First cases of culture proven Legionnaires’ disease in Bulgaria

Abstract

Background. Legionella pneumophila is the most common cause of the potentially fatal Legionnaires’ disease with worldwide increasing incidence reports. The bacterium is fastidious and slow growing and most laboratories do not perform culture. Aim. To present results from the first culture proven cases of Legionnaires’ disease in Bulgaria. Materials and methods.  Ten lower respiratory tract materials from 10 patients were cultured for legionellae with GVPC supplement. Identification was based on growth characteristics, latex agglutination and monoclonal typing.  Results. Seven L.pneumophila strains (serogroup1 and serogroup6) were isolated. Five belong to monoclonal sub-types Allentown/France, Knoxville and Philadelphia.  One culture positive sputum was received at the lab 5 days after sampling. Other materials were plated on the day of sampling, but three of them were obtained long after specific therapy was started and remain negative on culture. Five from the ten patients were with fatal outcome. Three were reported to ELDSNet in real-time as travel-associated. Conclusions. Isolation of legionellae from patients remains the diagnostic ‘gold standard’.  The use of selective supplement designed for water samples had no obvious impact on our results in contrast with late sampling. Isolates were from the most frequent reported L. pneumophila serogroups and five of them – from the virulence-associated Pontiac sub-groups. Legionnaires’ disease is still underdiagnosed in Bulgaria. Clinicians must be encouraged to send appropriate and timely obtained respiratory materials.  This should happen even in cases with other positive microbiological results, since co-infection with viral, fungal or other bacterial pulmonary pathogens might be of importance for patients’ treatment and health.