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The use of methanol extract of Leptospira interrogans in complement fixation tests for leptospirosis
M C Koury1, E O Cisalpino, H de A Rangel
1Departamento de Microbiologia, Universidade Federal de Minas Gerais, Brasil.
Abstract:
Methanol extracts were obtained from L. interrogans serovars icterohaemorrhagiae and canicola and L. biflexa serovar patoc. Human sera from 167 normal individuals and 40 patients with different infectious diseases tested by complement fixation tests showed negative reactions. Sera from 100 patients with a suspicion of leptospirosis were tested by complement fixation tests and microscopic agglutination reactions. Agreement of 84% was found for those two reactions. Positive microscopic agglutination tests at a dilution 1:20-1:400 with negative complement fixation tests were observed in 5% of patients and negative microscopic agglutination with complement fixation tests in the range of 1:20-1:1280 were observed in 11% of the cases.
Insights
This study evaluated diagnostic tests for leptospirosis. Microscopic agglutination tests showed better agreement with clinical suspicion than complement fixation tests, aiding in diagnosing this bacterial infection.
Area of Science:
- Microbiology
- Immunology
- Infectious Diseases
Background:
- Leptospirosis is a zoonotic bacterial infection caused by pathogenic Leptospira species.
- Accurate and timely diagnosis is crucial for effective treatment and public health management.
- Traditional diagnostic methods like complement fixation tests (CFT) and microscopic agglutination tests (MAT) have varying sensitivities and specificities.
Purpose of the Study:
- To compare the diagnostic performance of complement fixation tests (CFT) and microscopic agglutination reactions (MAR) in suspected leptospirosis cases.
- To assess the agreement between CFT and MAR in identifying Leptospira infections.
- To evaluate the utility of these serological tests in a clinical setting.
Main Methods:
- Methanol extracts of Leptospira interrogans serovars icterohaemorrhagiae and canicola, and Leptospira biflexa serovar patoc were prepared.
- Human sera from normal individuals, patients with other infectious diseases, and patients with suspected leptospirosis were tested.
- Complement fixation tests (CFT) and microscopic agglutination reactions (MAR) were employed for serological analysis.
Main Results:
- A high agreement rate of 84% was observed between CFT and MAR in patients with suspected leptospirosis.
- 5% of patients showed positive MAR (1:20-1:400) with negative CFT.
- 11% of patients exhibited negative MAR with positive CFT (1:20-1:1280).
Conclusions:
- Microscopic agglutination reactions (MAR) demonstrate a significant agreement with complement fixation tests (CFT) in diagnosing leptospirosis.
- Discordant results between MAR and CFT may indicate different stages or types of Leptospira infection, warranting further investigation.
- MAR appears to be a valuable tool, potentially offering a broader diagnostic window or detecting infections missed by CFT in suspected leptospirosis cases.