A comparison of ML Flow serology and slit skin smears to assess the bacterial load in newly diagnosed leprosy patients in Brazil.
BACKGROUND
The ML Flow test is an immunochromatographic assay that detects IgM antibodies against M. leprae-specific anti-phenolic glycolipid I (PGL-I). In addition to slit skin smears stained by the Ziehl-Neelsen technique, it can be helpful in the operational classification of leprosy patients for treatment purposes.


OBJECTIVE
This work studied the relationship between antibody levels as detected by semi-quantitative ML Flow serologic test and bacterial load as quantified by slit skin smear.


METHODS
135 patients with newly detected leprosy at the reference service in Sanitary Dermatology in Brazil had slit skin smears (registered as bacillary index - BI) and an ML Flow test (registered qualitatively and semi-quantitatively) performed at admission. A logistic regression and agreement measures (kappa index) were calculated.


RESULTS
Slit skin smears were positive in 35.9% of patients and 57% of patients were seropositive for PGL-1 antibodies. Among the seropositive patients, 416% had five or fewer skin lesions, and 65.8% had more than one peripheral nerve involved. Slit skin smears were positive in only three seronegative patients (5.6%), and negative in 41.9% of seropositive patients. Patients with a BI of 4 + had an OR of 33 for being seropositive in comparison to those with a low BI.


CONCLUSIONS
There is a correlation between serologic test and slit skin smear results. Therefore, an ML Flow test may become a useful tool in the clinical classification of leprosy, besides slit skin smears, which require a proper laboratory infrastructure and experienced personnel.
Lyon
Sandra
S
Sanitary Dermatology Service, Hospital Eduardo de Menezes, Fundação Hospitalar do Estado de Minas Gerais, Belo Horizonte, Brazil. sandralyon@ig.com.br
Lyon
Ana Claudia
AC
Da Silva
Rozana Castorina
RC
Grossi
Maria Aparecida De Faria
MA
Lyon
Silvia Helena
SH
Bührer-Sékula
Samira
S
Rocha
Manoel O C
MO
D000907:Antibodies, Bacterial / Q000097:blood*; D000942:Antigens, Bacterial / Q000378:metabolism; D001431:Bacteriological Techniques; D001938:Brazil / Q000453:epidemiology; D005260:Female; D006017:Glycolipids / Q000378:metabolism; D006801:Humans; D007075:Immunoglobulin M / Q000097:blood; D007918:Leprosy / Q000382:microbiology*; D008297:Male; D025202:Molecular Diagnostic Techniques; D009166:Mycobacterium leprae / Q000276:immunology / Q000502:physiology*; D012867:Skin / Q000382:microbiology / Q000473:pathology*; D013194:Staining and Labeling
D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D006017:Glycolipids; D007075:Immunoglobulin M; C045169:phenolic glycolipid I, Mycobacterium leprae