First isolation of a CTX-M-3-producing Enterobacter cloacae in France.
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Anti-Bacterial Agents↗
Biomedical subjects
J Sirot
Publications and source records attributed to J Sirot.
Prevalence of beta-lactamases among 1,072 clinical strains of Proteus mirabilis: a 2-year survey in a French hospital.
beta-Lactam resistance was studied in 1,072 consecutive P. mirabilis clinical strains isolated at the Clermont-Ferrand teaching hospital between April 1996 and March 1998. The frequency of amoxicillin resistance was 48.5%. Among the 520 amoxicillin-resistant isolates, three resistance phenotypes were detected: penicillinase (407 strains [78.3%]), extended-spectrum beta-lactamase (74 strains [14. 2%]), and inhibitor resistance (39 strains [7.5%]). The penicillinase phenotype isolates were divided into three groups according to the level of resistance to beta-lactams, which was shown to be related to the strength of the promoter. The characterization of the different beta-lactamases showed that amoxicillin resistance in P. mirabilis was almost always (97%) associated with TEM or TEM-derived beta-lactamases, most of which evolved via TEM-2.
Amoxicillin↗
A novel CTX-M beta-lactamase (CTX-M-8) in cefotaxime-resistant Enterobacteriaceae isolated in Brazil.
To estimate the diversity of extended-spectrum beta-lactamases in Brazil, 18 strains from different species of the family Enterobacteriaceae 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 a bla(CTX-M) gene. E. coli HB101 transconjugants and the E. coli DH5alpha transformant harboring a recombinant plasmid produced a CTX-M beta-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.
Amino Acid Sequence↗
Isolation of Pantoea agglomerans in two cases of septic monoarthritis after plant thorn and wood sliver injuries.
Arthritis after plant injury is often apparently aseptic. We report two cases due to Pantoea agglomerans. In one case, the bacterium was isolated only from the pediatric blood culture media, BACTEC Peds Plus, monitored in BACTEC 9240, and not from the other media inoculated with the joint fluid. This procedure could help improve the diagnosis of septic arthritis.
Adolescent↗
Prevalence and characterization of Shiga toxin-producing Escherichia coli isolated from cattle, food, and children during a one-year prospective study in France.
During a 1-year survey of Shiga toxin-producing Escherichia coli (STEC) prevalence in central France, 2,143 samples were investigated by PCR for Shiga toxin-encoding genes. A total of 330 (70%) of 471 fecal samples collected from healthy cattle at the Clermont-Ferrand slaughterhouse, 47 (11%) of 411 beef samples, 60 (10%) of 603 cheese samples, and 19 (3%) of 658 stool specimens from hospitalized children with and without diarrhea were positive for the stx gene(s). A STEC strain was isolated from 34% (162 of 471) of bovine feces, 4% (16 of 411) of beef samples, 1% (5 of 603) of cheese samples, and 1.5% (10 of 658) of stool specimens. Of the 220 STEC strains isolated, 34 (15%) harbored the stx(1) gene, 116 (53%) harbored the stx(2) gene, and 70 (32%) carried both the stx(1) and stx(2) genes. However, 32 (14.5%) were not cytotoxic for Vero cells. The eae gene, found in 12 (5%) of the 220 strains, was significantly associated with the stx(1) gene and with isolates from children. Sequences homologous to ehxA were found in 102 (46%) of the 220 strains. Thirteen serotypes, OX3:H2, O113:H21, O113:H4, OX3:H21, O6:H10, OX178:H19, O171:H2, O46:H38, O172:H21, O22:H16, O91:H10, O91:H21, and O22:H8, accounted for 102 (55%) of 186 typeable isolates, and only one strain (0.5% of the 186 STEC isolates from cattle), belonged to the O157:H7 serotype. We showed that the majority of the STEC isolates from cattle, beef, and cheese were not likely to be pathogenic for humans and that the STEC strains isolated from children in this study were probably not responsible for diarrheal disease. Finally, the strains associated with hemolytic-uremic syndrome in the same geographical area were shown to belong to particular subsets of the STEC population found in the bovine reservoir.
Abattoirs↗
[Antibiogram Committee of the French Microbiology Society. Report 2000-2001].
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Anti-Bacterial Agents↗
Dialysis and central venous catheter infections in critically ill patients: results of a prospective study.
OBJECTIVE: To determine the incidence of dialysis catheter (DC)-related infections in intensive care unit (ICU) patients, and to compare the frequency of DC and central venous catheter (CVC) infections in an ICU setting. DESIGN: Prospective, descriptive survey. SETTING: An adult, 10-bed medical/surgical ICU at a university hospital. PATIENTS: A total of 151 DCs and 230 CVCs placed in 170 patients were evaluated. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Catheter colonization was defined by a quantitative catheter tip culture yielding > or =10(3) colony-forming units/mL, catheter-related bacteremia was defined as catheter colonization and blood culture positive for the same organism, and site infection was defined as the presence of pus at the insertion site. The mean duration of catheterization was 6.8+/-6 days for DCs and 5.9+/-4.6 for CVCs (p = .52). There was no difference between DCs and CVCs in catheter colonization and catheter-related bacteremia incidence rates per 1000 days of catheter use (24.2 vs. 19.8 [p = .46] and 0.96 vs. 1.5 [p = .60], respectively). Site infection was observed in one patient (CVC placement). For DCs and CVCs the duration of catheterization was associated with catheter infection (p = .0007 and p = .04, respectively), but when the catheters were examined over 5-day intervals, the incidence of catheter infections did not increase with duration of catheter use (p = .23 and p = .10, respectively). CONCLUSIONS: DC-related infections are associated with DC longevity. As shown by the 5-day-interval analysis, the incidence of DC-related infections did not increase with DC duration, suggesting that the risk for DC-related infections remained unchanged with time. The characteristics of DC-related infections in ICU patients were comparable to those previously reported for CVC-related infections.
Aged↗
Diversity of TEM mutants in Proteus mirabilis.
In a survey of resistance to amoxicillin among clinical isolates of Proteus mirabilis, 10 TEM-type beta-lactamases were characterized: (i) the well-known penicillinases TEM-1 and TEM-2, the extended-spectrum beta-lactamases (ESBLs) TEM-3 and TEM-24, and the inhibitor-resistant TEM (IRT) TEM-44 and (ii) five novel enzymes, a penicillinase TEM-57 similar to TEM-1, an ESBL TEM-66 similar to TEM-3, and three IRTs, TEM-65, TEM-73, and TEM-74. The penicillinase TEM-57 and the ESBL TEM-66 differed from TEM-1 and TEM-3, respectively, by the amino acid substitution Gly-92-->Asp (nucleotide mutation G-477-->A). This substitution could have accounted for the decrease in pIs (5.2 for TEM-57 and 6.0 for TEM-66) but did not necessarily affect the intrinsic activities of these enzymes. The IRT TEM-65 was an IRT-1-like IRT (Cys-244) related to TEM-2 (Lys-39). The two other IRTs, TEM-73 and TEM-74, were related to IRT-1 (Cys-244) and IRT-2 (Ser-244), respectively, and harbored the amino acid substitutions Leu-21-->Phe and Thr-265-->Met. In this study, the ESBLs TEM-66, TEM-24, and TEM-3 were encoded by large (170- to 180-kb) conjugative plasmids that exhibited similar patterns after digestion and hybridization with the TEM and AAC(6')I probes. The three IRTs TEM-65, TEM-73, and TEM-74 were encoded by plasmids that ranged in size from 42 to 70 kb but for which no transfer was obtained. The characterization of five new plasmid-mediated TEM-type beta-lactamases and the first report of TEM-24 in P. mirabilis are evidence of the wide diversity of beta-lactamases produced in this species and of its possible role as a beta-lactamase-encoding plasmid reservoir.
Alleles↗
Chromosomally encoded ampC-type beta-lactamase in a clinical isolate of Proteus mirabilis.
A clinical strain of Proteus mirabilis (CF09) isolated from urine specimens of a patient displayed resistance to amoxicillin (MIC >4,096 microg/ml), ticarcillin (4,096 microg/ml), cefoxitin (64 microg/ml), cefotaxime (256 microg/ml), and ceftazidime (128 microg/ml) and required an elevated MIC of aztreonam (4 microg/ml). Clavulanic acid did not act synergistically with cephalosporins. Two beta-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 beta-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 with C. freundii-specific primers. Hybridization results showed that the ampC gene is only chromosomally located while the TEM 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 to blaCMY-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 beta-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 beta-lactamase observed in P. mirabilis. We suggest that it be designated CMY-3.
Bacterial Proteins↗
Inhibitor-resistant OXY-2-derived beta-lactamase produced by Klebsiella oxytoca.
Klebsiella oxytoca strains are generally moderately resistant to amoxicillin and ticarcillin due to the activities of the chromosomally encoded OXY-1 and OXY-2 class A beta-lactamase families. These enzymes have the ability to hydrolyze not only penicillins but also cephalosporins, including cefuroxime, ceftriaxone, and aztreonam, and are inhibited by clavulanic acid. A Klebsiella oxytoca strain was isolated from a culture of blood from a patient who had been treated with amoxicillin-clavulanate (3 g/day) for 10 days 1 month earlier. This strain harbored an unusual phenotype characterized by resistance to amoxicillin-clavulanate. It produced an OXY-2-type beta-lactamase (pI 6.3), as confirmed by PCR amplification with primers specific for the OXY-2-encoding gene. Gene sequencing revealed a point mutation (A-->G) corresponding to the amino acid substitution Ser-->Gly at position 130. This mutant enzyme was poorly inhibited by inhibitors, and its kinetic constants compared to those of the parent enzyme were characterized by an increased Km value for ticarcillin, with a drastically reduced activity against cephalosporins, as is observed with inhibitor-resistant TEM enzymes. The substitution Ser-->Gly-130 was previously described in the inhibitor-resistant beta-lactamase SHV-10 derived from an SHV-5 variant, but this is the first report of such a mutant in OXY enzymes from K. oxytoca.
Drug Resistance, Microbial↗
Non-O157:H7 Stx2-producing Escherichia coli strains associated with sporadic cases of hemolytic-uremic syndrome in adults.
From August 1996 to May 1997, six verotoxin-producing Escherichia coli (VTEC) strains were isolated from stool specimens of adults suffering from hemolytic-uremic syndrome (HUS). All the isolates were stx2 positive and belonged to different serotypes: O6:H4, O91:H10, O91:H21, O rough:H16, OX3:H-, and O nontypeable: H-. The enterohemolysin (Ehly)-encoding genes were detected in two isolates, and none of the isolates harbors the intimin (Eae)-encoding gene. These findings suggest that stx2-positive non-O157:H7 VTEC is a major cause of HUS in adults and that several sources of pathogens are responsible for local endemic infections.
Adhesins, Bacterial↗
Inhibitor-resistant TEM (IRT) beta-lactamases with different substitutions at position 244.
A novel inhibitor-resistant TEM (IRT) beta-lactamase was detected in an Escherichia coli isolate resistant to amoxicillin-clavulanate and susceptible to cephalothin. The substrate and inhibitor profiles of this beta-lactamase were similar to those of IRT-1 and IRT-2. The novel IRT's bla gene was sequenced, and the deduced amino acid sequence showed the amino acid replacement Arg for His-244 of the TEM-1 sequence. Substitutions for Arg-244 have been reported in three TEM-1 mutants: IRT-1 (which corresponds to TEM-31) (Cys), IRT-2/TEM-30 (Ser), and TEM-41 (Thr). We designated this novel beta-lactamase, which corresponds to TEM-51, IRT-15.
Amino Acid Sequence↗
Novel extended-spectrum TEM-type beta-lactamase from an Escherichia coli isolate resistant to ceftazidime and susceptible to cephalothin.
A novel extended-spectrum TEM-type beta-lactamase was detected in an Escherichia coli isolate which was resistant to ceftazidime and susceptible to cephalothin. The corresponding bla gene was sequenced. The deduced amino acid sequence showed the following three amino acid replacements with respect to the TEM-2 sequence: Glu-->Lys-104, Arg-->Ser-164, and Glu-->Lys-240. Since it confers a ceftazidimase-type resistance phenotype, we propose for this novel enzyme the designation CAZ-9, corresponding to TEM-46 in the sequential numbering scheme of TEM beta-lactamases.
Ceftazidime↗
A complex mutant of TEM-1 beta-lactamase with mutations encountered in both IRT-4 and extended-spectrum TEM-15, produced by an Escherichia coli clinical isolate.
Escherichia coli GR102 was isolated from feces of a leukemic patient. It expressed different levels of resistance to amoxicillin or ticarcillin plus clavulanate and to the various cephalosporins tested. The double-disk synergy test was weakly positive. Production of a beta-lactamase with a pI of 5.6 was transferred to E. coli HB101 by conjugation. The nucleotide sequence was determined by direct sequencing of the amplification products obtained by PCR performed with TEM gene primers. This enzyme differed from TEM-1 (blaT-1B gene) by four amino acid substitutions: Met-->Leu-69, Glu-->Lys-104, Gly-->Ser-238 and Asn-->Asp-276. The amino acid susbstitutions Leu-69 and Asp-276 are known to be responsible for inhibitor resistance of the IRT-4 mutant, as are Lys-104 and Ser-238 substitutions for hydrolytic activity of the extended-spectrum beta-lactamases TEM-15, TEM-4, and TEM-3. These combined mutations led to a mutant enzyme which conferred a level of resistance to coamoxiclav (MIC, 64 microg/ml) much lower than that conferred by IRT-4 (MIC, 2,048 microg/ml) but higher than that conferred by TEM-15 or TEM-1 (MIC, 16 microg/ml). In addition, the MIC of ceftazidime for E. coli transconjugant GR202 (1 microg/ml) was lower than that for E. coli TEM-15 (16 microg/ml) and higher than that for E. coli IRT-4 or TEM-1 (0.06 microg/ml). The MICs observed for this TEM-type enzyme were related to the kinetic constants Km and k(cat) and the 50% inhibitory concentration, which were intermediate between those observed for IRT-4 and TEM-15. In conclusion, this new type of complex mutant derived from TEM-1 (CMT-1) is able to confer resistance at a very low level to inhibitors and at a low level to extended-spectrum cephalosporins. CMT-1 received the designation TEM-50.
Anti-Bacterial Agents↗
[Statistical study of the SIRSCAN computerised camera].
The antibiograms of 1162 bacterial strains, including references, have been performed within four centres. They have been read manually and by the SIRSCAN camera, which yields to 30936 couples of diameters values. A non-concordance, at a 3 mm level, was observed fot 11.14% of the diameters. The mean of difference is 0.82 mm and the standard deviation 3.34 mm. Round Petri dishes gave results less reliable than those obtained with square dishes. A deviation in function of the centres is obtained for wild-strains as for the references. For the whole population a S/R discordance (sensible/résistant confusion) is obtained for 1.76% of the diameters. This value drops to 0.93% for enterobacteriaceae, P. aeruginosa and S. aureus (968 strains).
Anti-Bacterial Agents↗
Survey of prevalence of extended spectrum beta-lactamases among enterobacteriaceae.
During the first six months of 1990 and 1994 respectively, 3179 and 2721 non-repetitive strains of Enterobacteriaceae were isolated at the teaching hospital of Clermont-Ferrand. Extended-spectrum beta-lactamases were found in 147 isolates, mainly in Klebsiella pneumoniae (n = 73), Enterobacter aerogenes (n = 37) and Proteus mirabilis (n = 15). TEM-3/CTX-1, SHV-4/CAZ-5 and TEM-24/CAZ-6 were the prevalent enzymes. However, the most frequently involved enzyme in 1990 was TEM-3 (48.6%) whereas in 1994 it was SHV-4 (56.0%). Two salient features emerged from this study: the high frequency of TEM-3 production in P. mirabilis and the production of SHV-4 enzyme, heretofore observed solely in K. pneumoniae, in two other species, E. aerogenes and Escherichia coli.
Anti-Bacterial Agents↗
Characterization of an inhibitor-resistant enzyme IRT-2 derived from TEM-2 beta-lactamase produced by Proteus mirabilis strains.
Ten clinical isolates of Proteus mirabilis were found to produce an inhibitor-resistant TEM beta-lactamase (IRT) in association with a TEM-1 enzyme. The IRT enzyme was derived from TEM-2. The blaIRT gene differs from blaTEM-2 gene by one point mutation which leads to the amino-acid substitution Arg-->Ser at position 244, as observed for the original IRT-2 enzyme derived from TEM-1 reported in Escherichia coli. This is the first report of an IRT beta-lactamase derived from TEM-2.
Microbial Sensitivity Tests↗
Enteroadherent Escherichia coli and diarrhea in children: a prospective case-control study.
The relative contribution of diarrheagenic Escherichia coli was examined during a 1-year prospective study of hospitalized children in Clermont-Ferrand, France, including 220 case patients (with diarrhea) and 211 matched controls. Fecal isolates were characterized by means of their pattern of adherence to HEp-2 cells and by colony hybridization with DNA probes specific for the six categories of diarrheagenic E. coli. No enteroinvasive or enterotoxigenic E. coli isolates were isolated. Twenty-eight (6.5%) eae-positive isolates and 39 (9%) enteroaggregative E. coli isolates characterized with the aggregative adherence probe and/or by their adherence pattern were detected; they were equally distributed among the patients and the controls. Diffusely adhering E. coli was the predominant pathotype: 30.7% were detected by their adherence pattern and 13.7% were detected with the daaC probe. They were isolated with similar frequencies from the patients and the controls, thereby showing no association with diarrhea. However, daaC-positive strains were significantly associated with a past record of urinary tract infections. These results suggest that the diffusely adhering E. coli organisms isolated in the present study are not true intestinal pathogens but may be regarded as resident colonic strains.
Adolescent↗