Identification of Legionella Pneumophila in Intubated Patients With TaqMan Real Time PCR

Abstract

Background:Legionellaceae contains Legionella genus with over 52 species and 64 serogroups. It is one of the most important causes of respiratory disease in human. More than 30% of hospital-acquired pneumonia is caused by Legionella. Ventilator-associated pneumonia (VAP) is an infection acquired in hospital wards, particularly in intensive care unit (ICU). This disease approximately affects 9% to 20% of intubated patients. Mortality in these patients varies between 8% and 76%. Legionella is one of the important factors for infection in intubated patients.Objectives:The present study was aimed to investigate the use of molecular methods in diagnosis of infection caused by Legionella pneumophila.Materials and Methods:In this study, 109 samples of lung secretions collected from intubated patients admitted to ICU wards of four university hospitals in a three-month period were examined. Cultivation and Real time Polymerase Chain Reaction (PCR) methods were used to assess L. pneumophila colonization in these samples.Results:Eleven samples had positive results using real time PCR analysis of 16s rRNA gene fragments specific for L. pneumophila, but according to culture method on specific buffered charcoal-yeast extract medium (BCYE), no positive cases were detected. Of the total positive cases, six were males, one female and four infants. The seven adults aged 40-65 years.Conclusions:Using molecular methods in diagnosis of infection caused by L. pneumophila has a great value because of its high specificity and rapid diagnosis potency.

Occurrence of the Legionella species in the respiratory samples of patients with pneumonia symptoms from Ahvaz, Iran; first detection of Legionella cherrii

“…In the current research, the most studied specimens (97.5 %) were BAL and pleural aspirates, while the sputum was the most (94 %) evaluated sample in the Moosavian et al research [14]. In another study by Khosroshahi et al [18] from Qazvin, Iran, no Legionella strain was identified in 109 lung secretions by culture on buffered charcoal-yeast extract (BCYE) agar that was in contrast to the current study. Also, in another study by Kottahachchi et al [19] from Sri Lanka, none of 75 sputum samples processed on BCYE medium showed Legionella species growth despite incubation for up to 7 days.…”

“…Although the culture method is still considered the golden standard technique for detecting Legionella spp., studies have shown that this method alone does not have the essential efficiency to detect Legionella species in clinical and environmental samples [18,20]. This method has a sensitivity of less than fifty percent for Legionella spp.…”

“…This method has a sensitivity of less than fifty percent for Legionella spp. detection [18]. In addition to being time consuming, the type of respiratory samples tested may also affect test results.…”

Comparison of in situ sequence type analysis of Legionella pneumophila in respiratory tract secretions and environmental samples of a hospital in East Jerusalem

“…According to the WHO Essential Medicines and Health Products report, there is irrational use of drugs in Palestinian National Authority (PNA) health institutions, and most patients use antibiotics prior to hospital admission [9, 10], making it difficult to isolate L. pneumophila strains from clinical specimens. On the other hand, molecular diagnostic techniques for L. pneumophila from respiratory samples, such as polymerase chain reaction (PCR), are well established and increasingly adopted worldwide [2, 11]. Endpoint and real-time PCR offer substantial advantages over cultivation for the detection and quantification of L. pneumophila , including high sensitivity, specificity and time efficiency [12–15].…”

Prevalence of Legionella among pneumonia patients and environmental water samples in an Egyptian University Hospital

“…It was not possible to compare between clinical manifestations of HA-Legionella patients versus HA non-Legionella cases due to difficulty in collecting data particularly in ICU settings [31]. Hospitalization for more than 10 days was a major risk factor for hospital acquired legionellosis (Table 3 & 4) [34]. Stroke or head trauma was also a significant risk factor, a finding that could be attributed to the impaired conscious level which is linked with higher frequency of aspiration.…”