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1.
Bujdáková H Hanzen J Jankovicová S Klimácková J Moravcíková M Milosovic P Michálková-Papajová D Kallová J Jakab A Kettner M 《Folia microbiologica》2001,46(4):339-344
Occurrence and transferability of β-lactam resistance in 30 multi-resistantEscherichia coli, Klebsiella spp.,Enterobacter spp.,Pantoea agglomerans, Citrobacter freundii andSerratia marcescens strains isolated from children between 0 and 3 years of age is presented. The strains were resistant to ampicillin (30),
cefoxitin (22), cefotaxime (30), ceftriaxone (30), ceftazidime (30) and aztreonam (28), but susceptible to cefepime (30) and
imipenem (26). Twenty-eight of 30 isolates possessed a transferable resistance confirmed by conjugation and isolation of 79–89-kb
plasmids. The β-lactam resistance was due to production of β-lactamases and ceftazidime proved to be stronger β-lactamase
inductor than ceftriaxone. Twenty-five clinical isolates expressed transferable extended spectrum β-lactamases, and chromosomally
encoded AmpC β-lactamase. 相似文献
2.
Ferreira LQ Avelar KE Vieira JM de Paula GR Colombo AP Domingues RM Ferreira MC 《Current microbiology》2007,54(5):348-353
The Bacteroides genus, the most prevalent anaerobic bacteria of the intestinal tract, carries a plethora of the mobile elements, such as
plasmids and conjugative and mobilizable transposons, which are probably responsible for the spreading of resistance genes.
Production of β-lactamases is the most important resistance mechanism including cephalosporin resistance to β-lactam agents
in species of the Bacteroides fragilis group. In our previous study, the cfxA gene was detected in B. distasonis species, which encodes a clinically significant broad-spectrum β-lactamase responsible for widespread resistance to cefoxitin
and other β-lactams. Such gene has been associated with the mobilizable transposon Tn4555. Therefore, the aim of this study was to detect the association between the cfxA gene and the presence of transposon Tn4555 in 53 Bacteroides strains isolated in Rio de Janeiro, Brazil, by PCR assay. The cfxA gene was detected in 11 strains and the Tn4555 in 15. The transposon sequence revealed similarities of approximately 96% with the B. vulgatus sequence which has been deposited in GenBank. Hybridization assay was performed in attempt to detect the cfxA gene in the transposon. It was possible to associate the cfxA gene in 11 of 15 strains that harbored Tn4555. Among such strains, 9 presented the cfxA gene as well as Tn4555, but in 2 strains the cfxA gene was not detected by PCR assay. Our results confirm the involvement of Tn4555 in spreading the cfxA gene in Bacteroides species. 相似文献
3.
Carbapenems such as imipenem are stable to most β-lactamases. Recently, increased numbers of carbapenemase producing Gram-negative
bacterial strains have been isolated because of the increased use of cabapenems. In this respect, control of these infectious
carbapenemase producing Gram-negative bacteria and understanding their resistance mechanism are becoming more important. These
carbapenem-hydrolyzing β-lactamase genes have been reported to exist mostly as gene cassettes in an integron. This implies
that antibiotic resistance genes may be transferred to other bacteria via the integron. In the present study, we identified
and analyzed an integron containing VIM-2 type metallo-β-lactamase gene in a carbapenemase producing Pseudomonas aeruginosa. In addition, the possibility of resistance spread by integron located in a plasmid was tested. Among glucose non-fermenting
Gram-negative bacilli with reduced imipenem susceptibility (MIC≥8 μg/ml) isolated from Korean patients, P. aeruginosa 1082 showed resistance to most β-lactams, cephalosporin, and aminoglycoside. We found that P. aeruginosa 1082 was inhibited by EDTA in EDTA double disk synergy test which means that this strain produces metallo-β-lactamase. Class
1 integron containing bla
VIM-2 (carbapenem resistance gene), qacF (quaternary ammonium compound resistance gene), aacA4 (aminoglycoside resistance gene), catB3 (chloramphenicol resistance gene), bla
oxa-30 (extended-spectrum β-lactam resistance gene), and aadAl (aminoglycoside resistance gene) gene cassettes was detected in P. aeruginosa 1082. The size of the integron was 5,246 bp and the structure and arrangement of the integron was a novel one in comparison
with other integrons found in other P. aeruginosa. The integron could be transferred to Escherichia coli JM109 from P. aeruginosa 1082 possibly via self-transferable plasmid DNA. The integron and a bla
VIM-2 gene were detected in the plasmid DNA of the transconjugants whose imipenem resistance was slightly increased as a result
of accepting the integron from the donor strain. 相似文献
4.
5.
Songmee Bae Jaehoon Lee Eunah Kim Jaehwa Lee Jaeyon Yu Yeonho Kang 《Journal of microbiology (Seoul, Korea)》2010,48(1):84-88
Haemophilus influenzae is a frequent causative bacterial pathogen of respiratory tract infections. Resistance to β-lactam antibiotics has been a
significant clinical problem in treatment for H. influenzae respiratory infections. This study describes the serotype, antibiotic resistance and distribution of TEM-1 or ROB-1 β-lactamase
in H. influenzae isolates from local private hospitals from 2002 to 2004. Among the 100 H. influenzae respiratory isolates, only 7% were identified as serotypes a, b, e, and f, with the remaining 93% being nontypeable. Resistance
to ampicillin, cefaclor, and tetracycline was 57%, 46%, and 16%, respectively. All strains were susceptible to azithromycin
and ciprofloxacin, whereas amoxicillin/clavulanate, cefotaxime, and imipenem exhibited reduced susceptibilities of 99%, 99%,
and 91%, respectively. All 57 ampicillinresistant strains (minimum inhibitory concentration, MIC≥4 μg/ml) were β-lactamase-positive
and possessed the TEM-1 type β-lactamase. One β-lactamase-positive amoxicillin/clavulanate-resistant isolate that was resistant
to ampicillin (MIC>128 μg/ml) had the TEM-1 type β-lactamase and not susceptible to cefaclor and cefotaxime. Analysis of penicillin
binding protein 3 revealed six residues (Asp-350, Met-377, Ala-502, Asn-526, Val-547, and Asn-569) that were substituted by
Asn, Ile, Val, Lys, Ile, and Ser, respectively. 相似文献
6.
Terrance O. Kurtz Drew J. Winston William J. Martin Lowell S. Young William L. Hewitt 《Current microbiology》1980,4(1):21-26
Moxalactam (LY127935), a novel beta-lactam antibiotic, was compared with semisynthetic penicillins, cephalosporins, and aminoglycosides
by the agar dilution method against 5,317 recent clinical isolates of facultative and anaerobic bactria. At 0.5 μg/ml, moxalactam
inhibited 90% of all Gram-negative bacilli tested except forPseudomonas aeruginosa (81% inhibited by 32 μg/ml) andAcinetobacter calcoaceticus (88% inhibited by 32 μg/ml). More than 90% ofBacteroides fragilis andStaphylococcus aureus were inhibited by 4 μg/ml and 8 μg/ml, respectively. Moxalactam was at least 16-fold more active by weight than cephalothin,
cefamandole, and cefoxitin forEscherichia coli, Klebsiella pneumoniae, andEnterobacter species, and 2- to 4-fold more active than cefoxitin forB. fragilis. Moxalactam was 4-fold less active than cefamandole and cephalothin forS. aureus and 2- to 4-fold less active than piperacillin forP. aeruginosa. Moxalactam was as active or more active than the aminoglycosides for all facultative Gram-negative bacilli except forP. aeruginosa. Moxalactam was inhibitory (minimal inhibitory concentration <16 μg/ml) for 20/27 gentamicin-resistant isolates and 8/13
amikacin-resistant organisms. Moxalactam’s in vitro activity against Gram-negative bacilli is markedly superior to presently
available cephalosporins and, except forP. aeruginosa, is comparable to the aminoglycosides. 相似文献
7.
From water samples collected monthly between 2000 and 2001 from the Han River in Seoul, sixteen strains of Escherichia coli which confer resistance to at least 10 kinds of antimicrobial agents were isolated. From these isolates, 2 kinds of extended-spectrum
β-lactamases (ESBLs) and one plasmid-mediated AmpC β-lactamase were detected; CTX-M-14 from 10 isolates, TEM-52 from 5 isolates,
and CMY-1 from one isolate. Class 1 integron gene cassettes, such as aadA1, dfr12-orfF-aadA2, and dfr17-aadA5, were also detected and the integrons are the same as those found in E. coli isolated from swine, poultry, and humans in Korea. The result of this study indicated the importance of river water as a
reservoir for antimicrobial resistance genes and resistant bacteria. 相似文献
8.
Muhammad Yaqoob Li Ping Wang Tang Fang Cheng-Ping Lu 《World journal of microbiology & biotechnology》2011,27(9):2041-2050
Thirty four avian Escherichia coli isolates were collected from different cities of Punjab province, Pakistan during 2008–2009. Twenty five phenotypic highly
ampicillin-resistant (MICs ≥ 256 μg/ml) avian E. coli strains were selected for the investigation of occurrence and transmission of class 1, 2 and 3 integrons and β-lactamase
genes. Amoxicillin, sulfonamide, trimethoprim, enrofloxacin, pefloxacin and tetracycline were the most common phenotypic resistant
among ampicillin-resistant avian E. coli strains. Integrons and β-lactamase were found 60 and 72% respectively. Class 1 and 2 integrons were found 52 and 8%, while class 3 integrons were
not found in all strains. All class 1 positive strains had variable fragments associated with gene cassettes dfrA7, dfrA1-aadA1, aadA1, aadA22 and dfrA12-orfF-aadA2 respectively, which confer resistance to trimethoprim and streptomycin. Class 2-positive strains had similar gene cassettes
array dfrA1-sat1-aadA1 conferring resistance to trimethoprim, streptothricin and spectinomicin/streptomycin. Integrons are frequently found in β-lactamase positive isolates and widely disseminate multidrug resistance genes but they do not play role in the spreading
of β-lactamase genes. Class 1 integrons gene cassette aadA22 is reported for the first time in avian E. coli. Findings of this study may provide important and useful information reflecting specific antibiotic selective pressure in
Punjab province, Pakistan. 相似文献
9.
Ahmet Yilmaz Coban Ugur Demırpek Tuba Yıldırım Yeliz Tanrıverdı Caycı Tanil Kocagoz Belma Durupınar 《World journal of microbiology & biotechnology》2011,27(8):1901-1904
In this study, it was aimed to evaluate colorimetric Quicolor ES agar for the rapid detection of methicillin resistance and
to determine susceptibility and resistance breakpoint zone diameters for cefoxitin by using 51 methicillin susceptible Staphylococcus aureus (MSSA) and 63 methicillin resistant S. aureus (MRSA) isolates. In the study, while oxacillin and cefoxitin results were obtained within 4–7 h (5.5 h in average) for MSSA
isolates, the results of MRSA isolates were obtained within 5.5–9 h (6.6 h in average) for both antibiotics on QC ES agar.
QC ES agar is an inexpensive medium for rapid detection (4–9 h) of methicillin resistance by disc diffusion method using oxacillin
or cefoxitin. Additional studies for further evaluation of the efficiency of QC-ES agar in rapid determination of methicillin
resistance in S. aureus may be beneficial. 相似文献
10.
Tejedor-Junco MT González-Martín M Lupiola P González-Lama Z 《Folia microbiologica》1998,43(6):683-686
The interaction of type-I β-lactamases fromEnterobacter cloacae with diverse β-lactam compounds was examined. The ability of penicillin and cefoxitin to induce β-lactamase production in
this strain was assessed. The effect of β-lactamase inhibitors was measured on β-lactamase extracts and on intact cells.E. cloacae 78 strain is a stably derepressed mutant showing limited susceptibility to a number of antibiotics except imipenem. Imipenem
would therefore be the appropiate choice for therapy of infections caused by stably derepressed mutants ofEnterobacter sp. producing type-I β-lactamases. 相似文献
11.
V. Kumar J. L. de la Fuente A. L. Leitão P. Liras J. F. Martin 《Applied microbiology and biotechnology》1996,45(5):621-628
The bla gene of the cephamycin cluster of Nocardia lactamdurans has been subcloned in the shuttle plasmids pULVK2 and pULVK2A and amplified in N. lactamdurans LC411. The transformants showed two- to threefold higher β-lactamase activity. Formation of β-lactamase preceded the onset
of cephamycin biosynthesis. The β-lactamase of N. lactamdurans inactivated penicillins and, to a lesser extent, cephalosporin C but did not hydrolyse cephamycin C. This β-lactamase was
highly sensitive to clavulanic acid (50% inhibition was observed at 0.48 μg/ml clavulanic acid). The N. lactamdurans bla gene was disrupted in vivo by inertion of the kanamycin-resistance gene. Three bla-disrupted mutants, BD4, BD8 and BD12, were selected that lacked β-lactamase activity. Overexpresion of the bla gene resulted in N. lactamdurans transformants that were resistant to penicillin whereas mutants in which the bla gene was disrupted were supersensitive to this antibiotic. The three N. lactamdurans mutants with the bla gene disrupted showed a significant increase of cephamycin biosynthesis in solid medium, whereas transformants with the amplified
bla gene produced reduced levels of cephamycin. The cephamycin-overproducing Merck strain N. lactamdurans MA4213 showed no detectable levels of β-lactamase activity. The β-lactamase plays a negative role in cephamycin biosynthesis
in solid medium, but not in liquid medium.
Received: 26 July 1995/Received revision: 18 December 1995/Accepted: 8 January 1996 相似文献
12.
Chunyan Wang Hongyue Dang Yongsheng Ding 《World journal of microbiology & biotechnology》2008,24(12):2889-2896
Environmental microbiology investigation was performed to determine the molecular diversity of β-lactamase genes among ampicillin-resistant
bacteria from Jiaozhou Bay. β-lactamase genes were detected in 93.8% of the bacterial isolates identified as Enterobacteriaceae. The most frequently detected gene was bla
TEM, followed by bla
SHV, bla
OAX-1, bla
MOX and bla
CMY. Most of the isolates (68.8%) were positive for the intI1 integrase gene, and two isolates were also found for the intI2 gene. The dfr and aadA gene cassettes were predominant. Anthropogenic contamination from onshore sewage processing plants might contribute predominantly
to the β-lactamase gene reservoir in the studied coastal waters. Environmental antibiotic-resistant bacteria and resistance
genes may serve as bioindicators of coastal environmental quality or biotracers of the potential contamination sources. This
is the first report of the prevalence and characterization of β-lactamase genes and integrons in coastal Enterobacteriaceae from China. 相似文献
13.
Of 50Salmonella species isolated from pigs, 30 were resistant to cadmium and 18 of these also to azlocillin. The azlocillin-resistant isolates
were resistant to cadmium at 80–500, mg/L CdSO4. A broader spectrum of resistance to azlocillin, ampicillin and cephazollin was found in strains resistant to <200 mg/L CdSO4. Resistance to silver, mercury, chloramphenicol and streptomycin was independent of the resistance to β-lactam antibiotics
and Cd2+. Production and levels of β-lactamase do not correlate with the spectrum of resistance. 相似文献
14.
《Anaerobe》1999,5(3-4):431-434
Bacteroides fragilis is one of the organisms known to produce carbapenem-hydrolysing metallo-β-lactamase, which can confer resistance to a wide variety of β-lactams. The purpose of this study was to identify carbapenem-hydrolysing metallo-β-lactamase-producing B. fragilis strains by means of PCR assay, nucleotide sequencing and enzyme inhibition studies. Ten β-lactam-resistant B. fragilis isolates were investigated. Four imipenem-resistant strains among the 10 isolates gave positive reactions in the PCR assay. The nucleotide sequences of the PCR products from two imipenem-resistant strains shared >98% similarity with the metallo-β-lactamase gene from B. fragilis TAL 3636, which was used as a control. The amino acid sequence homology between the two imipenem-resistant strains and B. fragilis TAL 3636 was 99.2%. These strains produced high amounts of Zn2+-dependent β-lactamases which were inactivated by EDTA. 相似文献
15.
G. O. Humphreys Geraldine A. Willshaw H. R. Smith E. S. Anderson 《Molecular & general genetics : MGG》1976,145(1):101-108
Summary An investigation of in vitro mutagenesis of plasmid DNA with hydroxylamine is described. The treated plasmid DNA was used to transform Escherichia coli K12. Mutants of the plasmid NTP3, which codes for resistance to ampicillin and sulphonamides, were isolated and characterised. They were classified according to the reduction in level of their -lactamase activity. Hydroxylamine-induced mutants of NTP14 were also isolated. This plasmid codes for ampicillin resistance, synthesis of colicin E1, and the EcoRI restriction and modification enzymes. One class of mutants is lethal to the host strain at temperatures above 33° C, but carrier strains grow well at 28° C. There is evidence that these mutants code for a temperature-sensitive EcoRI modification activity: the lethal effect probably results from the cleavage of the host-cell DNA by the restriction enzyme at non-permissive temperatures. The possible genetic uses of the mutant plasmids for the production of hybrid plasmids in the bacterial cell are discussed. 相似文献
16.
Staphylococcal Cassette Chromosome mec (SCCmec) is a mobile genetic element that carries the gene mecA mediating the methicillin resistance in staphylococci. It is composed of mec and ccr gene complexes. Six SCCmec types have been defined so far. SCCmec typing of 13 methicillin-resistant Staphylococcus aureus (MRSA) out of 72 (18%) non redundant S. aureus strains recovered in 1998–2007 at the Bone Marrow Transplant Centre of Tunis was carried out. The isolates were identified
by conventional methods. Antibiotic susceptibility was determined by oxacillin and cefoxitin disks and oxacillin MIC by E-test.
Methicillin resistance was detected by mecA PCR. The SCCmec complex types were determined by PCR. The epidemiology of MRSA has been investigated by PFGE. Among 13 mecA positive strains, 12 were resistant to oxacillin (MIC = 3 to >256 μg/μl) and to cefoxitin and one strain was pre-resistant:
susceptible to oxacillin (MIC = 0.19 μg/μl) and to cefoxitin. Hospital-acquired MRSA (HA-MRSA) strains had essentially SCCmec type IV (nine strains) or III (two strains) or I (one strain). One strain shown to carry ccrAB1 and ccrAB2 genes in combination with class B mec. Seven of 13 MRSA strains isolated from 2000 to 2006 were classified with major similarity group A harbored SCCmec type IV. 相似文献
17.
Transfer of plasmid-borne resistance from a multiply-resistant Staphylococcus aureus isolate,WBG1022
Staphylococcus aureus isolate, WBG1022, was resistant to penicillin, kanamycin, neomycin, streptomycin, chloramphenicol, trimethoprim, cadmium, and ethidium bromide and harbored plasmids of 34.5, 24.5, 4.4, 3.2, and 2.6 kilobases. The plasmids were transferred in mixed-culture transfer and conjugation experiments. No resistance phenotype was associated with the 2.6-kb plasmid. The 3.2-kb and 4.4-kb plasmids encoded chloramphenicol and streptomycin resistance respectively. The 24.5-kb plasmid, pWBG626, encoded joint resistance to penicillin, kanamycin, neomycin, and ethidium bromide. Resistance to trimethoprim and cadmium were chromosomal. The 34.5-kb plasmid, pWBG661, had no resistance phenotype but was found to be conjugative. It also mobilized the 4.4-kb and 24.5-kb plasmids in WBG1022. Restriction endonuclease analysis of pWBG661 with EcoRI, ClaI, PvuII, and BglII restriction enzymes demonstrated that pWBG661 was identical to two previously isolated S. aureus conjugative plasmids, p WBG620 and pWBG637, that also lack resistance phenotypes. 相似文献
18.
Jun Cheng Wei Gao Jun Yin Zhen Sun Ying Ye Yu-Feng Gao Xu Li Jia-Bin Li 《Molecular biology reports》2010,37(3):1261-1267
Two clinical strains (Klebsiella
pneumoniae 516 and K.
pneumoniae 1335) collected in September 2006 from different hospitals in Anhui Province (China) harboured two novel plasmid-mediated
bla
CTX-M genes, designated bla
CTX-M-80 and bla
CTX-M-81, respectively. Both CTX-M-80 with pI of 9.0 and CTX-M-81 with pI of 8.4 were extended-spectrum β-lactamases (ESBLs). The
results of susceptibility testing demonstrated two enzymes were highly activity against broad spectrum β-lactams, but the
level of resistance was reduced with the addition of β-lactamase inhibitors. The bla
CTX-M-80 gene was detected on a 110-kb plasmid and the bla
CTX-M-81 gene existed on a 120-kb plasmid. The deduced amino acid sequence of CTX-M-80 differed from that of CTX-M-3 by the substitution
Ala-27→Val, and CTX-M-81 possessed the Lys→Glu, Lys→Gln, and Asn→His changes at respective position 82, 98, and 132 in compassion
with CTX-M-14. The enzymatic properties showed CTX-M-80 and CTX-M-81 had higher affinities for penicillin G (lower Km values) than for cephalosporins. The activities of novel enzymes against ceftazidime were undetectable or limited, as indicated
by MICs data, the same response being observed for many other CTX-M enzymes. This report was evidence of the diversity of
CTX-M-type ESBLs in China. 相似文献
19.
The fate of gene duplicates subjected to diversifying selection was tested experimentally in a bacterial system. The wild-type
TEM-1 β-lactamase gene confers resistance to ampicillin but not to cefotaxime. Point mutations confer cefotaxime resistance, but they compromise
ampicillin resistance. Thus, selection for both drug resistances in a bacterium with two copies of β-lactamase should favor the divergence of one copy to improve cefotaxime resistance while maintaining the other copy to preserve ampicillin
resistance. This selection was performed on a bacterium with identical sequences of β-lactamase on two separate, compatible plasmids. As expected, one plasmid evolved increased cefotaxime resistance when appropriately
strong cefotaxime selection was applied. However, the cefotaxime-resistant plasmid maintained sufficient ampicillin resistance
to tolerate the concentration of ampicillin used, and the other plasmid was lost. Hosts carrying both the cefotaxime-resistant
and wild-type plasmids were then subjected to various higher concentrations of both drugs to find conditions that would ensure
the maintenance of both plasmids. In a striking contradiction to our model, no such conditions were found. The fitness cost
of carrying both plasmids increased dramatically as antibiotic levels were raised, and either the wild-type plasmid was lost
or the cells did not grow. This study highlights the importance of the cost of duplicate genes and the quantitative nature
of the tradeoff in the evolution of gene duplication through functional divergence.
Reviewing
Editor: Dr. Margaret Riley 相似文献