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 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 In Vitro Activities of the Novel Ketolide Telithromycin (HMR 3647) against Erythromycin-Resistant StreptococcusSpecies

2001 ◽  
Vol 45 (3) ◽  
pp. 789-793 ◽  
Author(s):  
Jari Jalava ◽  
Janne Kataja ◽  
Helena Seppälä ◽  
Pentti Huovinen
Keyword(s):  
Streptococcus Pneumoniae ◽  
Resistance Gene ◽  
Streptococcus Pyogenes ◽  
Clinical Isolates ◽  
The Novel ◽  
Methylase Gene ◽  
Vitro Data ◽  
In Vitro Data

ABSTRACT The in vitro susceptibilities of 184 erythromycin-resistant streptococci to a novel ketolide, telithromycin (HMR 3647), were tested. These clinical isolates included 111 Streptococcus pyogenes, 18 group C streptococcus, 18 group G streptococcus, and 37 Streptococcus pneumoniae strains. The MICs for all but eight S. pyogenes strains were ≤0.5 μg/ml, indicating that telithromycin is active in vitro against erythromycin-resistant Streptococcus strains. All strains for which MICs were ≥1 μg/ml had an erm(B) resistance gene and six strains for which MICs were ≥4 μg/ml had a constitutiveerm(B) gene (MIC range, 4 to 64 μg/ml). Interestingly, for S. pneumoniae strains with a constitutiveerm(B) gene, MICs were ≤0.25 μg/ml (MIC range, ≤0.008 to 0.25 μg/ml). Our in vitro data show that for S. pyogenes strains which constitutively express theerm(B) methylase gene, MICs are so high that the strains might be clinically resistant to telithromycin.

scholarly journals Molecular Basis for Different Levels oftet(M) Expression in Streptococcus pneumoniae Clinical Isolates

2012 ◽  
Vol 56 (10) ◽  
pp. 5040-5045 ◽  
Author(s):  
Patrick Grohs ◽  
Patrick Trieu-Cuot ◽  
Isabelle Podglajen ◽  
Sophie Grondin ◽  
Arnaud Firon ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Molecular Basis ◽  
Clinical Isolates ◽  
M Gene ◽  
Content Type ◽  
Frameshift Mutations ◽  
Resistant Mutants ◽  
Promoter Mutations ◽  
Different Levels

ABSTRACTSeventy-four unrelated clinical isolates ofStreptococcus pneumoniaeharboring thetet(M) gene were studied. Seven strains with low tetracycline (Tc) MICs (0.25 to 0.5 μg/ml) were found to harbor truncatedtet(M) alleles that were inactivated by different frameshift mutations. In contrast, five strains bore deletions in thetet(M) promoter region, among which four displayed increased Tc MICs (16 to 64 μg/ml). The same promoter mutations were detected in Tc-resistant mutants selectedin vitrofrom various susceptible strains. Sequence analysis revealed that these deletions might impede the formation of the transcriptional attenuator located immediately upstream oftet(M). Expression inEnterococcus faecalisof atet(M) reporter gene transcribed from these promoter mutants conferred a level of Tc resistance similar to that observed in the parentalS. pneumoniaestrains. These results show that different levels of Tc susceptibility found in clinical isolates ofS. pneumoniaecan be explained by frameshift mutations withintet(M) and by alterations of the upstream transcriptional attenuator.

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.

Molecular Characterisation of ESBL producer E. coli

2018 ◽  
Vol 1 (2) ◽  
pp. 40-57
Author(s):  
Abdulghani Alsamarai ◽  
Shler Khorshed ◽  
Imad Weli
Keyword(s):  
Urinary Tract Infection ◽  
Urinary Tract ◽  
Tract Infection ◽  
Female Student ◽  
Clinical Problem ◽  
Clinical Isolates ◽  
Molecular Characterisation ◽  
M Gene ◽  
Esbl Producer ◽  
E Coli

Background: Antibiotic resistance emerged as clinical problem challenge the effective treatment of infections. Virulence factor may play an important role in the influence of antimicrobial resistance. Objective: To determine the frequency of resistance gene in E. coli clinical isolates from women with urinary tract infection. Materials and Methods: Fifteen E.coli clinical isolates were tested by PCR to determine their molecular characterization. Results: The bla CTX –M gene was not detected in 6.7% out of the tested 15 E. coli clinical isolates from women with urinary tract infection. However, bla OXA gene was detected in all E. coli tested clinical isolates from pregnant women, female student and diabetic women with urinary tract infection. While bla TEM gene and bla SHV gene were not detected in 33.3% and 40% out of the tested E. coli clinical isolates respectively. Conclusions: Four types of ESBL genes were detected, and shows new trend of distribution, which indicated the predominance of OXA and CTX-M genes.

scholarly journals Mosaic-Like Structure of Penicillin-Binding Protein 2 Gene (penA) in Clinical Isolates of Neisseria gonorrhoeae with Reduced Susceptibility to Cefixime

2002 ◽  
Vol 46 (12) ◽  
pp. 3744-3749 ◽  
Author(s):  
Satoshi Ameyama ◽  
Shoichi Onodera ◽  
Masahiro Takahata ◽  
Shinzaburo Minami ◽  
Nobuko Maki ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Neisseria Gonorrhoeae ◽  
Neisseria Meningitidis ◽  
Binding Protein ◽  
Clinical Isolates ◽  
Penicillin Binding Protein ◽  
Gene Sequences ◽  
Neisseria Flavescens ◽  
Neisseria Perflava

ABSTRACT Neisseria gonorrhoeae strains with reduced susceptibility to cefixime (MICs, 0.25 to 0.5 μg/ml) were isolated from male urethritis patients in Tokyo, Japan, in 2000 and 2001. The resistance to cephems including cefixime and penicillin was transferred to a susceptible recipient, N. gonorrhoeae ATCC 19424, by transformation of the penicillin-binding protein 2 gene (penA) that had been amplified by PCR from a strain with reduced susceptibility to cefixime (MIC, 0.5 μg/ml). The sequences of penA in the strains with reduced susceptibilities to cefixime were different from those of other susceptible isolates and did not correspond to the reported N. gonorrhoeae penA gene sequences. Some regions in the transpeptidase-encoding domain in this penA gene were similar to those in the penA genes of Neisseria perflava (N. sicca), Neisseria cinerea, Neisseria flavescens, and Neisseria meningitidis. These results showed that a mosaic-like structure in the penA gene conferred reductions in the levels of susceptibility of N. gonorrhoeae to cephems and penicillin in a manner similar to that found for N. meningitidis and Streptococcus pneumoniae.

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