Clinical and Microbiological Characteristics of Klebsiella pneumoniae Co-Infections in Pulmonary Tuberculosis: A Retrospective Study

Background: Klebsiella pneumoniae (K. pneumoniae) is one of the most common pathogens leading to pulmonary tuberculosis (PTB) co-infection, but the data of co-infections is scarce. This research aimed to study the clinical and microbiological characteristics of K. pneumoniae co-infections in pulmonary tuberculosis cases.Methods: Clinical manifestations and examination results of PTB cases co-infected by K. pneumoniae were retrospectively collected from the medical record database of a tertiary teaching hospital in China between November 2019 and October 2021. The K. pneumoniae strains isolated from the patients were sent for whole-genome sequencing. Statistical analyses were conducted using Stata v.14.0.Results: A total of 80 strains were collected from 76 PTB patients with K. pneumoniae co-infections (two strains were isolated from each of the four patients at different time points), including 37 primary and 39 retreated TB cases. Among these, 29 (36.3%) of the K. pneumoniae isolates were extended-spectrum beta-lactamase (ESBL)-producing strains, and seven (8.8%) were determined as carbapenem-resistant Enterobacteriaceae (CRE) strains. We found that patients in the multidrug resistance (MDR)-group received more respiratory support than the non-MDR group (40.6% vs 18.2%, P= 0.031) and possessed higher elevated C-reactive protein (62.6% vs 41.8%, P=0.008) and lower haemoglobin (87.5% vs 47.7%, P=0.001). We found that 80.3% (61/76) patients had lung lesions and 57.8% (44/76) patients were immunocompromised within one month. The most common K. pneumoniae strain sequence type was ST23 (15%), followed by ST15 (12.5%) and ST273 (7.5%). Among the strains, 26.25% were classically hypervirulent K1/K2 K. pneumoniae, and all carried salmochelin and rmpA.Conclusion: This study demonstrated the important clinical features, phenotypic and genomic characteristics of isolated strains of PTB patients with K. pneumoniae co-infection. These data suggested a special attention for multidrug resistant K. pneumoniae infections with more obvious inflammatory responses which calls for more respiratory support and timely clinical management.