scholarly journals mefE is necessary for the erythromycin-resistant M phenotype in Streptococcus pneumoniae.

1997 ◽  
Vol 41 (10) ◽  
pp. 2251-2255 ◽  
Author(s):  
A Tait-Kamradt ◽  
J Clancy ◽  
M Cronan ◽  
F Dib-Hajj ◽  
L Wondrack ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Substrate Specificity ◽  
Streptococcus Pyogenes ◽  
Dna Sequences ◽  
Efflux Pump ◽  
Erythromycin Resistance ◽  
Gene Encoding

Recently, it was shown that a significant number of erythromycin-resistant Streptococcus pneumoniae and Streptococcus pyogenes strains contain a determinant that mediates resistance via a putative efflux pump. The gene encoding the erythromycin-resistant determinant was cloned and sequenced from three strains of S. pneumoniae bearing the M phenotype (macrolide resistant but clindamycin and streptogramin B susceptible). The DNA sequences of mefE were nearly identical, with only 2-nucleotide differences between genes from any two strains. When the mefE sequences were compared to the mefA sequence from S. pyogenes, the two genes were found to be closely related (90% identity). Strains of S. pneumoniae were constructed to confirm that mefE is necessary to confer erythromycin resistance and to explore the substrate specificity of the pump; no substrates other than 14- and 15-membered macrolides were identified.

scholarly journals Phenotypic and Molecular Characterization of Tetracycline- and Erythromycin-Resistant Strains of Streptococcus pneumoniae

2003 ◽  
Vol 47 (7) ◽  
pp. 2236-2241 ◽  
Author(s):  
Maria P. Montanari ◽  
Ileana Cochetti ◽  
Marina Mingoia ◽  
Pietro E. Varaldo
Keyword(s):  
Streptococcus Pneumoniae ◽  
Resistance Gene ◽  
Restriction Analysis ◽  
Tetracycline Resistance ◽  
Erythromycin Resistance ◽  
Gene Encoding ◽  
Conjugative Transposons ◽  
Numerous Type ◽  
The One

ABSTRACT Sixty-five clinical isolates of Streptococcus pneumoniae, all collected in Italy between 1999 and 2002 and resistant to both tetracycline (MIC, ≥8 μg/ml) and erythromycin (MIC, ≥1 μg/ml), were investigated. Of these strains, 11% were penicillin resistant and 23% were penicillin intermediate. With the use of the erythromycin-clindamycin-rokitamycin triple-disk test, 14 strains were assigned to the constitutive (cMLS) phenotype of macrolide resistance, 44 were assigned to the partially inducible (iMcLS) phenotype, 1 was assigned to the inducible (iMLS) phenotype, and 6 were assigned to the efflux-mediated (M) phenotype. In PCR assays, 64 of the 65 strains were positive for the tetracycline resistance gene tet(M), the exception being the one M isolate susceptible to kanamycin, whereas tet(K), tet(L), and tet(O) were never found. All cMLS, iMcLS, and iMLS isolates had the erythromycin resistance gene erm(B), and all M phenotype isolates had the mef(A) or mef(E) gene. No isolate had the erm(A) gene. The int-Tn gene, encoding the integrase of the Tn916-Tn1545 family of conjugative transposons, was detected in 62 of the 65 test strains. Typing assays showed the strains to be to a great extent unrelated. Of 16 different serotypes detected, the most numerous were 23F (n = 13), 19A (n = 10), 19F (n = 9), 6B (n = 8), and 14 (n = 6). Of 49 different pulsed-field gel electrophoresis types identified, the majority (n = 39) were represented by a single isolate, while the most numerous type included five isolates. By high-resolution restriction analysis of PCR amplicons with four endonucleases, the tet(M) loci from the 64 tet(M)-positive pneumococci were classified into seven distinct restriction types. Overall, a Tn1545-like transposon could reasonably account for tetracycline and erythromycin resistance in the vast majority of the pneumococci of cMLS, iMcLS, and iMLS phenotypes, whereas a Tn916-like transposon could account for tetracycline resistance in most M phenotype strains.

scholarly journals Expression of Efflux Pump Gene pmrA in Fluoroquinolone-Resistant and -Susceptible Clinical Isolates of Streptococcus pneumoniae

2002 ◽  
Vol 46 (3) ◽  
pp. 808-812 ◽  
Author(s):  
Laura J. V. Piddock ◽  
Maggie M. Johnson ◽  
S. Simjee ◽  
L. Pumbwe
Keyword(s):  
Streptococcus Pneumoniae ◽  
Reverse Transcriptase ◽  
Ethidium Bromide ◽  
Marked Effect ◽  
Efflux Pump ◽  
Northern Blotting ◽  
Clinical Isolates ◽  
Efflux Pump Inhibitor ◽  
Gene Encoding ◽  
Genes Expression

ABSTRACT Thirty-four ciprofloxacin-resistant (MIC ≥ 2 μg/ml) and 12 ciprofloxacin-susceptible clinical isolates of Streptococcus pneumoniae were divided into four groups based upon susceptibility to norfloxacin and the effect of reserpine (20 μg/ml). The quinolone-resistance-determining regions of parC, parE, gyrA, and gyrB of all ciprofloxacin-resistant clinical isolates were sequenced, and the activities of eight other fluoroquinolones, acriflavine, ethidium bromide, chloramphenicol, and tetracycline in the presence and absence of reserpine were determined. Despite a marked effect of reserpine upon the activity of norfloxacin, there were only a few isolates for which the activity of another fluoroquinolone was enhanced by reserpine. For most isolates the MICs of acriflavine and ethidium bromide were lowered in the presence of reserpine despite the lack of effect of this efflux pump inhibitor on fluoroquinolone activity. The strains that were most resistant to the fluoroquinolones were predominantly those with mutations in three genes. Expression of the gene encoding the efflux pump PmrA was examined by Northern blotting (quantified by quantitative competitive reverse transcriptase PCR) and compared with that of S. pneumoniae R6 and R6N. Within each group there were isolates that had high-, medium-, and low-level expression of this gene; however, increased expression was not exclusively associated with those isolates with a phenotype suggestive of an efflux mutant. These data suggest that there is another reserpine-sensitive efflux pump in S. pneumoniae that extrudes ethidium bromide and acriflavine but not fluoroquinolones.

scholarly journals Genetic Resistance Elements CarryingmefSubclasses Other thanmef(A) in Streptococcus pyogenes

2011 ◽  
Vol 55 (7) ◽  
pp. 3226-3230 ◽  
Author(s):  
Maria Del Grosso ◽  
Romina Camilli ◽  
Giada Barbabella ◽  
John Blackman Northwood ◽  
David J. Farrell ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Streptococcus Pyogenes ◽  
Resistance Genes ◽  
Genetic Resistance ◽  
The Novel ◽  
Genetic Element ◽  
Erythromycin Resistance ◽  
Content Type ◽  
Genetic Elements

ABSTRACTInStreptococcus pyogenes, efflux-mediated erythromycin resistance is associated with themefgene, represented mostly bymef(A), although a small portion of strains carry differentmefsubclasses. We characterized the composite genetic elements, includingmefsubclasses other thanmef(A), associated with other resistance genes inS. pyogenesisolates. Determination of the genetic elements was performed by PCR mapping. The strains carrying mosaicmef(A/E), in which the 5′ region was identical tomef(A) and the 3′ region was identical tomef(E), also carriedtet(O). The two genes were found enclosed in an element similar toS. pyogenesprophage Φm46.1, designated the Φm46.1-like element. InS. pyogenesstrains carryingmef(E) andtet(M),mef(E) was included in a typical mega element, and in some strains, it was physically associated withtet(M) in the composite element Tn2009.S. pyogenesstrains carryingmef(I) also carriedcatQ; the two genes were linked in a fragment representing a portion of the 5216IQ complex ofStreptococcus pneumoniae, designated the defective IQ element. In the only isolate carrying a novelmefgene, this was associated withcatQandtet(M) in a genetic element similar to the 5216IQ complex ofS. pneumoniae(5216IQ-like complex), suggesting that the novelmefis in fact a variant ofmef(I). This study demonstrates that the composite elements containingmefare shared betweenS. pyogenesandS. pneumoniaeand suggests that it is important to distinguish themefsubclass on the basis of the genetic element containing it.

scholarly journals New Genetic Element Carrying the Erythromycin Resistance Determinant erm(TR) in Streptococcus pneumoniae

2007 ◽  
Vol 52 (2) ◽  
pp. 619-625 ◽  
Author(s):  
Romina Camilli ◽  
Maria Del Grosso ◽  
Francesco Iannelli ◽  
Annalisa Pantosti
Keyword(s):  
Streptococcus Pneumoniae ◽  
Genomic Sequence ◽  
Efflux Pump ◽  
Regulatory Protein ◽  
Resistance Determinant ◽  
Type I ◽  
Genetic Element ◽  
Erythromycin Resistance ◽  
Modification System ◽  
Restriction Modification System

ABSTRACT erm(A) subclass erm(TR), a common macrolide resistance determinant in Streptococcus pyogenes but quite rare in Streptococcus pneumoniae, was found in a clinical S. pneumoniae isolate (AP200) from Italy. In this isolate, erm(TR) was found included in a genetic element approximately 56 kb in size that did not appear to be conjugative but could be transferred by transformation. An erm(TR)-containing DNA fragment of approximately 10 kb was sequenced and 12 open reading frames (ORFs) were identified. Upstream of erm(TR), a regulatory protein of the TetR family and the two components of an efflux pump of the ABC type were found. Downstream of erm(TR), there were ORFs homologous to a spectinomycin phosphotransferase, transposases, and a relaxase. Since the genomic sequence of S. pyogenes MGAS10750 carrying erm(TR) became available, comparison between the erm(TR)-containing genetic elements in AP200 and in MGAS10750 was performed. The region flanking erm(TR) in MGAS10750 showed identity with AP200 for 10 ORFs out of 12. PCR mapping using primers designed on the sequence of MGAS10750 confirmed that AP200 carries a genetic element similar to that of MGAS10750. In AP200 the genetic element was inserted inside an ORF homologous to spr0790 of S. pneumoniae R6, coding for a type I restriction modification system. Homologies between the insertion sites in AP200 and MGAS10750 consisted of eight conserved nucleotides, of which three were duplicated, likely representing target site duplication. The structure of the erm(TR)-carrying genetic element shows characteristics of a transposon/prophage remnant chimera. In AP200 this genetic element was designated Tn1806.

scholarly journals Mechanistic basis for decreased antimicrobial susceptibility in a clinical isolate ofNeisseria gonorrhoeaepossessing a mosaic-likemtrefflux pump locus

2018 ◽  
Author(s):  
Corinne E. Rouquette-Loughlin ◽  
Jennifer L. Reimche ◽  
Jacqueline T. Balthazar ◽  
Vijaya Dhulipala ◽  
Kim M. Gernert ◽  
...  
Keyword(s):  
Amino Acid ◽  
Antimicrobial Susceptibility ◽  
Dna Sequences ◽  
Efflux Pump ◽  
Spontaneous Mutation ◽  
Gene Encoding ◽  
Transporter Protein ◽  
Single Nucleotide Change ◽  
Clinical Resistance ◽  
Mechanistic Basis

AbstractRecent reports suggest that mosaic-like sequences within themtr(multipletransferableresistance) efflux pump locus ofNeisseria gonorrhoeaelikely originating from commensalNeisseria sp.by transformation can increase the ability of gonococci to resist structurally diverse antimicrobials. Thus, acquisition of numerous nucleotide changes within themtrRgene encoding the transcriptional repressor (MtrR) of themtrCDEefflux pump-encoding operon or overlapping promoter region for both along with those that cause amino acid changes in the MtrD transporter protein were recently reported to decrease gonococcal susceptibility to numerous antimicrobials, including azithromycin (Azi) (Wadsworthet al.2018. MBio. doi.org/10.1128/mBio.01419-18). We performed detailed genetic and molecular studies to define the mechanistic basis for why such strains can exhibit decreased susceptibility to MtrCDE antimicrobial substrates including Azi. We report that a strongcis-acting transcriptional impact of a single nucleotide change within the -35 hexamer of themtrCDEpromoter as well gain-of-function amino acid changes at theC-terminal region of MtrD can mechanistically account for the decreased antimicrobial susceptibility of gonococci with a mosaic-likemtrlocus.IMPORTANCEHistorically, after introduction of an antibiotic for treatment of gonorrhea, strains ofN. gonorrhoeaeemerge that display clinical resistance due to spontaneous mutation or acquisition of resistance genes. Genetic exchange between members of theNeisseriagenus occurring by transformation can cause significant changes in gonococci that impact the structure of an antibiotic target or expression of genes involved in resistance. The results presented herein provide a framework for understanding how mosaic-like DNA sequences from commensalNeisseriathat recombine within the gonococcalmtrefflux pump locus function to decrease bacterial susceptibility to antimicrobials including antibiotics used in therapy of gonorrhea.

Loss of erythromycin resistance genes from strains of Streptococcus pyogenes that have developed resistance to levofloxacin

2009 ◽  
Vol 64 (2) ◽  
pp. 225-228 ◽  
Author(s):  
Dewan Sakhawat Billal ◽  
Muneki Hotomi ◽  
Steve S. Yan ◽  
Daniel P. Fedorko ◽  
Jun Shimada ◽  
...  
Keyword(s):  
Streptococcus Pyogenes ◽  
Resistance Genes ◽  
Erythromycin Resistance

Bacterial Aetiology of Pharyngotonsillitis in Paediatric Age Group in a Tertiary Care Hospital in Kerala

2021 ◽  
Vol 8 (39) ◽  
pp. 3441-3447
Author(s):  
Thushara Ushakumari Bhuvanendran ◽  
Beena V.G.
Keyword(s):  
Staphylococcus Aureus ◽  
Streptococcus Pneumoniae ◽  
Rheumatic Fever ◽  
Streptococcus Pyogenes ◽  
Acute Rheumatic Fever ◽  
Bacterial Pathogens ◽  
Antibiotic Sensitivity ◽  
Acute Glomerulonephritis ◽  
Age Group ◽  
Common Organism

BACKGROUND Pharyngotonsillitis is defined as a spectrum of conditions ranging from inflammation primarily confined to the tonsils to pharyngitis implying generalized inflammation of the whole of pharynx. Children are more prone to get several episodes of pharyngotonsillitis per year during their school years. Pharyngitis caused by Streptococcus pyogenes can cause two non-suppurative complications, acute rheumatic fever and acute glomerulonephritis which is responsible for significant morbidity and mortality. The present study was conducted to identify the prevalence of bacterial pathogens causing pharyngotonsillitis and to study their antibiotic sensitivity pattern that would indicate the optimum line of treatment. METHOD A total of 200 children at the age group of 2 - 12 years who had clinical features of pharyngotonsillitis according to the inclusion criteria were recruited for this study over a period of one year. With the help of a disposable wooden spatula, pus from the pharyngo tonsillar region was collected and processed. Predominant isolates obtained were identified and antibiotic sensitivity was done. RESULTS Bacteria was isolated from 70 samples. Pharyngotonsillitis was found most prevalent at the age group of 8 – 10 years. Intake of cold food stuffs and passive smoking at home was found to have statistically significant association as risk factor for pharyngotonsillitis. Staphylococcus aureus was the most common organism isolated followed by Streptococcus pyogenes. The other organisms isolated were group G and C streptococci, Streptococcus pneumoniae, Pseudomonas aeruginosa and Klebsiella pneumonia sub species (spp) aerogenes. CONCLUSIONS Staphylococcus aureus was the most common organism isolated, followed by Streptococcus pyogenes. All the isolates of beta haemolytic streptococci were found to be sensitive to penicillin. There was increased incidence of resistance to macrolides among the gram-positive isolates except Streptococcus pneumoniae and it may be due to the wide spread use of macrolides injudiciously. All the bacterial pharyngotonsillitis cases were cured with the antibiotic given according to the sensitivity except one case. KEYWORDS Pharyngotonsillitis, Acute Rheumatic Fever, Acute Glomerulonephritis, Bacterial Pathogens, Antibiogram

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