Work

Detection of L. pneumophila non-serogroup 1 in hospital-acquired pneumonia: A cross-sectional study from Eastern India

Year: 2026

Type: article

Abstract: BACKGROUND AND OBJECTIVE: Legionella pneumophila (Lp) has been recognized as an important cause of Hospital Acquired Pneumonia (HAP). However, the frequency distribution of Lp as etiological agents of HAP is less studied in India. The aim of this study was to determine the frequency of Lp in cases of HAP by using a combination of culture, urinary Lp sg1 antigen testing, and Lp-specific 16S RNA gene PCR. METHODS: Admitted patients fulfilling the clinical and radiological criteria of HAP were enrolled in the study between February 2023 and June 2024. Respiratory specimens of patients were subjected to culture in BCYE agar and the Lp-specific PCR, and urine Lp sg1 antigen testing. RESULTS: Of the 195 suspected HAP patients enrolled, 160 (82.05%) were microbiologically confirmed as HAP. All respiratory specimens tested negative for Lp by culture and urine antigen tests. However, 20 of the 160 microbiologically confirmed HAP cases were positive for Lp by 16S rRNA gene PCR. New-onset pulmonary infiltrates were significantly associated with Lp HAP compared to non-Legionella HAP cases (50% vs. 5%, p < 0.001). Lp-positive HAP cases had higher total protein (6.13 vs. 5.56 g/dL, p = 0.043) and globulin (3.24 vs. 2.84 g/dL, P = 0.037), and lower serum phosphate levels (2.94 vs. 4.58 mg/dL, p < 0.001) compared to negative cases. In the present study, Lp was a co-pathogen in fifteen HAP cases (Eight cases with Klebsiella pneumoniae, six with Pseudomonas aeruginosa, and one with Burkholderia cepacia complex). CONCLUSION: This study highlights the significant role of Lp non serogroup 1 as a pathogen in 12.5% of microbiologically confirmed HAP cases, using PCR, which were negative by culture and commercially available urinary antigen testing targeting Lp serogroup 1. The findings emphasize incorporating Lp molecular tests along with Ag testing in the diagnostic algorithm of HAP cases.

Source: Lung India

DOI: 10.4103/lungindia.lungindia_346_25

Authors: M. L. Sivalekshmi, Bijayini Behera, Krishna M. Gulla, Shakti Kumar Bal, Ashoka Mahapatra

Institution: All India Institute of Medical Sciences Bhubaneswar

Language: English

Topic: Legionella and Acanthamoeba research

Subfield: Endocrinology

Field: Biochemistry, Genetics and Molecular Biology

Domain: Life Sciences

SDG: Good health and well-being

Open Access status: diamond

Funder: Indian Council of Medical Research