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Leptospiral Culture without 5'-Fluorouracil Revealed Improved Leptospira Isolation from Febrile Patients in North-Eastern Malaysia.

ABSTRACT: Objectives: Isolation of Leptospira by culture represents a definitive growth and confirmation of the disease, yet it is hampered with its nature of slow growth. With slight modification of culture method, the study aims to isolate and characterize Leptospira spp. from patients with acute febrile illness. Methods: A total of 109 blood samples were collected from patients with acute febrile illness that presented at the Emergency Department of Hospital Universiti Sains Malaysia, Malaysia. Clinical samples were subjected to Leptospira IgM Rapid test, microscopic agglutination test (MAT), isolation by culture method, and direct real-time PCR test. For leptospiral isolation, the samples (whole blood and deposit from spun plasma) were cultured into modified Ellinghausen McCullough Johnson Harris (EMJH) media with and without 5'-fluorouracil (5-FU). In every culture positive sample, partial 16S rRNA gene sequencing was performed for molecular identification of the isolates. Phylogenetic analysis was carried out to determine the genetic relatedness among the isolates. An inhibition of 5-FU study was performed on Leptospira interrogans serovar Canicola with different concentrations to compare the growth detection of the tested Leptospira with or without 5-FU within 7 days of incubation. Results: Leptospirosis was diagnosed in 14.7% of patients with acute febrile illness. Two Leptospira spp. (n = 2/109, 1.85%) were successfully isolated from whole blood and deposit from spun plasma samples. B004 and B208 samples were positive at day 11 and day 7, respectively, in EMJH media without addition of 5-FU. Sample B004 was identified as Leptospira interrogans and B208 as Leptospira weilli. Phylogenetic analysis confirmed that both of them were within pathogenic group and they were not related. The 5-FU inhibition study revealed that additional of 5-FU at final concentration of 200 µg/mL to EMJH media demonstrated an inhibitory effect on the growth of the tested strain Conclusion: Isolation of Leptospira spp. using EMJH media without addition of 5'-fluorouracil resulted in a better outcome. Two pathogenic Leptospira isolates were successfully cultivated from patients with acute febrile illness that were genetically not related.

SUBMITTER: Mohamad Safiee AW

PROVIDER: S-EPMC7068603 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:The whole genome analysis of two strains of the first intermediately pathogenic leptospiral species to be sequenced (Leptospira licerasiae strains VAR010 and MMD0835) provides insight into their pathogenic potential and deepens our understanding of leptospiral evolution. Comparative analysis of eight leptospiral genomes shows the existence of a core leptospiral genome comprising 1547 genes and 452 conserved genes restricted to infectious species (including L. licerasiae) that are likely to be pathogenicity-related. Comparisons of the functional content of the genomes suggests that L. licerasiae retains several proteins related to nitrogen, amino acid and carbohydrate metabolism which might help to explain why these Leptospira grow well in artificial media compared with pathogenic species. L. licerasiae strains VAR010(T) and MMD0835 possess two prophage elements. While one element is circular and shares homology with LE1 of L. biflexa, the second is cryptic and homologous to a previously identified but unnamed region in L. interrogans serovars Copenhageni and Lai. We also report a unique O-antigen locus in L. licerasiae comprised of a 6-gene cluster that is unexpectedly short compared with L. interrogans in which analogous regions may include >90 such genes. Sequence homology searches suggest that these genes were acquired by lateral gene transfer (LGT). Furthermore, seven putative genomic islands ranging in size from 5 to 36 kb are present also suggestive of antecedent LGT. How Leptospira become naturally competent remains to be determined, but considering the phylogenetic origins of the genes comprising the O-antigen cluster and other putative laterally transferred genes, L. licerasiae must be able to exchange genetic material with non-invasive environmental bacteria. The data presented here demonstrate that L. licerasiae is genetically more closely related to pathogenic than to saprophytic Leptospira and provide insight into the genomic bases for its infectiousness and its unique antigenic characteristics.

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Leptospiral Culture without 5'-Fluorouracil Revealed Improved Leptospira Isolation from Febrile Patients in North-Eastern Malaysia.

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