Diagnostic Utility of Real Time Multiplex PCR for Identification of Atypical Bacterial Respiratory Pathogens

Abstract

Introduction: Infections are common in cirrhosis and is the leading cause of progression of liver failure and increased mortality. Non-specific findings on radiology prompt a need for a diagnostic armamentarium targeting both typical as well as atypical pathogens. With the advent of molecular diagnostic techniques, an early diagnosis and timely initiation of therapy prevents the injudicious use of antibiotics. Aim: To determine the utility of real time multiplex Polymerase Chain Reaction (PCR) as a diagnostic aid in identification of atypical bacterial respiratory pathogens in cirrhotic patients. Materials and Methods: The observational study was conducted at Tertiary Hepatobiliary Centre, Institute of Liver and Biliary Sciences Hospital, New Delhi, India, from April to September 2018. Bronchoalveolar Lavage (BAL)/mini-BAL samples were collected from 88 suspected cases of pneumonia for routine laboratory work-up as per clinician request. The lower respiratory tract samples were subjected to semi-quantitative culture and PCR. Results were analysed on the basis of aetiological categorisation of liver diseases, radiological and microbiological findings. Results: Among 88 samples, nine were positive either by culture or PCR. PCR analysis revealed three positive samples. A sample positive for Legionella species on PCR showed growth of A. flavus in culture. Another sample was positive for both Legionella species and S. aureus on PCR. The third sample was positive for S. aureus on PCR and on culture grew Methicillin Sensitive S. aureus (MSSA). Conclusion: Liver disease is a risk factor for development of Legionella and other atypical pathogens. Therefore, it becomes important to actively look for such pathogens during the workup of a patient with clinical suspicion of pneumonia. Thus, early diagnosis help in limiting the use of indiscriminate antimicrobials, and timely initiation of targeted antimicrobials. Use of molecular techniques like PCR help in identifying the atypical pathogens which are neglected and thus determines the course of treatment.

Keywords

• antibiotic management
• cirrhosis
• legionella
• pneumonia