Clinical and microbiological factors predicting outcomes of nonfermenting gram-negative bacilli peritonitis in peritoneal dialysis.

Peritonitis due to gram-negative bacilli (GNB), particularly nonfermenting GNB (NF-GNB), is a serious complication of peritoneal dialysis with a low resolution rate. Beyond the patient's condition, microbiological properties such as antimicrobial resistance, biofilm production and other virulence factors can explain the poor outcomes. This study aimed to evaluate the influence of patient condition, microbiological characteristics, including biofilm production, and treatment on peritonitis outcome. We reviewed the records of 62 index episodes caused by NF-GNB that occurred between 1997 and 2015 in our center. The etiologies were species of Pseudomonas (51.6%), Acinetobacter (32.2%), and other NF-GNB (16.1%). There was a high (72.9%) proportion of biofilm producer lineages. The in vitro susceptibility rate of Pseudomonas spp. to amikacin, ciprofloxacin, and ceftazidime was significantly greater than that of Acinetobacter spp. and other species; however, there was a similar low resolution rate (< 45%) among the episodes attributable to them. Preexisting exit-site infection was independently associated with nonresolution. No other factor, including biofilm production, was associated with the outcome. The higher in vitro susceptibility of Pseudomonas compared to other NF-GNB that presented a similar resolution rate suggests that bacterial virulence factors such as biofilms can act in concert, thereby worsening the outcome.

Risk factors for infection with coagulase-negative staphylococci in newborns from the neonatal unit of a brazilian university hospital.

BACKGROUND: Coagulase-negative staphylococci (CoNS) are one of the most frequent causative agents of neonatal nosocomial infections, especially in premature and low-weight newborns. Risk factors for infection include extracellular polysaccharide production and consequent biofilm formation that permit adhesion to the smooth surface of catheters and other medical devices. The objective of this study was to identify CoNS strains isolated from 105 newborns admitted to the Neonatal Unit of our hospital, and to evaluate the association of biofilm production and host risk factors with the occurrence of infection. METHODS: CoNS isolates were identified and classified as significant or contaminant based on clinical and laboratory data of the newborn medical records. Perinatal risk factors for infection, neonatal clinical evolution, and antibiotic treatment were analysed. In addition, the presence of genes (icaA, icaC and icaD) responsible for biofilm production in CoNS was investigated. RESULTS: Among the 130 CoNS strains studied, 66 (50.8%) were classified as clinically significant and 64 (49.2%) as contaminant. There was no difference in the detection of biofilm-specific genes between CoNS strains isolated from newborns with (81.8%) and without infection (84.3%), although 11 (91.7%) of the 12 children whose death was related to CoNS were infected with strains that were positive for these genes. Forty-five (83.3%) of the 54 newborns infected with CoNS were premature and 33 (61.1%) had a birth weight ≤ 1,500 g. Most newborns infected with CoNS had been submitted to invasive procedures, including catheter use (85.2%), parenteral nutrition (61.1%), and mechanical ventilation (57.4%). S. epidermidis was the most frequently isolated species (81.5%) and was more related to infection (86.3%) than to contamination (76.5%). CONCLUSION: Most newborns infected with CoNS presented factors that contributed to the colonization and development of infection with these microorganisms, including a birth weight ≤ 1,500 g, catheter complications, use of a drain, and previous antibiotic treatment. The fact that most children who died of CoNS-related infection carried strains positive for biofilm-specific genes indicates the importance of this virulence factor for the outcome of staphylococcal infections.

Detection of Oxacillin Resistance in Staphylococcus aureus Isolated from the Neonatal and Pediatric Units of a Brazilian Teaching Hospital.

OBJECTIVE: To determine, by phenotypic and genotypic methods, oxacillin susceptibility in Staphylococcus aureus strains isolated from pediatric and neonatal intensive care unit patients seen at the University Hospital of the Botucatu School of Medicine. METHODS: A total of 100 S. aureus strains isolated from the following materials were studied: 25 blood cultures, 21 secretions, 12 catheters, 3 cannulae and one chest drain from 62 patients in the neonatal unit, and 36 blood cultures, one pleural fluid sample and one peritoneal fluid sample from 38 patients in the pediatric unit. Resistance of the S. aureus isolates to oxacillin was evaluated by the disk diffusion method with oxacillin (1 µg) and cefoxitin (30 µg), agar screening test using Mueller-Hinton agar supplemented with 6 µg/ml oxacillin and 4% NaCl, and detection of the mecA gene by PCR. In addition, the isolates were tested for ß-lactamase production using disks impregnated with Nitrocefin and hyperproduction of ß-lactamase using amoxicillin (20 µg) and clavulanic acid (10 µg) disks. RESULTS: Among the 100 S. aureus strains included in the study, 18.0% were resistant to oxacillin, with 16.1% MRSA being detected in the neonatal unit and 21.0% in the pediatric unit. The oxacillin (1 µg) and cefoxitin (30 µg) disk diffusion methods presented 94.4% and 100% sensitivity, respectively, and 98.8% specificity. The screening test showed 100% sensitivity and 98.8% specificity. All isolates produced ß-lactamase and one of these strains was considered to be a hyperproducer. CONCLUSIONS: The 30 µg cefoxitin disk diffusion method presented the best result when compared to the 1 µg oxacillin disk. The sensitivity of the agar screening test was similar to that of the cefoxitin disk diffusion method and higher than that of the oxacillin disk diffusion method. We observed variations in the percentage of oxacillin-resistant isolates during the study period, with a decline over the last years which might be related to improved nosocomial infection control and the rational use of antibiotics.

Detection of enterotoxins genes in coagulase-negative staphylococci isolated from foods

Staphylococcal food poisoning is caused by ingestion of enterotoxins preformed in the food contaminated essentially through human manipulation or raw material obtained from animals. Although coagulase-positive Staphylococcus aureus is the main agent responsible for food intoxication, some researches emphasise that coagulase-negative staphylococci (CNS) are able to produce staphylococcal enterotoxins and may be a potential cause of food poisoning. In the present study CNS were isolated from foods and the toxigenic capacity of the strains determined. A total of 88 food samples were analysed and 22.7% were positive for CNS strains. Staphylococcal counts ranged from 3.0 x 10² to 1.4 x 10(6) CFU/g or mL of food examined. S. epidermidis predominated among the isolates (40%). Further isolates included S. xylosus (20%), S. warneri (20%), S. saccharolyticus (15%), and S. hominis (5%). Four isolates were positive for enterotoxin genes, as detected by polymerase chain reaction, with sea being the predominant gene. Although no enterotoxin production was detected by the reverse passive latex agglutination method, the data showed that the toxigenic capacity of CNS should not be ignored, requiring investigation of this group of microorganisms in food.

A intoxicação alimentar estafilocócica ocorre devido à ingestão de alimentos contaminados com enterotoxinas. Essa contaminação tem sido oriunda, principalmente, da manipulação humana, ou de matérias-primas procedentes de animais portadores. Embora Staphylococcus aureus coagulase positiva, seja o principal agente de intoxicação alimentar, alguns pesquisadores enfatizam que os estafilococos coagulase-negativa (ECN) podem produzir as enterotoxinas estafilocócicas, podendo contribuir para a intoxicação alimentar. Este estudo teve como objetivos isolar os ECN de alimentos e verificar a capacidade enterotoxigênica dessas linhagens. Foram estudadas 88 amostras de alimentos, sendo que 22,7% foram positivas para ECN com crescimento entre 10² e 10(6) UFC/g or mL. A espécie predominante dentre as linhagens isoladas foi S. epidermidis (40%), seguido por S. warneri (20%), S. xylosus (20%), S. saccharolyticus (15%) e S. hominis (5%). Entre as linhagens isoladas, quatro apresentaram genes para produção de enterotoxinas pelo método de Reação da Polimerase em Cadeia (PCR), com predominância do gene sea. Não se detectou a produção de enterotoxina pelo método de aglutinação em látex (RPLA). Através dos resultados obtidos, observou-se que os ECN isolados de alimentos não devem ser ignorados quanto à sua capacidade toxigênica, necessitando de maior estudo e atenção para melhor caracterização desse grupo de microrganismos em alimentos.

Bovine milk and soybean: microbiological and nutritional interaction resulted from the mixture of both components / Leite bovino e extrato de soja: aspecto microbiológico - nutricional da suplementação de produtos de origem animal com soja

Besides being one of the most important food in human diet, the milk is also an excellent environment for the microbial growth. However, the high cost of the milk restricting the consumption by the low profit population, has led to the use of soybean - based products. The soybean chemical composition proves its superiority comparing to other vegetables and its equivalence to animal products, but the alimentary habits have restricted its acceptance. In order to improve the consumption, encouragement is given to mix soybean components and animal origin products. The influence of the mixture on the microbial growth resulted from the interaction of both ingredients is extremely important for the food preservation. The review reports the nutritional and microbial aspects of milk and soybean extract, with emphasis on the effect of addition of soybean components to the animal origin products.

O leite, além de ser um alimento fundamental na dieta humana, é um excelente meio para o crescimento microbiano. Entretanto, o custo do leite limitando o consumo pela população de baixo poder aquisitivo tem levado à busca de outras opções alimentares, com ênfase à introdução de produtos à base de soja. A composição química da soja evidencia sua superioridade em relação aos outros vegetais e equivalência aos produtos animais. Porém, os hábitos alimentares constituem fator limitante à aceitação de produtos contendo soja e, na tentativa de difundir o consumo, tem-se estimulado a mistura de derivados de soja com produtos de origem animal. Por outro lado, pouco se sabe sobre o comportamento microbiano nessas misturas, sendo portanto de extrema importância a avaliação do crescimento de microrganismos. Esta revisão discute as características nutricionais e microbiológicas do leite bovino e extrato de soja, com ênfase ao efeito da suplementação de produtos de origem animal com derivados de soja.

Bovine milk and soybean: microbiological and nutritional interaction resulted from the mixture of both components / Leite bovino e extrato de soja: aspecto microbiológico - nutricional da suplementação de produtos de origem animal com soja

Besides being one of the most important food in human diet, the milk is also an excellent environment for the microbial growth. However, the high cost of the milk restricting the consumption by the low profit population, has led to the use of soybean - based products. The soybean chemical composition proves its superiority comparing to other vegetables and its equivalence to animal products, but the alimentary habits have restricted its acceptance. In order to improve the consumption, encouragement is given to mix soybean components and animal origin products. The influence of the mixture on the microbial growth resulted from the interaction of both ingredients is extremely important for the food preservation. The review reports the nutritional and microbial aspects of milk and soybean extract, with emphasis on the effect of addition of soybean components to the animal origin products.  

O leite, além de ser um alimento fundamental na dieta humana, é um excelente meio para o crescimento microbiano. Entretanto, o custo do leite limitando o consumo pela população de baixo poder aquisitivo tem levado à busca de outras opções alimentares, com ênfase à introdução de produtos à base de soja. A composição química da soja evidencia sua superioridade em relação aos outros vegetais e equivalência aos produtos animais. Porém, os hábitos alimentares constituem fator limitante à aceitação de produtos contendo soja e, na tentativa de difundir o consumo, tem-se estimulado a mistura de derivados de soja com produtos de origem animal. Por outro lado, pouco se sabe sobre o comportamento microbiano nessas misturas, sendo portanto de extrema importância a avaliação do crescimento de microrganismos. Esta revisão discute as características nutricionais e microbiológicas do leite bovino e extrato de soja, com ênfase ao efeito da suplementação de produtos de origem animal com derivados de soja.    

Staphylococcal enterotoxins. / icas

Staphylococcal intoxication, caused by enterotoxins produced by species of Staphylococcus, is a constant problem in the Public Health, in consequence of the frequency of cases and thermostability of the toxin. Considering that this microorganism is one of the most common agents isolated from human and animal flora, the review relates briefly about structure, physicochemical and biological properties of staphylococcal enterotoxins and factors involved with their production in foods.  

Intoxicação estafilocócica, causada por enterotoxinas produzidas por espécies de Staphylococcus, tem sido um problema constante em Saúde Pública, em vista da freqüência dos casos e da termoestabilidade das toxinas. Considerando que este microrganismo é um dos agentes mais frequentes na microbiota humana e animal, apresenta-se uma breve revisão sobre as características estruturais, propriedades físico-químicas e biológicas das enterotoxinas estafilocócicas, assim como fatores que afetam a sua produção em alimentos.  

Risk of aflatoxin production in soybean. / toxina em soja

Soybean, considered as inadequate substrate for aflatoxin production, may have an alteration in its natural resistance as a result of the frequent changes it was submitted for the development of new varieties, aiming at better nutritional value, productivity, resistance and adaption to different Brazilian Regions. The potencial risks wich arose from the modifications, in addition to the high toxigenicity of tropical origin Aspergilius flavus group are reported.    

Soja, classificada como substrato inadequado para produção de aflatoxina poderá ter a resistência natural alterada, em vista de constantes modificações oriundas da busca de novas variedades, visando a um maior valor nutritivo, produtividade, resistência e adaptações a diferentes regiões brasileiras. A revisão analisa os riscos potenciais emergentes de modificações, somados à elevada toxigenicidade do grupo Aspergillus flavus de origem tropical.