Paulo Fernando de Almeida

Occurrence of Listeria spp. in critical control points and the environment of Minas Frescal cheese processing

Critical control points (CCPs) associated with Minas Frescal cheese (a Brazilian soft white cheese, eaten fresh) processing in two dairy factories were determined using flow diagrams and microbiological tests for detection of Listeria monocytogenes and other species of Listeria. A total of 218 samples were collected along the production line and environment. The CCPs identified were reception of raw milk, pasteurization, coagulation and storage. Thirteen samples were positive for Listeria; 9 samples were Listeria innocua, 2 were Listeria grayi and 2 were L. monocytogenes. In factory A, Listeria was found in 50% of raw milk samples, 33.3% of curd samples, 16.7% of pasteurized milk samples, 16.7% of cheese samples and 25% of rubber pipes used to transport the whey. The microorganism was not obtained from environmental samples in this plant. In factory B, Listeria was found in one sample of raw milk (16.7%) and in three samples of environment (17.6%) and L. monocytogenes was obtained from raw milk (16.7%) and the floor of the cheese refrigeration room (14.3%). Two serotypes, 4b and 1/2a, were observed among the strains of L. monocytogenes isolated, both which are frequently involved in outbreaks of food-borne listeriosis and sporadic cases of the disease all over the world.

Avaliação e controle da qualidade microbiológica de mãos de manipuladores de alimentos

Foi conduzido monitoramento microbiologico das maos de manipuladores de alimentos como parte de um estudo para implantacao do Sistema de Analise de Perigos e Pontos Criticos de Controle em um restaurante institucional, atraves da contagem padrao de aerobios mesofilos e anaerobios facultativos, S. aureus, C. perfringens e presenca de Salmonella spp. Foram observadas contagens de microrganismos aerobios mesofilos e anaerobios facultativos em niveis de ate 10(7) UFC/mao, contaminacoes por S. aureus e C. perfringens e oportunidades de contaminacao cruzada por essas maos principalmente no fatiamento da carne assada. Salmonella spp. nao foram isoladas. Foram adotadas medidas corretivas para este ponto critico de controle, constatando de lavagem das maos dos manipuladores com agua corrente e sabonete liquido neutro seguida de antissepsia com iodoforo. Foram observadas reducoes da contagem de aerobios mesofilos em ate 2,6 ciclos log e, apesar desta reducao nao ser a ideal, ela demonstra a contribuicao que esta pratica pode trazer aos servicos de alimentacao, alem do que nao foram mais detectados microrganismos patogenicos como S. aureus e C. perfringens.

A PCR protocol using inl gene as a target for specific detection of Listeria monocytogenes

Polymerase chain reaction is a powerful technique for detection of pathogens in foods. It is a rapid procedure with both sensitivity and specificity for quick detection and identification of specific pathogenic bacteria from diAerent sources. Listeria monocytogenes detection methods based on PCR amplification of the iap, prfA and hly gene sequences have been reported. The present study undertakes the development of an alternative PCR method using the inl gene sequences as a target to detect pathogenic L. monocytogenes. The presence of a unique and specific DNA amplification fragment of 760 bp for the intragenic repeats B of the inlA gene in all strains of L. monocytogenes as compared to none in other Listeria and unrelated Gram positive and Gram negative species confirms that this procedure is an alternative PCR protocol for detection of L. monocytogenes. ” 2000 Elsevier Science Ltd. All rights reserved.

Molecular detection and genetic diversity of norovirus in hospitalized young adults with acute gastroenteritis in Bahia, Brazil

The molecular epidemiology of a recent norovirus (NoV) outbreak in Brazil performed by comparative analysis with Genebank NoV sequences showed that the GII.4 strain was responsible for 72.5% of all NoV-positive cases (58/80). Other detected NoV strains included GII.3 (7/80; 8.8%) and GII.9 (8/80; 10%). This is the first outbreak reported in Bahia state, Brazil, during June–July of 2006, where NoV was identified as the principal etiologic agent in hospitalized young adults with acute gastroenteritis symptoms. These findings suggest that GII.4 is a predominant circulating genotype in NoV outbreaks in Brazil.

Influence of the Combination of Infrared and Red Laser Light on the Healing of Cutaneous Wounds Infected by Staphylococcus aureus

AIM We aimed to assess the use of two wavelengths on the healing of infected wounds. BACKGROUND Infection is the most significant cause of impaired wound repair or healing. Several therapeutic approaches are used for improving wound healing including the use of different light sources, such as the laser. Some wavelengths yield positive photobiological effects on the healing process. MATERIAL AND METHODS The backs of 24 young adult male Wistar rats under general anesthesia were shaved and cleaned, and a 1 by 1 cm cutaneous wound was created with a scalpel and left untreated. The wounds were infected with Staphylococcus aureus, and the rats were randomly divided into two sets of four subgroups with three animals in each subgroup: control, red laser light, infrared laser light, and red + infrared laser light. Laser phototherapy was carried out with a diode [λ680 nm/790 nm, power (P) = 30 mW/40 mW, continuous wave laser, Ø = 3 mm, power density (P) = 424 and 566 mW/cm(2), time = 11.8/8.8 sec, E = 0.35 J] and started immediately after surgery and repeated every other day for 7 d. Laser light was applied on four points around the wounded area (5 J/cm(2)). The animals were killed either 8 or 15 d after contamination. Specimens were taken, embedded in paraffin, and sectioned and stained for histological analysis. RESULTS Histological analysis showed that control subjects had a lower amount of blood vessels when compared with irradiated subjects. Irradiated subjects had more advanced resolution of inflammation compared with controls. Irradiated subjects also showed a more intense expression of the collagen matrix. The collagen fibers were mostly mature and well organized in these subjects at the end of the experimental time especially when both wavelengths were used. CONCLUSION The results of the present study indicate that laser phototherapy has a positive effect on the healing of infected wounds, particularly with the association of λ680 + λ790 nm.

Hygienic-sanitary quality of vegetables and evaluation of treatments for the elimination of indigenous E. coli and E. coli O157:H7 from the surface of leaves of lettuce (Lactuca sativa L.)

The purpose of this study is to evaluate the hygienic-sanitary quality of vegetables and irrigation water and assess the effectiveness of lemon juice and vinegar in reducing E. coli strains inoculated on lettuce. One hundred and forty samples of vegetables and 45 samples of irrigation water were investigated for thermotolerant coliforms and Salmonella spp. In order to verify the effectiveness of natural household sanitizers in reducing E. coli in inoculated lettuce, four treatment solutions were tested: fresh lemon juice, alcohol vinegar, lemon juice-vinegar mixture, and lemon juice-vinegar-water mixture. The microbiological analysis revealed high rates of contamination by thermotolerant coliforms and identified the presence of E. coli in 32% of the tested vegetable samples and 56% of the water samples. While no significant statistical difference (p < 0, 05) was identified in the tested solutions, the treatment with a combination of lemon juice and vinegar resulted in the highest Decimal Reductions (DR) of E. coli O157: H7 while the treatment with vinegar alone was the most effective against the indigenous E. coli strain

Implementation of a HACCP system for on-site hospital preparation of infant formula

Abstract Hazard Analysis and Critical Control Point (HACCP) system was introduced to infant formula preparation rooms in four hospitals in Salvador, Bahia, Brazil. The homogenization of powdered milk and ingredients, refrigeration and holding steps before service were identified as critical control points (CCPs). Utensils and workers’ hands were identified as sources of cross contamination. Educational training courses emphasizing food safety and good preparation practices were introduced to the personnel of the rooms. Corrective actions were adopted at the CCPs that were found to be out-of-control. Implementation of HACCP system improved infant formula quality by reducing total aerobic microbial counts in the formula, and on utensils and workers’ hands of approximately 4.0, 3.0 and 4.0 log cycles, respectively. S. aureus and fecal coliforms were no longer found.

Photodynamic Antimicrobial Chemotherapy (PACT) in osteomyelitis induced by Staphylococcus aureus: Microbiological and histological study.

Osteomyelitis is an inflammation either of medullar spaces or of the surface of cortical bones, which represents a bacterial infection. Photodynamic Antimicrobial Chemotherapy (PACT) is a treatment based on a cytotoxic photochemical reaction that induces a series of metabolic reactions and culminates in bacterial suppression. Such effect led to the idea that it could be used as a treatment of osteomyelitis. Following approval by the Animal Experimentation Committee of the School of Dentistry of the Federal University of Bahia, the present randomized study used eighty Wistar rats with the aim to evaluate, by microbiological and histological analysis, the effects of Photodynamic Antimicrobial Chemotherapy - PACT on tibial surgical bone defects in rats infected by Staphylococcus aureus. The animals were divided in groups: Control (non-infected); Control Osteomyelitis Induction; Saline solution; Photosensitizer; Red Laser and PACT - on this group, a diode laser (40mW; λ660nm ∅=0.04cm(2), CW, 10J/cm(2)) was used in combination with 5μg/ml of toluidine blue as the photosensitizer. On the microbiological study, immediately after treatment, the PACT group presented a bacterial reduction of 97.4% (p<0.001). Thirty days after treatment, there was a bacterial reduction of more than 99.9% (p<0.001). In the histological study, it was observed that the PACT group demonstrated an intense presence of osteocytes and absence of bone sequestration and micro-abscesses. The PACT using toluidine blue was effective in reducing the number of S. aureus enabling a better quality bone repair.

Novel potential inhibitors for adenylylsulfate reductase to control souring of water in oil industries

The biogenic production of hydrogen sulfide gas by sulfate-reducing bacteria (SRB) causes serious economic problems for natural gas and oil industry. One of the key enzymes important in this biologic process is adenosine phosphosulfate reductase (APSr). Using virtual screening technique we have discovered 15 compounds that are novel potential APSr inhibitors. Three of them have been selected for molecular docking and microbiological studies which have shown good inhibition of SRB in the produced water from the oil industry.

Metagenomic analysis of bacterial and archaeal assemblages in the soil-mousse surrounding a geothermal spring.

The soil-mousse surrounding a geothermal spring was analyzed for bacterial and archaeal diversity using 16S rRNA gene amplicon metagenomic sequencing which revealed the presence of 18 bacterial phyla distributed across 109 families and 219 genera. Firmicutes, Actinobacteria, and the Deinococcus-Thermus group were the predominant bacterial assemblages with Crenarchaeota and Thaumarchaeota as the main archaeal assemblages in this largely understudied geothermal habitat. Several metagenome sequences remained taxonomically unassigned suggesting the presence of a repertoire of hitherto undescribed microbes in this geothermal soil-mousse econiche.