Prevalence and epidemiologic features of nontuberculous mycobacteria causing persistent surgical site infections in Bangladesh

Abstract

Objectives: Nontuberculous mycobacteria (NTM) are an increasing cause of extrapulmonary infections affecting skin and soft tissue. This study aimed to determine the involvement of NTM in persistent surgical site infections (SSIs) in Bangladesh.

Methods: Specimens of SSIs (wound swab, pus, sinus discharge) were collected from patients who attended a tertiary care hospital during a 6-month period in 2024. NTM were detected by phenotypic methods (microscopic examination, culture, biochemical tests), immunochromatography, and polymerase chain reaction. Species of NTM were identified by sequence analysis of hps65 gene. Antimicrobial susceptibility was determined by broth microdilution test.

Results: Among a total of 155 samples collected, NTM were detected in 12 samples (7.7%), which were identified to be Mycobacterium abscessus (n = 5), Mycobacterium fortuitum (n = 4), Mycobacterium intracellulare, Mycobacterium engbaekii, and Mycobacterium kubicae (one specimen each). NTM were detected in patients aged 0-50 years who were showing variable durations of non-healing wound (3 to >14 weeks), more commonly after surgery of laparoscopic cholecystectomy and laparotomy. Resistance to amikacin, ciprofloxacin, and clarithromycin was noted for M. abscessus and M. fortuitum.

Conclusions: NTM represented by M. abscessus and M. fortuitum were revealed to be a significant cause of persistent SSIs of various patient groups in Bangladesh, associated with specific types of surgery.

Keywords: Bangladesh; M. abscessus; NTM; SSI; hsp65.

Figure 1

Phylogenetic dendrogram based on partial hsp65 (65kDa heat shock protein) gene sequences of NTM constructed by maximum likelihood method using MEGA6 program after alignment with ClustalW algorithm. Sequence data of representative NTM species were retrieved from GenBank database. The trees were statistically supported by bootstrapping with 1000 replicates, and phylogenetic distances were measured using the Kimura 2-parameter model, with uniform rates among sites. Samples analyzed in the present study are marked with closed circles. Closed square indicates M. tuberculosis. Bootstrap values more than 85% are shown. Scale bar represents the genetic distance, i.e. the number of substitutions per site.