Surgical site infections by atypical mycobacteria: prevalence and species characterization using MALDI-TOF and molecular LCD chip array

Background Surgical site infection (SSI) is a post-operative complication of high concern with adverse impact on patient prognosis and public health systems. Recently, SSI pathogens have experienced a change in microbial profile with increasing reports of non-tuberculous mycobacteria (NTM) as important pathogens. Aim of the study The study aimed to detect the prevalence of NTM among cases with SSIs and describe their species using matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) and PCR-based microarray. Methods The study was conducted with 192 pus samples collected from patients with SSI. Mycobacterial investigations were done in the form of Ziehl–Neelsen (ZN) smears for acid-fast bacilli, automated mycobacterial culture to isolate mycobacteria, followed by immunochromatography test to predict NTM. NTM-positive cultures were tested by MALDI -TOF MS and PCR-based microarray to reach species-level identification. Results Mycobacterial growth was found in 11/192 samples (5.7%) and identified as 4 NTM and 7 M . tuberculosis isolates with prevalence of 2.1% and 3.64%, respectively. The NTM species were described by MALDI-TOF as M. abscessus, M. porcinum, M. bacteremicum, and M. gordonae. Microarray agreed with MALDI-TOF in identifying one isolate (M. abscessus), while two isolates were classified as belonging to broad groups and one isolate failed to be identified. Conclusions The prevalence of NTM among SSI was found to be low, yet have to be considered in the diagnosis of mycobacteria. Employing advanced technologies in diagnosis is recommended to guide for appropriate treatment.