Adriano França da Cunha

Avaliação da qualidade microbiológica de bebida láctea e creme de leite UAT por ATP-Bioluminescência

Although traditional methods are used for the microbiological evaluation of UHT products, rapid methodologies based on ATP-Bioluminescence have been developed. The results of applying this technique in 54 samples of chocolate UHT milk drink and 12 of UHT milk cream were compared with the results of microbiological methods, using different culture media and incubation times for the referred samples. The ATP-Bioluminescence technique was applied through the MLS system and the results were expressed as relative light units (RLU). In all incubation times - 48, 72, and 168 hours - , the samples showed lower counts of mesophilic and psychrotrophic aerobic microorganisms when analyzed using PCA, BHI, PetrifilmTMAC and ATP-Bioluminescence (<150RLU), demonstrating the techniques high specificity. Only one sample of UHT milk cream showed a mesophilic aerobic count above the standard established by Brazilian legislation (<100CFU/mL) when analyzed in PCA (260 CFU/mL) and PetrifilmTMAC (108CFU/mL) at 168 hours. This high count of aerobic mesophilic microorganisms was also detected by the ATP-Bioluminescence (416 RLU) technique. The results of the ATP-Bioluminescence technique were equal to the results in PCA, BHI and PetrifilmTMAC.

Contagem de células somáticas e detecção de patógenos causadores de mastite em amostras de leite compostas e individuais simples ou em duplicata

The most acceptable criteria for diagnosing bovine intramammary infections include results of bacteriological culture and measures of inflammation. Therefore, information on the diagnostic characteristics of the procedures used to identify infected quarters is required. Thus, this study was designed to evaluate a set of criteria to classify the infectious status of an udder at the quarter (single and duplicate milk samples) and cow (composite milk sample) levels, and to compare the infectious status with somatic cell counts (SCCs) of the samples. Here, the SCC thresholds determined by receiver operating characteristic curve analysis had a higher Youden index using mammary quarter duplicate milk samples as the gold standard for testing compared with single quarter and composite milk samples, especially for samples for which at least one of the duplicates was microbiologically positive, regardless of the mastitis pathogen isolated. The kappa coefficient for bacteriological results of the single quarter milk samples (single S1 and S2) was 0.85+0.019, indicating that single quarter milk sampling can be useful in mastitis control programs. Therefore, the use of composite milk samples to detect mastitis pathogens may be limited to the detection of major pathogens, given their predictive values. Thus, our findings suggest that the milk SCCs and microbiological examinations, although regarded as the most reliable indicators of ongoing mastitis, should be used in an integrated manner in mastitis control programs. Furthermore, the accuracy of single, duplicate and composite microbiological analyses to diagnosis mastitis should be considered for its implications in mastitis control strategies.The most acceptable criteria for diagnosing bovine intramammary infections include results of bacteriological culture and measures of inflammation. Therefore, information on the diagnostic characteristics of the procedures used to identify infected quarters is required. Thus, this study was designed to evaluate a set of criteria to classify the infectious status of an udder at the quarter (single and duplicate milk samples) and cow (composite milk sample) levels, and to compare the infectious status with somatic cell counts (SCCs) of the samples. Here, the SCC thresholds determined by receiver operating characteristic curve analysis had a higher Youden index using mammary quarter duplicate milk samples as the gold standard for testing compared with single quarter and composite milk samples, especially for samples for which at least one of the duplicates was microbiologically positive, regardless of the mastitis pathogen isolated. The kappa coefficient for bacteriological results of the single quarter milk samples (single S1 and S2) was 0.85+0.019, indicating that single quarter milk sampling can be useful in mastitis control programs. Therefore, the use of composite milk samples to detect mastitis pathogens may be limited to the detection of major pathogens, given their predictive values. Thus, our findings suggest that the milk SCCs and microbiological examinations, although regarded as the most reliable indicators of ongoing mastitis, should be used in an integrated manner in mastitis control programs. Furthermore, the accuracy of single, duplicate and composite microbiological analyses to diagnosis mastitis should be considered for its implications in mastitis control strategies.

ATP-Bioluminescence as a method to evaluated microbiological quality of UHT milk

New approaches are needed to quickly indicate possible contamination of UHT milk, among them the technique of ATP-Bioluminescence. Therefore, the aim of this study was to compare the results of culture methods with the results of ATP-Bioluminescence technique of 102 UHT whole milk samples incubated at 48, 72, and 168 hours. UHT milk samples were analyzed for the presence of mesophilic and psychrotrophic aerobic microorganisms using Plate Count Agar (PCA), Brain-Heart Infusion (BHI) media and PetrifilmTM Aerobic Count (AC) plates. The ATP-Bioluminescence technique was applied through the Microbial Luminescent Screening (MLS) system. Significant correlations were found between counts of aerobic mesophilic microorganisms on PCA, PetrifilmTM AC, BHI and results of ATP bioluminescence technique (P≤0.05). The ATP-Bioluminescence technique had higher correlation with counting method in PCA than BHI media. At lower pass/fail limits of Relative Light Units (60, 50, 45 and 40 RLU), the number of samples identified as positive increased and statistically agreed with aerobic mesophilic microorganism counts (P>0.05). For the dairy industry, the ATP-Bioluminescence technique may become an important tool that assists the official methods to quickly monitor the microbiological quality of UHT milk though this will likely require a threshold below 150 RLU.

Detection of antimicrobial and anthelmintic residues in bulk tank milk from four different mesoregions of Minas Gerais State - Brazil

Avaliou-se a presenca de residuos antimicrobianos (ceftiofur, estreptomicinas, quinolonas, tetraciclinas, tianfenicol e tilosina) e anti-helminticos (benzimidazois, aminobenzimidazois, levamisol, avermectinas, tiabendazois, moxidectina e triclabendazois) em, respectivamente, 70 e 83 amostras de leite cru provenientes de quatro mesorregioes (Triângulo Mineiro/Alto Paranaiba, Central Mineira, Oeste de Minas e Metropolitana de Belo Horizonte) do estado de Minas Gerais. Este estudo demonstrou a presenca de quinolonas (2,86%), estreptomicinas (2,86%) e tetraciclinas (11,43%) nas amostras de leite cru analisadas. Ademais, observou-se expressiva porcentagem de amostras de leite cru positivas para os anti-helminticos amino- benzimidazois (55,42%), levamisol (53,57%), avermectinas (60,24%), tiabendazois (67.47%), moxidectina (73,49%) e triclabendazois (45,78%), e em menor porcentagem os benzimidazois (6,02%). Desta forma, os resultados do presente estudo indicam que os residuos de antimicrobianos e anti-helminticos no leite em Minas Gerais devem ser constantemente monitorados pelas autoridades competentes com intuito de oferecer aos consumidores um alimento sem riscos a saude humana.

In vitro probiotic potential of Lactobacillus spp. isolated from fermented milks

O potencial probiotico in vitro de Lactobacillus spp. foi avaliado em leites fermentados comercializados em Belo Horizonte, MG, Brasil. Das amostras analisadas, 86,7% apresentaram quantidade minima de 106UFC/mL de Lactobacillus spp., enquadrando-se no padrao brasileiro de qualidade de leites fermentados. Alem disso, 56,7% apresentaram quantidade minima de 108a 109UFC/mL, estando em conformidade com os parâmetros legais vigentes. As demais 43,3% nao estariam aptas a garantir satisfatoriamente efeitos beneficos aos consumidores. Observou-se variacao na quantidade de Lactobacillus spp. entre lotes dos produtos, o que pode indicar falhas no monitoramento durante a fabricacao, transporte ou estocagem destes. Todas as amostras de Lactobacillus spp. demonstraram alguma atividade inibitoria frente aos microrganismos indicadores, sendo mais intensa contra microrganismos patogenicos que nao patogenicos (P<0,05). As amostras de Lactobacillus spp. apresentaram diferentes perfis de susceptibilidade aos antimicrobianos, ocorrendo casos de multirresistencia. Todas as amostras testadas apresentaram sensibilidade in vitro a sais biliares (0,3%) e resistencia in vitro ao pH gastrico (2,0). Lactobacillus spp. dos leites fermentados testados deveriam estar presentes em quantidades mais elevadas em algumas marcas comerciais, possuir resistencia aos sais biliares e nao apresentar resistencia multipla aos antimicrobianos.