An outbreak of two strains of OXA-48 producing Klebsiella pneumoniae in a teaching hospital.

OXA-48 producers can be difficult to detect in clinical specimens due to phenotypic low-level resistance to carbapenems. Additionally, low infection rates make clinical specimens poor sentinels for the presence of OXA-48 producers within a healthcare institution. We report an outbreak of OXA-48-producing Klebsiella pneumoniae (OXAKp) that was discovered following culture of OXAKp in a urine specimen from a patient with no known risk factors for acquisition. Widespread screening across medical wards in the trust revealed evidence of transmission across several wards. Samples from 60 patients were positive for OXAKp. Five patients had OXAKp clinical infection, four of whom were treated with ceftazidime/avibactam. Variable number tandem repeat analysis of the OXAKp isolates revealed two predominant strain types clustered around two groups of wards. Infection prevention measures included isolation and cohort nursing of infected and colonized patients, restriction of affected ward areas to new admissions, stringent hand hygiene and use of personal protective equipment. Environmental cleaning of patient areas was carried out using chlorine-releasing disinfectants and hydrogen peroxide vapour. Entire wards were decanted to enable effective cleaning of empty ward areas. The outbreak lasted almost five months and is estimated to have cost around £400 000. During the course of the outbreak, there were five reported prescription and administration incidents related to confusion between ceftazidime and ceftazidime/avibactam. No patient harm resulted from these incidents and the implementation of brand name prescribing for ceftazidime/avibactam prevented further incidents.

Value of syndromic surveillance in monitoring a focal waterborne outbreak due to an unusual Cryptosporidium genotype in Northamptonshire, United Kingdom, June - July 2008.

The United Kingdom (UK) has several national syndromic surveillance systems. The Health Protection Agency (HPA)/NHS Direct syndromic surveillance system uses pre-diagnostic syndromic data from a national telephone helpline, while the HPA/QSurveillance national surveillance system uses clinical diagnosis data extracted from general practitioner (GP)-based clinical information systems. Data from both of these systems were used to monitor a local outbreak of cryptosporidiosis that occurred following Cryptosporidium oocyst contamination of drinking water supplied from the Pitsford Reservoir in Northamptonshire, United Kingdom, in June 2008. There was a peak in the number of calls to NHS Direct concerning diarrhoea that coincided with the incident. QSurveillance data for the local areas affected by the outbreak showed a significant increase in GP consultations for diarrhoea and gastroenteritis in the week of the incident but there was no increase in consultations for vomiting. A total of 33 clinical cases of cryptosporidiosis were identified in the outbreak investigation, of which 23 were confirmed as infected with the outbreak strain. However, QSurveillance data suggest that there were an estimated 422 excess diarrhoea cases during the outbreak, an increase of about 25% over baseline weekly levels. To our knowledge, this is the first time that data from a syndromic surveillance system, the HPA/QSurveillance national surveillance system, have been able to show the extent of such a small outbreak at a local level. QSurveillance, which covers about 38% of the UK population, is currently the only GP database that is able to provide data at local health district (primary care trust) level. The Cryptosporidium contamination incident described demonstrates the potential usefulness of this information, as it is unusual for syndromic surveillance systems to be able to help monitor such a small-scale outbreak.

Interaction of E1B 19K with Bax is required to block Bax-induced loss of mitochondrial membrane potential and apoptosis.

The Bcl-2 homologous region 3 (BH3) is sufficient for interaction of pro-apoptotic with anti-apoptotic Bcl-2 family members, and functional antagonism may determine whether cell survival or death is the outcome of this protein-protein interaction. To address the biological role of BH3, two Bax-Bcl2 chimeras were generated in which 13 amino acids encompassing BH3 was swapped between anti-apoptotic Bcl-2 and pro-apoptotic Bax, thereby generating Bax with BH3 of Bcl-2 (Bax-BH3Bcl2), and Bcl-2 with BH3 of Bax (Bcl2-BH3Bax). Function and binding of the chimeras was then assessed utilizing the adenoviral Bcl-2 homologue, E1B 19K, which blocks apoptosis, and interacts with Bax, but not with Bcl-2. E1B 19K did not interact with Bax-BH3Bcl2 but did interact with Bcl2-BH3Bax. Bax-BH3Bcl2 retained pro-apoptotic function, while Bcl2-BH3Bax did not exhibit either pro- or anti-apoptotic activity. Thus, BH3 of Bcl-2 encodes binding specificity but not the apoptotic propensity. E1B 19K could not block Bax-BH3Bcl2-induced apoptosis, suggesting that E1B 19K may act to antagonize pro-apoptotic proteins rather than as an effector of survival. Furthermore, Bax expression disrupted the mitochondrial membrane potential, which could be rescued by E1B 19K expression. Thus, BH3 controls the binding specificity among Bcl-2 family members, and direct interaction between pro-apoptotic and anti-apoptotic proteins is a mechanism to regulate mitochondrial membrane potential and apoptosis.

The E1B 19K protein associates with lamins in vivo and its proper localization is required for inhibition of apoptosis.

Expression of the E1B 19K protein is required to inhibit apoptosis induced by E1A during adenovirus infection and transformation. E1B 19K is homologous to Bcl-2 in function and the two proteins also share limited amino acid sequence homology. Consequently, the E1B 19K and Bcl-2 proteins bind to and inhibit the cellular death-inducing proteins Bax, Bak and Nbk/Bik. Both E1B 19K and Bcl-2 localize to membranes of the nucleus and the endoplasmic reticulum. In addition to membrane association, and unlike Bcl-2, the E1B 19K protein is found associated with intermediate filament proteins in the cytoplasm and the nuclear lamina and copurifies with the lamins both during infection and transformation. While a membrane targeting domain at the C-terminus of Bcl-2 ensures its proper localization, the mechanism by which the E1B 19K protein localizes is unknown. Not surprisingly, lamin A fragments were cloned from a yeast two-hybrid screen for E1B 19K-interacting proteins. The interaction was demonstrated in yeast and mammalian cells in vivo and in vitro and was unique and specific to E1B 19K, with no interaction evident between Bcl-2 and lamin A. Mutants of lamin A/C which localized inappropriately in the cytoplasm or nucleus but retained E1B 19K binding, interfered with the nuclear envelope and cytoplasmic membrane targeting of the E1B 19K protein. Improper localization impaired the ability of the E1B 19K protein to inhibit apoptosis. Thus, proper localization of the E1B 19K protein is required for its function and the interaction of the E1B 19K protein with lamin A/C may represent a means for nuclear envelope localization.

Optimisation of ultraclean air. The role of instrument preparation.

The use of ultraclean air (UCA) in operating theatres reduces the infection rate after joint replacement but some cases of infection still occur. We investigated one possible source of contamination, namely the setting up of instruments in a conventional plenum-ventilated preparation room. We measured bacterial fallout using agar settle plates and compared instruments set up in the preparation room with those set up in the UCA theatre, assessed the effect of covering instruments after preparation and compared fallout during their preparation with total fallout throughout the operation. Our findings showed that covering the instruments reduced total bacterial fallout fourfold by reducing the exposure time, particularly during periods of increased activity and bacterial dispersal. Preparation in the UCA theatre and subsequent covering of the instruments reduced total fallout 28-fold. All measurable bacterial fallout occurred during the setting up and not during surgery.

The E1B 19K protein blocks apoptosis by interacting with and inhibiting the p53-inducible and death-promoting Bax protein.

The E1B 19K protein is a potent apoptosis inhibitor and the putative adenovirus Bcl-2 homolog. To investigate the mechanism of apoptosis regulation, 19K-interacting cellular proteins were identified using the yeast two-hybrid system, and Bax was one of seven 19-K interacting clones. Residues 50-78 of Bax containing a conserved region designated Bcl-2 homology region 3 (BH3) were sufficient for specific binding to both the E1B 19K and Bcl-2 proteins. The Bax-E1B 19K interaction was detectable in vitro and in lysates from mammalian cells, and Bax expression antagonized E1B 19K protein function. bax mRNA and protein levels were p53-inducible with kinetics identical to that of p21/Waf-1/Cip-1, and E1B 19K and Bcl-2 expression did not affect Bax or p21/Waf-1/Cip-1 accumulation. In cells where p53 was mutant, Bax expression induced apoptosis, suggesting that Bax was sufficient for apoptosis, and acted downstream of p53. p53 may simultaneously activate the transcription of genes required for both growth arrest (p21/Waf-1/Cip-1) and death (bax), and E1B 19K and Bcl-2 may act distally and function through interaction with and antagonism of Bax to prevent apoptosis. With the death pathway disabled, induction of growth arrest by p53 can then be manifested.

A learning law for density estimation.

Probability density functions are estimated by an exponential family of densities based on multilayer feedforward networks. The role of the multilayer feedforward networks, in the proposed estimator, is to approximate the logarithm of the probability density functions. The method of maximum likelihood is used, as the main contribution, to derive an unsupervised backpropagation learning law to estimate the probability density functions. Computer simulation results demonstrating the use of the derived learning law are presented.