[Severe form of Legionnaires' disease in an immunocompetent patient]

Severe pneumonia caused by Legionella pneumophila detected by a multiplex polymerase chain reaction assay and confirmed by serology

Legionella pneumophila is a rarely diagnosed microorganism in Serbia. It causes legionellosis, usually a mild respiratory infection. However, in some cases it can be severe and even life threatening. In June 2020, during the COVID-19 pandemic, a patient with symptoms of the aforesaid infection, namely severe pneumonia and acute respiratory distress syndrome, was admitted to the hospital. The multiplex polymerase chain reaction (PCR) test (The BioFire FilmArray Pneumonia Panel plus) detected the presence of L. pneumophila in the patient’s bronchial secretions. The specific culture for the detection of that organism, however, remained sterile. The patient’s paired sera had been sent for serology and the results in both of them came back positive for Legionella spp. 1–6, while the assays specific for each one of the 10 serogroups detected more than a fourfold increase of antibody titers in an uncommon serogroup 2 only. The patient was treated with moxifloxacin; he recovered well and was discharged after 26 days of hospitalization. Having being diagnosed with the L. pneumophila infection correctly through the multiplex PCR test, the patient was given the right therapy with moxifloxacin. The serologic assays corroborated this result and revealed the uncommon group 2, thus confirming the necessity of carrying out all the tests available to attain the exact diagnosis of legionellosis.

An outbreak of Legionnaires' disease in newborns in Serbia

Legionnaires' disease is an atypical pneumonia caused by inhaling small droplets of water containing the bacterium Legionella spp. In newborns, it is a rare event, usually associated with water births and the use of air conditioning systems or air humidifiers. A nosocomial outbreak of Legionnaires' disease in the maternity ward of a secondary-care hospital in Arandjelovac, Serbia is described.Two male newborns were found to be infected with Legionnella pneumophila. On Days 7 and 6 of life, respectively, they were transferred to a tertiary-care hospital with signs of severe pneumonia which was radiologically confirmed. L. pneumophila was detected in tracheal secretions from both infants by RT-PCR, and its antigens were also positive in urine samples. The source of infection in the secondary-care hospital was the internal hot water heating system, and the main contributory factor to the emergence of the infection was the low temperature of the hot water which did not kill the bacteria during the available exposure time.These two cases highlight the importance of being cautious about possible Legionnaires' disease in maternity wards with outdated or irregularly maintained internal water supply systems. The adoption of official guidelines for the control and regular maintenance of water supply systems, including the multidisciplinary cooperation of all relevant parties, forms the basis for direct monitoring for Legionella and the prevention of new outbreaks.Abbreviations: BCYE: buffered charcoal yeast extract agar; GVPC: glycine vancomycin polymyxin cycloheximide agar; LD - Legionnaires' disease; TR-PCR: Reverse transcription polymerase chain reaction.