Preservation of leptospiral cultures is tantamount to success in leptospiral diagnostics, research, and development of preventive strategies. Each Leptospira isolate has imperative value not only in disease diagnosis but also in epidemiology, virulence, pathogenesis, and drug development studies. As the number of circulating leptospires is continuously increasing and congruent with the importance to retain their original characteristics and properties, an efficient long-term preservation is critically needed to be well-established. However, the preservation of Leptospira is currently characterized by difficulties and conflicting results mainly due to the biological nature of this organism. Hence, this review seeks to describe the efforts in developing efficient preservation methods, to discover the challenges in preserving this organism and to identify the factors that can contribute to an effective long-term preservation of Leptospira. Through the enlightenment of the previous studies, a potentially effective method has been suggested. The article also attempts to evaluate novel strategies used in other industrial and biotechnological preservation efforts and consider their potential application to the conservation of Leptospira spp.
Leptospirosis is one of the most widespread zoonotic diseases and can infect both humans and animals worldwide. Healthy cat, as a potential source of exposure to humans, are likely underestimated owing to the lack of overt clinical signs associated with Leptospira spp. infection in this species. The aim of the study was to determine the exposure, shedding, and carrier status of leptospires in shelter cats in Malaysia by using serological, molecular, and bacteriological methods. For this study, 82 healthy cats from two shelters were sampled. The blood, urine, and kidneys were tested using the microscopic agglutination test (MAT), polymerase chain reaction (PCR), and bacterial culture. On the basis of serological, molecular, and/or culture techniques, the total detection of leptospiral infection was 29.3% (n = 24/82). Through culture techniques, 16.7% (n = 4/24) of the cats that tested positive were carriers with positive kidney cultures, and one cat was culture positive for both urine and kidney. The Leptospira spp. isolates were identified as pathogenic L. interrogans serovar Bataviae through serological and molecular methods. Through serological techniques, 87.5% (n = 21/24) had positive antibody titers (100-1600) and most of the Bataviae serogroup (n = 19/21). Using PCR, 16.7% (n = 4/24) of cats were shown to have pathogenic Leptospira spp. DNA in their urine. Furthermore, three out of four culture positive cats were serology negative. The present study reports the first retrieval of pathogenic leptospires from urine and kidneys obtained from naturally infected cats. The results provide evidence of the potential role of naturally infected cats in the transmission of leptospires. Additionally, leptospiral infection occurs sub-clinically in cats. The culture isolation provides evidence that healthy cats could be reservoirs of leptospiral infection, and this information may promote the development of disease prevention strategies for the cat population.
A single Leptospira strain (designated Bejo-Iso9(T)) was isolated from a soil sample taken in Johor, Malaysia. The isolate showed motility and morphology typical of the genus Leptospira under dark-field microscopy. Cells were found to be 10-13 microm in length and 0.2 microm in diameter, with a wavelength of 0.5 microm and an amplitude of approximately 0.2 microm. Phenotypically, strain Bejo-Iso9(T) grew in Ellinghausen-McCullough-Johnson-Harris medium at 13, 30 and 37 degrees C, and also in the presence of 8-azaguanine. Serologically, strain Bejo-Iso9(T) produced titres towards several members of the Tarassovi serogroup, but was found to be serologically unique by cross-agglutinin absorption test and thus represented a novel serovar. The proposed name for this serovar is Malaysia. Phylogenetic analysis of 16S rRNA gene sequences placed this novel strain within the radiation of the genus Leptospira, with sequence similarities within the range 90.4-99.5% with respect to recognized Leptospira species. DNA-DNA hybridization against the three most closely related Leptospira species was used to confirm the results of the 16S rRNA gene sequence analysis. The G+C content of the genome of strain Bejo-Iso9(T) was 36.2 mol%. On the basis of phenotypic, serological and phylogenetic data, strain Bejo-Iso9(T) represents a novel species of the genus Leptospira, for which the name Leptospira kmetyi sp. nov. is proposed. The type strain is Bejo-Iso9(T) (=WHO LT1101(T)=KIT Bejo-Iso9(T)).