Moghaddam Sina, Nojoomi Farshad, Dabbagh Moghaddam Arasb, Mohammadimehr Mojgan, Sakhaee Fatemeh, Masoumi Morteza, Siadat Seyed Davar, Fateh Abolfazl
Department of Microbiology, School of Medicine, Aja University of Medical Sciences, Tehran, Iran.
Infectious Diseases Research Center, Aja University of Medical Sciences, Tehran, Iran.
BMC Microbiol. 2022 Oct 29;22(1):261. doi: 10.1186/s12866-022-02674-z.
Nontuberculous mycobacteria (NTM) are ubiquitous bacteria that are naturally resistant to disinfectants and antibiotics and can colonize systems for supplying drinking water. Therefore, this study aimed to evaluate the prevalence of NTM in the drinking water of six hospitals in Tehran, Iran.
Totally, 198 water samples were collected. Each water sample was filtered via a membrane filter with a pore size of 0.45 µm and then decontaminated by 0.005% cetylpyridinium chloride. The membrane filters were incubated on two Lowenstein-Jensen media at 25 °C and 37 °C for 8 weeks. The positive cultures were identified with phenotypic tests, and then NTM species were detected according to the hsp65, rpoB, and 16S rDNA genes. Drug susceptibility testing (DST) was also carried out.
Overall, 76 (40.4%) of the isolates were slowly growing mycobacteria (SGM) and 112 (59.6%) of the ones were rapidly growing mycobacteria (RGM). The most common NTM were Mycobacterium aurum, M. gordonae, M. phocaicum, M. mucogenicum, M. kansasii, M. simiae, M. gadium, M. lentiflavum, M. fortuitum, and M. porcinum. Among these 188 samples, NTM ranged from 1 to > 300 colony-forming unit (CFU) /500 mL, with a median of 182 CFU/500 mL. In the infectious department of all hospitals, the amount of CFU was higher than in other parts of the hospitals. The DST findings in this study indicated the diversity of resistance to different drugs. Among RGM, M. mucogenicum was the most susceptible isolate; however, M. fortuitum showed a different resistance pattern. Also, among SGM isolates, M. kansasii and M. simiae, the diversity of DST indicated.
The current study showed NTM strains could be an important component of hospital water supplies and a possible source of nosocomial infections according to the CFU reported in this study. The obtained findings also help clarify the dynamics of NTM variety and distribution in the water systems of hospitals in the research area.
非结核分枝杆菌（NTM）是普遍存在的细菌，天然对消毒剂和抗生素具有抗性，并且可在饮用水供应系统中定殖。因此，本研究旨在评估伊朗德黑兰六家医院饮用水中NTM的流行情况。
共收集198份水样。每个水样通过孔径为0.45 µm的膜过滤器过滤，然后用0.005%的十六烷基吡啶氯化物进行净化处理。将膜过滤器在两种罗-琴培养基上于25℃和37℃培养8周。通过表型试验鉴定阳性培养物，然后根据hsp65、rpoB和16S rDNA基因检测NTM菌种。还进行了药敏试验（DST）。
总体而言，76株（40.4%）分离株为缓慢生长分枝杆菌（SGM），112株（59.6%）为快速生长分枝杆菌（RGM）。最常见的NTM是金色分枝杆菌、戈登分枝杆菌、海豹分枝杆菌、产黏液分枝杆菌、堪萨斯分枝杆菌、猿分枝杆菌、加地分枝杆菌、淡黄分枝杆菌、偶然分枝杆菌和猪分枝杆菌。在这188份样本中，NTM的数量范围为1至>300菌落形成单位（CFU）/500 mL，中位数为182 CFU/500 mL。在所有医院的感染科，CFU数量高于医院的其他部门。本研究的DST结果表明对不同药物的耐药性存在差异。在RGM中，产黏液分枝杆菌是最敏感的分离株；然而，偶然分枝杆菌表现出不同的耐药模式。此外，在SGM分离株中，堪萨斯分枝杆菌和猿分枝杆菌的DST也显示出差异。
根据本研究报告的CFU，当前研究表明NTM菌株可能是医院供水的重要组成部分以及医院感染的可能来源。所获得的研究结果也有助于阐明研究区域内医院水系统中NTM种类和分布的动态情况。
