title: Coexistence and survival of pathogenic leptospires by formation of biofilm with Azospirillum.
abstract: 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.
authors.affiliation: Regional Medical Research Centre (ICMR), WHO Collaborating Centre for Diagnosis, Reference, Research and Training in Leptospirosis, Port Blair 744101, Andaman and Nicobar Islands, India.
authors.forename: K Vinod
authors.initials: KV
authors.lastname: Kumar
authors.affiliation: Regional Medical Research Centre (ICMR), WHO Collaborating Centre for Diagnosis, Reference, Research and Training in Leptospirosis, Port Blair 744101, Andaman and Nicobar Islands, India.
authors.forename: Chandan
authors.initials: C
authors.lastname: Lall
authors.affiliation: Regional Medical Research Centre (ICMR), WHO Collaborating Centre for Diagnosis, Reference, Research and Training in Leptospirosis, Port Blair 744101, Andaman and Nicobar Islands, India.
authors.forename: R Vimal
authors.initials: RV
authors.lastname: Raj
authors.affiliation: Regional Medical Research Centre (ICMR), WHO Collaborating Centre for Diagnosis, Reference, Research and Training in Leptospirosis, Port Blair 744101, Andaman and Nicobar Islands, India.
authors.forename: K
authors.initials: K
authors.lastname: Vedhagiri
authors.affiliation: Regional Medical Research Centre (ICMR), WHO Collaborating Centre for Diagnosis, Reference, Research and Training in Leptospirosis, Port Blair 744101, Andaman and Nicobar Islands, India pblicmr@sancharnet.in.
authors.forename: P
authors.initials: P
authors.lastname: Vijayachari
mesh_terms: D000667:Ampicillin / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D016949:Azospirillum / Q000187:drug effects / Q000254:growth & development* / Q000302:isolation & purification; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D024901:Drug Resistance, Multiple, Bacterial; D004777:Environment; D006358:Hot Temperature; D007921:Leptospira interrogans / Q000187:drug effects / Q000254:growth & development* / Q000302:isolation & purification; D007922:Leptospirosis / Q000382:microbiology; D056265:Microbial Interactions / Q000502:physiology*; D008826:Microbial Sensitivity Tests; D010400:Penicillin G / Q000494:pharmacology; D013752:Tetracycline / Q000494:pharmacology; D014466:Ultraviolet Rays
chemical_list: D000900:Anti-Bacterial Agents; D000667:Ampicillin; D013752:Tetracycline; D010400:Penicillin G
keywords: Azospirillum; Biofilm; Leptospira; Microbial cooperation