From Rare to Rising: A Story of Enterobacter-associated Pneumonia Evolving in the Community

Pneumonia is a common cause of mortality and morbidity worldwide and is the fifth leading cause of death. It is generally caused by Streptococcus pneumoniae, Klebsiella pneumoniae, Haemophilus influenzae, and some atypical microorganisms. Interestingly, a member of ESKAPE pathogens, mainly Enterobacter cloacae complex, is increasingly showing its presence in the samples of lower respiratory tract specimens. Emergence of multidrug resistance (MDR) in these bacteria, including resistance to last-resort carbapenems, has led to an increased interest in this organism causing pneumonia.

(1) Prevalence of E. cloacae complex among community-acquired pneumonia (CAP) patients and (2) antibiotic resistance pattern of these pathogens.

Respiratory samples from adult patients were processed according to standard microbiological techniques, including direct smear examination, incubation in blood, MacConkey and chocolate agar plates, and Gram staining. Identification of E. cloacae complex and antibiotic susceptibility testing, along with resistance patterns, was performed by automated ID/AST instrument.

About 15.7% of E. cloacae complex-associated CAP patients were found over a 1-year study period. Antimicrobial susceptibility tests indicated a MDR profile in 58.3% of isolates. Resistance was mostly to carbapenems (72.73%), followed by aztreonam (69.7%), piperacillin-tazobactam (68%), and fluoroquinolones (63.6%).

E. cloacae complex is an emerging and clinically significant pathogen causing CAP. Its MDR profile contributes to an increased tendency to intensive care unit admission and the development of sepsis. Hence, detecting this pathogen in lower respiratory tract specimens should be treated as a high alert and should prompt treatment at the earliest.