Leptospirosis laboratory findings

Kidney tissue, using a silver staining technique, revealing the presence of Leptospira bacteria

Leptospirosis Microchapters
Home
Patient Information
Overview
Historical Perspective
Classification
Pathophysiology
Causes
Differentiating Leptospirosis from other Diseases
Epidemiology and Demographics
Risk Factors
Natural History, Complications and Prognosis
Diagnosis
History and Symptoms
Physical Examination
Laboratory Findings
Other Imaging Findings
Treatment
Medical Therapy
Surgery
Primary Prevention
Future or Investigational Therapies
Case Studies
Case #1
Leptospirosis laboratory findings On the Web
Most recent articles
Most cited articles
Review articles
CME Programs
Powerpoint slides
Images
American Roentgen Ray Society Images of Leptospirosis laboratory findings All Images X-rays Echo & Ultrasound CT Images MRI
Ongoing Trials at Clinical Trials.gov
US National Guidelines Clearinghouse
NICE Guidance
FDA on Leptospirosis laboratory findings
CDC on Leptospirosis laboratory findings
Leptospirosis laboratory findings in the news
Blogs on Leptospirosis laboratory findings
Directions to Hospitals Treating Leptospirosis
Risk calculators and risk factors for Leptospirosis laboratory findings

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1];Associate Editor(s)-in-Chief: Venkata Sivakrishna Kumar Pulivarthi M.B.B.S [2]

Overview

The diagnosis of leptospirosis is based upon clinical suspicion and lab diagnosis, so lab tests should be considered in a patient with a history of contact with potentially infected animals, soil or surface waters contaminated by animal urine. Leptospires can be found in blood and CSF for the first 7 to 10 days and then in the urine. Hence, in the early diagnosis specimen of choice should be blood or CSF for culture. From the second week onwards serological tests are useful in the diagnosis.

Laboratory findings

Laboratory Findings

As the clinical manifestations of the disease are non specific, the clinical diagnosis is difficult. The laboratory investigations for leptospirosis should be considered in patient with an abrupt onset of fever, chills, conjunctival suffusion, headache, myalgia and jaundice with history of occupational exposure to infected animals or contaminated with animal urine. Laboratory criteria for the diagnosis of leptospirosis are presence of one or more of the following:

• Culture positivity
• Antibody titre of ≥1 in 320 by Microscopic Agglutination test (MAT) in a single serum sample
• Seroconversion in paired sera collected in the acute and convalescent phase established by ELISA IgM and/or MAT methods
• Evidence of leptospira antigen by molecular methods.

Laboratory investigations useful in the diagnosis of leptospirosis include:

• Identification of leptospires in tissues using antibodies labelled with fluorescent markers
• Antibody detection by serological studies
• Culture the bacteria from blood, urine or tissues
• Other methods such as PCR, Immunostaining etc.

Laboratory investigations for leptospirosis

Culture

Microscopic

Immunological

Molecular

• Isolation

• Dark field microscopy • Immunofluoroscence microscopy

• Microscopic agglutination test • ELISA test • Latex agglutination test

• Polymerase chain reaction

Blood Tests

Blood tests in leptospirosis include:

• CBC: Peripheral leukocytosis with a left shift, thrombocytopenia,
• Elevated ESR
• Liver functional tests: Mild elevation in aminotransferases, bilirubin, and alkaline phosphatase.
• Elevated plasma creatinine, elevated blood urea nitrogen(BUN)
• Elevated creatinine phosphokinase(CPK)

Urinalysis

• Proteinuria
• Pyuria
• Microscopic hematuria
• Hyaline and granular casts

CSF Analysis

CSF findings are common in first or second week of illness.

• Opening pressure: normal or slightly elevated
• Cells: Lymphocyte predominance
• Protein: Normal to elevated
• Glucose: Normal
• Xanthochromasia is seen in severe Icteric leptospirosis

Isolation of Leptospires

Isolation of leptospires from clinical specimens is the strongest evidence for conrmation of leptospirosis. Leptospira can be cultured in Ellinghausen-McCullough-Johnson-Harris medium, which is incubated at 28 to 30ºC. The median time to positivity is three weeks with a maximum of 3 months. This makes culture techniques useless for diagnostic purposes, but is commonly used in research.

Blood culture:

• Should be done before starting of antibiotics
• Useful if done with in 10days after the initial presentaion

Urine culture:

• Should be tested between 10-30days of initial presentaion
• Sample should be tested within 2hours of collection

CSF culture:

• Should be tested between 5-10days of initial presentaion

Identification of Leptospires

Dark field microscopy: In order to detect under dark field microscopy 10⁴ leptospires/ml are necessary for one cell per field.

• Specimen: Blood, urine, CSF
• Disadvantages: Test is insensitive and lacks specificity

Other microscopic techniques: Immunofluoroscence, Light microscopy

Antigen detection tests

Leptospiral antigens can be identified from different specimen such as blood, urine with higher sensitivity than dark field microspy. Techniques include:

• Radioimmunoassay (RIA)
• Enzyme-linked immunosorbent assay (ELISA)

Serological Tests

Serological test are useful to detect leptospira-specific IgM antibodies in the early acute phase of illness, especially after first week of clinical symptoms. Antibodies production start 5-7 days after the onset of the initial presentation. Serological test in the 1st week will give false negative results.
Screening tests

• Enzyme-linked immunosorbent assay (ELISA): sensitivity of 90% and specificity of 94%. Positive test results shows high IgM titre in a single serum sample or a 4-fold rise in titre in a paired tests is consistent with current or recent infection.

Confirmatory tests

• Microscopic agglutination test (MAT): Specificity of 94%. All positive screening tests should be confirmed by the MAT. Agglutinating antibodies can detects both IgM and IgG classes and are detectable from about Days 7 to 10 after onset of symptoms.