scholarly journals A novel mechanism of streptomycin resistance in Yersinia pestis: Mutation in the rpsL gene

2021 ◽  
Vol 15 (4) ◽  
pp. e0009324
Author(s):  
Ruixia Dai ◽  
Jian He ◽  
Xi Zha ◽  
Yiting Wang ◽  
Xuefei Zhang ◽  
...  
Keyword(s):  
Ribosomal Protein ◽  
Public Health Problem ◽  
Streptomycin Resistance ◽  
Tibet Plateau ◽  
Tibet Autonomous Region ◽  
Ribosomal Protein S12 ◽  
High Level ◽  
Critical Public Health ◽  
Level Resistance

Streptomycin is considered to be one of the effective antibiotics for the treatment of plague. In order to investigate the streptomycin resistance of Y. pestis in China, we evaluated streptomycin susceptibility of 536 Y. pestis strains in China in vitro using the minimal inhibitory concentration (MIC) and screened streptomycin resistance-associated genes (strA and strB) by PCR method. A clinical Y. pestis isolate (S19960127) exhibited high-level resistance to streptomycin (the MIC was 4,096 mg/L). The strain (biovar antiqua) was isolated from a pneumonic plague outbreak in 1996 in Tibet Autonomous Region, China, belonging to the Marmota himalayana Qinghai–Tibet Plateau plague focus. In contrast to previously reported streptomycin resistance mediated by conjugative plasmids, the genome sequencing and allelic replacement experiments demonstrated that an rpsL gene (ribosomal protein S12) mutation with substitution of amino-acid 43 (K43R) was responsible for the high-level resistance to streptomycin in strain S19960127, which is consistent with the mutation reported in some streptomycin-resistant Mycobacterium tuberculosis strains. Streptomycin is used as the first-line treatment against plague in many countries. The emergence of streptomycin resistance in Y. pestis represents a critical public health problem. So streptomycin susceptibility monitoring of Y. pestis isolates should not only include plasmid-mediated resistance but also include the ribosomal protein S12 gene (rpsL) mutation, especially when treatment failure is suspected due to antibiotic resistance.

scholarly journals Mutations in fbiD (Rv2983) as a Novel Determinant of Resistance to Pretomanid and Delamanid in Mycobacterium tuberculosis

2020 ◽  
Vol 65 (1) ◽  
pp. e01948-20
Author(s):  
Dalin Rifat ◽  
Si-Yang Li ◽  
Thomas Ioerger ◽  
Keshav Shah ◽  
Jean-Philippe Lanoix ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Clinical Evidence ◽  
Clinical Samples ◽  
Loss Of Function ◽  
Wild Type ◽  
Content Type ◽  
Solid Media ◽  
High Level ◽  
Level Resistance

ABSTRACTThe nitroimidazole prodrugs delamanid and pretomanid comprise one of only two new antimicrobial classes approved to treat tuberculosis (TB) in 50 years. Prior in vitro studies suggest a relatively low barrier to nitroimidazole resistance in Mycobacterium tuberculosis, but clinical evidence is limited to date. We selected pretomanid-resistant M. tuberculosis mutants in two mouse models of TB using a range of pretomanid doses. The frequency of spontaneous resistance was approximately 10−5 CFU. Whole-genome sequencing of 161 resistant isolates from 47 mice revealed 99 unique mutations, of which 91% occurred in 1 of 5 genes previously associated with nitroimidazole activation and resistance, namely, fbiC (56%), fbiA (15%), ddn (12%), fgd (4%), and fbiB (4%). Nearly all mutations were unique to a single mouse and not previously identified. The remaining 9% of resistant mutants harbored mutations in Rv2983 (fbiD), a gene not previously associated with nitroimidazole resistance but recently shown to be a guanylyltransferase necessary for cofactor F420 synthesis. Most mutants exhibited high-level resistance to pretomanid and delamanid, although Rv2983 and fbiB mutants exhibited high-level pretomanid resistance but relatively small changes in delamanid susceptibility. Complementing an Rv2983 mutant with wild-type Rv2983 restored susceptibility to pretomanid and delamanid. By quantifying intracellular F420 and its precursor Fo in overexpressing and loss-of-function mutants, we provide further evidence that Rv2983 is necessary for F420 biosynthesis. Finally, Rv2983 mutants and other F420H2-deficient mutants displayed hypersusceptibility to some antibiotics and to concentrations of malachite green found in solid media used to isolate and propagate mycobacteria from clinical samples.

Experimental Prediction of the Evolution of Cefepime Resistance From the CMY-2 AmpC β-Lactamase

Genetics ◽  
2003 ◽  
Vol 164 (1) ◽  
pp. 23-29
Author(s):  
Miriam Barlow ◽  
Barry G Hall
Keyword(s):  
Good Predictor ◽  
Evolutionary Potential ◽  
Biochemical Activity ◽  
Class A ◽  
Naturally Occurring ◽  
Experimental Prediction ◽  
Lactam Antibiotic ◽  
High Level ◽  
Level Resistance

Abstract Understanding of the evolutionary histories of many genes has not yet allowed us to predict the evolutionary potential of those genes. Intuition suggests that current biochemical activity of gene products should be a good predictor of the potential to evolve related activities; however, we have little evidence to support that intuition. Here we use our in vitro evolution method to evaluate biochemical activity as a predictor of future evolutionary potential. Neither the class C Citrobacter freundii CMY-2 AmpC β-lactamase nor the class A TEM-1 β-lactamase confer resistance to the β-lactam antibiotic cefepime, nor do any of the naturally occurring alleles descended from them. However, the CMY-2 AmpC enzyme and some alleles descended from TEM-1 confer high-level resistance to the structurally similar ceftazidime. On the basis of the comparison of TEM-1 and CMY-2, we asked whether biochemical activity is a good predictor of the evolutionary potential of an enzyme. If it is, then CMY-2 should be more able than the TEMs to evolve the ability to confer higher levels of cefepime resistance. Although we generated CMY-2 evolvants that conferred increased cefepime resistance, we did not recover any CMY-2 evolvants that conferred resistance levels as high as the best cefepime-resistant TEM alleles.

Rapid Emergence of Daptomycin Resistance in Nonstriatum Corynebacterium Species: A Multicenter Study

2019 ◽  
Vol 152 (Supplement_1) ◽  
pp. S32-S33
Author(s):  
Kaitlin Mitchell ◽  
Erin McElvania ◽  
Meghan Wallace ◽  
Amy Robertson ◽  
Lars Westblade ◽  
...  
Keyword(s):  
Multicenter Study ◽  
Tertiary Care ◽  
Total N ◽  
Gradient Diffusion ◽  
Corynebacterium Species ◽  
Short Period ◽  
High Level ◽  
Level Resistance

Abstract Members of the genus Corynebacterium are increasingly recognized as causes of opportunistic infection; some species can be multidrug resistant, posing a treatment challenge. Daptomycin is frequently used as therapy of last resort in this setting, but previous work from our group demonstrated the ability of C striatum clinical isolates to rapidly develop high-level resistance to daptomycin, both in vivo and in vitro. Here, our objective was to expand this investigation into a multicenter study evaluating multiple Corynebacterium species. Corynebacterium strains from three tertiary-care academic medical centers (total, n = 76; site 1, n = 44; site 2, n = 15; site 3, n = 17) were evaluated, representing 16 species. Isolates were identified during routine clinical testing and reported to species level in accordance with each laboratory’s standard operating procedures. Identification of each species was confirmed using both VITEK MS and Bruker BioTyper MALDI-TOF MS. MICs to daptomycin (Etest), vancomycin (Etest), and telavancin (Liofilchem) at baseline were determined using gradient diffusion methods on Mueller-Hinton agar with blood (Hardy Diagnostics). Each isolate was then inoculated in duplicate to 5 mL Tryptic Soy Broth. A daptomycin Etest was submerged in one tube from each pair, and growth was observed after 24-hour incubation. If turbidity was observed in the tube with daptomycin, MICs for each of the 3 antimicrobials were reassessed. High-level daptomycin resistance emerged in 24 strains: C aurimucosum (1/1 isolate tested), C bovis (1/2), C jeikeium (2/11), C macginleyi (3/3), C resistens (1/1), C simulans (1/1), C striatum (14/14 isolates), and C ulcerans (1/1). The majority of these isolates had MIC values >256 µg/mL following exposure to daptomycin. Forty-eight other isolates remained susceptible to daptomycin: C afermentans (1/1), C amycolatum (19/20), C diphtheriae (1/1), C jeikeium (7/11), C kroppenstedtii (2/2), C propinquum (3/3), C pseudodiphtheriticum (6/6), C tuberculostearicum (0/6), and C urealyticum (0/3). Many of these isolates did not undergo MIC testing postdaptomycin exposure in broth due to complete lack of growth. Among those that did (n = 19), the median daptomycin MIC was 0.38 µg/mL (mean 0.42 µg/mL; range 0.023-1.0 µg/mL). One isolate of C bovis and two isolates of C jeikeium yielded variable susceptibility to daptomycin; a subset of resistant colonies grew adjacent to the gradient diffusion strip. Upon isolation and further MIC testing, these colonies maintained high-level resistance. In addition, one isolate of C amycolatum exhibited high-level daptomycin resistance (MIC >256 µg/mL) prior to in vitro exposure. All isolates in the cohort were susceptible to vancomycin and telavancin, both before and after daptomycin exposure. Our findings suggest that multiple Corynebacterium species can rapidly develop high-level daptomycin resistance after a short period of exposure to this antimicrobial. This finding has important clinical implications, especially in the treatment of invasive infections or infections of indwelling medical devices.

scholarly journals Antimicrobial Resistance of DiarrheagenicEscherichia coli Isolated from Children under the Age of 5 Years from Ifakara, Tanzania

1999 ◽  
Vol 43 (12) ◽  
pp. 3022-3024 ◽  
Author(s):  
Jordi Vila ◽  
Martha Vargas ◽  
Climent Casals ◽  
Honorato Urassa ◽  
Hassan Mshinda ◽  
...  
Keyword(s):  
Developing Countries ◽  
Public Health Problem ◽  
Multidrug Resistant ◽  
Resistant Bacteria ◽  
Important Public Health Problem ◽  
Important Public Health ◽  
E Coli ◽  
High Level ◽  
Level Resistance ◽  
Children Under 5

ABSTRACT Diarrhea caused by multidrug-resistant bacteria is an important public health problem among children in developing countries. The prevalence and antimicrobial susceptibility of diarrheagenicEscherichia coli in 346 children under 5 years of age in Ifakara, Tanzania, were studied. Thirty-eight percent of the cases of diarrhea were due to multiresistant enterotoxigenic E. coli, enteroaggregative E. coli, or enteropathogenicE. coli. Strains of all three E. colicategories showed high-level resistance to ampicillin, tetracycline, co-trimoxazole, and chloramphenicol but were highly susceptible to quinolones. Guidelines for appropriate use of antibiotics in developing countries need updating.

scholarly journals Efficacy of Ampicillin plus Ceftriaxone in Treatment of Experimental Endocarditis Due to Enterococcus faecalis Strains Highly Resistant to Aminoglycosides

1999 ◽  
Vol 43 (3) ◽  
pp. 639-646 ◽  
Author(s):  
Joan Gavaldà ◽  
Carmen Torres ◽  
Carmen Tenorio ◽  
Pedro López ◽  
Myriam Zaragoza ◽  
...  
Keyword(s):  
Aortic Valve ◽  
Enterococcus Faecalis ◽  
Pharmacokinetic Parameters ◽  
Initial Inoculum ◽  
High Level ◽  
Time Kill ◽  
Disk Method ◽  
Level Resistance

The purpose of this work was to evaluate the in vitro possibilities of ampicillin-ceftriaxone combinations for 10 Enterococcus faecalis strains with high-level resistance to aminoglycosides (HLRAg) and to assess the efficacy of ampicillin plus ceftriaxone, both administered with humanlike pharmacokinetics, for the treatment of experimental endocarditis due to HLRAg E. faecalis. A reduction of 1 to 4 dilutions in MICs of ampicillin was obtained when ampicillin was combined with a fixed subinhibitory ceftriaxone concentration of 4 μg/ml. This potentiating effect was also observed by the double disk method with all 10 strains. Time-kill studies performed with 1 and 2 μg of ampicillin alone per ml or in combination with 5, 10, 20, 40, and 60 μg of ceftriaxone per ml showed a ≥2 log10 reduction in CFU per milliliter with respect to ampicillin alone and to the initial inoculum for all 10E. faecalis strains studied. This effect was obtained for seven strains with the combination of 2 μg of ampicillin per ml plus 10 μg of ceftriaxone per ml and for six strains with 5 μg of ceftriaxone per ml. Animals with catheter-induced endocarditis were infected intravenously with 108 CFU of E. faecalis V48 or 105 CFU of E. faecalisV45 and were treated for 3 days with humanlike pharmacokinetics of 2 g of ampicillin every 4 h, alone or combined with 2 g of ceftriaxone every 12 h. The levels in serum and the pharmacokinetic parameters of the humanlike pharmacokinetics of ampicillin or ceftriaxone in rabbits were similar to those found in humans treated with 2 g of ampicillin or ceftriaxone intravenously. Results of the therapy for experimental endocarditis caused by E. faecalis V48 or V45 showed that the residual bacterial titers in aortic valve vegetations were significantly lower in the animals treated with the combinations of ampicillin plus ceftriaxone than in those treated with ampicillin alone (P < 0.001). The combination of ampicillin and ceftriaxone showed in vitro and in vivo synergism against HLRAgE. faecalis.

scholarly journals In Vitro Study of Stepwise Acquisition of rv0678 and atpE Mutations Conferring Bedaquiline Resistance

2019 ◽  
Vol 63 (8) ◽  
Author(s):  
Nabila Ismail ◽  
Nazir A. Ismail ◽  
Shaheed V. Omar ◽  
Remco P. H. Peters
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Solid Medium ◽  
In Vitro Study ◽  
Whole Genome ◽  
Content Type ◽  
Phenotypic Resistance ◽  
Atcc Strain ◽  
High Level ◽  
Level Resistance

ABSTRACT Bedaquiline resistance within Mycobacterium tuberculosis may arise through efflux-based (rv0678) or target-based (atpE) pathway mutations. M. tuberculosis mutant populations from each of five sequential steps in a passaging approach, using a pyrazinamide-resistant ATCC strain, were subjected to MIC determinations and whole-genome sequencing. Exposure to increasing bedaquiline concentrations resulted in increasing phenotypic resistance (up to >2 μg/ml) through MIC determination on solid medium (Middlebrook 7H10). rv0678 mutations were dynamic, while atpE mutations were fixed, once occurring. We present the following hypothesis for in vitro emergence of bedaquiline resistance: rv0678 mutations may be the first transient step in low-level resistance acquisition, followed by high-level resistance due to fixed atpE mutations.

scholarly journals Severity of the Streptomycin Resistance and Streptomycin Dependence Phenotypes of Ribosomal Protein S12 of Thermus thermophilus Depends on the Identity of Highly Conserved Amino Acid Residues

2005 ◽  
Vol 187 (10) ◽  
pp. 3548-3550 ◽  
Author(s):  
Jennifer F. Carr ◽  
Steven T. Gregory ◽  
Albert E. Dahlberg
Keyword(s):  
Ribosomal Protein ◽  
Thermus Thermophilus ◽  
Gene Replacement ◽  
Streptomycin Resistance ◽  
Site Directed Mutagenesis ◽  
Structural Basis ◽  
Side Chain ◽  
Amino Acid Residues ◽  
Drug Dependent ◽  
Ribosomal Protein S12

ABSTRACT The structural basis for the streptomycin dependence phenotype of ribosomal protein S12 mutants is poorly understood. Here we describe the application of site-directed mutagenesis and gene replacement of Thermus thermophilus rpsL to assess the importance of side chain identity and tertiary interactions as phenotypic determinants of drug-dependent mutants.

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