Salmonellosis in calves without intestinal lesions / Salmonelose em bezerros sem manifestações intestinais

Salmonellosis is a known cause of enteric disorders in calves. However, cases in the septicemic form may not present enteric lesions, which may lead the veterinary practitioner to not suspect salmonellosis, compromising the diagnosis. The current study describes the epidemiological, clinical, pathological and immunohistochemical aspects of septicemic salmonellosis in calves without enteric lesions. The protocols involving bovine material submitted to the Pathology Laboratory (LAP) of the "Faculdade de Medicina Veterinária e Zootecnia" (FAMEZ) of the "Universidade Federal do Mato Grosso do Sul" (UFMS) from January 1995 to July 2018 were studied. Cases confirmed or suggestive of septicemic salmonellosis in calves without enteric manifestations were selected. Fragments of the liver, lung, and spleen embedded in paraffin were submitted to immunohistochemistry (IHC). Only cases in which there was positive marking on the IHC or culture isolation of Salmonella were included in this study. Of a total of 5,550 cattle examined in the period, ten presented septicemic salmonellosis without enteric lesions. Clinical signs included mucosal pallor, apathy, hyperthermia, and dyspnea. Only three calves presented diarrhea, and two were found dead before clinical changes were observed. The most common necropsy findings were hepatosplenomegaly; yellow, orange or brown discolored livers; pale mucous membranes; inflated and sometimes red lungs; fibrin or fluid within body cavities; and gallbladder filled with inspissated bile. Jaundice was observed in three calves that had a concomitant infection with Anaplasma sp. Microscopically, paratyphoid hepatic nodules and interstitial pneumonia were the most frequent manifestations, followed by thrombosis and bacterial colonies in the spleen, lung, liver, and brain. A strong positive marking was observed in IHC, predominantly in the lung and to a lesser extent in the liver. Polymerase chain reaction (PCR) indicated the Dublin serotype as the causative agent in the samples of the four calves submitted to this procedure. In calves, the septicemic form was the major cause of death due to salmonellosis. Septicemic salmonellosis was usually not accompanied by diarrhea. The clinical signs of septicemia are nonspecific and of little assistance in the diagnosis. IHC has been shown to be efficient in the detection of the agent, mainly in the lung and especially in situations where it is not possible to perform bacterial culture.(AU)

A salmonelose é uma causa conhecida de distúrbios entéricos em bezerros. Porém, casos na forma septicêmica podem não apresentar manifestação entérica, o que leva o médico veterinário a não suspeitar de salmonelose, comprometendo o diagnóstico. Este estudo descreve os aspectos epidemiológicos, clínicos, patológicos e imuno-histoquímicos da salmonelose septicêmica em bezerros sem lesões entéricas. O estudo foi realizado a partir dos protocolos referentes a materiais de bovinos enviados para diagnóstico ao Laboratório de Anatomia Patológica (LAP) da Faculdade de Medicina Veterinária e Zootecnia (FAMEZ) da Universidade Federal de Mato Grosso do Sul (UFMS) de janeiro de 1995 a julho de 2018. Foram selecionados os casos de bezerros confirmados ou sugestivos de salmonelose septicêmica sem lesões entéricas. Fragmentos de fígado, pulmão e baço embebidos em parafina foram submetidos ao exame de imuno-histoquímica (IHQ). Somente foram incluídos neste estudo casos em que houve marcação positiva na IHQ ou isolamento da bactéria em cultura. De um total de 5.550 bovinos examinados no período, dez apresentaram salmonelose septicêmica sem lesão entérica. Os sinais clínicos incluíram palidez de mucosas, apatia, hipertermia e dispneia. Apenas três bezerros apresentaram diarreia e dois foram encontrados mortos sem terem sido observadas alterações clínicas. Os achados mais frequentes de necropsia foram hepatoesplenomegalia, fígado amarelado, alaranjado ou acastanhado, palidez de mucosas, pulmões inflados e, por vezes, vermelhos, fibrina ou líquido nas cavidades do organismo e vesícula biliar repleta de bile grumosa. Icterícia foi observada em três bezerros que apresentavam infecção concomitante por Anaplasma sp. Microscopicamente, os nódulos paratifoides hepáticos e pneumonia intersticial foram as manifestações mais encontradas, seguidas por trombose e colônias bacterianas no baço, pulmão, fígado e encéfalo. Na IHQ, marcação fortemente positiva foi observada, predominantemente, no pulmão e, em menor intensidade, no fígado. A técnica de reação em cadeia de polimerase (PCR) tipificou o sorotipo Dublin como agente etiológico nas amostras dos quatro bezerros submetidos a este procedimento. Em bezerros, a forma septicêmica foi a principal responsável pelas mortes por salmonelose. Na maioria das vezes essa forma não estava acompanhada por diarreia. Os sinais clínicos da forma septicêmica são inespecíficos e de pouco auxílio no direcionamento do diagnóstico. A IHQ mostrou-se eficiente na detecção do agente principalmente no pulmão e especialmente nas situações em que não é possível a realização da cultura bacteriana.(AU)

Inactivation of phoPQ genes attenuates Salmonella Gallinarum biovar Gallinarum to susceptible chickens

Abstract Salmonella Gallinarum is a host-restrict pathogen that causes fowl typhoid, a severe systemic disease that is one of the major concerns to the poultry industry worldwide. When infecting the bird, SG makes use of evasion mechanisms to survive and to replicate within macrophages. In this context, phoPQ genes encode a two-component regulatory system (PhoPQ) that regulates virulence genes responsible for adaptation of Salmonella spp. to antimicrobial factors such as low pH, antimicrobial peptides and deprivation of bivalent cations. The role of the mentioned genes to SG remains to be investigated. In the present study a phoPQ-depleted SG strain (SG ΔphoPQ) was constructed and its virulence assessed in twenty-day-old laying hens susceptible to fowl typhoid. SG ΔphoPQ did cause neither clinical signs nor mortality in birds orally challenged, being non-pathogenic. Furthermore, this strain was not recovered from livers or spleens. On the other hand, chickens challenged subcutaneously with the mutant strain had discreet to moderate pathological changes and also low bacterial counts in liver and spleen tissues. These findings show that SG ΔphoPQ is attenuated to susceptible chickens and suggest that these genes are important during chicken infection by SG.

Contribution of flagella and motility to gut colonisation and pathogenicity of Salmonella Enteritidis in the chicken

ABSTRACT Salmonella Enteritidis causes fowl paratyphoid in poultry and is frequently associated to outbreaks of food-borne diseases in humans. The role of flagella and flagella-mediated motility into host-pathogen interplay is not fully understood and requires further investigation. In this study, one-day-old chickens were challenged orally with a wild-type strain Salmonella Enteritidis, a non-motile but fully flagellated (SE ΔmotB) or non-flagellated (SE ΔfliC) strain to evaluate their ability to colonise the intestine and spread systemically and also of eliciting gross and histopathological changes. SE ΔmotB and SE ΔfliC were recovered in significantly lower numbers from caecal contents in comparison with Salmonella Enteritidis at early stages of infection (3 and 5 dpi). The SE ΔmotB strain, which synthesises paralysed flagella, showed poorer intestinal colonisation ability than the non-flagellated SE ΔfliC. Histopathological analyses demonstrated that the flagellated strains induced more intense lymphoid reactivity in liver, ileum and caeca. Thus, in the present study the flagellar structure and motility seemed to play a role in the early stages of the intestinal colonisation by Salmonella Enteritidis in the chicken.

Establishment of a pathogenicity index in Salmonella Enteritidis and Salmonella Typhimurium strains inoculated in one-day-old broiler chicks / Estabelecimento de um índice de patogenicidade em cepas de Salmonella Enteritidis e Salmonella Typhimurium inoculadas em pintos de um dia de idade

Salmonella Enteritidis and Salmonella Typhimurium are responsible for causing huge economic loses in aviculture, as they lead young broiler chicks to develop clinical disease and thus increase mortality. Salmonella's pathogenicity is considered complex and multifactorial, demanding more studies that could elucidate the interaction between host and pathogen. The present study aims to evaluate the virulence of 130S. Enteritidis isolates and 70S. Typhimurium inoculated in one-day-old chicks through the establishment of a pathogenicity index. For each strain, 10 commercial chicks from the Cobb lineage were used. Then, 200µL of a solution containing 2x108 CFU of S. Enteritidis or S. Typhimurium were inoculated in the birds by intraperitoneal via. Mortality and presence of lesions such as aerosaculitis (A), perihepatitis (Ph), pericarditis (Pc), peritonitis (Pt), onfalitis (O) and cellulitis (C) were registered daily for seven days. From the second to the seventh day there was a proportional decrease in the punctuation of the time of death (TD) for each day that the bird had survived. The pathogenicity index was calculated using the following formula: PI = (TD x 5) + A + Ph + Pc + Pt + O + C. The obtainment of the PI of each bacterial sample was achieved by calculating the rate of the ten inoculated birds. Based on the obtained results, it was possible to attribute the pathogenicity value for each strain, which enabled us to classify them in groups of low (27/200), intermediate (95/200) and high (78/200) pathogenicity. The utilization of standards like time of death and presence of septicemic lesions made it possible to determine the pathogenicity rate for each strain. Besides that, the proposed model has presented dramatic differences between the high, intermediate and low pathogenicity groups, which makes this mechanism useful for further classification of strains isolated in poultry farms.

Salmonella Enteritidis e Salmonella Typhimurium são responsáveis por imensos prejuízos econômicos ao setor avícola, podendo levar ao desenvolvimento de doença clínica e ao aumento da mortalidade em aves jovens. A patogenicidade de Salmonella é considerada complexa e multifatorial, necessitando de estudos que possam esclarecer a interação entre patógeno e hospedeiro. O presente trabalho teve por objetivo avaliar a virulência de 130 isolados de S. Enteritidis e 70 de S.Typhimurium, inoculadas em pintos de um dia de idade, por meio do estabelecimento de um índice de patogenicidade. Para cada cepa, foram utilizados 10 pintos comerciais da linhagem Cobb. As aves foram inoculadas com 200µL de uma solução contendo 2x108 UFC de S. Enteritidis ou S. Typhimurium, por via intraperitoneal. A mortalidade e a presença de lesões como aerossaculite (A), peri-hepatite (Ph), pericardite (Pc), peritonite (Pt), onfalite (O) e celulite (C) foram registradas diariamente durante sete dias. Do segundo ao sétimo dia, houve uma diminuição proporcional da pontuação no tempo de morte (TM) a cada dia em que o animal sobrevivia. O cálculo do índice de patogenicidade de cada pintinho inoculado (IP) obedeceu à seguinte fórmula: IP = (TMx5) + A + Ph + Pc + Pt + O + C. Para obtenção do IP de cada amostra, foi realizada a média do IP obtido com as 10 aves inoculadas. Com base nos resultados observados, foi possível atribuir um valor de patogenicidade a cada uma das cepas, permitindo classificá-las em grupos de baixa (27/200), intermediária (95/200) e alta patogenicidade (78/200). A utilização de critérios, como tempo de morte e presença de lesões septicêmicas, permitiu a determinação de um índice de patogenicidade para cada cepa. Além disso, o modelo proposto apresentou diferença significativa entre os grupos de alta, intermediária e baixa patogenicidade, permitindo, assim, a sua aplicação para classificação futura das cepas isoladas em granjas avícolas.

Surto de salmonelose pelo sorovar Dublin em bezerros no Maranhão / Outbreak of salmonellosis by serovar Dublin in calves in the State of Maranhão, Brazil

Um surto de salmonelose em bezerros causado pela Salmonella enterica subsp. enterica sorovar Dublin é relatado em uma fazenda no município de Timon, Maranhão. De um total de 62 bezerros, 22 (35,5%) adoeceram e destes nove (40,9%) morreram. Os sinais clínicos incluíram febre, depressão, anorexia e, em alguns casos, sinais respiratórios, neurológicos, entéricos ou artrites, com curso clínico hiperagudo ou subagudo. As principais lesões macroscópicas foram hepatomegalia com áreas pálidas multifocais a coalescentes, esplenomegalia e líquido nas cavidades torácica e abdominal. Histologicamente foram observados granulomas paratifoides no fígado, rim e baço, além de trombos e agregados bacterianos em vasos sanguíneos de diversos órgãos. O surto foi controlado com a adoção de antibioticoterapia adequada aliada a correção de algumas medidas sanitárias na propriedade.

An outbreak of salmonellosis due to Salmonella enterica subsp. enterica sorovar Dublin is reported in calves in a farm in the municipality of Timon, state of Maranhão. From a total of 62 calves, 22 (35.5%) were affected and 9 (40.9%) died. Clinical signs were fever, depression, anorexia, and, in some cases, respiratory, neurological or enteric signs, or arthritis. The clinical manifestation period was hyperacute to subacute. Main gross lesions were enlarged liver and spleen, and presence of exudate in the cavities. Histologically, paratyphoid granuloma were seen in the liver, kidney, and spleen. Thrombosis and bacterial aggregates in blood vessels were observed in various organs. After the realization of the antibiogram the outbreak was controlled by adoption of appropriate antibiotic therapy combined with the correction of sanitary measures.