Coexistence and survival of pathogenic leptospires by formation of biofilm with Azospirillum

• Published in: FEMS microbiology ecology 2015-06, Vol.91 (6), p.1
• Main Authors: Vinod Kumar, K., Lall, Chandan, Raj, R. Vimal, Vedhagiri, K., Vijayachari, P.
• Format: Article
• Language: English
• Subjects: Ampicillin; Ampicillin - pharmacology; Anti-Bacterial Agents - pharmacology; Aquatic environment; Azospirillum - drug effects; Azospirillum - growth & development; Azospirillum - isolation & purification; Biofilms; Biofilms - drug effects; Biofilms - growth & development; Coexistence; Drug Resistance, Multiple, Bacterial; Ecology; Environment; Environmental conditions; Gram-negative bacteria; High resistance; High temperature; Hot Temperature; Leptospira; Leptospira interrogans - drug effects; Leptospira interrogans - growth & development; Leptospira interrogans - isolation & purification; Leptospirosis; Leptospirosis - microbiology; Microbial Interactions - physiology; Microbial mats; Microbial Sensitivity Tests; Microbiology; Penicillin; Penicillin G - pharmacology; Physiological aspects; Survival; Temperature tolerance; Tetracycline - pharmacology; Ultraviolet radiation; Ultraviolet Rays
• ISSN: 1574-6941; 0168-6496; 1574-6941
• DOI: 10.1093/femsec/fiv051

Pathogenic Leptospira spp. represent one cause of leptospirosis worldwide and have long been regarded as solitary organisms in soil and aquatic environments. However, in the present study, Leptospira interrogans was observed to be associated with environmental biofilms with 21 bacterial isolates belonging to 10 genera. All 21 isolates were examined for their coaggregation and biofilm-forming ability with leptospires in vitro. Among these, Azospirillum brasilense RMRCPB showed maximum interspecies coaggregation with leptospiral strains (>75%, visual score of +4). Other significant coaggregating isolates belonged to the genera Sphingomonas, Micrococcus, Brevundimonas, Acinetobacter and Paracoccus. Biofilms of leptospires in combination with A. brasilense RMRCPB showed high resistance to penicillin G, ampicillin and tetracycline (minimum bactericidal concentration ≥800 μg/mL) and tolerance to UV radiation and high temperature (up to 49°C). This study hypothesized that biofilm formation with A. brasilense protects the pathogenic Leptospira from adverse environmental conditions/stress. This coexistence of pathogenic Leptospira with other bacteria may be the key factor for its persistence and survival. However, the mechanism of biofilm formation by leptospires needs to be explored to help devise an appropriate control strategy and reduce transmission of leptospires. Little is known regarding the mechanisms by which pathogenic leptospires persist in aqueous environments. This is the first report demonstrating association of pathogenic Leptospira with the environmental biofilms.