Background:

Severe bacterial community-onset pneumonia (COP) which comprises both community-acquired pneumonia (CAP) and healthcare-associated pneumonia (HCAP) is a major cause of morbidity and mortality in adults globally. Studies on the aetiology of severe adult bacterial COP are lacking in Malaysia

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Methods:

A retrospective study was conducted on all adult patients aged ≥ 18 years old with bacterial COP requiring admission to the intensive care unit (ICU) at University Malaya Medical Centre, Kuala Lumpur, Malaysia from January 2015 to December 2016. Only patients with microbiologically confirmed and monomicrobial bacterial COP were included. Patients were identified from the microbiology laboratory database and case notes.

 

The following data were collected using a standardised data collection form: demographic data, aetiological agents, and their antibiotic susceptibility patterns.

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Results:

 A total of 61 patients were identified, of whom the majority were males (n = 39; 63.9%). The mean age was 55 years (range, 40 to 64 years). The most common aetiological agent of severe adult bacterial COP in our cohort was Mycobacterium tuberculosis complex (MTBC) (n = 22; 36.1%), followed by Klebsiella pneumoniae (KP) (n = 14; 23.0%).

 

Gram-negative bacilli organisms as a group accounted for more than half of the cases (n = 31; 50.8%). Staphylococcus aureus (SA) which accounted for 8 of the cases (13.1%) was the only Gram-positive organism identified. All the MTBC isolates were sensitive to all the first-line antituberculous drugs tested including rifampicin and isoniazid, except for one isolate which showed mono-resistance to ethambutol.

 

Majority of the KP isolates were sensitive to the third- and fourth-generation cephalosporins (n = 10; 71.4%) and carbapenems (n = 12; 85.7%). Four out of the 14 KP isolates (28.6%) were due to an extended-spectrum beta-lactamase (ESBL)-producer. Of the 61 patients with severe bacterial COP, 48 (78.7%) were classified as having CAP, and the remaining 13 (21.3%) were classified as having HCAP. MTBC and KP accounted for the majority of the severe bacterial CAP (22/48; 45.8%) and severe bacterial HCAP cases (6/13; 46.2%) respectively. 

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Conclusion:

Mycobacterium tuberculosis complex and Klebsiella pneumoniae are important aetiological agents of severe adult bacterial COP.