scholarly journals Evaluation ofShigellaSpecies Azithromycin CLSI Epidemiological Cutoff Values and Macrolide Resistance Genes

2019 ◽  
Vol 57 (4) ◽  
Author(s):  
Muna Salah ◽  
Issa Shtayeh ◽  
Raed Ghneim ◽  
Randa Al-Qass ◽  
Ali Sabateen ◽  
...  
Keyword(s):  
Resistance Genes ◽  
Diffusion Zone ◽  
Shigella Flexneri ◽  
Macrolide Resistance ◽  
Disk Diffusion ◽  
Content Type ◽  
Zone Diameter ◽  
Cutoff Values ◽  
Macrolide Resistance Gene ◽  
Content Support

ABSTRACTAzithromycin (AZM) has been recommended by the American Academy of Pediatrics for the treatment of shigellosis in children. In this study, 502Shigellaspecies isolated between 2004 and 2014 were tested for AZM epidemiological cutoff values (ECV) by disk diffusion. AZM MICs and the presence of the macrolide resistance genes [erm(A),erm(B),erm(C),ere(A),ere(B),mph(A),mph(B),mph(D),mef(A), andmsr(A)] were determined for all 56 (11.1%) isolates with an AZM disk diffusion zone diameter of ≤15 mm. The distribution of AZM ECV MICs was also determined for 186Shigellaisolates with a disk zone diameter of ≥16 mm. Finally, pulsed-field gel electrophoresis (PFGE) was performed on 15Shigella flexneriisolates with an AZM disk zone diameter of <16 mm from different years and geographic locations. Serotyping the 502Shigellaspecies isolates revealed that 373 (74%) wereS. sonnei, 119 (24%) wereS. flexneri,and 10 (2%) wereS. boydii. Of the 119Shigella flexneriisolates, 48 (42%) isolates had an AZM disk diffusion zone diameter of ≤15 mm and a MIC of ≥16 µg/ml. With the exception of one isolate, all were positive for the macrolide resistance genemph(A).S. flexneriPFGE showed four distinct patterns, with patterns I and II presenting with 92.3% genetic similarity. On the other hand, 2 (0.5%) of the 373S. sonneiisolates had the AZM non-wild-type (NWT) ECV phenotype (those with acquired or mutational resistance), as the AZM MICs were ≥32 µg/ml and the isolates were positive for themph(A) gene. Overall, ourS. flexneriresults are in concordance with the CLSI AZM ECV, but isolates with an AZM disk diffusion zone diameter between 14 and 15 mm should be carefully evaluated, as theS. flexneriAZM MIC for NWT isolates may need adjustment to 32 µg/ml. Our data onS. sonneisupport that the AZM NWT ECV should be 11 mm for the disk diffusion zone diameter and ≥32 µg/ml for the MICs.

scholarly journals Antimicrobial Susceptibility Testing and Tentative Epidemiological Cutoff Values for FiveBacillusSpecies Relevant for Use as Animal Feed Additives or for Plant Protection

2018 ◽  
Vol 84 (19) ◽  
Author(s):  
Yvonne Agersø ◽  
Birgitte Stuer-Lauridsen ◽  
Karin Bjerre ◽  
Michelle Geervliet Jensen ◽  
Eric Johansen ◽  
...  
Keyword(s):  
Antimicrobial Resistance ◽  
Resistance Genes ◽  
Pathogenic Bacteria ◽  
Animal Feed ◽  
Bacterial Species ◽  
Feed Additives ◽  
Content Type ◽  
Cutoff Values ◽  
Antimicrobial Resistance Genes ◽  
Species Specific

ABSTRACTBacillus megaterium(n= 29),Bacillus velezensis(n= 26),Bacillus amyloliquefaciens(n= 6),Bacillus paralicheniformis(n= 28), andBacillus licheniformis(n= 35) strains from different sources, origins, and time periods were tested for the MICs for nine antimicrobial agents by the CLSI-recommended method (Mueller-Hinton broth, 35°C, for 18 to 20 h), as well as with a modified CLSI method (Iso-Sensitest [IST] broth, 37°C [35°C forB. megaterium], 24 h). This allows a proposal of species-specific epidemiological cutoff values (ECOFFs) for the interpretation of antimicrobial resistance in these species. MICs determined by the modified CLSI method were 2- to 16-fold higher than with the CLSI-recommended method for several antimicrobials. The MIC distributions differed between species for five of the nine antimicrobials. Consequently, use of the modified CLSI method and interpretation of resistance by use of species-specific ECOFFs is recommended. The genome sequences of all strains were determined and used for screening for resistance genes against the ResFinder database and for multilocus sequence typing. A putative chloramphenicol acetyltransferase (cat) gene was found in oneB. megateriumstrain with an elevated chloramphenicol MIC compared to the otherB. megateriumstrains. InB. velezensisandB. amyloliquefaciens, a putative tetracycline efflux gene,tet(L), was found in all strains (n= 27) with reduced tetracycline susceptibility but was absent in susceptible strains. AllB. paralicheniformisand 23% ofB. licheniformisstrains had elevated MICs for erythromycin and harboredermD. The presence of these resistance genes follows taxonomy suggesting they may be intrinsic rather than horizontally acquired. Reduced susceptibility to chloramphenicol, streptomycin, and clindamycin could not be explained in all species.IMPORTANCEWhen commercializing bacterial strains, likeBacillusspp., for feed applications or plant bioprotection, it is required that the strains are free of acquired antimicrobial resistance genes that could potentially spread to pathogenic bacteria, thereby adding to the pool of resistance genes that may cause treatment failures in humans or animals. Conversely, if antimicrobial resistance is intrinsic to a bacterial species, the risk of spreading horizontally to other bacteria is considered very low. Reliable susceptibility test methods and interpretation criteria at the species level are needed to accurately assess antimicrobial resistance levels. In the present study, tentative ECOFFs for fiveBacillusspecies were determined, and the results showed that the variation in MICs followed the respective species. Moreover, putative resistance genes, which were detected by whole-genome sequencing and suggested to be intrinsic rather that acquired, could explain the resistance phenotypes in most cases.

scholarly journals Impact of Long-Term Erythromycin Therapy on the Oropharyngeal Microbiome and Resistance Gene Reservoir in Non-Cystic Fibrosis Bronchiectasis

mSphere ◽  
2018 ◽  
Vol 3 (2) ◽  
pp. e00103-18 ◽  
Author(s):  
Jocelyn M. Choo ◽  
Guy C. J. Abell ◽  
Rachel Thomson ◽  
Lucy Morgan ◽  
Grant Waterer ◽  
...  
Keyword(s):  
Resistance Gene ◽  
Quantitative Pcr ◽  
Resistance Genes ◽  
Low Dose ◽  
Controlled Trial ◽  
Macrolide Resistance ◽  
Microbiota Composition ◽  
Content Type ◽  
Commensal Microbiota

ABSTRACT Long-term macrolide therapy reduces rates of pulmonary exacerbation in bronchiectasis. However, little is known about the potential for macrolide therapy to alter the composition and function of the oropharyngeal commensal microbiota or to increase the carriage of transmissible antimicrobial resistance. We assessed the effect of long-term erythromycin on oropharyngeal microbiota composition and the carriage of transmissible macrolide resistance genes in 84 adults with bronchiectasis, enrolled in the Bronchiectasis and Low-dose Erythromycin Study (BLESS) 48-week placebo-controlled trial of twice-daily erythromycin ethylsuccinate (400 mg). Oropharyngeal microbiota composition and macrolide resistance gene carriage were determined by 16S rRNA gene amplicon sequencing and quantitative PCR, respectively. Long-term erythromycin treatment was associated with a significant increase in the relative abundance of oropharyngeal Haemophilus parainfluenzae (P = 0.041) and with significant decreases in the relative abundances of Streptococcus pseudopneumoniae (P = 0.024) and Actinomyces odontolyticus (P = 0.027). Validation of the sequencing results by quantitative PCR confirmed a significant decrease in the abundance of Actinomyces spp. (P = 0.046). Erythromycin treatment did not result in a significant increase in the number of subjects who carried erm(A), erm(B), erm(C), erm(F), mef(A/E), and msrA macrolide resistance genes. However, the abundance of erm(B) and mef(A/E) gene copies within carriers who had received erythromycin increased significantly (P < 0.05). Our findings indicate that changes in oropharyngeal microbiota composition resulting from long-term erythromycin treatment are modest and are limited to a discrete group of taxa. Associated increases in levels of transmissible antibiotic resistance genes within the oropharyngeal microbiota highlight the potential for this microbial system to act as a reservoir for resistance. IMPORTANCE Recent demonstrations that long-term macrolide therapy can prevent exacerbations in chronic airways diseases have led to a dramatic increase in their use. However, little is known about the wider, potentially adverse impacts of these treatments. Substantial disruption of the upper airway commensal microbiota might reduce its contribution to host defense and local immune regulation, while increases in macrolide resistance carriage would represent a serious public health concern. Using samples from a randomized controlled trial, we show that low-dose erythromycin given over 48 weeks influences the composition of the oropharyngeal commensal microbiota. We report that macrolide therapy is associated with significant changes in the relative abundances of members of the Actinomyces genus and with significant increases in the carriage of transmissible macrolide resistance. Determining the clinical significance of these changes, relative to treatment benefit, now represents a research priority.

scholarly journals Disruption of an Enterococcus faecium Species-Specific Gene, a Homologue of Acquired Macrolide Resistance Genes of Staphylococci, Is Associated with an Increase in Macrolide Susceptibility

2001 ◽  
Vol 45 (1) ◽  
pp. 263-266 ◽  
Author(s):  
Kavindra V. Singh ◽  
Kumthorn Malathum ◽  
Barbara E. Murray
Keyword(s):  
Resistance Gene ◽  
Resistance Genes ◽  
Enterococcus Faecium ◽  
Complete Sequence ◽  
Macrolide Resistance ◽  
Specific Gene ◽  
Intrinsic Resistance ◽  
Macrolide Resistance Gene ◽  
Species Specific

ABSTRACT The complete sequence (1,479 nucleotides) of msrC, part of which was recently reported by others using a different strain, was determined. This gene was found in 233 of 233 isolates ofEnterococcus faecium but in none of 265 other enterococci. Disruption of msrC was associated with a two- to eightfold decrease in MICs of erythromycin azithromycin, tylosin, and quinupristin, suggesting that it may explain in part the apparent greater intrinsic resistance to macrolides of isolates of E. faecium relative to many streptococci. This endogenous, species-specific gene of E. faecium is 53% identical tomsr(A), suggesting that it may be a remote progenitor of the acquired macrolide resistance gene found in some isolates of staphylococci.

scholarly journals First Report of Macrolide Resistance Geneerm(T) Harbored by a Novel Small Plasmid from Erysipelothrix rhusiopathiae

2015 ◽  
Vol 59 (4) ◽  
pp. 2462-2465 ◽  
Author(s):  
Chang-Wen Xu ◽  
An-Yun Zhang ◽  
Chun-Mei Yang ◽  
Yun Pan ◽  
Zhong-Bin Guan ◽  
...  
Keyword(s):  
Low Frequency ◽  
Macrolide Resistance ◽  
Open Reading Frames ◽  
The Novel ◽  
Erysipelothrix Rhusiopathiae ◽  
Small Plasmid ◽  
Content Type ◽  
Macrolide Resistance Gene ◽  
First Time ◽  
Reading Frames

ABSTRACTThe macrolide resistance geneerm(T) was identified for the first time in a porcineErysipelothrix rhusiopathiaeisolate from swine in China. The novel 3,749-bp small plasmid pER29, which carrieserm(T), had a G+C content of 31% and four distinct open reading frames. The presence of pER29 increased by at least 128-fold the MICs of clindamycin and erythromycin forE. rhusiopathiae. The fitness cost of pER29 could be responsible for the low frequency oferm(T) inE. rhusiopathiae.

scholarly journals Antimicrobial Susceptibilities of Commonly Encountered Bacterial Isolates to Fosfomycin Determined by Agar Dilution and Disk Diffusion Methods

2011 ◽  
Vol 55 (9) ◽  
pp. 4295-4301 ◽  
Author(s):  
Ching-Lan Lu ◽  
Chia-Ying Liu ◽  
Yu-Tsung Huang ◽  
Chun-Hsing Liao ◽  
Lee-Jene Teng ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Urinary Tract ◽  
Enterococcus Faecalis ◽  
Susceptibility Testing ◽  
Inhibition Zone ◽  
Common Species ◽  
Disk Diffusion ◽  
Content Type ◽  
Zone Diameter ◽  
Agar Dilution

ABSTRACTWe studied the antimicrobial activity of fosfomycin against 960 strains of commonly encountered bacteria associated with urinary tract infection using standard agar dilution and disk diffusion methods. Species studied included 3 common species ofEnterobacteriaceae,Pseudomonas aeruginosa,Acinetobacter baumannii, andStenotrophomonas maltophilia; methicillin-susceptible and -resistantStaphylococcus aureus; and vancomycin-susceptible and resistantEnterococcus faecalisandE. faecium. MICs and inhibition zone diameters were interpreted in accordance with both the currently recommended Clinical and Laboratory Standards Institute (CLSI) criteria for urinary tract isolates ofEscherichia coliandEnterococcus faecalisand the European Committee on Antimicrobial Susceptibility Testing (EUCAST) criteria forEnterobacteriaceae. Tentative zone diameter interpretive criteria were developed for species not currently published by CLSI or EUCAST.Escherichia coliwas uniformly susceptible to fosfomycin, as were most strains ofKlebsiella pneumoniaeandEnterobacter cloacae. A. baumanniiwas resistant to fosfomycin, while the prevalence of resistance inP. aeruginosaandS. maltophiliawas greatly affected by the choice of MIC breakpoint. New tentative zone diameter criteria forK. pneumoniae,E. cloacae,S. aureus, andE. faeciumwere able to be set, providing some interim laboratory guidance for disk diffusion until further breakpoint evaluations are undertaken by CLSI and EUCAST.

scholarly journals The Novel Macrolide Resistance Genes mef(D), msr(F), and msr(H) Are Present on Resistance Islands in Macrococcus canis, Macrococcus caseolyticus, and Staphylococcus aureus

2020 ◽  
Vol 64 (5) ◽  
Author(s):  
Sybille Schwendener ◽  
Valentina Donà ◽  
Vincent Perreten
Keyword(s):  
Staphylococcus Aureus ◽  
Resistance Gene ◽  
Resistance Genes ◽  
Methicillin Resistance ◽  
Macrolide Resistance ◽  
Moderate Increase ◽  
The Novel ◽  
Integrase Gene ◽  
Content Type ◽  
And Staphylococcus Aureus

ABSTRACT Chromosomal resistance islands containing the methicillin resistance gene mecD (McRImecD) have been reported in Macrococcus caseolyticus. Here, we identified novel macrolide resistance genes in Macrococcus canis on similar elements, called McRImsr. These elements were also integrated into the 3′ end of the 30S ribosomal protein S9 gene (rpsI), delimited by characteristic attachment (att) sites, and carried a related site-specific integrase gene (int) at the 5′ end. They carried novel macrolide resistance genes belonging to the msr family of ABC subfamily F (ABC-F)-type ribosomal protection protein [msr(F) and msr(H)] and the macrolide efflux mef family [mef(D)]. Highly related mef(D)-msr(F) fragments were found on diverse McRImsr elements in M. canis, M. caseolyticus, and Staphylococcus aureus. Another McRImsr-like element identified in an M. canis strain lacked the classical att site at the 3′ end and carried the msr(H) gene but no neighboring mef gene. The expression of the novel resistance genes in S. aureus resulted in a low-to-moderate increase in the MIC of erythromycin but not streptogramin B. In the mef(D)-msr(F) operon, the msr(F) gene was shown to be the crucial determinant for macrolide resistance. The detection of circular forms of McRImsr and the mef(D)-msr(F) fragment suggested mobility of both the island and the resistance gene subunit. The discovery of McRImsr in different Macrococcus species and S. aureus indicates that these islands have a potential for dissemination of antibiotic resistance within the Staphylococcaceae family.

scholarly journals Phenotypes and genotypes of macrolide-resistant Streptococcus pneumoniae in Serbia

2014 ◽  
Vol 66 (1) ◽  
pp. 99-105 ◽  
Author(s):  
Mirjana Hadnadjev ◽  
Ina Gajic ◽  
Vera Mijac ◽  
Tatjana Kurucin ◽  
Anika Povazan ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Resistance Genes ◽  
Macrolide Resistance ◽  
Disk Diffusion ◽  
Pneumococcal Infections ◽  
Diffusion Test ◽  
Disk Diffusion Test ◽  
Resistance To Penicillin ◽  
Resistant Strains

Although macrolides are widely used for treating pneumococcal infections, an increase in macrolide resistance might compromise their use. The objective of this study was to determine the prevalence of macrolide-resistant phenotypes and genotypes in macrolide-resistant S. pneumoniae isolates in Serbia. A total of 228 macrolide-resistant strains isolated during the period of 2009-2012, were analyzed. Macrolide resistance phenotypes were determined by a double disk diffusion test. The presence of macrolide resistance genes was detected by PCR. Antibiotics susceptibilities were tested using the VITEK2 system and E test. Among the examined isolates, the MLSB phenotype which is linked to the presence of the erm(B) gene dominated (83.3%), while the mef(A) gene which is associated with the M phenotype, was identified in 16.7% isolates. Over 40% of isolates expressed co-resistance to penicillin. A multiple-resistant pattern was found in 36.4% strains, more frequently in children. However, all strains were susceptible to telithromycin, vancomycin, linezolid, fluoroquinolones and rifampicin.

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