Diagnostic approaches for oculoglandular tularemia: advantages of PCR

Abstract

Aim: The authors describe a diagnostic approach that proved to be particularly valuable in rare cases of ocular tularemia registered during the tularemia outbreak in 1997-2005 in Bulgaria. The authors describe the laboratory findings and diagnosis of four cases with an oculoglandular form of infection.

Methods: Several different specimens from each patient were analysed. Oculoglandular tularemia was diagnosed in four patients either by culture, immunofluorescent antibody analysis (IFA), serology or by a polymerase chain reaction (PCR) assay.

Results and discussion: Three F tularensis strains were isolated and characterised. One of these was isolated from a conjuctival swab specimen obtained from a seronegative patient. The authors report for the first time a successful application of diagnostic PCR performed directly on conjuctival swab specimen. From all analysed specimens IFA was diagnostically effective only in the case of lymph node aspirates and was not sensitive enough for conjuctival swabs or blood samples. The authors also describe the histological picture of a conjunctival granuloma in course of infection. All patients were successfully treated with ciprofloxacin.

Conclusions: Some of the proposed laboratory diagnostic strategies (swab PCR) are not invasive and could represent a new approach for resolving rare and hard-to-diagnose cases of oculoglandular tularemia.