the strains isolated from clinical infections (P<0.02). The strains with MIC³0.125µgml-1 to penicillin were positive for s-lactamase production.

Water Buffaloes (Bubalus bubalis) Identified as an Important Reservoir of Shiga Toxin-Producing Escherichia coli in Brazil

ABSTRACT The presence of Shiga toxin-producing Escherichia coli (STEC) in water buffaloes is reported for the first time in South America. The prevalence of STEC ranged from 0 to 64% depending on the farm. STEC isolates exhibiting the genetic profiles stx1stx2ehxA iha saa and stx2ehxA iha saa predominated. Of the 20 distinct serotypes identified, more than 50% corresponded to serotypes associated with human diseases.

Fatores de risco para mastite subclínica em vacas leiteiras

This study was carried out to identify risk factors for subclinical mastitis (SCC > 200,000 cells/ml). A total of 2,657 lactating cows from 24 herds in the State of Minas Gerais, Brazil, were included in the study. Each farm was visited three times in an 8-month period from November 2005 to June 2006. At each visit, all milking cows were examined for clinical mastitis by a single observer. A total of 3,987 milk samples were examined for somatic cell counts (SCC). The mean, median, and standard deviation values for SCC were, respectively, 608,000, 219,000, and 967,000 cells/ml. Risk factors for subclinical mastitis were: udder positioned at the same height or below the hock, presence of cracks or fissures in the rubber parts of the milking machine, inadequacy of teat cups, infrequent and unsuitable scheme for cleaning the pulsators, milkers unable to operate the milking equipments, no information about the mastitis pathogens present in the herd, immersion of teat cups in disinfectant solution between milkings, and total insertion of cannula in teats during antibiotic treatment. The high variation of the SCC values (608,000± 967,000 cells/ml) suggests that other factors such as number of infected mammary quarters and pathogens involved could have influenced the results. The used methodology did not allow to identify all risk factors that increase SCC. Therefore, the results can also be used to improve the currently mastitis control programs adopted by those herds.

Variação da contagem de células somáticas em vacas leiteiras de acordo com patógenos da mastite

The influence of mastitis pathogens on variation of milk somatic cell count (SCC) was evaluated. Three thousand nine hundred eighty-seven milk samples were colected from 2,657 dairy cows in 24 herds located in the states of Minas Gerais and Rio de Janeiro. The milk samples were used to SCC and identification of mastitis pathogens. Descriptive statistics, T test for independent samples, and generalized linear model were used to data analysis. The generalized linear model identified the effects of herd, animal within herd, parity, year season, intramammary infection, and infection caused by Streptococcus agalactiae and Streptococcus spp. except S. agalactiae as significant on SCC variation. The effect of animal within herd was higher than the effect of herd. S. agalactiae was the pathogen responsible for higher SCC increasing and presented the average of 1,520,000 cells/mL. The specific effect on SCC variation was observed in the study.

Contagem de células somáticas e isolamento de agentes causadores de mastite em búfalas (Bubalus bubalis)

The research was accomplished in eight dairy water buffalo herds, randomically choosen in Regiao do Alto Sao Francisco, State of Minas Gerais, Brazil. Information was collected from March to November, 2003 during 270 days of observation. In order to determine the somatic cell count (SCC) in presence or absence of microbial isolation, 1,393 samples were collected from 285 lactating females and microbiological exams and SCC were done. Samples obtained from udders without evidence of clinical or subclinical inflammation showed infection for a great variety of microbial mastitis pathogens. The low SCC did not necessarily indicate the absence of intramammary infection, suggesting that SCC patterns used for bovine cannot be appropriate in order to control mastitis in buffalo herds.

Fatores de risco associados à alta contagem de células somáticas do leite do tanque em rebanhos leiteiros da Zona da Mata de Minas Gerais

Herd features and management practices associated with high bulk milk somatic cell count (BMSCC) were studied in 175 dairy herds enrolled on BMSCC programs. Herds data were obtained from June/2000 to December/2001 by questionnaires application. Herds were classified according to the geometric mean of six consecutive BMSCC records. Exploratory analysis and logistic regression models were the statistical analysis applied. Procedures about mastitis control and prevention were adopted in a few herds. Type of milking (machine or hand milking), herd age, milking place (milking parlour, pen, corral) and strip test practice (first streams of milk) were not associated with high BMSCC. Factors associated with high BMSCC were the following: do not milk clinical mastitic cows at the end of milking, feeding cows at milking and absence of post milking teat disinfection.

Avaliação da sensibilidade da cultura de leite do tanque para isolamento de agentes contagiosos da mastite bovina

Samples of bulk tank milk from 33 herds were collected at the dairy processing plant and cultured, as a means of detecting specific (contagious) bovine mastitis pathogens. Somatic cell counts (SCC) were made on a Fossomatic 90. Two and three weekly consecutive samples were obtained from 13 and 12 herds, respectively. Only one sample was examined from eight herds. Three daily consecutive samples of bulk milk and individual quarter samples from all lactating cows from four herds (A, B, C and D) were also examined. Milk from individual quarters were cultured on blood agar, while tank milk samples were cultured on TKT, Mannitol Salt, MacConkey agars and Sabouraud containing chloramphenicol. Staphylococcus aureus was recovered from 26 of the 33 herds sampled in the dairy processing plant. Nine of these samples also contained Streptococcus agalactiae. Nine herds had SCC above 500,000 ml-1. The remaining 23 herds had SCC levels below 400,000 ml-1. S. aureus and S. agalactiae were isolated from five of the nine herds with high SCC, S. agalactiae from one and S. aureus from three. Six herds had SSC below 200,000 ml-1. S. aureus and S. agalactiae were isolated from one, S. aureus from three, while the other two were negative for both pathogens. The results of herds A, B, C and D sampled at the farms showed that S. aureus was isolated from 1.8%, 19.2%, 17.0% and 8.4% of the animals and 0.9%, 5.9%, 5.4% and 2.2% of the mammary quarters, respectively. S. agalactiae was isolated from herds A, C and D. Within these herds the percentages of isolation were, respectively, 1.8%, 10.6% and 8.4% for the cows and 0.46%, 3.8% and 3.7% for the mammary quarters. S. aureus was recovered from all three bulk tank cultures from herds A, B and D. Only the third sample from herd C was positive for S. aureus. S. agalactiae was recovered from all samples collected from herd D, two samples from herd C and one sample from herd A. Coliforms were isolated from all tank samples from herds A, B, C and D and from all but one sample collected in the processing plant. Yeasts were recovered from 16 herds sampled at the processing plant and from all tank samples from herds A, B, C, and D. Neither coliforms or yeasts were isolated from the individual animals of herds A, B, C and D. These findings indicate that the milk was contaminated during or after milking, probably due to deficient hygiene and cleaning procedures. The analysis of the bulk tank milk cultures showed that the test was sensitive enough to detect contagious mastitis pathogens. The sensitivity of the test increased when more than two consecutive samples were examined.