Staphylococcus sciuri associated to subcutaneous abscess and dermatitis in ICR mouse / Staphylococcus sciuri associado a abcesso subcutâneo e dermatite em ratos

Subcutaneous mass was found in ICR mouse during daily health observation in the breeding colony of the National Laboratory Animal Center, Mahidol University, Thailand. The animal was subsequently culled and humanely sacrificed due to the institutional preventive medicine policy. Microbiological and histopathological studies were performed for definitive diagnosis. The results described that the case was subcutaneous abscess and chronic dermatitis in association with Staphylococcus sciuri infection without epizootic and mortality. This was determined as the first reported case in Thailand occurring in mouse. Reproductive stress and abrasion skin wound may be the predisposing factors. Although pathogenic staphylococci in laboratory animals are limited to S. aureus and S. xylosus, S. sciuri opportunistic properties, natural history, and heterogeneity should not be forgotten.(AU)

Uma massa subcutânea foi encontrada em um rato ICR durante uma observação diária de saúde na colônia reprodutora do Laboratório do Centro Animal Nacional, na Universidade de Mahidol, Tailândia. O animal foi selecionado e humanamente sacrificado devido à política institucional de medicina preventiva. Estudos microbiológicos e histopatológicos foram realizados para um diagnóstico definitivo. Os resultados descrevem que o caso foi um abcesso subcutâneo e dermatite crônica associado com infecção por Staphylococcus sciuri sem epizootia e mortalidade. Este foi determinado como o primeiro caso relatado em ratos na Tailândia. Estresse reprodutivo e ferida abrasiva na pele podem ser os fatores de predisposição. Apesar de staphylococci patogênicos em animais de laboratório serem limitados a S. aureus E S. xylosus, as propriedades oportunistas, história natural e heterogeneidade do S. sciuri não devem ser esquecidos.(AU)

Genetic analysis of mecA gene and detection of homologue pbpD in Stahylococcus sciuri group

Oxacillin/methicillin-resistance is related to the mecA and its regulatory genes mecR1 and mecI. Its origin is still unknown, although evidences support that it is related to CNS, once mecA and a homologue gene, pbpD, were both detected in Staphylococcus sciuri species group. The present work evaluated 210 samples of skin and ear swabs from rodents and 60 nasal swabs from equines of Army Biologic Institute, Rio de Janeiro. Pheno- and genotypic characterization provided 59.52% (25/42) and 78.57% (11/14) S. lentus and S. sciuri, respectively. It was observed that although all S. sciuri isolates tested positive for pbpD, there was no correlation with oxacillin-resistance. On the other hand, isolates tested positive for mecA gene also presented phenotypic oxacillin-resistance in at least one assay. The alignment of the mecA gene showed that the nucleotide sequences were sorted into 2 different groups, one comprising the bovine strains and the other containing human and equine strains.

Establishment and research on Staphylococcus-infected-corneal C57BL/6 mouse model / 眼科研究

Background An ethylnitrosourea(ENU)-induced mutant strain C57BL/6 mouse model has been established by our research group.This model is proved to have the spontaneous phenotype of corneal opacity and the typical pathological process similar to human keratitis.Therefore,this model is expected to be a good animal model in the research of the mechanism,hereditary property,and development of drugs for corneal infectious diseases.Objective The present study is to investigate the biological features of opportunistic pathogens using a mouse Staphylococcus-infected corneal model(C57BL/6 mouse) induced by N-ethyl-N-nitrosourea(ENU),and offers an evidence of stability in this animal model.Methods Ten-week-old male C57BL/6 mice were treated with ENU at 150mg/kg by intraperitoneal injection,and then mated with female mice after 60 days.Corneal opacity mutant mice in the F1 generation were selected to backcross with C57BL/6 mice.The bacteria were isolated from the eyeballs of the mutants and cultivated,purified and identified.Drug sensitivity assay was carried out to screen for effective antibiotics for clinic medical care.Results The staphylococcus-infected corneal mouse model(B6-Co) was established successfully,and the Staphylococcus sciuri strain was separated and purified,and then the sensitive antibiotics were distinguished from resistant ones.The sensitive drugs for Staphylococcus sciuri included azithromycin,clindamycin,chloramphenicol,gentamicin,rifampicin,tetracycline,amikacin,sulfamethoxazole compound sinomin,minocycline,levofloxacin,cephalothin,cefotaxime,and furazolidone;whereas this Staphylococcal strain was resistant to cefoxitin,penicillin,ampicillin,novobiocin.Nitrofurantoin showed an intermediate sensitivity.Conclusion The C57BL/6 mouse model is a spontaneous-derived animal model that is infected by coagulase-negative staphylococci,among which the most abundant strain is Staphylococcus sciuri.