Heterogenic colonization patterns by Leptospira interrogans in Rattus norvegicus from urban slums

Abstract We evaluated the renal colonization by Leptospira interrogans in Rattus norvegicus (rats), as it is the major natural reservoir of urban leptospirosis. We caught 72 R. norvegicus, out of which 32 were found to be positive for L. interrogans by immunofluorescence assay. From these rats, we selected 17 and divided them into six groups based on the mass-age/sex. We performed the immunohistochemistry test against L. interrogans in the kidney sections of the rats and systematically counted the colonized tubules (CTs) in 20 fields. The proportion of positive fields varied from 5% to 95%. The number of CTs in 20 fields varied from 0.5 to 85.5. These differences were not related to age or sex of the animals. The characterization of leptospiral colonization patterns in the natural reservoirs is important to better understand the host-pathogen interactions in leptospirosis.

Identificação de biofilme renal em ratos naturalmente infectados por Leptospira interrogans através de técnicas histoquímicas e de microscopia eletrônica de varredura, Brasil / Identification of renal biofilm in rats naturally infected with Leptospira interrogans using histochemical and scanning electron microscopy techniques, Brazil

INTRODUÇÃO: A leptospirose é um importante agravo de saúde pública e afeta ao menos um milhão de humanos por ano no mundo. Ratos de esgoto (Rattus norvegicus) são os principais reservatórios de leptospiras patogênicas nas áreas urbanas e excretam, através da urina, elevadas quantidades de bactérias diariamente. As leptospiras sobrevivem no ambiente e são transmitidas para novos hospedeiros através do contato com mucosas e pele. Leptospiras patogênicas formam densos biofilmes in vitro. A patogênese da leptospirose em reservatórios crônicos é pouco conhecida. OBJETIVO: Estudar a formação de biofilme por Leptospira interrogans em R. norvegicus capturados em uma área hiperendêmica de Salvador, Bahia, Brasil. MATERIAIS E MÉTODOS: Capturamos 86 ratos, dos quais 76 (88,4%) foram considerados portadores de L. interrogans através da avaliação por imunohistoquímica (IHQ) anti-L. interrogans e/ou Reação em Cadeia da Polimerase quantitativa em Tempo Real (RT-qPCR) utilizando iniciadores específicos para o gene lipL32. RESULTADOS: Ao exame de IHQ anti-L. interrogans, 69 ratos foram positivos. Destes, 24 (35%)...

INTRODUCTION: Leptospirosis is an important public health problem and affects at least one million people each year worldwide. Norway rats (Rattus norvegicus) are the main reservoir hosts of leptospires in urban environments. They excrete large amounts of bacteria daily. Leptospires survive in the environment and are transmitted to new hosts by contact with mucous membranes and skin. Pathogenic leptospires form dense biofilms in vitro. The pathogenesis of chronic leptospirosis in reservoirs is largely unknown. The aim of this work was to study biofilm formation by Leptospira interrogans in R. norvegicus caught in a hyperendemic area in Salvador, Bahia, Brazil. MATERIAL AND METHODS: We caught 86 rats, out of which 76 (88.4%) were carriers of L. interrogans according to immunohistochemistry (IHC) anti-L. interrogans and/or quantitative real time PCR (RT-qPCR) using LipL32 primers. RESULTS: From the 69 rats positive for IHC anti-L. interrogans, 24 (35%)...