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Clinical and Microbiological Characteristics of Mycobacterium kansasii Pulmonary Infections in China.

ABSTRACT: Mycobacterium kansasii, an important opportunistic pathogen of humans, causes serious pulmonary disease. Sixty M. kansasii isolates were collected for investigating the clinical characteristics of patients with M. kansasii infections as well as drug susceptibility and genotypes of M. kansasii. More than 90% of the patients infected with M. kansasii were from eastern China. According to the internal transcribed spacers (ITS), rpoB, hsp65, and tuf, all M. kansasii isolates were classified as molecular type I, irrespective of the disease manifestation. Sixty M. kansasii isolates from China were diverse and separated into four branches. Pairwise average nucleotide identity (ANI) values for M. kansasii isolates affiliated with different genotypes were more than 85%. The earliest isolate was isolated from Jiangsu in 1983. Of the isolates, 78.3% (47/60) were isolated since 1999. All isolates were sensitive to rifabutin. All but one isolate was sensitive to clarithromycin. Sensitivity rates to rifampin, amikacin, moxifloxacin, and linezolid were 80.0%, 90.0%, 88.3%, and 91.7%, respectively. A high rate of resistance was noted for ciprofloxacin (44 isolates, 73.3%) and ethambutol (46 isolates, 76.7%). Compared with M. tuberculosis H37Rv, 12 mutations of embCA were observed in all M. kansasii isolates. All these 60 M. kansasii isolates shared identical sequences of rpoB, inhA, katG, rrl, rrs, rpsL, gyrA, and gyrB. In conclusion, M. kansasii isolates are exhibiting greater genetic diversity globally. The resistance mechanism of M. kansasii is not necessarily related to gene mutation. IMPORTANCE M. kansasii type I is the main genotype spreading worldwide. The molecular history of the global spread of type I isolates remains largely unclear. We conducted a detailed analysis of genomic evolution of global M. kansasii isolates. Our results suggest that M. kansasii isolates exhibit greater genetic diversity globally.

SUBMITTER: Guo Y

PROVIDER: S-EPMC8754148 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundKlebsiella 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.MethodsClinical 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.ResultsA 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 β-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.ConclusionThis 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.

Project description:BackgroundKlebsiella pneumoniae (K. pneumoniae) is a common pathogen associated with hospital and community-onset infections. This study aimed to compare the clinical and microbiological characteristics of nosocomial, healthcare-associated (HCA), and community-acquired (CA) K. pneumoniae infections.MethodsClinical data were extracted from electronic medical records and analyzed retrospectively. Antimicrobial susceptibility and extended-spectrum beta-lactamase (ESBL) production were determined for all identified strains. Carbapenemase and ESBL genes were amplified by PCR. Genotyping of carbapenem-resistant K. pneumoniae (CRKP) and ESBL-producing strains was performed by pulsed-field gel electrophoresis (PFGE).ResultsOf 379 K. pneumoniae infections, 98 (25.9%) were nosocomial, 195 (51.5%) were healthcare-associated, and 86 (22.6%) were community-acquired. Hematological malignancy (OR = 4.467), and hypertension (OR = 2.08) and cerebral vascular disease (OR = 2.486) were associated with nosocomial and HCA infections respectively, when compared to CA infections. Overall, the incidence of antimicrobial resistance for the majority of agents tested was similar between nosocomial and HCA infections (P > 0.05) and both groups had a higher incidence than CA infections (P < 0.05). Moreover, 95.1% (78/82) of CRKP strains were isolated from the nosocomial and HCA groups. The blaKPC was the most prevalent carbapenemase gene among CRKP strains (80.5%, 66/82). ESBL-producing strains were prevalent among nosocomial (40.8%), HCA (35.9%) and CA groups (24.4%). The blaCTX-M-9-group and blaCTX-M-1-group genes were predominant in nosocomial (65.0%) and CA strains (66.7%), respectively. PFGE results showed ESBL-producing and CRKP strains were genetically diverse. Identical PFGE profiles were observed among HCA and nosocomial strains.ConclusionsNosocomial and HCA K. pneumoniae infections presented similar clinical features and antimicrobial resistance, and both two types of infections were different to CA infections. CRKP and ESBL-producing strains were disseminated mainly in HCA and nosocomial groups, and showed a clonal diversity. The cross transmission of CRKP was existed among HCA and nosocomial patients. This finding suggests that similar empirical therapy should be considered for patients with nosocomial and HCA K. pneumoniae infections and bacterial resistance surveillance of these infections is necessary.

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Clinical and Microbiological Characteristics of Mycobacterium kansasii Pulmonary Infections in China.

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