scholarly journals Composite Structure of Streptococcus pneumoniae Containing the Erythromycin Efflux Resistance Gene mef(I) and the Chloramphenicol Resistance Gene catQ

2007 ◽  
Vol 51 (11) ◽  
pp. 3983-3987 ◽  
Author(s):  
Marina Mingoia ◽  
Manuela Vecchi ◽  
Ileana Cochetti ◽  
Emily Tili ◽  
Luca A. Vitali ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Resistance Gene ◽  
Composite Structure ◽  
Chromosomal Region ◽  
Erythromycin Resistance ◽  
M Gene ◽  
Chloramphenicol Resistance ◽  
Genes Encoding ◽  
Left And Right ◽  
Chloramphenicol Acetyltransferase Gene

ABSTRACT In recent years mef genes, encoding efflux pumps responsible for M-type macrolide resistance, have been investigated extensively for streptococci. mef(I) is a recently described mef variant detected in particular isolates of Streptococcus pneumoniae instead of the more common mef(E) and mef(A). This study shows that mef(I) is located in a new composite genetic element, whose sequence was completely analyzed and the left and right junctions determined, demonstrating a unique genetic organization. The new composite structure (30,505 bp), designated the 5216IQ complex, consists of two halves: a left one (15,316 bp) formed by parts of the known transposons Tn5252 and Tn916, and a right one (15,115 bp) formed by a new fragment, designated the IQ element. While the defective Tn916 contained a silent tet(M) gene, the IQ element, ending with identical transposase genes on both sides and containing the mef(I) gene with an adjacent new msr(D) gene variant and a catQ chloramphenicol acetyltransferase gene, was completely different from the genetic elements carrying other mef genes in pneumococci. This is the first report demonstrating catQ in S. pneumoniae and showing its linkage with a mef gene. Analysis of the chromosomal region beyond the left junction revealed an organization more similar to that of S. pneumoniae strain TIGR4 than to that of strain R6. The 5216IQ complex was apparently nonmobile, with no detectable transfer of erythromycin resistance being obtained in repeated transformation and conjugation assays.

scholarly journals erm(B)-Carrying Elements in Tetracycline-Resistant Pneumococci and Correspondence between Tn1545 and Tn6003

2008 ◽  
Vol 52 (4) ◽  
pp. 1285-1290 ◽  
Author(s):  
Ileana Cochetti ◽  
Emily Tili ◽  
Marina Mingoia ◽  
Pietro E. Varaldo ◽  
Maria Pia Montanari
Keyword(s):  
Streptococcus Pneumoniae ◽  
Resistance Gene ◽  
Insertion Sequence ◽  
Reference Strain ◽  
Clinical Isolates ◽  
Erythromycin Resistance ◽  
M Gene ◽  
Genetic Organization ◽  
Gene Combination ◽  
Related Element

ABSTRACT This study investigated the genetic organization of erm(B)-carrying transposons of Streptococcus pneumoniae and their distribution in tetracycline-resistant clinical isolates. By comparatively analyzing reference pneumococci carrying erm(B)/tet(M) transposon Tn1545, Tn6003, Tn6002, or Tn3872, we demonstrated a substantial correspondence between Tn1545 and Tn6003, which have the same resistance gene combination [tet(M) (tetracycline), erm(B) (erythromycin), and aphA-3 (kanamycin)]; share the macrolide-aminoglycoside-streptothricin element, containing a second erm(B); and only differ by a ca. 1.2-kb insertion (containing a putative IS1239 insertion sequence) detected in Tn1545 from S. pneumoniae reference strain BM4200. These results enabled elucidation of the structure of Tn1545, the first erm(B)-carrying transposon described in S. pneumoniae. A collection of 83 erythromycin- and tetracycline-resistant clinical pneumococci, representative of recent Italian isolates carrying erm(B) as the sole erythromycin resistance gene, was used to investigate the distribution of the different transposons. All 83 organisms were positive for tet(M) and bore an erm(B)/tet(M) transposon that could be characterized by using a specific set of primer pairs; Tn3872 was detected in 18 isolates, Tn6002 in 59 isolates, and Tn6003 in 6 (the sole kanamycin-resistant) isolates. The genetic organization of transposon Tn1545, with its specific insertion, was not detected in any of the isolates tested. The erm(B)-carrying elements of tetracycline-resistant pneumococci substantially corresponded to those [bearing a silent tet(M) gene] recently detected in tetracycline-susceptible pneumococci. Overall, in erm(B)-positive pneumococci, Tn6003 was the least common erm(B)-carrying Tn916-related element and Tn6002 the most common.

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 Serotype 19F Multiresistant Pneumococcal Clone Harboring Two Erythromycin Resistance Determinants [erm(B) and mef(A)] in South Africa

2001 ◽  
Vol 45 (5) ◽  
pp. 1595-1598 ◽  
Author(s):  
Lesley McGee ◽  
Keith P. Klugman ◽  
Avril Wasas ◽  
Thora Capper ◽  
Adrian Brink
Keyword(s):  
South Africa ◽  
Streptococcus Pneumoniae ◽  
Private Sector ◽  
Dna Fingerprinting ◽  
Gel Electrophoresis ◽  
Pulsed Field Gel Electrophoresis ◽  
Erythromycin Resistance ◽  
Pulsed Field ◽  
Resistance Determinants ◽  
Genes Encoding

ABSTRACT One hundred eighteen erythromycin-resistant Streptococcus pneumoniae (ERSP) strains (MICs of ≥0.5 μg/ml) from five laboratories serving the private sector in South Africa were analyzed for the genes encoding resistance to macrolides. Sixty-seven ERSP strains (56.8%) contained the erm(B) gene, and 15 isolates (12.7%) contained the mef(A) gene. Thirty-six isolates (30.5%) harbored both the erm(B) and mef(A) genes and were highly resistant to erythromycin and clindamycin. DNA fingerprinting by BOX-PCR and pulsed-field gel electrophoresis identified 83% of these strains as belonging to a single multiresistant serotype 19F clone.

scholarly journals Genetic Relatedness of the Streptococcus pneumoniae Capsular Biosynthetic Loci

2007 ◽  
Vol 189 (21) ◽  
pp. 7841-7855 ◽  
Author(s):  
Angeliki Mavroidi ◽  
David M. Aanensen ◽  
Daniel Godoy ◽  
Ian C. Skovsted ◽  
Margit S. Kaltoft ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Genetic Relatedness ◽  
Pneumococcal Serotypes ◽  
Major Cluster ◽  
Genes Encoding ◽  
Pneumococcal Serotype ◽  
Streptococcal Polysaccharide ◽  
Single Cluster ◽  
Dependent Pathway ◽  
Sequence Similarities

ABSTRACT Streptococcus pneumoniae (the pneumococcus) produces 1 of 91 capsular polysaccharides (CPS) that define the serotype. The cps loci of 88 pneumococcal serotypes whose CPS is synthesized by the Wzy-dependent pathway were compared with each other and with additional streptococcal polysaccharide biosynthetic loci and were clustered according to the proportion of shared homology groups (HGs), weighted for the sequence similarities between the genes encoding the shared HGs. The cps loci of the 88 pneumococcal serotypes were distributed into eight major clusters and 21 subclusters. All serotypes within the same serogroup fell into the same major cluster, but in six cases, serotypes within the same serogroup were in different subclusters and, conversely, nine subclusters included completely different serotypes. The closely related cps loci within a subcluster were compared to the known CPS structures to relate gene content to structure. The Streptococcus oralis and Streptococcus mitis polysaccharide biosynthetic loci clustered within the pneumococcal cps loci and were in a subcluster that also included the cps locus of pneumococcal serotype 21, whereas the Streptococcus agalactiae cps loci formed a single cluster that was not closely related to any of the pneumococcal cps clusters.

scholarly journals A Novel Multiresistant Streptococcus pneumoniae Serogroup 19 Clone from Washington State Identified by Pulsed-Field Gel Electrophoresis and Restriction Fragment Length Patterns

2000 ◽  
Vol 38 (4) ◽  
pp. 1575-1580 ◽  
Author(s):  
Vicki A. Luna ◽  
Daniel B. Jernigan ◽  
Alan Tice ◽  
James D. Kellner ◽  
Marilyn C. Roberts
Keyword(s):  
Streptococcus Pneumoniae ◽  
Restriction Fragment ◽  
Fragment Length ◽  
Gel Electrophoresis ◽  
Washington State ◽  
Pulsed Field Gel Electrophoresis ◽  
Erythromycin Resistance ◽  
Eastern Canada ◽  
Pulsed Field ◽  
Restriction Fragment Length

In 1997, a cluster of multiresistant invasive serogroup 19 pneumococcus infections, including two fatalities, was reported in Washington State. Further investigation identified other cases. Fourteen Washington Streptococcus pneumoniae isolates, four from Alaska, and eight isolates from eastern Canada with reduced penicillin susceptibility (MIC of ≥1 μg/ml) were included in the study. Pulsed-field gel electrophoresis (PFGE) with ApaI,SacII, and SmaI restriction enzymes and IS1167 and mef restriction fragment length polymorphism (RFLP) pattern analysis were performed. Twenty of the 26 isolates had identical or related PFGE patterns, with two or all three enzymes, and identical or related IS1167 RFLP patterns, indicating that they were genetically related. These 20 isolates contained the mef gene conferring erythromycin resistance and had identical mef RFLP patterns. The PFGE and RFLP patterns were distinct from those of six multiresistant clones previously described and suggest that a new multiresistant clone has appeared in Washington, Alaska, and eastern Canada. This newly characterized clone should be included in the Pneumococcal Molecular Epidemiology Network.

scholarly journals Coexistence of aminoglycoside resistance genes in CTX-M-producing isolates of Klebsiella pneumoniae in Bushehr province, Iran

2021 ◽  
Author(s):  
Behrouz Latifi ◽  
Saeed Tajbakhsh ◽  
Leila Ahadi ◽  
Forough Yousefi
Keyword(s):  
Klebsiella Pneumoniae ◽  
Resistance Genes ◽  
Confirmatory Test ◽  
M Gene ◽  
Aminoglycoside Resistance ◽  
Genetic Groups ◽  
Genes Encoding ◽  
Resistance Patterns ◽  
Aminoglycoside Resistance Genes ◽  
Antibiotic Resistance Patterns

Background and Objectives: Increasing the rate of extended-spectrum β-lactamase (ESBL)-producing Klebsiella pneumoniae has given rise to a major healthcare issue in clinical settings over the past few years. Treatment of these strains is hardly effective since the plasmid encoding ESBL may also carry other resistance genes including aminoglycosides. The current study aimed to evaluate the prevalence of ESBL-producing K. pneumoniae and investigate the coexistence of Cefoxitamase-Munich (bla ) with aminoglycoside-modifying enzyme (AME) genes, aac(3)IIa as well as aac(6′)Ib, in CTX‑M‑producing K. pneumoniae isolated from patients in Bushehr province, Iran. Materials and Methods: A total of 212 K. pneumoniae isolates were collected and confirmed using polymerase chain re‑ action (PCR) of the malate dehydrogenase gene. Isolates were screened for production of ESBL. Phenotypic confirmatory test was performed using combined disk test. The genes encoding CTX-M groups and AME genes, aac(3)IIa and aac(6′)Ib, were investigated by PCR. Results: The ESBL phenotype was detected in 56 (26.4%) K. pneumoniae isolates. Moreover, 83.9% of ESBL-producing isolates carried the genes for CTX-M type β-lactamases, which were distributed into the two genetic groups of CTX-M-1 (97.8%)- and CTX-M-2 (2.1%)-related enzymes. Notably, among K. pneumoniae isolates containing the blaCTX‑M gene, 68.08% of isolates harbored AME genes. In addition, the coexistence of bla in 46.8% of CTX-M-producing K. pneumoniae isolates. Conclusion: This study provides evidence of a high prevalence of AME genes in CTX-M- producing K. pneumoniae iso‑ lates; therefore, in the initial empirical treatment of infections caused by ESBL-KP in regions with such antibiotic resistance patterns, aminoglycoside combination therapy should be undertaken carefully.

scholarly journals A Locus on Mouse Chromosome 2 Is Involved in Susceptibility to Congenital Hypothyroidism and Contains an Essential Gene Expressed in Thyroid

Endocrinology ◽  
2010 ◽  
Vol 151 (4) ◽  
pp. 1948-1958 ◽  
Author(s):  
Elena Amendola ◽  
Remo Sanges ◽  
Antonella Galvan ◽  
Nina Dathan ◽  
Giacomo Manenti ◽  
...  
Keyword(s):  
Congenital Hypothyroidism ◽  
Chromosomal Region ◽  
Essential Gene ◽  
Chromosome 2 ◽  
Nucleotide Polymorphisms ◽  
Single Nucleotide ◽  
Genes Encoding ◽  
Mouse Chromosome 2 ◽  
Essential Function

We report here the mapping of a chromosomal region responsible for strain-specific development of congenital hypothyroidism in mice heterozygous for null mutations in genes encoding Nkx2-1/Titf1 and Pax8. The two strains showing a differential predisposition to congenital hypothyroidism contain several single-nucleotide polymorphisms in this locus, one of which leads to a nonsynonymous amino acid change in a highly conserved region of Dnajc17, a member of the type III heat-shock protein-40 (Hsp40) family. We demonstrate that Dnajc17 is highly expressed in the thyroid bud and had an essential function in development, suggesting an important role of this protein in organogenesis and/or function of the thyroid gland.

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