Community and hospital spread of Escherichia coli producing CTX-M extended-spectrum β-lactamases in the UK

OBJECTIVES

During 2003, the Health Protection Agency's Antibiotic Resistance Monitoring and Reference Laboratory began to receive isolates of Escherichia coli for confirmation of extended-spectrum beta-lactamase production with a phenotype implying a CTX-M-type beta-lactamase, i.e. MICs of cefotaxime > or = 8-fold higher than MICs of ceftazidime. Many were referred as being from community patients. We examined 291 CTX-M-producing isolates from the UK and investigated the genetic basis of their phenotype.

METHODS

PCR was used to detect alleles encoding CTX-M enzymes and to assign these to their blaCTX-M phylogenetic groups. Selected alleles were sequenced. Producers were compared by analysis of banding patterns generated by pulsed-field gel electrophoresis of XbaI-digested genomic DNA. MICs were determined by an agar dilution method or by Etest.

RESULTS

Of 291 CTX-M-producing E. coli isolates studied from 42 UK centres, 70 (24%) were reportedly from community patients, many of whom had only limited recent hospital contact. Community isolates were referred by 12 centres. Two hundred and seventy-nine (95.9%) producers contained genes encoding group 1 CTX-M enzymes and 12 contained blaCTX-M-9-like alleles. An epidemic CTX-M-15-producing strain was identified, with 110 community and inpatient isolates referred from six centres. Representatives of four other major strains also produced CTX-M-15, as did several sporadic isolates examined. Most producers were multi-resistant to fluoroquinolones, trimethoprim, tetracycline and aminoglycosides as well as to non-carbapenem beta-lactams.

CONCLUSIONS

CTX-M-producing E. coli are a rapidly developing problem in the UK, with CTX-M-15 particularly common. The diversity of producers and geographical scatter of referring laboratories indicates wide dissemination of blaCTX-M genes. Because of the public health implications, including for the treatment of community-acquired urinary tract infections, the spread of these strains--and CTX-M-15 beta-lactamase in particular--merits close monitoring.

The multiple forms of trypsin-like activity present in various strains of Porphyromonas gingivalis are due to the presence of either Arg-gingipain or Lys-gingipain

Porphyromonas gingivalis contains high concentrations of numerous cysteine proteinases with trypsin-like activity which have been implicated as important virulence factors in adult-onset periodontitis. We have analyzed the subfractions of six P. gingivalis strains for the presence of arginine-X- and lysine-X-specific proteinases (Arg-gingipain [RGP] and Lys-gingipain [KGP]) previously purified from P. gingivalis H66. Western blot (immunoblot) analysis using antibodies produced against RGP and the N-terminal peptides of RGP or the catalytic subunit of KGP indicated that these enzymes are synthesized by the strains studied and exist as multiple molecular mass species. The major forms of RGP were identified as 110-, 95-, 70- to 90-, and 50-kDa proteins, the first two being a complex of the 50-kDa catalytic subunit with hemagglutinins, with or without an added membrane anchorage peptide. The other forms are single-chain enzymes. While the 95- and 50-kDa RGP were found predominantly in culture medium, the 110- and 70- to 90-kDa forms associated with membranous fractions of the bacteria. The predominant form of KGP in all strains was a complex of the 60-kDa catalytic domain with hemagglutinins, and vesicle- and membrane-associated KGP was about 15 kDa larger than the 105-kDa enzyme present in culture media. These data explain the apparent complexity of P. gingivalis proteinases and indicate that in all strains tested there are two identical enzymes, one with arginine-X specificity and the other with lysine-X specificity, which, working in concert, are responsible for the trypsin-like activity associated with this bacterium.

Phylogenetic diversity of Escherichia coli strains producing NDM-type carbapenemases

BACKGROUND

The global accumulation of Escherichia coli with CTX-M extended-spectrum β-lactamases partly reflects the dissemination of clonal lineages, notably ST131 and ST405. More recently, E. coli have emerged that produce NDM carbapenemase. We sought to determine the clonal diversity of E. coli with this enzyme from English hospitals, and to compare them with isolates from Pakistan and India.

METHODS

The 18 NDM-positive E. coli were from hospitals in England (n = 10), Pakistan (n = 7) and India (n = 1). Isolates were compared by phylogenetic grouping, multilocus sequence typing and PFGE of XbaI-digested DNA. Isolates were screened by PCR for acquired AmpC genes, bla(CTX-M), and the 16S rRNA methylase genes armA and rmtC.

RESULTS

Most of the isolates belonged to phylogenetic groups B1 (n = 9) or D (n = 7); two were group A and none was group B2. Nine isolates from England and Pakistan belonged to the B1 lineage ST101, with seven of these clustering at >77% similarity by PFGE. Other lineages included ST405 (n = 3, group D), ST648 (n = 3, group D), the ST23 complex (one each of ST90 and ST410, both group A) and ST156 (n = 1, group D). Sixteen of 18 isolates had a group 1 CTX-M gene, 13 had a CIT-type acquired AmpC, and 16 had either or both of armA and rmtC.

CONCLUSIONS

The E. coli isolates producing NDM-1 carbapenemase belonged to six sequence types and included diverse clonal lineages. Nevertheless, isolates of B1-ST101 accounted for half the collection, and included isolates from both England and Pakistan. None of the isolates belonged to ST131 or to phylogroup B2.

Porphyromonas gingivalis proteinases as virulence factors in the development of periodontitis

Porphyromonas gingivalis contains exceedingly high concentrations of cysteine proteinases with trypsin-like activity which have been implicated as virulence factors in adult-onset periodontitis. These enzymes, referred to as gingipains, cleave protein and peptide substrates after arginine (gingipain R) and lysine residues (gingipain K), and it has been found that neither is easily inhibited by host proteinase inhibitors. Examination of the properties of each proteinase clearly indicates a role(s) for both in the dysregulation of a number of normally tightly controlled pathways. The effects of such uncontrolled proteolysis are the development of edema (kallikrein/kinin pathway activation by gingipain R), neutrophil infiltration (complement pathway activation by gingipain R), and bleeding (degradation of fibrinogen by gingipain K). Since three of the major hallmarks of periodontitis involve increased crevicular flow, neutrophil accumulation at infected sites and bleeding on probing, it seems likely that both P. gingivalis-derived proteinases are important virulence factors in the development of periodontal disease.

Titration and mapping of the active site of cysteine proteinases from Porphyromonas gingivalis (gingipains) using peptidyl chloromethanes

Porphyromonas gingivalis is one of the major pathogens associated with periodontal disease and releases powerful cysteine proteinases known as the gingipains, which are key virulence factors for this organism. The three forms of gingipains, gingipain R1, gingipain R2 (gingipain Rs) and gingipain K, which cleave specifically after arginine (R) or lysine (K) residues, were characterized in terms of the kinetics of their interaction with a wide range of synthetic peptidyl chloromethane inhibitors and a peptidyl (acyloxy)methane. Chloromethane inhibitors were found to inhibit all the enzymes to varying degree dependent on the peptidyl components of the inhibitor. Thus, inhibitors containing a basic residue at P1 rapidly inactivated the gingipains and some specificity could be seen at the P2 site. The (acyloxy)methane inhibitor, Cbz-Phe-Lys-CH2OCO-2,4,6-Me3-Ph, was very specific in its rapid inhibition of gingipain K over the gingipains R. This inhibitor, together with the peptidyl chloromethanes, D-Phe-Pro-Arg-CH2Cl and D-Phe-Phe-Arg-CH2Cl, which reacted most rapidly with the Arg-specific proteinases, could be used to active site titrate purified forms of the enzymes and enzymes found in crude fractions such as intact P. gingivalis cells, vesicles or membrane fractions. From these titrations it was evident that gingipains R were always in an excess of about 3-fold over gingipain K and that the gingipains as a whole made up 85% of the proteolytic activity associated with the bacterium. The elucidation of the kinetics of inhibition by the range of compounds and the development of the titration method for gingipains will considerably aid in future studies on the proteases elaborated by P. gingivalis.

Molecular characterization of plasmids encoding CTX-M-15 -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.

Proteolytic inactivation of the leukocyte C5a receptor by proteinases derived from Porphyromonas gingivalis

The anaerobic bacterium Porphyromonas gingivalis has been implicated as a primary causative agent in adult periodontitis. Several proteinases are produced by this bacterium, and it is suggested that they contribute to virulence and to local tissue injury resulting from infection by P. gingivalis. Cysteine proteinases with specificities to cleave either Arg-X or Lys-X peptide bonds (i.e., gingipains) have been characterized as predominant enzymes associated with vesicles shed from the surface of this bacterium. It has recently been demonstrated that these proteinases are capable of degrading the blood complement component C5, resulting in the generation of biologically active C5a. By using an affinity-purified rabbit antibody raised against residues 9 to 29 of the C5a receptor (C5aR; CD88), we demonstrate that noncysteinyl proteinases associated with vesicles obtained from P. gingivalis cleave the C5aR on human neutrophils. Proteolytic attack of the C5aR by enzymes from the P. gingivalis vesicles was inhibited by TPCK (tolylsullonyl phenylalanyl chloromethyl ketone), PMSF (phenylmethylsulfonyl fluoride), and dichloroisocoumarin, suggesting that serine proteinases are primarily responsible for this degradative activity. The purified vesicle proteinase Lys-gingipain but not Arg-gingipain also cleaved the N-terminal region of the C5aR on the human neutrophils. Lys-gingipain activity was essentially resistant to these inhibitors but was inhibited by TLCK (Nalpha-p-tosyl-L-lysine chloromethyl ketone) and iodoacetamide. A synthetic peptide that mimics the N-terminal region of C5aR (residues 9 to 29; PDYGHY DDKDTLDLNTPVDKT) was readily cleaved by chymotrypsin but not by trypsin, despite the presence of two potential trypsin (i.e., lysyl-X) cleavage sites. The specific sites of cleavage in the C5aR 9-29 peptide were determined by mass spectroscopy for both chymotrypsin and Lys-gingipain digests. This analysis demonstrated that the C5aR peptide is susceptible to cleavage at both potential Lys-gingipain sites (i.e., between residues 17 and 18 [K-D] and 28 and 29 [K-T]) and at two chymotrypsin sites (between residues 14 and 15 [Y-D] and 20 and 21 [L-D]), respectively. These studies suggest that P. gingivalis contains at least two enzymes capable of cleaving the C5aR, Lys-gingipain and a second nontryptic serine proteinase that is distinct from either Arg- or Lys-gingipain.

Purification and characterization of a novel endopeptidase in ragweed (Ambrosia artemisiifolia) pollen

Ragweed (Ambrosia artemisiifolia), the major cause of late summer hay fever (allergic rhinitis) in the United States and Canada, is clinically the most important source of the seasonal aeroallergens. A novel endopeptidase was extracted from the pollen of this plant and purified by a series of column chromatographic steps. It has a molecular mass of 82 kDa according to gel filtration and SDS-polyacrylamide gel electrophoresis and a pH optimum near 9.0, and its activity is unaffected by chelating or reducing agents. A 17-amino acid amino-terminal sequence of this protein showed no similarity with any other proteases. The enzyme was inhibited by diisopropyl fluorophosphate, a general serine class inhibitor, and more specifically N-p-tosyl-L-phenylalanine chloromethyl ketone, a chymotrypsin-like proteinase inhibitor. Various synthetic substrates were efficiently cleaved with a strong preference for Phe in the P1 and P3 position and Pro in the P2 position. This specificity was confirmed through inhibition studies with both peptidyl chloromethyl ketone and organophosphate inhibitors. In addition to synthetic substrates, the neuropeptides, vasoactive intestinal peptide and substance P, which are required for normalized lung functions, were also rapidly hydrolyzed. Activity toward protein substrates was not detected with the exception of the inactivation of alpha-1-proteinase inhibitor, which occurred through cleavage within the reactive site loop. These results indicate that the purified enzyme is a novel endopeptidase, which may be involved in both the degradation of neuropeptides and the inactivation of protective proteinase inhibitors during pollen-initiated allergic reactions.

The role of proteolytic enzymes in the development of pulmonary emphysema and periodontal disease

Pulmonary emphysema and periodontal disease are each characterized by the uncontrolled proteolysis of connective tissue proteins by proteinases derived from human neutrophils. Although these diseases would not appear to be related in terms of the initial insult to individual tissues, the ultimate result in each disease is the accumulation and degranulation of neutrophils at inflammatory sites, apparently as a result of frustrated phagocytosis and specific activation of these phagocytic cells. This result is easily recognized in the case of emphysema, where there is clear evidence that the primary cause of the disease is the accumulation of foreign materials in the lung (e.g., smoke condensate), followed by the recruitment of neutrophils to the organ and the release of oxidative and hydrolytic enzymes. In periodontitis, however, the problem begins with the accumulation of plaque at the base of the teeth, followed by the growth of opportunistic anaerobic bacteria below the gum line. These parasitic microbes, which are resistant to killing by both monocytes and granulocytes, secrete proteinases that can activate the kallikrein-kinin pathway, degrade clotting factors, and release the potent neutrophil chemotactic factor, C5a, from complement. It is under such conditions that neutrophils are recruited to infected sites within the periodontium. After the neutrophil-recruitment stage, the two diseases become similar in that degranulation of neutrophils occurs during attempted phagocytosis of either cigarette smoke components (emphysema) or bacteria (periodontitis), followed by inactivation of tissue proteinase inhibitors and degradation of connective tissue proteins, the ultimate result being the destruction of the alveolus or gingiva, respectively.

Cleavage of human complement component C5 by cysteine proteinases from Porphyromonas (Bacteroides) gingivalis. Prior oxidation of C5 augments proteinase digestion of C5

Since severe periodontitis is characterized by an acute inflammatory response with cellular infiltration and microbial overgrowth, plasma proteins could be exposed to both proteinases and oxidants released from the granulocytes, as well as to proteinases from the microorganisms. When human complement component C5 was digested by cysteine proteinases (i.e. gingipain-R and gingipain-K) from Porphyromonas gingivalis, limited cleavage of the C5 molecule was observed. If C5 was first oxidized by hydroxyl radicals, these gingipains converted modified C5 to fragments that exhibited significantly greater pro-inflammatory activity than did digests of unmodified C5. After cleavage of oxidized C5 by gingipain-R, the digest exhibited measurably greater neutrophil enzyme release and chemotaxis of human polymorphonuclear leukocytes (PMNs) compared with the activities of unoxidized C5 digests. Gingipain-K generates virtually no polarization or chemotactic activity of human PMNs from C5, nor is enzyme release stimulated by these C5 digests. However, when oxidized C5 was digested by gingipain-K, human PMNs were stimulated for polarization, chemotaxis and enzyme release indicating that an active fragment had been generated. Proteolysis of oxidized C5 evokes greater neutrophil activation than does proteolysis of unoxidized protein, a fact which supports the hypothesis that oxidation and proteolysis may be coupled to enhance the destructive effects of the inflammatory process. These results, in which digests of both oxidized and unmodified complement component C5 were evaluated, support the general concept that oxidation and proteolysis may participate cooperatively in amplifying both the severity and duration of the inflammatory reaction.

The potential role of alpha 2-macroglobulin in the control of cysteine proteinases (gingipains) from Porphyromonas gingivalis

Porphyromonas gingivalis is closely associated with the development of some forms of periodontitis. The major cysteine proteinases released by this bacterium hydrolyze peptide bonds only after arginyl (gingipain R) or lysyl residues (gingipain K). No target protein inhibitors have been identified for either enzyme, leading us to investigate their inhibition by human plasma alpha 2-macroglobulin (alpha 2M). Both 50- and 95 kDa gingipain R were efficiently inhibited by alpha 2M, whereas the catalytic activity of gingipain K could not be eliminated. All 3 enzymes were, however, inhibited by a homologous macroglobulin from rat plasma, alpha 1-inhibitor-3 (alpha 1I3). alpha-Macroglobulins must be cleaved in the so-called "bait region" in order to inhibit proteinases by a mechanism involving physical entrapment of the enzyme. A comparison of the amino acid sequences of the 2 macroglobulins indicates that the lack of lysyl residues within the bait region of alpha 2M protects Lys-specific proteinases from being trapped. On this basis, other highly specific proteinases might also not be inhibited by alpha 2M, possibly explaining the inability of the inhibitor to control proteolytic activity in some bacterially induced inflammatory states, despite its abundance (2-5 mg/ml) in vascular fluids.

Cleavage of the human C5A receptor by proteinases derived from Porphyromonas gingivalis: cleavage of leukocyte C5a receptor

The anaerobic bacteria P. gingivalis has been implicated as a primary causative agent in adult periodontitis. Several proteinases are produced by this bacteria and it is suggested that they contribute to virulence and to local tissue injury resulting from infection by P. gingivalis. Collagenases and cysteine proteinases (i.e., the gingipains) have been characterized as the predominant vesicular enzymes produced by this bacterium. It has been shown that an arginine-specific cysteine proteinase from P. gingivalis, called gingipain-1 or Arg-gingipain, can selectively cleave complement components C3 and C5. In the case of C5, cleavage by Arg-gingipain results in the generation of C5a, a potent chemotactic factor for PMNs. Since these bacterial proteinases are capable of generating pro-inflammatory factors at sites of infection, we examined the possibility that gingipains or other proteinases from this bacterium might attack or destroy cell surface proteins, such as receptor molecules. Using an affinity-purified rabbit antibody raised against residues 9-29 of the C5a receptor (i.e., C5aR; CD88), the signal transmitting element for the pro-inflammatory mediator C5a, we demonstrated that the mixture of proteinases in P. gingivalis vesicles cleaves the C5a receptor on human neutrophils. This vesicular proteinase activity did not require cysteine activation which indicates that proteinases other than the gingipains may be responsible for cleavage of the C5aR molecule. in addition, the purified Lys-gingipain, but not Arg-gingipain, also cleaved C5aR on the human neutrophils. The N-terminal region of CaR (residues 9-29, PDYGHYDDKDTLDLNTPVDKT) was readily cleaved by chymotrypsin, but not by trypsin, despite the presence of potential trypsin (i.e., lysyl-X) cleavage sites. The specific sites of C5aR 9-29 peptide cleavage were determined by mass spectroscopy for both chymotrypsin and Lys-gingipain. These studies suggest that the proteolytic activity in the bacterial vesicles that is responsible for cleaving C5aR is primarily a non-tryptic proteinase, distance from either Arg- or Lys-gingipain. Consequently, there appear to be additional proteinase(s) in the vesicles that attacks the cell surface molecule C5aR which are not the same (i.e., Arg- and Lys-gingipain) as were shown to generate pro-inflammatory activity from complement components C3 and C5. Evidence that the proteinases which attack the inflammatory precursor molecules (i.e., C3 and C5) exhibit different specificities than those that attack receptors to these bioactive complement products makes a particularly interesting story of how this bacteria avoids major host defense mechanisms. It is well known that generation of pro-inflammatory factors such as C3a and C5a at extra-vascular sites can promote edema, leukocyte recruitment and cellular activation responses that could lead to the release of toxic oxygen products and to phagocytosis of the bacteria. Destruction of receptors to these cellular activating factors generated by bacterial proteinases may eliminate the ability of these (i.e., complement-derived) and other mediators to carry out their anti-bacterial actions and thereby limit the host's defense mechanisms in responses to the infecting bacteria. The concept of anti-bacterial responses (i.e., oxygen radical generation and phagocytosis) being effectively eliminated at the injury site, by bacterial proteinases acting at the cellular receptor level, has not been studied in detail. In this case, the situation is particularly unusual because, once the bacterial gingipains generate potent plasma-derived inflammatory factors that can enhance edema and deliver essential nutrients to the bactgeria, other bacterial proteinases may destsroy their cellular receptors. These receptors transmit the signal activation mechanisms in the infiltrating cells that elicit bacterial killing.(ABSTRACT TRUNCATED)

Prevalence and antibiotic resistance profile of mercury-resistant oral bacteria from children with and without mercury amalgam fillings

Genes encoding resistance to mercury and to antibiotics are often carried on the same mobile genetic element and so it is possible that mercury-containing dental materials may select for bacteria resistant to mercury and to antibiotics. The main aim of this study was to determine whether the prevalence of Hg-resistant oral bacteria was greater in children with mercury amalgam fillings than in those without. A secondary aim was to determine whether the Hg-resistant isolates were also antibiotic resistant. Bacteria in dental plaque and saliva from 41 children with amalgam fillings and 42 children without such fillings were screened for mercury resistance by cultivation on a HgCl(2)-containing medium. Surviving organisms were identified and their susceptibility to mercury and to several antibiotics was determined. Seventy-eight per cent and 74% of children in the amalgam group and amalgam-free group, respectively, harboured Hg-resistant bacteria; this difference was not statistically significant. Nor was there any significant difference between the groups in terms of the proportions of Hg-resistant bacteria in the oral microflora of the children. Of Hg-resistant bacteria, 88% and 92% from the amalgam group and the amalgam-free group, respectively, were streptococci; 41% and 33% were resistant to at least one antibiotic, most frequently tetracycline. The results of this study show that there was no significant difference between children with amalgam fillings and those without such fillings with regard to the prevalence, or the proportion, of Hg-resistant bacteria in their oral microflora. The study also found that Hg-resistant bacteria were common in children regardless of whether or not they had amalgam fillings and that many of these organisms were also resistant to antibiotics.

The impact of local surface changes in Borneo on atmospheric composition at wider spatial scales: coastal processes, land-use change and air quality

We present results from the OP3 campaign in Sabah during 2008 that allow us to study the impact of local emission changes over Borneo on atmospheric composition at the regional and wider scale. OP3 constituent data provide an important constraint on model performance. Treatment of boundary layer processes is highlighted as an important area of model uncertainty. Model studies of land-use change confirm earlier work, indicating that further changes to intensive oil palm agriculture in South East Asia, and the tropics in general, could have important impacts on air quality, with the biggest factor being the concomitant changes in NO(x) emissions. With the model scenarios used here, local increases in ozone of around 50 per cent could occur. We also report measurements of short-lived brominated compounds around Sabah suggesting that oceanic (and, especially, coastal) emission sources dominate locally. The concentration of bromine in short-lived halocarbons measured at the surface during OP3 amounted to about 7 ppt, setting an upper limit on the amount of these species that can reach the lower stratosphere.

Multiple sources initiating atrial fibrillation from a single pulmonary vein identified by a circumferential catheter

The pulmonary veins are the predominant source of ectopic activity initiating AF. The reproducibility of intrapulmonary vein activation during ectopic activity and/or initiation of multiple AF episodes was examined. Eighty-nine pulmonary veins (PVs) among 29 patients undergoing radiofrequency ablation of AF were studied with a 15- to 20-mm diameter, circumferential PV catheter equipped with ten electrodes and a deflectable shaft. Local electrograms were recorded simultaneously during sinus rhythm, ectopic activity, or AF onset, spontaneously or induced via the catheter left in a stable position. Fifty-four arrhythmogenic veins were identified, 39 showing isolated ectopy, and 8 displayed repetitive ectopy (in salvos). The earliest site of activation and the sequence of intra-PV activation during isolated ectopy was identical to that observed during consecutive ectopic complexes in 77% and variable in 23% during isolated ectopy. The earliest activity was sometimes limited to a single bipole. During repetitive ectopy and AF initiation, multiple sources and/or variable activation patterns were noted in 53% of instances, indicating the presence of multiple arrhythmogenic foci within the same PV. Simultaneous electrogram recordings with a circumferential PV catheter identified the presence of multiple arrhythmogenic foci within a single PV.

Sialadenosis in dogs

OBJECTIVE

To determine clinical findings, cytologic and histologic characteristics of salivary glands, and response to treatment with phenobarbital in dogs with clinical signs typical of sialadenosis.

DESIGN

Prospective study.

ANIMALS

13 dogs with enlarged salivary glands.

PROCEDURE

Data were collected from dogs with clinical signs attributable to enlarged salivary glands. Salivary gland biopsy and cytologic specimens were examined. Dogs were treated with phenobarbital and monitored for response to treatment.

RESULTS

Clinical signs commonly associated with sialadenosis included retching and gulping. Substantial cellular changes were not detected by histologic or cytologic examination of enlarged salivary glands. Response to treatment with phenobarbital was rapid, although most dogs required continuous treatment to prevent recurrence of clinical signs.

CONCLUSIONS AND CLINICAL RELEVANCE

Sialadenosis is a condition of unknown cause that may have been underdiagnosed in dogs. Criteria for diagnosis include typical clinical signs, enlarged salivary glands, and lack of substantial microscopic lesions. Response to treatment with phenobarbital is rapid.

Klebsiella pneumoniae producing KPC carbapenemase in a district general hospital in the UK

We report two patients with multidrug-resistant KPC-carbapenemase-producing Klebsiella pneumoniae urinary tract infections. A bla(KPC-2) gene was detected in both of the isolates by polymerase chain reaction and sequencing. The isolates had identical pulsed-field gel electrophoresis patterns and belonged to sequence type ST11. The index patient probably acquired the KPC-producing strain while in hospital in Curaçao, with subsequent nosocomial transmission to the second patient occurring in our hospital. We describe the interventions that were taken to prevent its further spread within the acute Trust and the community.