Distribution and drug resistance of pathogenic bacteriacausing lower respiratory tract infection in patients withnon-tuberculosis Mycobacterium pulmonary disease

OBJECTIVE To retrospectively analyze the distribution and drug resistance of non-tuberculosis Mycobacteria（NTM）isolated from the patients with NTM pulmonary disease in Tianjin so as to provide guidance for treatment of the NTM pulmonary disease and its complication with other species of pathogens infections.METHODS A total of 62 patients who were diagnosed with NTM in the department of tuberculosis from May 2014 to Nov 2015 were enrolled in the study,then the lower respiratory tract specimens were collected for culture of NTM,the strains were identified,the drug resistance to antituberculosis drugs was determined,the common bacteriological culture was conducted for the specimens,and the bacterial identification and drug susceptibility testing were performed by using VITEK-2Compact automatic microorganism identification system.RESULTS Totally 7species of NTM were identified,and the Mycobacterium intracellulare and Mycobacterium chelonei-abscessus accounted for 38.7%and 32.3%,respectively.The NTM strains were highly resistant to most of the antituberculosis drugs,especially to streptomycin,isoniazid,aminosalicylic acid,etc;however,the different species of NTM varied in the drug resistance.A total of 36 strains of pathogens were isolated from the lower respiratory tract specimens obtained from the patients with NTM pulmonary disease,including 21（58.3%）strains of the gram-negative bacilli,the gram-positive cocci（only 2strains of Staphylococcus aureus）,and 13（36.1%）strains of fungi.The drug resistance rates of the gram-negative bacteria to amikacin,cefoperazone-sulbactam,and ciprofloxacin were less than 5.7%;the two strains of S.aureus were susceptible to the 16 kinds of commonly used antibiotics;the 13 strains of fungi were susceptible to amphotericin B,itraconazole,and 5-fluorocytosine.CONCLUSION The NTM strains are highly resistant to the conventional antituberculosis drugs,and it is necessary to reasonably use antibiotics and develop new antituberculosis drugs based on the results of drug susceptibility testing.The gramnegative bacteria are dominant among the pathogens causing the lower respiratory tract infection in the patients with NTM pulmonary disease,the gram-positive bacteria are rarely isolated,and it is necessary to reasonably use antibiotics based on the results of drug susceptibility testing.