Leptospira interrogans biofilm formation in Rattus norvegicus (Norway rats) natural reservoirs

Abstract

Rattus norvegicus (Norway rat) is the main reservoir host of pathogenic Leptospira, the causative agent of leptospirosis, in urban environments. Pathogenic Leptospira forms biofilms in the environment, possibly contributing for bacterial survival and maintenance. Nonetheless, biofilms have not yet been studied in natural animal reservoirs presenting leptospiral renal carriage. Here, we described biofilm formation by pathogenic Leptospira inside the renal tubules of R. norvegicus naturally infected and captured in an urban slum endemic for leptospirosis. From the 65 rats carrying Leptospira in their kidneys, 24 (37%) presented biofilms inside the renal tubules. The intensity of leptospiral colonization in the renal tubules (OR: 1.00; 95% CI 1.05–1.1) and the type of occlusion pattern of the colonized renal tubules (OR: 3.46; 95% CI 1.20–9.98) were independently associated with the presence of Leptospira biofilm. Our data showed that Leptospira interrogans produce biofilms during renal chronic colonization in rat reservoirs, suggesting a possible role for leptospiral biofilms in the pathogenesis of leptospirosis and bacterial carriage in host reservoirs.

Biofilm formation in vitro by Leptospira interrogans strains isolated from naturally infected dogs and their role in antimicrobial resistance

“…Biofilms are described as colonization and virulence factors who partake in the pathogenesis of several infectious diseases [ 32 ], including leptospirosis [ 12 ]. Some factors such as the genotypic and phenotypic expression inherent to each strain are determinant for the production of bacterial biofilms [ 33 ].…”

“…Studies also reported bacterial aggregates within the lumen of proximal renal tubules in mammalian hosts [ 10 , 11 ]. More recently, Santos et al [ 12 ] documented Leptospira biofilm formation in the kidneys of reservoir animals (mice). According to Thibeaux et al [ 13 ], leptospire biofilms may play a key role not only in maintaining infection but also in antimicrobial resistance.…”

Infectious Uveitis in Horses and New Insights in Its Leptospiral Biofilm-Related Pathogenesis

“…Similarly, the detection of specific IgA antibodies in specimens from eyes affected with ERU is particularly sensitive for the detection of chronic intraocular leptospiral infection [194,195]. Apart from intraocular infections, chronic leptospiral infections have been described, especially for proximal renal tubules, and have also been associated with biofilm formation [524][525][526][527]. In cattle, the detection of urinary IgA specific for leptospires has recently been described as a "hallmark" to identifying reservoir hosts [528].…”

“…In vivo biofilm formation of leptospires in the proximal renal tubules of chronic shedders has been suspected for some time [524,535]; it has been demonstrated by electron microscopy after experimental infections [525,526], and recently in naturally infected Rattus norvegicus [527]. Experimental infections of mice were used to understand the in vivo immune evasion [543].…”

A global one health perspective on leptospirosis in humans and animals

“…56 The organism forms biofilms within the renal tubules that may contribute to its persistence in the face of the immune response and antimicrobial therapy. 57 Although a distinction has been made between incidental hosts and reservoir hosts, the recognition of reservoir host-associated leptospiral strains in disease outbreaks affecting those reservoir hosts suggest that a continuum of infection outcomes may exist and that host factors such as immunosuppression may be important in influencing such outcomes. For example, in California sea lions, cyclical outbreaks of disease in yearlings are accompanied by continuous subclinical infections in the adult sea lion population, with shedding documented for up to 154 days after infection.…”