Nationwide survey of CTX-M-type extended-spectrum beta-lactamases among Klebsiella pneumoniae isolates in Slovenian hospitals.

Among 177 extended-spectrum beta-lactamase-producing Klebsiella pneumoniae isolates collected from 11 Slovenian hospitals in 2005 and 2006, 60 (34%), from eight hospitals, harbored genes for CTX-M enzymes, with bla(CTX-M-15) detected by sequencing. These 60 isolates comprised 11 pulsed-field gel electrophoresis-defined strains, with several clusters of closely related isolates. Plasmids encoding CTX-M-15 enzyme were highly transmissible.

Virulence factors in Escherichia coli with CTX-M-15 and other extended-spectrum beta-lactamases in the UK.

OBJECTIVES: Multiresistant Escherichia coli with CTX-M-15 extended-spectrum beta-lactamase (ESBL) are widespread in the UK. We examined their phylogenetic groups and virulence factors. METHODS: Clinical E. coli isolates (n = 114), collected between 2003 and 2006, were phylogenetically grouped and screened by PCR for 33 virulence factor genes. They included representatives of the five major UK epidemic E. coli strains with CTX-M-15 enzyme, as well as non-clonal isolates with CTX-M or other types of ESBLs. RESULTS: All representatives of the epidemic E. coli strains belonged to the virulent extra-intestinal phylogenetic group B2, as did 60% (34/56) of the non-clonal isolates with CTX-M-15-like enzymes and 75% (15/20) of those with non-CTX-M ESBLs. Half of those with CTX-M-9-like enzymes belonged to virulence group D. Within phylogenetic group B2, the prevalence of most virulence factors was comparable among clonal and non-clonal isolates with CTX-M enzymes, and among those with non-CTX-M ESBLs. The most frequent virulence genes were PAI, fimH, fyuA, iutA, kpsMTII, K5, traT, uidA and usp. Among the five epidemic clones, afa/draBC was specific to strain A, whereas P fimbriae were only detected in strain D, and only representatives of the B-C-E group specifically harboured sfaS, kpsMTII and K5. However, afa/draBC was also found in 30% of non-clonal isolates with CTX-M ESBLs, and no virulence gene was unique to the epidemic strains. CONCLUSIONS: Most E. coli with CTX-M ESBLs belonged to virulent phylogenetic groups, mainly B2. The successful epidemic strains did not appear more virulent, but iutA and fyuA were significantly more prevalent among these than in non-clonal isolates also belonging to phylogenetic group B2. The most successful clone with CTX-M-15 enzyme (A) differed from other epidemic clones in harbouring afa/draBC, but this was also found in non-clonal isolates with CTX-M-15 enzyme.

Development of high-level ceftazidime resistance via single-base substitutions of blaCTX-M-3 in hyper-mutable Escherichia coli.

Mutations can increase the ceftazidimase activity of CTX-M-3 beta-lactamase, as seen with its widespread variant CTX-M-15. This study compared the frequencies of emerging ceftazidime resistance in isogenic wild-type and hyper-mutable mutS CTX-M-3-producing Escherichia coli strains, and sequenced the mutant bla(CTX-M) alleles selected. Ceftazidime resistance emerged more readily in the hyper-mutable background than in the wild-type strain. All selected CTX-M mutants, in both the wild-type and the mutS derivatives, had single amino-acid changes at position 167, including a novel Pro167Gln substitution. These data emphasise the potential for further diversification of CTX-M enzymes.

Molecular characterization of plasmids encoding CTX-M-15 beta-lactamases from Escherichia coli strains in the United Kingdom.

OBJECTIVES: The UK, like other countries worldwide, has a growing problem with CTX-M beta-lactamase-producing Escherichia coli. Five major clonally related strains have been identified among CTX-M-15 producers. We characterize here the plasmids from clonal strains A and D. METHODS: Plasmids were extracted and transformed into E. coli DH5alpha; conjugative mating was attempted on agar. MICs were determined by agar dilution. beta-Lactamases were typed by isoelectric focusing; antibiotic resistance genes and integrons were identified by PCR and sequenced. Plasmid incompatibility groups were determined by replicon PCR. RESULTS: bla(CTX-M-15) was carried by a 150 kb plasmid in strain A and a 70 kb plasmid in strain D. Conjugative transfer of cefotaxime resistance was only achieved from strain D; plasmids from both strains were transferred by transformation. The plasmid from strain A additionally carried bla(TEM-1) (variably), bla(OXA-1), aac(6')-Ib-cr and tet(A), as well as a class 1 integron with the gene cassettes aadA5 and dfr(17); the plasmid from strain D carried bla(TEM-1) consistently, also bla(OXA-1), aac(6')-Ib-cr, aac3-IIa and tet(A). Both plasmids belonged to incompatibility group FII. CONCLUSIONS: bla(CTX-M-15) was plasmid-mediated in both strains A and D and was linked to other antibiotic resistance genes including aac(6')-Ib-cr, which encodes an acetyltransferase, not previously found in Europe, acting on both aminoglycosides and some fluoroquinolones. Although the plasmids from the two strains differed in size, both were related and conferred similar multi-drug resistance phenotypes, suggesting that they may share a similar genetic scaffold. Both shared features with plasmids encoding CTX-M-15 beta-lactamases in E. coli from Canada and India.

Hyperglycemia-induced attenuation of rectal perception depends upon pattern of rectal balloon inflation.

This study investigated the effects of acute hyperglycemia on conscious rectal perception in response to two different rectal distension paradigms. Eleven healthy males were studied in random order on two separate days during euglycemia and hyperglycemia with blood glucose concentrations clamped to 3.8 +/- 0.6 and 14.8 +/- 0.86 mmol/liter, respectively. In order to evoke sensory responses, rapid phasic and ramplike distensions were applied to an intrarectal balloon. Rectal sensation thresholds for initial sensation, sensation of stool and discomfort, and sensory intensities were recorded. Additionally, anorectal motor responses were investigated during phasic distension. Acute hyperglycemia did not modify rectal sensory pressure thresholds and perception scores in response to phasic distension. Neither did hyperglycemia alter the resting anal sphincter pressure, the pressure threshold for eliciting the rectoanal inhibitory reflex, or the maximal anal squeeze pressure. In contrast, hyperglycemia attenuated rectal perception in response to ramplike distension. The pressure thresholds, 10.0 +/- 1.8 and 17.0 +/- 3.6 mm Hg for initial sensation and discomfort, respectively, during hyperglycemia were significantly higher than the corresponding thresholds of 4.4 +/- 1.4 and 11.4 +/- 1.9 mm Hg observed during euglycemia (P < 0.01). Higher rectal pressures were observed at all intensities of sensation of stool and discomfort during hyperglycemia than those obtained during euglycemia (P < 0.01). Hyperglycemia did not alter the compliance of the rectum. The results of this study demonstrate that acute hyperglycemia attenuates rectal perception, and this attenuation depends upon the type of distension employed. Our findings also demonstrate that anal sphincter motor function is not appreciably modified by hyperglycemia.