Antimicrobial susceptibility and MIC distribution of 41 drugs against clinical isolates from China and reference strains of nontuberculous mycobacteria

ABSTRACT Due to the natural resistance of nontuberculous mycobacteria (NTM) against multiple antibiotics, treatment of infections caused by them is often long-course and less successful. The main objective of our study was the evaluation of in vitro susceptibility of 209 isolates consisting of different NTM species against bedaquiline and delamanid. Furthermore, reference strains of 33 rapidly growing mycobacterium (RGM) species and 19 slowly growing mycobacterium (SGM) species were also tested. Bedaquiline exhibited strong in vitro activity against both reference strains and clinical isolates of different SGM species, as the majority of the strains demonstrated MICs far below 1 μg/ml. Bedaquiline (Bdq) also exhibited potent activity against the recruited RGM species. A total of 29 out of 33 reference RGM strains had MICs lower than 1 μg/ml. According to the MIC distributions, the tentative epidemiological cutoff (ECOFF) values, and the pharmacokinetic data, a uniform breakpoint of 2 μg/ml was temporarily proposed for NTM’s Bdq susceptibility testing. Although delamanid (Dlm) was not active against most of the tested reference strains and clinical isolates of RGM species, it exhibited highly variable antimicrobial activities against the 19 tested SGM species. Eleven species had MICs lower than 0.25 μg/ml, and 7 species had MICs greater than 32 μg/ml. Large numbers of M. kansasii (39/45) and M. gordonae (6/10) clinical isolates had MICs of ≤0.125 μg/ml. This study demonstrated that bedaquiline had potent activity against different NTM species in vitro, and delamanid had moderate activity against certain species of SGM. The data provided important insights on the possible clinical application of Bdq and Dlm to treat NTM infections.

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In Vitro Activity of Clofazimine against Nontuberculous Mycobacteria Isolated in Beijing, China

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00072-18 ◽

2018 ◽

Vol 62 (7) ◽

Cited By ~ 9

Author(s):

Jingjing Luo ◽

Xia Yu ◽

Guanglu Jiang ◽

Yuhong Fu ◽

Fengmin Huo ◽

...

Keyword(s):

Nontuberculous Mycobacteria ◽

Clinical Isolates ◽

Natural Resistance ◽

Cross Resistance ◽

Mycobacterium Fortuitum ◽

Strong Activity ◽

Content Type ◽

Beijing China ◽

Reference Strains

ABSTRACT Due to the natural resistance of nontuberculous mycobacteria (NTM) to many antibiotics, the treatment of diseases caused by NTM is often long-term but unsuccessful. The main goal of this study was to evaluate the in vitro susceptibilities to clofazimine of 209 isolates consisting of different NTM species isolated in Beijing, China. Furthermore, 47 reference strains were also tested, including 30 rapidly growing mycobacterium (RGM) species and 17 slowly growing mycobacterium (SGM) species. The potential molecular mechanism contributing to clofazimine resistance of NTM was investigated as well. Clofazimine exhibited excellent activity against both reference strains and clinical isolates of different SGM species, and most of the strains had MICs far below 1 μg/ml. Although the majority of the clinical isolates of Mycobacterium abscessus and Mycobacterium fortuitum had MICs higher than 2 μg/ml, 17 out of the 30 reference strains of different RGM species had MICs below 1 μg/ml in vitro . According to the MIC distributions, the tentative epidemiological cutoff (ECOFF) values for Mycobacterium kansasii , Mycobacterium avium , and Mycobacterium intracellulare were defined at 0.5 μg/ml, 1 μg/ml, and 2 μg/ml, respectively. Intriguingly, single-direction cross-resistance between bedaquiline- and clofazimine (Cfz)-resistant isolates was observed among the tested NTM species. This study demonstrates that clofazimine had strong activity against most SGM species in vitro , as well as some RGM species. The data provide important insights into the possible clinical application of Cfz to treat NTM infections.

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Antimicrobial susceptibility, serotype distribution, virulence profile and molecular typing of piliated clinical isolates of pneumococci from east coast, Peninsular Malaysia

Scientific Reports ◽

10.1038/s41598-021-87428-z ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Nurul Diana Dzaraly ◽

Mohd Nasir Mohd Desa ◽

AbdulRahman Muthanna ◽

Siti Norbaya Masri ◽

Niazlin Mohd Taib ◽

...

Keyword(s):

Phylogenetic Analysis ◽

Antimicrobial Susceptibility ◽

East Coast ◽

Tertiary Hospital ◽

Multidrug Resistant ◽

Peninsular Malaysia ◽

Clinical Isolates ◽

Serotype Distribution ◽

Antimicrobial Susceptibility Test ◽

Conjugate Vaccines

AbstractPilus has been recently associated with pneumococcal pathogenesis in humans. The information regarding piliated isolates in Malaysia is scarce, especially in the less developed states on the east coast of Peninsular Malaysia. Therefore, we studied the characteristics of pneumococci, including the piliated isolates, in relation to antimicrobial susceptibility, serotypes, and genotypes at a major tertiary hospital on the east coast of Peninsular Malaysia. A total of 100 clinical isolates collected between September 2017 and December 2019 were subjected to serotyping, antimicrobial susceptibility test, and detection of pneumococcal virulence and pilus genes. Multilocus sequence typing (MLST) and phylogenetic analysis were performed only for piliated strains. The most frequent serotypes were 14 (17%), 6A/B (16%), 23F (12%), 19A (11%), and 19F (11%). The majority of isolates were resistant to erythromycin (42%), tetracycline (37%), and trimethoprim-sulfamethoxazole (24%). Piliated isolates occurred in a proportion of 19%; 47.3% of them were multidrug-resistant (MDR) and a majority had serotype 19F. This study showed ST236 was the most predominant sequence type (ST) among piliated isolates, which was related to PMEN clone Taiwan19F-14 (CC271). In the phylogenetic analysis, the piliated isolates were grouped into three major clades supported with 100% bootstrap values. Most piliated isolates belonged to internationally disseminated clones of S. pneumoniae, but pneumococcal conjugate vaccines (PCVs) have the potential to control them.

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Species identification and antimicrobial susceptibility testing of nontuberculous mycobacteria isolated in Chongqing, Southwest China

Epidemiology and Infection ◽

10.1017/s0950268820003088 ◽

2020 ◽

pp. 1-16

Author(s):

Huizheng Zhang ◽

Ming Luo ◽

Ke Zhang ◽

Xin Yang ◽

Kui Hu ◽

...

Keyword(s):

Species Identification ◽

Antimicrobial Susceptibility ◽

Southwest China ◽

Susceptibility Testing ◽

Nontuberculous Mycobacteria ◽

Antimicrobial Susceptibility Testing

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Antimicrobial Susceptibility Patterns among a Large, Nationwide Cohort of Abiotrophia and Granulicatella Clinical Isolates

Journal of Clinical Microbiology ◽

10.1128/jcm.02054-16 ◽

2017 ◽

Vol 55 (4) ◽

pp. 1025-1031 ◽

Cited By ~ 8

Author(s):

Kunatum Prasidthrathsint ◽

Mark A. Fisher

Keyword(s):

Antimicrobial Susceptibility ◽

Clinical Isolates ◽

Broth Microdilution ◽

Content Type ◽

Geographical Regions ◽

Susceptibility Patterns

ABSTRACTAntimicrobial susceptibility patterns from 599A. defectiva,G. adiacens, andG. elegansclinical isolates were determined by broth microdilution. We observed significant differences in susceptibility across species, particularly to penicillin and ceftriaxone, and across geographical regions.A. defectivawas the least susceptible species overall to penicillin. All isolates were susceptible to vancomycin and >90% were susceptible to levofloxacin.

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