scholarly journals A Novel CTX-M β-Lactamase (CTX-M-8) in Cefotaxime-ResistantEnterobacteriaceae Isolated in Brazil

2000 ◽  
Vol 44 (7) ◽  
pp. 1936-1942 ◽  
Author(s):  
R. Bonnet ◽  
J. L. M. Sampaio ◽  
R. Labia ◽  
C. De Champs ◽  
D. Sirot ◽  
...  
Keyword(s):  
Protein Sequence ◽  
Clinical Laboratory ◽  
Enterobacter Aerogenes ◽  
Enterobacter Cloacae ◽  
Cloning And Sequencing ◽  
E Coli ◽  
Class A ◽  
The Family ◽  
Synergy Test ◽  
Citrobacter Amalonaticus

ABSTRACT To estimate the diversity of extended-spectrum β-lactamases in Brazil, 18 strains from different species of the familyEnterobacteriaceae exhibiting a positive double-disk synergy test were collected by a clinical laboratory from several hospitals in Rio de Janeiro, Brazil, in 1996 and 1997. Four strains (Proteus mirabilis, Enterobacter cloacae,Enterobacter aerogenes, and Citrobacter amalonaticus) hybridized with a 550-bp CTX-M probe. The P. mirabilis strain produced a CTX-M-2 enzyme. The E. cloacae, E. aerogenes, and C. amalonaticus isolates harbored a bla gene which was identified by cloning and sequencing as abla CTX-M gene. E. coli HB101 transconjugants and the E. coli DH5α transformant harboring a recombinant plasmid produced a CTX-M β-lactamase with an isoelectric point of 7.6 conferring a resistance phenotype characterized by a higher level of resistance to cefotaxime than to ceftazidime, as observed with the other CTX-M enzymes. The deduced protein sequence showed a novel Ambler class A CTX-M enzyme, named CTX-M-8, which had 83 to 88% identity with the previously described CTX-M enzymes. The phylogenic study of the CTX-M family including CTX-M-8 revealed four CTX-M types, CTX-M-8 being the first member of a new phylum of CTX-M enzymes. The evolutionary distances between the four types of CTX-M were large, suggesting that the four clusters branched off early from a distant unknown enzyme and that intermediate enzymes probably existed.

Антимікробна резистентність провідних збудників інфекцій сечових шляхів у Києві (Україна)

2017 ◽  
Vol 1 (2) ◽  
pp. 48-60
Author(s):  
A.G. Salmanov ◽  
A.V. Rudenko
Keyword(s):  
Escherichia Coli ◽  
Pseudomonas Aeruginosa ◽  
Klebsiella Pneumoniae ◽  
Staphylococcus Epidermidis ◽  
Klebsiella Oxytoca ◽  
Enterobacter Aerogenes ◽  
Enterobacter Cloacae ◽  
Proteus Vulgaris ◽  
Providencia Rettgeri ◽  
E Coli

Мета роботи — вивчити резистентність до антибіотиків бактеріальних збудників інфекцій сечових шляхів (ІСШ), виділених у пацієнтів урологічного стаціонару в м. Києві. Матеріали і методи. Досліджено 1612 штамів бактерій, виділених із сечі хворих з ІСШ (цистит, уретрит, пієлонефрит), госпіталізованих в урологічне відділення ДУ «Інститут урології НАМН України» у м. Києві протягом 2016 р. Серед пацієнтів переважали жінки — 1201 (74,5 %). Вік хворих становив від 17 до 74 років. Для збору даних використано медичну документацію лікарні. Мікробіологічні дослідження виконано у лабораторії мікробіології ДУ «Інститут урології НАМН України». Аналізували результати культурального дослідження зразків сечі, зібраних за наявності клінічних ознак ІСШ. Дослідження клінічного матеріалу та інтерпретацію отриманих результатів проводили загальноприйнятими методами. Вивчено чутливість уропатогенів до 31 антибіотика дискодифузійним методом відповідно до рекомендацій Інституту клінічних та лабораторних стандартів США (Clinical and Laboratory Standards Institute (CLSI)). Результати та обговорення. Аналіз мікробного спектра сечі виявив домінування серед уропатогенів штамів Escherichia coli (32,0 %), Enterococcus faecalis (19,5 %), Klebsiella pneumoniae (10,9 %), Staphylococcus epidermidis (8,9 %), S. haemolyticus (6,5 %) та Pseudomonas aeruginosa (6,4 %). Частка Enterococcus faecium, Enterobacter aerogenes і Streptococcus viridans становила відповідно 2,5, 2,2 і 1,6 %, Enterobacter cloacae, Klebsiella oxytoca, Acinetobacter baumannii, Proteus vulgaris та Providencia rettgeri — менше 1,0 %. У більшості випадків (69,7 %) мікроорганізми виділено у монокультурі, у решті випадків — у мікробних асоціа- ціях. Високу резистентність до тестованих антибіотиків виявили штами E. aerogenes (45,1 %), E. cloacae (45,7 %), E. faecium (40,9 %), E. faecalis (40,7 %), E. coli (39,9 %), P. aeruginosa (34,0 %), K. pneumoniae (28,6 %). Найбільш активними до уропатогенів були іміпенем (E. coli — 87,6 %, P. aeruginosa — 75,7 %, E. cloacae — 67,3 %, E. aerogenes — 72,6 %, K. pneumoniae — 93,2 %), меропенем (E. coli — 89,1 %, P. aeruginosa — 76,7 %, K. pneumoniae — 82,6 %), лефлоцин (E. coli — 74,5 %, ентерококи — 78,7 %, P. aeruginosa — 76,7 %, E. cloacae — 73,9 %, E. aerogenes — 80,4 %, K. pneumoniae — 83,5 %), амоксицилін/клавуланат (ентерококи — 84,6 %), фурагін (ентерококи — 82,6 %), цефоперазон (K. pneumoniae — 89,2 %, P. aeruginosa — 73,8 %), цефтріаксон (K. pneumoniae — 80,1 %). Висновки. Антибіотикорезистентність збудників ІСШ — важлива терапевтична проблема. Найбільшою активністю до уропатогенів характеризуються іміпенем, меропенем, лефлоцин, амоксицилін/ клавуланат, фурагін, цефоперазон, цефтріаксон, які можна розглядати як препарат вибору для призначення стартової терапії ІСШ. Необхідно здійснювати постійний моніторинг за резистентністю до дії антибіотиків. Політику використання антибіотиків у кожному стаціонарі слід визначати залежно від локальних даних щодо резистентності до протимікробних препаратів.

scholarly journals BEL-1, a Novel Clavulanic Acid-Inhibited Extended-Spectrum β-Lactamase, and the Class 1 Integron In120 in Pseudomonas aeruginosa

2005 ◽  
Vol 49 (9) ◽  
pp. 3743-3748 ◽  
Author(s):  
Laurent Poirel ◽  
Laura Brinas ◽  
Annemie Verlinde ◽  
Louis Ide ◽  
Patrice Nordmann
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Clavulanic Acid ◽  
Cloning And Sequencing ◽  
Class 1 Integron ◽  
Gene Cassettes ◽  
Esbl Gene ◽  
Class A ◽  
Class 1 ◽  
Synergy Test ◽  
Specific Sequences

ABSTRACT Screening by a double-disk synergy test identified a Pseudomonas aeruginosa isolate that produced a clavulanic acid-inhibited expanded-spectrum β-lactamase (ESBL). Cloning and sequencing identified a novel ESBL, BEL-1, weakly related to other Ambler class A ESBLs. β-Lactamase BEL-1 hydrolyzed significantly most expanded-spectrum cephalosporins and aztreonam, and its activity was inhibited by clavulanic acid, tazobactam, cefoxitin, moxalactam, and imipenem. This chromosome-encoded ESBL gene was embedded in a class 1 integron containing three other gene cassettes. In addition, this integron was bracketed by Tn1404 transposon sequences at its right end and by P. aeruginosa-specific sequences at its left end.

scholarly journals Interactions of Ceftobiprole with β-Lactamases from Molecular Classes A to D

2007 ◽  
Vol 51 (9) ◽  
pp. 3089-3095 ◽  
Author(s):  
Anne Marie Queenan ◽  
Wenchi Shang ◽  
Malgosia Kania ◽  
Malcolm G. P. Page ◽  
Karen Bush
Keyword(s):  
Functional Groups ◽  
Hydrolytic Stability ◽  
Enterobacter Cloacae ◽  
Class A ◽  
Extended Spectrum ◽  
Class D ◽  
The Family ◽  
Class B ◽  
The Common ◽  
Antibacterial Spectrum

ABSTRACT The interactions of ceftobiprole with purified β-lactamases from molecular classes A, B, C, and D were determined and compared with those of benzylpenicillin, cephaloridine, cefepime, and ceftazidime. Enzymes were selected from functional groups 1, 2a, 2b, 2be, 2d, 2e, and 3 to represent β-lactamases from organisms within the antibacterial spectrum of ceftobiprole. Ceftobiprole was refractory to hydrolysis by the common staphylococcal PC1 β-lactamase, the class A TEM-1 β-lactamase, and the class C AmpC β-lactamase but was labile to hydrolysis by class B, class D, and class A extended-spectrum β-lactamases. Cefepime and ceftazidime followed similar patterns. In most cases, the hydrolytic stability of a substrate correlated with the MIC for the producing organism. Ceftobiprole and cefepime generally had lower MICs than ceftazidime for AmpC-producing organisms, particularly AmpC-overexpressing Enterobacter cloacae organisms. However, all three cephalosporins were hydrolyzed very slowly by AmpC cephalosporinases, suggesting that factors other than β-lactamase stability contribute to lower ceftobiprole and cefepime MICs against many members of the family Enterobacteriaceae.

scholarly journals Fatores de risco e perfil do uso de antimicrobianos entre pacientes com infecção no trato urinário em uma unidade de terapia intensiva

2021 ◽  
Vol 10 (3) ◽  
pp. e43910313516
Author(s):  
Lucas Harassim ◽  
Olibio Lopes Fiebig da Silva ◽  
Luiz Felipe Soares Pinheiro ◽  
Elber José Assaiante dos Santos ◽  
Cláudio Daniel Cerdeira ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Pseudomonas Aeruginosa ◽  
Klebsiella Oxytoca ◽  
Enterobacter Aerogenes ◽  
Enterobacter Cloacae ◽  
Citrobacter Freundii ◽  
Providencia Rettgeri ◽  
E Coli ◽  
Terapia Intensiva

A Infecção no Trato Urinário (ITU) acometendo pacientes em Unidades de Terapia Intensiva (UTIs) é uma realidade preocupante, agravada pelo uso irracional de antimicrobianos e a alarmante multirresistência em microrganismos. Nós avaliamos o nível de assertividade quanto ao uso de antimicrobianos durante à antibioticoterapia empírica (ATE), em pacientes diagnosticados com ITU, comparando tal tratamento farmacológico empírico e o realizado após o antibiograma (antibioticoterapia direcionada), além disto, estimamos a prevalência dos agentes etiológicos e analisamos os fatores de risco associados. Este é um estudo observacional e transversal, realizado em 2015, no qual foram avaliados pacientes de ambos os sexos e todas as idades apresentando ITU e submetidos à antibioticoterapia, internados em uma UTI de um hospital no sul de Minas Gerais, Brasil. Dos 49 pacientes avaliados (28 mulheres [M] e 21 homens [H]), a média de idade foi 55±19 anos (IC(95) 49-61) e a faixa etária ≥70 anos foi a predominante. Quatorze diferentes microrganismos foram causadores de ITUs, sendo que 28,3% (IC(95%) 16,2-40,4) dos isolados clínicos tiveram Escherichia coli como o agente etiológico (33,3% H e 28,6% M); 18,9% (IC(95%) 8,3-29,4) Acinetobacter baumannii (33,3% H e 10,7% M); 15,1% (IC(95%) 5,5-24,7) Klebsiella pneumoniae (19% H e 14,3% M); 11,3% Pseudomonas aeruginosa (9,5% H e 14,3% M); 5,7% Enterobacter aerogenes (14,3% H); 3,8% Klebsiella oxytoca; 3,8% Staphylococcus aureus (7,1% M); e 1,9% para cada um dos seguintes microrganismos: Enterococcus faecalis (4,8% H); Proteus mirabilis (3,6% M); Enterobacter cloacae (3,6% M); Providencia rettgeri (4,8% H); Citrobacter koseri (3,6% M); Citrobacter freundii (3,6% M); e Fungos leveduriformes (4,8% H). As prevalências de ITUs causadas por A. baumannii e P. aeruginosa foram influenciadas pelo sexo (χ² com p<0,001). No sexo masculino, houve correlações positivas “substanciais” entre o aumento da idade (em anos) e a prevalência de ITU causada por E. coli (r = 0,69) ou entre idades menos avançadas e a prevalência de ITU causada por A. baumannii (r = -0,7). No sexo feminino, houve uma correlação positiva “extremamente forte” entre o aumento da idade e a prevalência de ITU causada por E. coli (r = 0,94; IC(95) 0,66-0,99; p<0,0014). Os antibióticos mais utilizados de forma empírica (ATE) foram: Ciprofloxacina (14,3% IC(95%) 4,7-24,1), Cefepima (14,3%) e Vancomicina (10%), e após o antibiograma (antibioticoterapia direcionada): Ceftazidima (16,3% IC(95%) 6-26,7), Ciprofloxacina (14,3% IC(95%) 4,5-24,1), Polimixina B (10,2%), Imipenem (10,2%) e Ampicilina + Sulbac. (8,2%). Em 20% dos casos, as terapias empíricas (ATE) foram consideradas “inapropriadas/não acertadas”. Contudo, também devemos ter ciência da necessidade clínica e quanto ao imediatismo para o tratamento de uma ITU em UTI, uma vez que a doença pode ser fatal se uma terapia não for instituída, portanto, nós aconselhamos avaliações mais minuciosas, tanto da racionalidade do uso de antibióticos, quanto dos fatores de risco para o desenvolvimento de ITUs em UTIs.

scholarly journals Chromosomally Encoded AmpC-Type β-Lactamase in a Clinical Isolate of Proteus mirabilis

1998 ◽  
Vol 42 (5) ◽  
pp. 1110-1114 ◽  
Author(s):  
L. Bret ◽  
C. Chanal-Claris ◽  
D. Sirot ◽  
E. B. Chaibi ◽  
R. Labia ◽  
...  
Keyword(s):  
Proteus Mirabilis ◽  
Point Mutations ◽  
Enterobacter Aerogenes ◽  
Enterobacter Cloacae ◽  
Clinical Strain ◽  
Citrobacter Freundii ◽  
Specific Primers ◽  
E Coli ◽  
Dna Fragment ◽  
Urine Specimens

ABSTRACT A clinical strain of Proteus mirabilis (CF09) isolated from urine specimens of a patient displayed resistance to amoxicillin (MIC >4,096 μg/ml), ticarcillin (4,096 μg/ml), cefoxitin (64 μg/ml), cefotaxime (256 μg/ml), and ceftazidime (128 μg/ml) and required an elevated MIC of aztreonam (4 μg/ml). Clavulanic acid did not act synergistically with cephalosporins. Two β-lactamases with apparent pIs of 5.6 and 9.0 were identified by isoelectric focusing on a gel. Substrate and inhibition profiles were characteristic of an AmpC-type β-lactamase with a pI of 9.0. Amplification by PCR with primers for ampC genes (Escherichia coli,Enterobacter cloacae, and Citrobacter freundii) of a 756-bp DNA fragment from strain CF09 was obtained only withC. freundii-specific primers. Hybridization results showed that the ampC gene is only chromosomally located while theTEM gene is plasmid located. After cloning of the gene, analysis of the complete nucleotide sequence (1,146 bp) showed that this ampC gene is close tobla CMY-2, from which it differs by three point mutations leading to amino acid substitutions Glu → Gly at position 22, Trp → Arg at position 201, and Ser → Asn at position 343. AmpC β-lactamases derived from that of C. freundii (LAT-1, LAT-2, BIL-1, and CMY-2) have been found in Klebsiella pneumoniae, E. coli, and Enterobacter aerogenes and have been reported to be plasmid borne. This is the first example of a chromosomally encoded AmpC-type β-lactamase observed in P. mirabilis. We suggest that it be designated CMY-3.

scholarly journals Characterization of SFO-1, a Plasmid-Mediated Inducible Class A β-Lactamase from Enterobacter cloacae

1999 ◽  
Vol 43 (2) ◽  
pp. 307-313 ◽  
Author(s):  
Yoshimi Matsumoto ◽  
Matsuhisa Inoue
Keyword(s):  
Klebsiella Oxytoca ◽  
Enterobacter Cloacae ◽  
Gram Negative Bacteria ◽  
Phenotypic Characteristics ◽  
Gene Encoding ◽  
E Coli ◽  
Class A ◽  
Citrobacter Diversus ◽  
High Degree

ABSTRACT Enterobacter cloacae 8009 produced an inducible class A β-lactamase which hydrolyzed cefotaxime efficiently. It also hydrolyzed other β-lactams except cephamycins and carbapenems. The activity was inhibited by clavulanic acid and imipenem. Thebla gene was transferable to Escherichia coliby electroporation of plasmid DNA. The molecular mass of the β-lactamase was 29 kDa and its pI was 7.3. All of these phenotypic characteristics of the enzyme except for inducible production resemble those of some extended-spectrum class A β-lactamases like FEC-1. The gene encoding this β-lactamase was cloned and sequenced. The deduced amino acid sequence of the β-lactamase was homologous to the AmpA sequences of the Serratia fonticola chromosomal enzyme (96%), MEN-1 (78%), Klebsiella oxytoca chromosomal enzymes (77%), TOHO-1 (75%), and FEC-1 (72%). The conserved sequences of class A β-lactamases, including the S-X(T)-X(S)-K motif, in the active site were all conserved in this enzyme. On the basis of the high degree of homology to the β-lactamase of S. fonticola, the enzyme was named SFO-1. The ampR gene was located upstream of the ampA gene, and the AmpR sequence of SFO-1 had homology with the AmpR sequences of the chromosomal β-lactamases from Citrobacter diversus(80%), Proteus vulgaris (68%), and Pseudomonas aeruginosa (60%). SFO-1 was also inducible in E. coli. However, a transformant harboring plasmid without intactampR produced a small amount of β-lactamase constitutively, suggesting that AmpR works as an activator ofampA of SFO-1. This is the first report from Japan describing an inducible plasmid-mediated class A β-lactamase in gram-negative bacteria.

scholarly journals Extended-Spectrum β-Lactamases in Ireland, Including a Novel Enzyme, TEM-102

2003 ◽  
Vol 47 (8) ◽  
pp. 2572-2578 ◽  
Author(s):  
Dearbháile Morris ◽  
Colette O'Hare ◽  
Maura Glennon ◽  
Majella Maher ◽  
Geraldine Corbett-Feeney ◽  
...  
Keyword(s):  
Molecular Typing ◽  
Clinical Laboratory ◽  
Enterobacter Cloacae ◽  
Disk Diffusion ◽  
National Committee ◽  
Esbl Production ◽  
Esbl Gene ◽  
Extended Spectrum ◽  
The Family ◽  
Esbl Producers

ABSTRACT Organisms producing extended-spectrum β-lactamases (ESBLs) have been reported in many countries, but there is no information on the prevalence of ESBL-producing members of the family Enterobacteriaceae in Ireland. A total of 925 isolates of ampicillin-resistant members of the Enterobacteriaceae were received from six hospitals in Ireland over a 3-year period from September 1996 to September 1999. Isolates were screened for ESBL production by the double-disk diffusion (DDD) method. DDD-positive isolates that were (i) confirmed as ESBL producers by National Committee for Clinical Laboratory Standards (NCCLS) confirmatory testing and (ii) susceptible to cefoxitin by disk diffusion were considered ESBL producers. By these criteria, 27 (3%) of the ampicillin-resistant members of the Enterobacteriaceae studied were categorized as ESBL producers. Molecular typing suggested that some intra- and interhospital spread of ESBL-producing isolates had occurred. DNA sequencing of amplified bla TEM and bla SHV genes resulted in the detection of a novel bla TEM ESBL gene, bla TEM-102 in two isolates (Klebsiella pneumoniae and Enterobacter cloacae) received from the same hospital but isolated from different patients. The study suggests dissemination of ESBL-producing bacteria within the health care system in Ireland and emphasizes the need for measures to control such spread.

scholarly journals AmpC β-Lactamases

2009 ◽  
Vol 22 (1) ◽  
pp. 161-182 ◽  
Author(s):  
George A. Jacoby
Keyword(s):  
Broad Spectrum ◽  
Efflux Pump ◽  
Clinical Laboratory ◽  
Resistance Mechanism ◽  
Enterobacter Aerogenes ◽  
Carbapenem Resistance ◽  
Enterobacter Cloacae ◽  
Outer Membrane Porin ◽  
The World ◽  
Plasmid Genes

SUMMARY AmpC β-lactamases are clinically important cephalosporinases encoded on the chromosomes of many of the Enterobacteriaceae and a few other organisms, where they mediate resistance to cephalothin, cefazolin, cefoxitin, most penicillins, and β-lactamase inhibitor-β-lactam combinations. In many bacteria, AmpC enzymes are inducible and can be expressed at high levels by mutation. Overexpression confers resistance to broad-spectrum cephalosporins including cefotaxime, ceftazidime, and ceftriaxone and is a problem especially in infections due to Enterobacter aerogenes and Enterobacter cloacae, where an isolate initially susceptible to these agents may become resistant upon therapy. Transmissible plasmids have acquired genes for AmpC enzymes, which consequently can now appear in bacteria lacking or poorly expressing a chromosomal blaAmpC gene, such as Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis. Resistance due to plasmid-mediated AmpC enzymes is less common than extended-spectrum β-lactamase production in most parts of the world but may be both harder to detect and broader in spectrum. AmpC enzymes encoded by both chromosomal and plasmid genes are also evolving to hydrolyze broad-spectrum cephalosporins more efficiently. Techniques to identify AmpC β-lactamase-producing isolates are available but are still evolving and are not yet optimized for the clinical laboratory, which probably now underestimates this resistance mechanism. Carbapenems can usually be used to treat infections due to AmpC-producing bacteria, but carbapenem resistance can arise in some organisms by mutations that reduce influx (outer membrane porin loss) or enhance efflux (efflux pump activation).

scholarly journals Modified Carbapenem Inactivation Method for Phenotypic Detection of Carbapenemase Production among Enterobacteriaceae

2017 ◽  
Vol 55 (8) ◽  
pp. 2321-2333 ◽  
Author(s):  
Virginia M. Pierce ◽  
Patricia J. Simner ◽  
David R. Lonsway ◽  
Darcie E. Roe-Carpenter ◽  
J. Kristie Johnson ◽  
...  
Keyword(s):  
Validation Study ◽  
Clinical Laboratory ◽  
Zone Size ◽  
Bacterial Isolates ◽  
Content Type ◽  
Second Stage ◽  
Class A ◽  
Carbapenem Resistant ◽  
The Family ◽  
Excellent Reproducibility

ABSTRACT The ability of clinical microbiology laboratories to reliably detect carbapenemase-producing carbapenem-resistant Enterobacteriaceae (CP-CRE) is an important element of the effort to prevent and contain the spread of these pathogens and an integral part of antimicrobial stewardship. All existing methods have limitations. A new, straightforward, inexpensive, and specific phenotypic method for the detection of carbapenemase production, the carbapenem inactivation method (CIM), was recently described. Here we describe a two-stage evaluation of a modified carbapenem inactivation method (mCIM), in which tryptic soy broth was substituted for water during the inactivation step and the length of this incubation was extended. A validation study was performed in a single clinical laboratory to determine the accuracy of the mCIM, followed by a nine-laboratory study to verify the reproducibility of these results and define the zone size cutoff that best discriminated between CP-CRE and members of the family Enterobacteriaceae that do not produce carbapenemases. Bacterial isolates previously characterized through whole-genome sequencing or targeted PCR as to the presence or absence of carbapenemase genes were tested for carbapenemase production using the mCIM; isolates with Ambler class A, B, and D carbapenemases, non-CP-CRE isolates, and carbapenem-susceptible isolates were included. The sensitivity of the mCIM observed in the validation study was 99% (95% confidence interval [95% CI], 93% to 100%), and the specificity was 100% (95% CI, 82% to 100%). In the second stage of the study, the range of sensitivities observed across nine laboratories was 93% to 100%, with a mean of 97%; the range of specificities was 97% to 100%, with a mean of 99%. The mCIM was easy to perform and interpret for Enterobacteriaceae , with results in less than 24 h and excellent reproducibility across laboratories.

scholarly journals Genetic Structure and Distribution of the Colibactin Genomic Island among Members of the Family Enterobacteriaceae

2009 ◽  
Vol 77 (11) ◽  
pp. 4696-4703 ◽  
Author(s):  
Johannes Putze ◽  
Claire Hennequin ◽  
Jean-Philippe Nougayrède ◽  
Wenlan Zhang ◽  
Stefan Homburg ◽  
...  
Keyword(s):  
Tandem Repeats ◽  
Genomic Island ◽  
Enterobacter Aerogenes ◽  
Eukaryotic Cell ◽  
Phylogenetic Group ◽  
Putative Hybrid ◽  
Trna Genes ◽  
Structural Variations ◽  
E Coli ◽  
The Family

ABSTRACT A genomic island encoding the biosynthesis and secretion pathway of putative hybrid nonribosomal peptide-polyketide colibactin has been recently described in Escherichia coli. Colibactin acts as a cyclomodulin and blocks the eukaryotic cell cycle. The origin and prevalence of the colibactin island among enterobacteria are unknown. We therefore screened 1,565 isolates of different genera and species related to the Enterobacteriaceae by PCR for the presence of this DNA element. The island was detected not only in E. coli but also in Klebsiella pneumoniae, Enterobacter aerogenes, and Citrobacter koseri isolates. It was highly conserved among these species and was always associated with the yersiniabactin determinant. Structural variations between individual strains were only observed in an intergenic region containing variable numbers of tandem repeats. In E. coli, the colibactin island was usually restricted to isolates of phylogenetic group B2 and inserted at the asnW tRNA locus. Interestingly, in K. pneumoniae, E. aerogenes, C. koseri, and three E. coli strains of phylogenetic group B1, the functional colibactin determinant was associated with a genetic element similar to the integrative and conjugative elements ICEEc1 and ICEKp1 and to several enterobacterial plasmids. Different asn tRNA genes served as chromosomal insertion sites of the ICE-associated colibactin determinant: asnU in the three E. coli strains of ECOR group B1, and different asn tRNA loci in K. pneumoniae. The detection of the colibactin genes associated with an ICE-like element in several enterobacteria provides new insights into the spread of this gene cluster and its putative mode of transfer. Our results shed light on the mechanisms of genetic exchange between members of the family Enterobacteriaceae.

Sign in / Sign up

Export Citation Format

Share Document