Foodborne diseases are one among the diseases with high morbidity and mortality rate. The concern is raised with the emergence of pathogenic strains that are resistant to the available set of antibiotics. Conventional regimens fail to treat the infections caused by these pathogens prolonging the sickness leading to increased morbidity and mortality. The situation can get further complicated with the dietary intake of the host. Of late it has been understood that the dietary flavonoids play an important role in regulating the immune system. Curcumin, a pigment from turmeric, is one among such bioflavonoid with an immunomodulatory potential. Curcumin has been a front-line topic of mainstream scientific research for a variety of diseases from cancer to Alzheimer’s to infectious diseases. Curcumin being considered as a spicy panacea is not a remedy for all diseases. Its ability to act differentially as an antioxidant or pro-oxidant can be either beneficial or harmful for the host. It exhibits antioxidant properties at concentrations achievable in the body; this can make the host vulnerable to infections due to the suppression of innate immune responses. Curcumin also suppresses the type 1 immune response, which might lead to alleviation of type 1 immune response disorders. However, the inhibition of type 1 immune response might invite infections with opportunistic pathogens. We have chosen curcumin to assess the effect of diet on the regulation of pathogenesis of Salmonella along with few medically important pathogens like Yersinia enterocolitica, Staphylococcus aureus, Shigella flexneri and Listeria monocytogenes. The thesis is divided into five chapters. As the main focus of the thesis is on Salmonella, in Chapter 1 we introduce diverse aspects of curcumin and the basic biology of Salmonella. Initially the properties of curcumin, the molecule of interest are introduced followed by brief overview to Salmonella biology and pathogenesis. Various activities of curcumin dealing with the variety of diseases are discussed. Further, the introduction to the intricate underlying mechanisms and the functional determinants of curcumin is given. The subsequent sections give an overview of different phases of Salmonella pathogenesis and the molecular mechanisms of Salmonella virulence and host defense. Towards the end of the chapter we discuss the strength, limitations and the distinctive characteristics of the murine model of typhoid fever. Curcumin has gained immense importance for its vast therapeutic and prophylactic applications. Its anti-bacterial effect has been demonstrated in bacteria, like B. subtilis, H. pylori and E. coli. Contrary to this, the results of the Chapter 2 reveals that curcumin at a nontoxic concentration to both host and pathogen, regulates the defense pathways of Salmonella enterica serovar Typhimurium (S. Typhimurium) to enhance its pathogenicity. In a murine model of typhoid fever, we observed higher bacterial load in reticuloendothelial organs when infected with curcumin-treated Salmonella. Curcumin increased the resistance of S. Typhimurium against antimicrobial agents like antimicrobial peptides, reactive oxygen and nitrogen species. It up-regulated the genes involved in resistance against antimicrobial peptides - pmrD and pmrHFIJKLM and genes with antioxidant function - mntH, sodA and sitA. We implicate that the iron chelation property of curcumin has a role in regulating mntH and sitA. Interestingly, we see that the curcumin-mediated modulation of pmr genes is through the PhoPQ two-component regulatory system (TCS). Curcumin downregulates SPI-1 genes required for entry into epithelial cells and upregulates SPI-2 genes required for intracellular survival, through PhoPQ TCS. Thus, this common regulator (PhoPQ) could explain curcumin's mode of action. Another important factor for the pathogen’s success is its ability to counteract the action of antibiotics. Almost all the bactericidal antibiotics act via production of reactive oxygen species in the bacteria. Curcumin has anti-oxidant property that might interfere with the action of antibiotics. Ciprofloxacin is a commonly used anti-typhoidal drug. It kills the bacteria by inhibiting DNA replication and increasing reactive oxygen species in bacterial cell. In Chapter 3 we present the results obtained after the investigation of the interference of curcumin with the anti-bacterial action of ciprofloxacin against Salmonella. We found that curcumin indeed increased the proliferation of Salmonella Typhi and Salmonella Typhimurium in ciprofloxacin treated macrophages by reducing the ciprofloxacin-induced reactive oxygen species. It also inhibited ciprofloxacin mediated DNA damage and the resultant SOS response and filamentation. However, curcumin was unable to rescue the ciprofloxacin induced gyrase inhibition. The reduced antibiotic (ciprofloxacin) efficacy against Salmonella by curcumin might aggravate the disease. Thus, the results of chapter 1 and 2 urge us to rethink the indiscriminate use of curcumin especially during Salmonella outbreaks. Bacteria modulate its virulence determinants in response to the environmental cues. Salmonella being a foodborne pathogen has a very likely chance of getting exposed to turmeric and hence curcumin. In Chapter 4 we have assessed the modulation of motility of S. Typhimurium, an important virulence determinant, by curcumin. We show that curcumin reduced the motility of the S. Typhimurium by decreasing the flagellar density around it. Surprisingly, this was achieved without affecting the expression of the flagellin gene and protein. Curcumin physically adhered to the flagella making it fragile and breaking it into fragments. This can hinder bacterial motility, chemotaxis, adherence and invasion into the host cells. However, aflagellate bacteria are hypervirulent as is the case with our experimental results with curcumin treated bacteria. Curcumin regulates myriad of bacterial (Salmonella) activities increasing its pathogenicity. Curcumin is known to regulate the host defenses in response to the disease. In Chapter 5 we have sought to address the effect of curcumin treatment of host cells on the outcome of infection by different pathogens. Pathogens have evolved different strategies to evade the host innate immune system, one of them being avoiding lysosome mediated degradation. Pathogens like Salmonella, Yersinia, Mycobacterium and Staphylococcus have acquired molecular machinery to inhibit the fusion of the pathogen containing vacuole with lysosomes and multiply within the vacuole whereas other pathogens like Shigella, Listeria and Rickettsia escape into and multiply in the cytosol. In our study we show that pretreatment of macrophage with curcumin increased the fold proliferation of S. Typhimurium, S. aureus and Y. enterocolitica whereas decreased that of S. flexneri and L. monocytogenes. From the results obtained, we can state that curcumin differentially regulates the pathogenesis of vacuolar and cytosolic pathogen. We hypothesized that curcumin pretreatment stabilizes the membrane of pathogen containing vacuole retarding the lysis of the phagolysosome harboring the cytosolic pathogen and hence facilitating its clearance. We indeed observed that the membrane stabilizing effect of curcumin led to increased fusion of cytosolic pathogen with the lysosome, decreasing its proliferation in the cells. As the vacuolar pathogens have an inherent ability to inhibit this fusion, they proliferate better in curcumin treated cells. In a nutshell curcumin can have multiple and sometimes unexpected effects not only on a pathogen’s potential to successfully cause infection but also on the host’s ability to counter it. A brief summary of the study that does not directly deal with the modulation of bacterial pathogenesis by curcumin is included in the Appendix. In this study a novel, simple, sensitive and efficient PCR based assay was devised to detect Salmonella contamination in milk, fruit juice and ice-cream without any pre-enrichment.

Includes two journal articles with contributions by the author / Bibliography: leaves 145-154 / vii, 164 leaves : ill ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Plant Pathology, 1988

Thesis (M.S.)--Michigan State University. Dept. of Fisheries and Wildlife, 2008. / Title from PDF t.p. (viewed on July 30, 2009) Includes bibliographical references (p. 176-183). Also issued in print.

Thesis (Ph. D.)--Michigan State University. Dept. of Microbiology, 1997. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--Michigan State University. Dept. of Microbiology, 1997. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.S.)--Michigan State University. Dept. of Biochemistry and Molecular Biology, 2008. / "Advisor, Todd A. Ciche"--Acknowledgements. Title from PDF t.p. (viewed on Aug. 5, 2009) Includes bibliographical references. Also issued in print.

La tuberculose (TB) est un problème de santé mondiale majeur à l’origine de 10.4 millions de nouveaux cas et 1.8 millions de morts en 2015 selon l’Organisation Mondiale de la Santé (OMS). Cette maladie est causée par la bactérie Mycobacterium tuberculosis (Mtb) qui infecte principalement les poumons et se transmet par l'inhalation d’aérosols contaminés.Le traitement de TB nécessite la prise quotidienne d’antibiotiques pendant 6 mois, dont une mauvaise utilisation peut être à l’origine de l’apparition de souches Mtb multi-résistantes.La nouvelle stratégie de l’OMS, “End TB”, vise à réduire de 90% l’incidence de TB d'ici 2035. Pour y parvenir, il est important de définir de nouvelles approches pour réduire la durée et la toxicité des traitements et améliorer leur efficacité vis-à-vis des bactéries actives et latentes.L’approche abordée lors de ma thèse vise à utiliser des nanoparticules (NP) pour développer de nouvelles thérapies anti-TB. La bibliographie sur le sujet montre que cela pourrait être une stratégie prometteuse. Nous avons par conséquent étudié quatre applications potentielles des NP:1-Vectorisation des médicaments pour les administrer au niveau pulmonaire. L’éthionamide (ETH) est un antibiotique utilisé pour le traitement de TB avec des effets secondaires indésirables. L’ETH est une «pro-drogue» qui nécessite une activation par une monooxygenase bactérienne, dont l’efficacité peut être elle-même augmentée par des molécules chimiques appelées “booster”. Nous avons étudié l’effet de l’ETH et de booster co-encapsulés dans des NP de poly-β-cyclodextrine (pCD) pour le traitement de TB. Nous avons d’abord évalué leur efficacité in vitro sur la croissance extracellulaire et intracellulaire (dans les macrophages) de Mtb grâce à l'utilisation d'un système automatisé de microscopie confocale à haut contenu. Dans les deux essais, nous avons constaté que les médicaments conservaient leur activité après encapsulation et que les NP n'étaient pas cytotoxiques. L’efficacité de ces NP a ensuite été étudiée in vivo chez des souris infectées avec Mtb. La suspension de NP a été délivrée sous forme d’aérosols directement dans les poumons par voie endotrachéale à l’aide d’un Microsprayer Aerosolizer. Une réduction significative de la charge bactérienne dans les poumons de 3 log a été observée après 6 administrations de doses inférieures à celles thérapeutiques.2-Amélioration de la solubilité et biodisponibilité des antibiotiques. La Clofazimine (CLZ) est un antibiotique utilisé dans le traitement de la lèpre et pourrait être, au regard de son efficacité in vitro sur les souches de Mtb multi-résistantes, un candidat potentiel pour celui de TB. La CLZ est extrêmement lipophile, gênant ainsi sa solubilité. Dans notre étude, son encapsulation dans des particules de silice nanoporeuses a stabilisé l'état amorphe de la CLZ et a augmenté radicalement sa solubilité. Après encapsulation ou solubilisation dans le DMSO, la CLZ a d’autre part montré une activité antibactérienne similaire sur Mtb.3-Stabilisation des antibiotiques. La Vancomycine (VAN) est utilisée pour des applications cliniques comme alternative de la pénicilline dans le traitement de Staphylococcus aureus et pourrait être utilisée pour celui de TB. Alors que la VAN présente une faible stabilité dans les milieux biologiques, nous avons montré que l'encapsulation de cet antibiotique à l'intérieur de NP à base de PLGA a amélioré son efficacité tant sur les bactéries Mtb extracellulaires qu’intracellulaires.4-Activité antimycobacterial Intrinsèque de NP. Différentes NP (60 pCD, 1 NanoMOF et 1 NP en argent) ont été évaluées in vitro. Aucune n'a présenté d'activité antituberculeuse intrinsèque prometteuse.En conclusion et au regard des options thérapeutiques limitées pour combattre les souches résistantes et de la rareté de solutions innovantes dans le pipeline de découverte de médicament, ces travaux ont montré que les NP pouvaient constituer une approche anti-TB originale. / Tuberculosis (TB) is a major problem of global health, responsible for 10.4 million new cases and 1.8 million deaths in 2015 according to the World Health Organization (WHO). This disease is caused by inhalation of small aerosol droplets containing Mycobacterium tuberculosis (Mtb), and lungs are usually the major site of infection.TB can usually be treated with a daily six months course of standard, or first-line, anti-TB drugs. If first-line drugs are misused, the onset of multidrug-resistant Mtb can occur.The new WHO global public health strategy “End TB” aims at the reduction of TB incidence 90% by 2035. To reach these ambitious targets, new approaches are urgently needed to get a faster, less harmful and more-efficient treatment for active and latent TB.My thesis focused on the use of nanoparticles (NPs) to develop new anti-TB therapies. Our review of the literature showed that it could be a promising approach. Here, we investigated four potential uses of the NPs.1- Nanocarrier for pulmonary delivery of drugs. Ethionamide (ETH) is a second line antibiotic with high toxicity and several adverse side effects. ETH is a prodrug that requires bioactivation by a bacterial monooxygenase, which can be enhanced by chemical molecules named “boosters”. We investigated the simultaneous delivery of ETH and boosters coencapsulated in biodegradable poly-β-cyclodextrin (pCD) based NPs by the pulmonary route for the treatment of TB. First, we evaluated the in vitro efficacy of the designed formulations on Mtb extracellular growth and intracellular growth inside macrophages using an automated confocal high-content microscopy system. And we found for both assays that the drugs maintained their activity after encapsulation and the pCD were not cytotoxic. Given these promising results, their efficacy was then tested in vivo. The NPs suspension, administered directly into mouse lungs by endotracheal way using a Microsprayer® aerosolizer, was proved to be well-tolerated and led to a 3-log decrease of the pulmonary mycobacterial load after 6 administrations and using lower doses than the therapeutic ones.2- Enhancement of the solubility and the bioavailability of antibiotics. Clofazimine (CLZ) is an antibiotic usually used in a combination therapy for the treatment of leprosy and could be a potential candidate for the treatment of TB because of its in vitro efficacy on resistant Mtb strains. CLZ is extremely lipophilic and has important solubility problem. In our study, its encapsulation in nanoporous silica particles stabilized the amorphous state of CLZ and dramatically increased the drug solubility. On the other hand, CLZ encapsulated in nanoporous silica particles or efficiently dissolved in DMSO showed a similar antibacterial activity on Mtb, validating the assessment of solubility of CLZ by encapsulation.3- Improvement of the antibiotic stabilization. Vancomycin (VAN) is used for clinical applications for nearly 50 years as a penicillin alternative to treat penicillinase-producing strains of Staphylococcus aureus. VAN can be used for TB treatment as a repurpose. While VAN presented low stability in biological media at 37°C, we showed that the encapsulation of this antibiotic inside PLGA-based NPs enhanced its efficacy both on extracellular and intracellular bacteria.4- Intrinsic antimycobacterial activity of NPs. Different NPs (60 pCD, 1 NanoMOF, and 1 silver NP) were tested in vitro but none presented promising intrinsic antitubercular activity. However some pCD were slightly active in vitro on extracellular Mtb but cytotoxic.In conclusion, these works demonstrated that nanoparticles can provide a novel anti-TB approach regarding the limited therapeutic options to fight drug-resistant Mtb and the scarcity of novel antituberculosis drugs in the drug discovery pipeline.

Rainbow trout represents the most prominent species in freshwater farming in UK aquaculture. One of the common diseases constraining rainbow trout production and increasingly causing problems in Atlantic salmon (Salmo salar L.) hatcheries worldwide is rainbow trout fry syndrome (RTFS) or bacterial cold water disease (BCWD). During the last 20 years, the development of a commercial vaccine against RTFS has been hindered by the prevalence of a wide range of the fish pathogen F. psychrophilum, thus the current treatment of choice is the use of antibiotics. Studies involved in understanding the innate and adaptive immune response of vaccinated rainbow trout fry using inactivated whole cell are still lacking. Therefore, the aim of this thesis is to characterise the strain diversity and antibiotic susceptibility of UK F. psychrophilum isolates, evaluate the efficacy of a whole-cell formalin-killed polyvalent vaccine, which was developed based on the characterisation results of this study, and investigate the immune response in trout fry following the immersion vaccination via the changes in expression of relevant immune genes. A total of 315 F. psychrophilum isolates, 293 of which were collected within the UK, were characterised using four genotyping methods and a serotyping scheme. A high strain diversity was identified among the isolates with 54 pulsotypes, ten (GTG)5-PCR types, two 16S rRNA allele lineages, seven plasmid profiles and three serotypes. The predominant profile observed within the F. psychrophilum isolates examined was PFGE cluster II – (GTG)5-PCR type r1 – 16S rRNA lineage II – serotype Th (n= 70/156, 45%). The characterisation results not only revealed the wide distribution within the UK and the persistence within a site of predominant pulsotypes, but also the presence of unique genotypes in certain sites or countries. Co-existence of genetically and serologically heterogeneous isolates within each farm was detected, highlighting the reasons this disease is so difficult to control, especially by vaccination. The occurrence over time of F. psychrophilum pulsotypes within a site could provide important epidemiological data for farm management and the development of site-specific vaccines. The antimicrobial susceptibilities of 140 F. psychrophilum strains, 125 of which were from the UK, were evaluated by the broth microdilution (MIC) and disc diffusion methods. There was evidence of reduced susceptibilities to three of the main antimicrobials used in UK aquaculture. Broth microdilution testing showed that only 12% of 118 UK isolates tested were WT to oxolinic acid (MIC COWT 0.25 mg L-1), 42% were WT for oxytetracycline (MIC COWT 0.25 mg L-1), and 66% were WT for amoxicillin. In contrast, all the isolates tested were WT (MIC COWT 2 mg L-1) for florfenicol, the antimicrobial of choice for RTFS control in the UK. Despite the imprecision of disc diffusion-based COWT values due to high standard deviations, there was a high categorical agreement between the classification of the strains (into WT or NWT) by MIC and disc diffusion methods for florfenicol (100%), oxolinic acid (99%), amoxicillin (97%) and oxytetracycline (94%). In general, this study showed that the UK F. psychrophilum isolates examined remain susceptible to florfenicol and also stresses the importance of performing susceptibility testing using standardised methods and COWT values. Several statistically significant associations between genotypes and the reduced susceptibilities of F. psychrophilum strains were revealed. A whole-cell formalin killed polyvalent vaccine against RTFS/BCWD was developed by combining three genetically and serologically divergent strains, recently collected from UK farms. The efficacy of this polyvalent vaccine was evaluated after immersion vaccination in 5 g trout and bath challenge using hydrogen peroxide as a pre-stressor with a virulent heterologous isolate of F. psychrophilum strain. Significant protection was achieved with an RPS of 84%. The combination of exposure to hydrogen peroxide prior to bath challenge may be an alternative to an injection challenge with 12 g trout, although further standardisation and optimisation of the challenge model is required. Changes in the innate immune response of trout fry following the initial vaccination included the up-regulation of the interleukin 1 β (IL-1β) gene in head kidney at 4 h and the up-regulation of toll-like receptor-2 (TLR-2) in skin at day 2. While the expression levels of C3 was unchanged, the down regulation of CD8-α in head kidney and spleen and CD4-1 in spleen were documented. IgM and IgT transcripts were found to be up-regulated in hind-gut two days post-vaccination. Understanding the strain diversity and the antibiotic susceptibility of UK F. psychrophilum isolates could help improve the control strategies, such as preventing the spreading of pathogenic F. psychrophilum clones between fish farms, reducing the use of antibiotics in RTFS/BCWD treatment and monitoring the development of acquired antibiotic resistance mechanisms. Moreover, strain characterisation data of UK F. psychrophilum species has assisted in selecting suitable candidates for developing an effective RTFS vaccine.

Made available in DSpace on 2014-06-11T19:27:15Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-06-28Bitstream added on 2014-06-13T18:31:12Z : No. of bitstreams: 1 baldin_jc_me_jabo.pdf: 183312 bytes, checksum: f9e945ecca299b8ddcedf222e57ec9d5 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O gelo é um excelente meio de prolongar o frescor do peixe e na indústria alimentícia tem um dos mais importantes papéis, uma vez que retarda a multiplicação bacteriana e, se fabricado sob más condições sanitárias pode se tornar um fator de risco para os consumidores. Sendo assim, este estudo objetivou avaliar a qualidade microbiológica do gelo utilizado na conservação do pescado por meio da quantificação de microrganismos heterotróficos mesófilos e psicrotróficos viáveis, coliformes totais e termotolerantes, além de investigar a presença de Escherichia coli, Staphylococcus aureus e Salmonella spp. Para tal, foram colhidas 63 amostras de gelo de seis estabelecimentos, sendo cinco hipermercados e uma peixaria, situados no município de Ribeirão Preto/SP. Os resultados obtidos mostraram populações de microrganismos heterotróficos mesófilos variando entre 1,0 x 10 e 3,0 x 104 UFC.mL-1 e psicrotróficos variando entre 1,0 x 10 e 1,0 x 106 UFC/mL, sendo que 19,05% das amostras contendo microrganismos mesófilos encontravam-se com populações acima do permitido pela legislação vigente. Já 22,22% das amostras foram positivas para coliformes totais e 9,52% para coliformes termotolerantes. A presença de Staphylococcus aureus foi confirmada em três amostras, E. coli e Salmonella spp. não foram encontradas. Portanto, a avaliação da qualidade microbiológica do gelo, neste experimento, permitiu concluir que a água utilizada na fabricação de gelo utilizado para conservação de pescado comercializado nos estabelecimentos pode ser contaminada por manuseio inadequado e seu incorreto acondicionamento, o que é um fator de risco para a saúde do consumidor uma vez que o gelo em contato com o peixe pode contaminá-lo / The ice is an excellent way to prolong the freshness of the fish and in the food industry has one of the most important roles, since it slows the bacterial growth, and if it is manufactured under poor sanitary conditions could become a risk factor for consumers. So, this study had as objective to evaluate the microbiological quality of the ice used in the seafood conservation by counting of mesophilic and psychrotrophics, total and thermoresistant coliforms and to investigate the presence or not of Escherichia coli, Staphylococcus aureus e Salmonella spp. For such, sixty-three samples of ice were collected from five supermarkets and one fish market located in the municipality of Ribeirão Preto/SP. The results showed populations of mesophilic heterotrophic microorganisms ranging from 1,0 x 10 to 3,0 x 104 UFC/mL and psychrotrophics ranging from 1,0 x 10 to 1,0 x 106 UFC/mL, being 19,05% of the samples containing mesophilic microorganisms above the allowed by the current legislation. It was found that 22,22% of the samples were positive for total coliforms and 9,52% for thermoresistant. The presence of Staphylococcus aureus was confirmed in three samples and E. coli and Salmonella spp. were not found. So, the evaluation of the microbiological quality in this study permitted to conclude that though there is a specific legislation about water quality, the unpotable water still in use in the ice manufactured utilized in the seafood conservation commercialized in food stores, what is a risk factor to the consumers health since the ice in contact with the fish can contaminate it

Orientador: Oswaldo Durival Rossi Junior / Banca: Angela Cleusa de Fátima Banzatto de Carvalho / Banca: Laudicéia Giacometti Lopes / Resumo: O gelo é um excelente meio de prolongar o frescor do peixe e na indústria alimentícia tem um dos mais importantes papéis, uma vez que retarda a multiplicação bacteriana e, se fabricado sob más condições sanitárias pode se tornar um fator de risco para os consumidores. Sendo assim, este estudo objetivou avaliar a qualidade microbiológica do gelo utilizado na conservação do pescado por meio da quantificação de microrganismos heterotróficos mesófilos e psicrotróficos viáveis, coliformes totais e termotolerantes, além de investigar a presença de Escherichia coli, Staphylococcus aureus e Salmonella spp. Para tal, foram colhidas 63 amostras de gelo de seis estabelecimentos, sendo cinco hipermercados e uma peixaria, situados no município de Ribeirão Preto/SP. Os resultados obtidos mostraram populações de microrganismos heterotróficos mesófilos variando entre 1,0 x 10 e 3,0 x 104 UFC.mL-1 e psicrotróficos variando entre 1,0 x 10 e 1,0 x 106 UFC/mL, sendo que 19,05% das amostras contendo microrganismos mesófilos encontravam-se com populações acima do permitido pela legislação vigente. Já 22,22% das amostras foram positivas para coliformes totais e 9,52% para coliformes termotolerantes. A presença de Staphylococcus aureus foi confirmada em três amostras, E. coli e Salmonella spp. não foram encontradas. Portanto, a avaliação da qualidade microbiológica do gelo, neste experimento, permitiu concluir que a água utilizada na fabricação de gelo utilizado para conservação de pescado comercializado nos estabelecimentos pode ser contaminada por manuseio inadequado e seu incorreto acondicionamento, o que é um fator de risco para a saúde do consumidor uma vez que o gelo em contato com o peixe pode contaminá-lo / Abstract: The ice is an excellent way to prolong the freshness of the fish and in the food industry has one of the most important roles, since it slows the bacterial growth, and if it is manufactured under poor sanitary conditions could become a risk factor for consumers. So, this study had as objective to evaluate the microbiological quality of the ice used in the seafood conservation by counting of mesophilic and psychrotrophics, total and thermoresistant coliforms and to investigate the presence or not of Escherichia coli, Staphylococcus aureus e Salmonella spp. For such, sixty-three samples of ice were collected from five supermarkets and one fish market located in the municipality of Ribeirão Preto/SP. The results showed populations of mesophilic heterotrophic microorganisms ranging from 1,0 x 10 to 3,0 x 104 UFC/mL and psychrotrophics ranging from 1,0 x 10 to 1,0 x 106 UFC/mL, being 19,05% of the samples containing mesophilic microorganisms above the allowed by the current legislation. It was found that 22,22% of the samples were positive for total coliforms and 9,52% for thermoresistant. The presence of Staphylococcus aureus was confirmed in three samples and E. coli and Salmonella spp. were not found. So, the evaluation of the microbiological quality in this study permitted to conclude that though there is a specific legislation about water quality, the unpotable water still in use in the ice manufactured utilized in the seafood conservation commercialized in food stores, what is a risk factor to the consumers health since the ice in contact with the fish can contaminate it / Mestre