A retrospective audit of adult and paediatric anaphylaxis management from two Australian metropolitan mixed emergency departments

BACKGROUND

Anaphylaxis is a potentially life-threatening allergic reaction, with presentations to emergency departments (EDs) increasing across Australia. Understanding the features of those presenting with anaphylaxis and aspects related to its optimal clinical management across the admission, treatment and discharge settings is needed to minimise its impact. We aimed to evaluate the nature and management of presentations related to anaphylaxis across two Australian EDs.

METHODS

Retrospective audit of paediatric and adult patients presenting to a community or tertiary level ED with anaphylaxis from 1 May 2018 to 30 April 2019. Data extracted from medical records included demographic characteristics, causative agents, clinical features, treatments administered across community, ambulance or ED settings, as well as post-discharge care arrangements including provision of Adrenaline Auto-Injector (AAI) and Allergy/Anaphylaxis Action Plan (AAP).

RESULTS

A total of 369 (107 paediatric and 262 adult) ED presentations were identified. A total of 94 (36%) adult and 46 (43%) paediatric patients received pre-hospital adrenaline, with a further 91 (35%) adult and 29 (27%) paediatric patients receiving a dose of adrenaline in the ED. The most commonly administered treatment in ED were corticosteroids, given to 157 (60%) adult and 55 (51%) paediatric patients. Among those requiring an AAI for discharge, 123/210 (59%) adult and 57/91 (63%) of paediatric patients left hospital with an AAI. In contrast, among those requiring an allergy/anaphylaxis action plan (AAP) on discharge, 61/206 (30%) adult and 30/90 (33%) of paediatric patients left hospital with one. Factors associated with an increased likelihood of receiving AAI on discharge in paediatric and adult patients included receipt of any adrenaline, receipt of two or more doses of adrenaline, and longer duration of hospital stay. Adults presenting within business hours were more likely to be discharged with AAI, but no such difference was observed for paediatric patients. Similar findings were evident for provision of AAP on discharge.

CONCLUSION

These findings demonstrate the need to improve assessment and treatment in the ED. In particular, the observed large variability in provision of AAI and AAP on discharge presents opportunities to explore strategies to improve awareness and provision of these critical components of post-discharge care.

Longitudinal farm study of extended-spectrum beta-lactamase-mediated resistance

Extended-spectrum beta-lactamase (ESBL)-mediated resistance is of considerable importance in human medicine. Recently, such enzymes have been reported in bacteria from animals. We describe a longitudinal study of a dairy farm suffering calf scour with high mortality rates. In November 2004, two Escherichia coli isolates with resistance to a wide range of beta-lactams (including amoxicillin-clavulanate and cefotaxime) were isolated from scouring calves. Testing by PCR and sequence analysis confirmed the isolates as being both bla(CTX-M14/17) and bla(TEM-35) ((IRT-4)) positive. They had indistinguishable plasmid and pulsed-field gel electrophoresis (PFGE) profiles. Transferability studies demonstrated that bla(CTX-M) was located on a conjugative 65-MDa IncK plasmid. Following a farm visit in December 2004, 31/48 calves and 2/60 cows were positive for E. coli with bla(CTX-M). Also, 5/48 calf and 28/60 cow samples yielded bla(CTX)- and bla(TEM)-negative E. coli isolates that were resistant to cefotaxime, and sequence analysis confirmed that these presented mutations in the promoter region of the chromosomal ampC gene. Fingerprinting showed 11 different PFGE types (seven in bla(CTX-M)-positive isolates). Six different PFGE clones conjugated the same bla(CTX-M)-positive IncK plasmid. One clone carried a different-sized, bla(CTX-M)-positive, transformable plasmid. This is the first report of bla(CTX-M) from livestock in the United Kingdom, and this report demonstrates the complexity of ESBL epidemiology. Results indicate that horizontal plasmid transfer between strains as well as horizontal gene transfer between plasmids have contributed to the spread of resistance. We have also shown that some clones can persist for months, suggesting that clonal spread also contributes to the perpetuation of resistance.

Resistance to Oxyiminocephalosporins Mediated byblaTEM-52Genes in Salmonella Typhimurium from Humans in England and Wales

The emergence of antimicrobial resistance among Salmonella is a matter of great public health concern, more so in the case of extended-spectrum cephalosporins, since these antimicrobials are normally regarded as the drugs of choice for complicated cases of infection. This study was designed to determine the occurrence of resistance mediated by the presence of extended-spectrum beta-lactamases (ESBL) enzymes belonging to the TEM family. Only two isolates were detected after analysis of the 278,308 Salmonella isolates from the last 10 years. In both cases, the gene involved was a bla (TEM-52)-like, and infections were linked with foreign travel. ESBL-TEM enzymes remain very rare in Salmonella in England and Wales, and no domestic cases have been detected to date.

Characterization of AmpC-mediated resistance in clinical Salmonella isolates recovered from humans during the period 1992 to 2003 in England and Wales

The increase in AmpC-mediated resistance in salmonellae constitutes a serious public health concern, since these enzymes confer resistance to a wide range of beta-lactams. One hundred six isolates were selected from 278,308 Salmonella isolates based on resistance to ampicillin and cephalosporins and were subjected to further characterization. Nine isolates had a cefoxitin inhibition diameter < or = 17 mm and were proven to be AmpC positive by multiplex PCR. Sequence analysis revealed the presence of bla(DHA-1), bla(CMY-2), and bla(CMY-4) genes. All nine isolates presented different pulsed-field gel electrophoresis restriction profiles. The AmpC genetic determinants were present in transferable plasmids of around 11, 42, 70, 98, and 99 MDa. A combination of size and restriction fragment length polymorphism (RFLP) analysis showed that all the bla(CMY) plasmids investigated in our study were different, which suggests that bla(CMY) may be located in different plasmid environments. Some United Kingdom isolates linked to foreign travel showed RFLP plasmid patterns consistent with plasmids previously seen in the United States, which suggests that bla(CMY-2) has also been disseminated through plasmid transfer. The fact that two of the domestically acquired United Kingdom isolates presented previously unseen RFLP plasmid patterns could indicate that these strains have followed routes different from those prevalent in North America or other parts of the world. This study represents the first report of bla(CMY) genes in Salmonella isolates in the United Kingdom and the first report of CMY-4 in Salmonella enterica serotype Senftenberg worldwide.

Detection of multiple cephalosporin-resistant Escherichia coli from a cattle fecal sample in Great Britain

We describe the isolation of multiple cephalosporin-resistant Escherichia coli from cattle feces collected from animals at slaughter in Great Britain. Six E. coli strains were isolated with distinct XbaI pulsed-field gel electrophoresis (PFGE) profiles and different mechanisms of cephalosporin resistance from a single fecal sample. Two of these strains were found to contain conjugative plasmids conferring resistance to extended-spectrum cephalosporins that were indistinguishable from each other by restriction endonuclease digestion. Sequence analysis of the plasmid-encoded ampC showed that they were identical to bla(CMY-2), previously described in multiple-drug-resistant Salmonella and E. coli from animals in other parts of the world. DNA sequence analysis of the chromosomal ampC promoter regions for three cephalosporin-resistant strains lacking CMY-2 was determined. Several mutations were detected in the isolates tested including changes at positions -42 and -32, which are known to increase promoter strength. This report represents the first isolation of E. coli containing bla(CMY-2) from cattle in Great Britain, and, also to our knowledge, the first demonstration of multiple cephalosporin-resistant strains in a single animal.

bla(CTX-M) genes in clinical Salmonella isolates recovered from humans in England and Wales from 1992 to 2003

Cefotaximases (CTX-M) are a rapidly growing class A beta-lactamase family that has been found among a wide range of clinical bacteria. One hundred and six isolates were selected from 278,308 Salmonella isolates based on resistance to ampicillin and cephalosporins and subjected to further characterization. Fourteen isolates were bla(CTX-M) PCR positive, and cefotaxime MICs for these isolates were > or = 16 mg/liter. Furthermore, sequence analysis revealed the presence of type CTX-M9, -15, or -17 to -18. All 14 isolates presented different PFGE restriction profiles, although six Salmonella enterica serotype Virchow isolates formed a tight cluster. The bla(CTX-M) genetic determinants were present in transferable plasmids of approximately 63, 105, and >148 kb. Plasmid restriction analysis showed that both horizontal transfer of similar plasmids among different clones and transfer of genes between different plasmids were likely mechanisms involved in the spread of bla(CTX-M) genes. We have found that CTX-M enzymes have emerged in community-acquired infections both linked to foreign travel and domestically acquired. This is the first report of a CTX-M enzyme in Salmonella in the United Kingdom. Also, it represents the first report of a bla(CTX-M) gene in Salmonella enterica serotype Stanley and a bla(CTX-M-15) gene in Salmonella enterica serotypes Anatum, Enteritidis, and Typhimurium.

Structural basis for recognition of the translocated intimin receptor (Tir) by intimin from enteropathogenic Escherichia coli

Intimin is a bacterial adhesion molecule involved in intimate attachment of enteropathogenic and enterohaemorrhagic Escherichia coli to mammalian host cells. Intimin targets the translocated intimin receptor (Tir), which is exported by the bacteria and integrated into the host cell plasma membrane. In this study we localized the Tir-binding region of intimin to the C-terminal 190 amino acids (Int190). We have also determined the region's high-resolution solution structure, which comprises an immunoglobulin domain that is intimately coupled to a novel C-type lectin domain. This fragment, which is necessary and sufficient for Tir interaction, defines a new super domain in intimin that exhibits striking structural similarity to the integrin-binding domain of the Yersinia invasin and C-type lectin families. The extracellular portion of intimin comprises an articulated rod of immunoglobulin domains extending from the bacterium surface, conveying a highly accessible 'adhesive tip' to the target cell. The interpretation of NMR-titration and mutagenesis data has enabled us to identify, for the first time, the binding site for Tir, which is located at the extremity of the Int190 moiety.

Human colostrum and serum contain antibodies reactive to the intimin-binding region of the enteropathogenic Escherichia coli translocated intimin receptor

BACKGROUND

In Brazil, enteropathogenic Escherichia coli (EPEC) diarrhoea is endemic in young infants. A characteristic feature of EPEC adhesion to host cells is intimate attachment leading to the formation of distinctive "attaching and effacing" (A/E) lesions on mammalian cells. Two genes directly involved in intimate adhesion, eae and tir, encode the adhesion molecule intimin and its translocated receptor Tir, respectively. The intimin-binding domain of Tir was recently mapped to the middle part of the polypeptide (Tir-M), and the amino (Tir-N) and carboxy (Tir-C) termini were found to be located within infected host cells. Recently, it was shown that colostrum samples from mothers living in Sao Paulo contain IgA-class antibodies reactive with a number of proteins associated with EPEC virulence. It has also been shown that patients infected with verocytotoxin-producing E. coli O157 can produce antibodies to Tir. In the current study antibody responses to the different Tir domains were analyzed in sera and colostrum samples collected in an EPEC-endemic area of Brazil.

METHODS

Recombinant Tir, Tir-N, Tir-M, and Tir-C were expressed as His-tagged protein in E. coli BL21a and purified on nickel columns. Western blot analysis was used to investigate colostrum IgA- and serum IgG-class antibodies reactive with the Tir fragments.

RESULTS

Anti-Tir IgG antibodies were detected in the serum of children, with (63%) or without (50%) diarrhoea. Anti-Tir IgA-class antibodies were detected in all the colostrum pools tested. With the use of both serum IgG- and colostrum IgA-class antibodies, an immunodominant domain of the Tir-polypeptide, Tir M, was identified.

CONCLUSION

The intimin-binding region of Tir (Tir-M) is the immunodominant region of the polypeptide in humans. Both serum IgG-class and colostrum IgA-class antibodies reacted predominantly with the Tir-M domain.

Antibody response of patients infected with verocytotoxin-producing Escherichia coli to protein antigens encoded on the LEE locus

Sera from patients infected with verocytotoxin-producing Escherichia coli (VTEC) O157, from patients with antibodies to E. coli O157 lipopolysaccharide (LPS) and from healthy controls were examined for antibodies to proteins involved in expressing the attaching and effacing phenotype. After SDS-PAGE, purified recombinant intimin, EspA-filament structural protein, translocated protein EspB and three separate domains of the translocated intimin receptor (Tir) were tested for reaction with patients' sera by immunoblotting. An ELISA was also used to detect antibodies to intimin in sera from E. coli O157 LPS antibody-positive individuals. Seven of nine culture-positive patients and one control patient had antibodies to EspA. Five of these patients and two controls had serum antibodies to the intimin-binding region of Tir, whereas none of the sera contained antibodies binding to either of the intracellular domains of Tir. By immunoblotting, 10 of 14 culture-positive patients had antibodies to the conserved region of intimin, eight of whom were infected with E. coli O157 phage type 2. Thirty-six of 60 sera from culture-negative but E. coli O157 LPS antibody-positive patients had antibodies to intimin as determined by ELISA. The secreted proteins are expressed in vivo during infection and are considered as pathogenic markers. Antibodies to these proteins may form the basis of a serodiagnostic test for the detection of patients infected with VTEC which carry the locus for the enterocyte effacement pathogenicity island and provide an adjunct test to the established serological tests based on VTEC LPS.

4-Pyridin-5-yl-2-(3,4,5-trimethoxyphenylamino)pyrimidines: potent and selective inhibitors of ZAP 70

Activation of the tyrosine kinase ZAP 70 has been shown to be crucial to the transduction of the T-cell receptor signalling pathway, which leads ultimately to proliferation, cytokine gene expression and T-cell effector functions. A series of 2-phenylaminopyrimidines have been identified as potent and selective inhibitors of ZAP 70.

Development of a universal intimin antiserum and PCR primers

Enteropathogenic Escherichia coli (EPEC) and enterohemorrhagic E. coli (EHEC) constitute a significant risk to human health worldwide. A hallmark of both pathogens is their ability to produce characteristic attaching-and-effacing (A/E) lesions in intestinal epithelial cells. Genes encoding A/E lesion formation map to a chromosomal pathogenicity island termed the locus of enterocyte effacement (LEE). Intimin, an LEE-encoded bacterial adhesion molecule, mediates the intimate bacterium-host cell interaction characteristic of A/E lesions. On the basis of characterization of the C-terminal 280-amino-acid cell binding domain of intimin (Int280(661-939)), four distinct Int280 types (types alpha, beta, gamma, and delta) have been identified. Importantly, Int280alpha and Int280beta antisera specifically recognized their respective intimin types. Using a conserved region of the intimin molecule (Int(388-667)) and primers synthesized to generate the recombinant Int(388-667), we have now generated universal intimin antiserum and PCR primers that are reactive with the different intimin types expressed by both human and animal A/E lesion-forming strains. Use of immunogold electron microscopy to visualize intimin on the surfaces of EPEC and EHEC strains revealed, in general, a uniform distribution on the bacterial cell surface. However, a filamentous staining pattern was observed with a few strains expressing intimin gamma. Cloning of the intimin eae gene from one such strain (strain ICC57) into strain CVD206, an EPEC strain which harbors a null deletion in eae, produced a uniform intimin staining pattern indicating that, if the filamentous staining pattern defines a filamentous form of intimin gamma, it is dependent upon the genetic background of the strain and is not a feature of the intimin molecule.

Identification of CesT, a chaperone for the type III secretion of Tir in enteropathogenic Escherichia coli

The locus of enterocyte effacement of enteropathogenic Escherichia coli encodes a type III secretion system, an outer membrane protein adhesin (intimin, the product of eae ) and Tir, a translocated protein that becomes a host cell receptor for intimin. Many type III secreted proteins require chaperones, which function to stabilize proteins, prevent inappropriate protein-protein interactions and aid in secretion. An open reading frame located between tir and eae, previously named orfU, was predicted to encode a protein with partial similarity to the Yersinia SycH chaperone. We examined the potential of the orfU gene product to serve as a chaperone for Tir. The orfU gene encoded a 15 kDa cytoplasmic protein that specifically interacted with Tir as demonstrated by the yeast two-hybrid assay, column binding and coimmunoprecipitation experiments. An orfU mutant was defective in attaching-effacing lesion formation and Tir secretion, but was unaffected in expression of other virulence factors. OrfU appeared to stabilize Tir levels in the cytoplasm, but was not absolutely necessary for secretion of Tir. Based upon the physical similarities, phenotypic characteristics and the demonstrated interaction with Tir, orfU is redesignated as cesT for the chaperone for E. coli secretion of T ir.

Binding of intimin from enteropathogenic Escherichia coli to Tir and to host cells

Enteropathogenic Escherichia coli (EPEC) induce characteristic attaching and effacing (A/E) lesions on epithelial cells. This event is mediated, in part, by binding of the bacterial outer membrane protein, intimin, to a second EPEC protein, Tir (translocated intimin receptor), which is exported by the bacteria and integrated into the host cell plasma membrane. In this study, we have localized the intimin-binding domain of Tir to a central 107-amino-acid region, designated Tir-M. We provide evidence that both the amino- and carboxy-termini of Tir are located within the host cell. In addition, using immunogold labelling electron microscopy, we have confirmed that intimin can bind independently to host cells even in the absence of Tir. This Tir-independent interaction and the ability of EPEC to induce A/E lesions requires an intact lectin-like module residing at the carboxy-terminus of the intimin polypeptide. Using the yeast two-hybrid system and gel overlays, we show that intimin can bind both Tir and Tir-M even when the lectin-like domain is disrupted. These data provide strong evidence that intimin interacts not only with Tir but also in a lectin-like manner with a host cell intimin receptor.

Protein kinase A activity may kinetically upregulate the striatal transporter for dopamine

The neuronal dopamine transporter (DAT) plays a key role in terminating dopaminergic chemical neurotransmission; thus, the study of the regulation of DAT activity is important in defining parameters relevant to the control of dopaminergic neurotransmission. Interpretation of the results from previous work of this laboratory suggests that occupation of presynaptic autoreceptors increases DAT activity. Second messenger signaling related to kinetic upregulation of DAT has not been examined previously. However, others have shown that protein kinase C activity may downregulate DAT activity, whereas protein kinase A has shown variable results. Herein it is shown that protein kinase A activity mediates the kinetic upregulation of DAT. Quinpirole increased DAT activity that was blocked by sulpiride and the protein kinase A selective inhibitor H-89. Brief incubations with forskolin and 8-bromo-cAMP (8-Br-cAMP) were found to stimulate striatal DAT activity by increasing the Vmax of transport without affecting the Km. Exposures >15 min had no effect. The 8-Br-cAMP-stimulated increases in DAT activity were blocked by pre-exposure to H-89. Thus, second messenger signaling via the cAMP cascade may mediate kinetic upregulation of DAT. Kinetic analyses of the results suggest that either insertion of DAT into the membrane or activation of pre-existing DAT within the membrane mediates the regulation.

Generation of Escherichia coli intimin derivatives with differing biological activities using site-directed mutagenesis of the intimin C-terminus domain

Intimins, encoded by eae genes, are outer membrane proteins involved in attaching-effacing (A/E) lesion formation and host cell invasion by pathogenic bacteria, including enteropathogenic Escherichia coli (EPEC) and Citrobacter rodentium. A series of intimins, harbouring specific mutations close to the C-terminus, were constructed using pCVD438, which encodes the eae gene from EPEC strain E2348/69. These mutant plasmids were introduced into EPEC strain CVD206 and C. rodentium strain DBS255, which both contain deletion mutations in their eae genes. CVD206, CVD206(pCVD438) and CVD206(pCVD438) derivatives were assessed for their ability to promote A/E lesion formation or invasion of HEp-2 cells and to induce A/E lesions on fresh human intestinal in vitro organ cultures (IVOC). The pathogenicity of C. rodentium DBS255 harbouring these plasmid derivatives was also studied in mice. Here, we report that intimin-mediated A/E lesion formation can be segregated from intimin-mediated HEp-2 cell invasion. Moreover, adherence to IVOC, EPEC-induced microvillus elongation and colonization of the murine intestine by C. rodentium were also modulated by the modified intimins.