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C Block

Publications and source records attributed to C Block.

At least 19 recordsLinked to original sources
PubMed2006

Evaluation of eight commercial tests for Mycoplasma pneumoniae antibodies in the absence of acute infection.

Eight commercially available tests for Mycoplasma pneumoniae (Serodia-Myco II, Labsystems IgM and IgG EIA, IgM and IgG LISA tests, ImmunoWell IgG test and SeroMP IgM and IgG) were compared using 204 single sera from healthy individuals. IgM peaked in late childhood and then declined, while IgG rose progressively into adulthood. Inter-assay agreement was poor. Positivity in Serodia-Myco II and LISA IgG was associated with blood group or Coombs positivity, suggesting non-specific reactions. The study confirmed that single serum serology is unsuitable for the diagnosis of M. pneumoniae infection, and that commercially available tests need further improvement.

Adolescent↗
PubMed2004

The effect of Perasafe and sodium dichloroisocyanurate (NaDCC) against spores of Clostridium difficile and Bacillus atrophaeus on stainless steel and polyvinyl chloride surfaces.

Clostridium difficile is an important cause of nosocomial diarrhoea. The aim of this study was to evaluate the potential for Perasafe, a recently introduced biocide, to contribute to control of C. difficile spores in the patient environment, in comparison with the chlorine-releasing agent sodium dichloroisocyanurate (NaDCC). These agents were evaluated against a water control, in a surface test on stainless steel and polyvinyl chloride (PVC) floor covering, materials commonly found in the hospital environment. The organisms studied were a toxigenic clinical isolate of C. difficile, and Bacillus atrophaeus (formerly B. subtilis var niger). The data indicate that in our in vitro system, Perasafe was significantly more active than NaDCC (1000 ppm available chlorine) against C. difficile spores dried on stainless steel surfaces, and against B. atrophaeus on PVC floor covering material, achieving mean log10 reduction factors in viable counts of 6 and 5.5, respectively, at 10 min exposures. Perasafe appeared to be less lethal in 10 min exposures to C. difficile spores fixed on PVC floor covering material. In general, 1000 ppm chlorine generated from NaDCC showed lower log10 reduction factors in viable counts at 10 min, ranging from 0.7 to 1.5, than Perasafe which ranged from 2.7 to 6.0. The potential efficacy of Perasafe in reducing the density of C. difficile spores in the patient environment in hospitals, nursing homes or other long-stay facilities should be evaluated in field studies.

Acetic Acid↗
PubMed2002

Cluster of neonatal infections in Jerusalem due to unusual biochemical variant of Enterobacter sakazakii.

Reported here is a cluster of infections due to a nitrate-negative variant of Enterobacter sakazakii, which occurred among premature neonates at the Hadassah Hospital, Mount Scopus, Jerusalem, in December 1999-January 2000. Pulsed-field gel electrophoresis showed cluster isolates to be identical but unrelated to previous systemic isolates recovered in 1993 and 1998. The organism was not isolated from infant formula powder, but it was recovered from prepared formula and from a kitchen blender. Elimination of the environmental focus, a change to factory-prepared infant formula, and isolation of affected infants terminated the event. Faecal carriage of Enterobacter sakazakii was observed for up to 18 weeks, emphasising the potential for cross-infection.

Bacteremia↗
PubMed2002

Increasing incidence of gonorrhea in Israel associated with countrywide dissemination of a ciprofloxacin-resistant strain.

The annual incidence of gonorrhea in Israel has sharply increased during the past 2 years. At the end of 1999, high-level ciprofloxacin-resistant strains of Neisseria gonorrhoeae (MIC90, > or =32 mcg/ml) also exhibiting decreased susceptibility to penicillin and tetracycline were isolated for the first time in southern Israel, as well as in other regions of the country. The incidence of male gonococcal urethritis in the south increased in a 1.5-year period from 3/100,000 to 12/100,000 ( P<0.05) in correlation with increased isolation of ciprofloxacin-resistant organisms. A marked increase in the incidence of gonorrhea was also encountered in Jerusalem, where ciprofloxacin resistance affected 54.5% of the isolates in 2000. Pulsed-field gel electrophoresis typing of gonococci from different areas of Israel indicated that all of the ciprofloxacin-resistant isolates belonged to identical or related strains. Since fluoroquinolone-resistant gonococci may emerge and disseminate extensively over a short period of time, continuous surveillance of antibiotic susceptibility among gonococcal isolates should be performed to guide empiric therapy.

Adult↗
PubMed2002

Association between intensity of chlorhexidine use and micro-organisms of reduced susceptibility in a hospital environment.

The potential for emergence of resistance to biocides has been a concern in recent years. This study tested whether an association exists between the intensity of chlorhexidine use and chlorhexidine susceptibility of micro-organisms isolated from patients in different clinical areas in an acute-care general hospital. Organisms frequently involved in nosocomial infections in the hospital were chosen for study over a six week period: Staphylococcus aureus (60 isolates), coagulase-negative staphylococci (48), Klebsiella pneumoniae (32), Pseudomonas aeruginosa (60), Acinetobacter baumannii (16) and Candida albicans (35). An index of chlorhexidine exposure for each clinical unit was derived for the year preceding organism collection. Chlorhexidine susceptibility was evaluated using agar incorporation minimum inhibitory concentrations (MICs) and disk diffusion. A statistically significant inverse correlation was shown between intensity of chlorhexidine use and the overall susceptibility of all study organisms taken together. There was no association when individual taxa were considered. These findings must be interpreted with caution considering that greater use of chlorhexidine is likely to occur in difficult clinical disciplines where antibiotic use, invasive procedures and other intensive care-related procedures, cross-infection and immunosuppression are all potential confounding factors. There was an excellent correlation between MICs and disk testing, suggesting that disk diffusion might be useful in studies involving more than one biocide.

Bacteria↗
PubMed2002

Fungemia in a cancer patient caused by fluconazole-resistant Cryptococcus laurentii.

We report the recent isolation of Cryptococcus laurentii from the blood of a patient given the diagnosis of ganglioneuroblastoma. The organism was identified using physiological and molecular characteristics, including morphology, carbohydrate and nitrate assimilation, urease activity, inability to form melanin on appropriate media, positive staining with diazonium blue B and sequence analysis of the D1/D2 domain of 26S ribosomal DNA. The isolate was resistant to fluconazole and 5-fluorocytosine using both the Etest and a broth microdilution assay. Repeated recovery of the organism from different blood cultures, and the patient's good response to treatment with amphotericin B support its etiological role. C. laurentii has rarely been implicated as a cause of clinically significant infections. The identity of reported isolates has not always been adequately documented, and some appear to have been isolated from lesions caused by Cryptococcus neoformans, emphasizing the true rarity of disease due to this fungus.

Adolescent↗
PubMed2001

Domain shuffling as a tool for investigation of protein function: substitution of the cysteine-rich region of Raf kinase and PKC eta for that of yeast Pkc1p.

With the completion of the sequences of entire genomes, the need for functional characterisation of proteins and their domains is becoming acute. Conserved regions within proteins often share overlapping functions but despite this conservation may fulfil quite different tasks in different species. In this work, we investigated the cysteine-rich motif (C1 domain) of yeast protein kinase C (Pkc1p) as a model to establish a test system for domain function. C1 domains activate kinases through binding of either diacylglycerol and/or phosphatidylserine, as in many members of the protein kinase C (PKC) family, or by binding small GTPases, as in Raf kinase. In contrast to other members of the protein kinase C superfamily, Pkc1p of Saccharomyces cerevisiae is activated via binding of the small G-protein Rho1p to its C1 domain. We developed a system for domain shuffling to establish the function of C1 domains from human Raf kinase and rat PKC eta in yeast. Only the C1 domain from Raf kinase enabled the chimeric enzyme to bind Rho1p when substituted for the native yeast domain. Accordingly, a chimeric Pkc1p carrying the C1 from Raf kinase, but not that from PKC eta, was able to partially complement the phenotypes of a yeast pkc1 deletion mutant. We interpret these data as further evidence that interaction with a small GTPase is the main regulatory function of the C1 domain in yeast.

Amino Acid Motifs↗
PubMed2001

Transient urethral obstruction predisposes to ascending pyelonephritis and tubulo-interstitial disease: studies in rats.

Chronic tubulo-interstitial disease, an important cause of end-stage renal disease, often results from the combined effects of a disturbed urinary outflow tract and urinary tract infection. Acute unilateral ureteral obstruction in rats rapidly induces foci of medullary necrosis, confined to the region of the papilla and fornices. This injury may provide a nidus for bacterial invasion and may invoke reactive and regenerative changes, ultimately leading to chronic pyelonephritis and tubulo-interstitial nephropathy. To explore this possibility, adult rats underwent renal morphological evaluation 2-7 days following transient 24-h unilateral ureteral obstruction. In some experiments the bladder was inoculated with bacteria (10(8)-10(9) cfu/ml Escherichia coli in 0.5 ml) after release of ureteral obstruction, with subsequent cultures obtained from the pelvis of both kidneys and from the urinary bladder. Morphologic evaluation of perfusion-fixed kidneys, 2-7 days after the release of 24-h ureteral obstruction disclosed papillary necrosis, urothelial proliferation, marked inner-stripe interstitial expansion, and fibrosis and proximal tubular (S3) dilatation. The lateral (perihilar region) was predominantly affected, with lesions spreading from the fornices. There was some progression of interstitial fibrosis during the postobstructive time course or following more prolonged ureteral obstruction. By contrast, infection hardly contributed to the tubulointerstitial changes. In rats subjected to infection, cultures were positive in all 15 postobstructive kidneys, as opposed to five contralateral kidneys (P < 0.0001). Viable counts from the postobstructive kidney were also higher than those from the contralateral side (79,000 +/- 12,000 vs 2900 +/- 1600 cfu/ml, mean +/- SEM, P < 0.0001), and were comparable to those obtained from the bladder (77,000 +/- 13,000 cfu/ml). We conclude that transient ureteral obstruction predisposes to ascending pyelonephritis and to tubulointerstitial disease. This vulnerability may relate to altered urodynamics and medullary tissue destruction.

Animals↗
PubMed2001

The yield of blood cultures in a department of emergency medicine.

This study sought to determine the yield of blood cultures drawn in the department of emergency medicine. The results of 730 blood cultures taken from 718 patients were retrospectively analysed. The total percentage of positive cultures was 9.7%. Only 3.4% of the blood cultures were classified as true bacteraemia and the rest as contaminants. The commonest type of isolate was coagulase-negative staphylococci (49%), which were considered contaminants in all cases. Other contaminants represented 13.2% of all the positive blood cultures. The following bacteria comprised the group of true bacteraemia: Escherichia coli (12.6%), Streptococcus pneumoniae (9.8%), viridans streptococci (7%), Staphylococcus aureus (2.8%), Bacteroides fragilis (2.8%), Moraxella species (1.4%) and Flavobacterium species (1.4%). Blood cultures were positive in 3.6% of patients with pneumonia and in 10% of patients with urinary tract infections. In patients with fever of unclear source blood cultures were positive in 3.1% of children between 0-36 months of age and in 1.1% of patients older than 16 years. As a whole, patients with positive blood cultures were clinically sicker, a higher percentage of them required admission to the hospital and had higher temperatures or rapidly fatal disease, compared with the group of patients with negative blood cultures. In order to improve the yield of blood cultures in febrile patients, first, better a priori identification of those subjects at high risk for bacteraemia will reduce the number of unnecessary blood cultures and second, sterile venipuncture techniques should be improved in order to reduce the number of contaminants.

Adolescent↗
PubMed2001

Acinetobacter baumannii at a tertiary-care teaching hospital in Jerusalem, Israel.

In a retrospective 10-year analysis of 3,536 patient-unique isolates, Acinetobacter baumannii imipenem susceptibility declined from 98.1 (1990) to 64.1% (2000), and ciprofloxacin susceptibility decreased from 50.5 to 13.1%. Imipenem median zone diameters decreased from 27. 7 (1997) to 18.8 mm (2000). No outbreaks were detected. Two clusters were identified for 41 strains genotyped by pulsed-field gel electrophoresis, but imipenem resistance was not clonal.

Acinetobacter↗
PubMed2001

Skin disease presenting as an outbreak of pseudobacteremia in a laboratory worker.

An outbreak of pseudobacteremia due to Streptococcus pyogenes (group A streptococci [GAS]) and methicillin-susceptible Staphylococcus aureus (MSSA) was traced to the venting procedure for aerobic bottles prior to their loading into the incubator of the BacT/Alert analyzer (Organon Teknika). Bacteria shed by a laboratory worker suffering from impetigo and cellulitis contaminated the aerobic bottles of 10 patients. All blood culture isolates, in addition to the isolates from the laboratory worker, were of the same GAS M and T types. All MSSA isolates from blood cultures and the index case's hands had the same lytic phage profile. Procedural breakdowns were identified in the laboratory. Bottles were vented outside the biological safety cabinet, gloves were not worn, and unprotected needles were used for the venting procedure. The source of the aspirated bacteria that contaminated the bottles was identified and the index case was treated promptly.

Bacteremia↗
PubMed2001

Multidrug-resistant Trichosporon asahii infection of nongranulocytopenic patients in three intensive care units.

Trichosporon asahii (Trichosporon beigelii) infections are rare but have been associated with a wide spectrum of clinical manifestations, ranging from superficial involvement in immunocompetent individuals to severe systemic disease in immunocompromised patients. We report on the recent recovery of T. asahii isolates with reduced susceptibility in vitro to amphotericin B (AMB), flucytosine, and azoles from six nongranulocytopenic patients who exhibited risk factors and who developed either superficial infections (four individuals) or invasive infections (two individuals) while in intensive care units. The latter two patients responded clinically and microbiologically to AMB treatment. All six isolates were closely related according to random amplified polymorphic DNA studies and showed 71% similarity by amplified fragment length polymorphism analysis, suggesting a common nosocomial origin. We also review the literature pertaining to T. asahii infections and discuss the salient characteristics of this fungus and recent taxonomic proposals for the genus.

Aged↗
PubMed2001

Enterobacter sakazakii infection in the newborn.

UNLABELLED: Enterobacter sakazakii, a Gram-negative bacillus, previously known as "yellow pigmented Enterobacter cloacae", is a rare cause of neonatal infection. We describe the detailed clinical presentation of two cases in whom E. sakazakii was isolated in our neonatal service during the course of 1 mo. These include one case of sepsis and meningitis complicated by cerebral infarction, and one case of sepsis. In addition, three cases of intestinal colonization were identified. The source of the organism was thoroughly sought and was found to be a blender in the milk kitchen that was used for preparation of the reconstituted powdered milk formula. CONCLUSION: Our paper adds clinical and laboratory information about the disease spectrum caused by this relatively rare organism and emphasizes the importance of a thorough search for the source of the infection.

Central Nervous System Infections↗
PubMed2000

Oncogenic insertional mutations in the P-loop of Ras are overactive in MAP kinase signaling.

Mutations of Ras with three extra amino acids inserted into the phosphate-binding (P) loop have been investigated both in vitro and in vivo. Such mutants have originally been detected as oncogenes both in the ras and the TC21 genes. Biochemical experiments reveal the molecular basis of their oncogenic potential: the mutants show a strongly attenuated binding affinity for nucleotides, most notably for GDP, leading to a preference for GTP binding. Furthermore, both the intrinsic as well as the GAP-stimulated GTP hydrolysis are drastically diminished. The binding interaction with GAP is reduced, whereas binding to the Ras-binding domain of the downstream effector c-Raf1 is not altered appreciably. Microinjection into PC12 cells shows the mutants to be as potent to induce neurite outgrowth as conventional oncogenic Ras mutants. Unexpectedly, their ability to stimulate the MAP kinase pathway as measured by a reporter gene assay in RK13 cells is much higher than that of the normal oncogenic mutant G12V. This characteristic was attributed to an increased stimulation of c-Raf1 kinase activity by the insertional Ras mutants.

Animals↗
PubMed2000

High rate of candidemia in patients sustaining injuries in a bomb blast at a marketplace: a possible environmental source.

In this study, a cluster of candidemia among patients sustaining injuries in a bomb blast at a marketplace was investigated by means of a multivariate analysis, a case-control study, and quantitative air sampling. Candidemia occurred in 7 (30%) of 21 patients (58% of those admitted to the intensive care unit [ICU]) between 4 and 16 days (mean, 12 days) after the injury and was the single most frequent cause of bloodstream infections. Inhalation injury was the strongest predictor for candidemia by multivariate analysis. Candidemia among the case patients occurred at a significantly higher rate than among comparable trauma patients injured in different urban settings, including a pedestrian mall (2 of 29; P=. 02), and among contemporary ICU control patients (1 of 40; P=.001). Air sampling revealed exclusive detection of Candida species and increased mold concentration in the market in comparison with the mall environment. These findings suggest a role for an exogenous, environmental source in the development of candidemia in some trauma patients.

Adolescent↗
PubMed2000

Phosphoinositide 3-kinase-dependent Ras activation by tauroursodesoxycholate in rat liver.

Ursodesoxycholic acid, widely used for the treatment of cholestatic liver disease, causes choleretic, anti-apoptotic and immunomodulatory effects. Here the effects on choleresis of its taurine conjugate tauroursodesoxycholate (TUDC), which is present in the enterohepatic circulation, were correlated with the activation of important elements of intracellular signal transduction in cultured rat hepatocytes and perfused rat liver. TUDC induced a time- and concentration-dependent activation of the small GTP-binding protein Ras and of phosphoinositide 3-kinase (PI 3-kinase) in cultured hepatocytes. Ras activation was dependent on PI 3-kinase activity, without the involvement of protein kinase C- and genistein-sensitive tyrosine kinases. Ras activation by TUDC was followed by an activation of the mitogen-activated protein kinases extracellular-signal-regulated kinase-1 (Erk-1) and Erk-2. In perfused rat liver, PI 3-kinase inhibitors largely abolished the stimulatory effect of TUDC on taurocholate excretion, suggesting an important role for a PI 3-kinase/Ras/Erk pathway in the choleretic effect of TUDC.

Animals↗
PubMed2000

Mitogenic signaling of Ras is regulated by differential interaction with Raf isozymes.

In the mitogenic signaling cascade interaction of Ras with Raf represents a critical step for the regulation of cell growth and differentiation. The major effector of Ras, the serine/threonine kinase Raf exists as three isoforms with different tissue distributions. We demonstrate that transient transfection of oncogenic Ha-Ras leads to a preferential activation of endogenous c-Raf-1 in HEK 293 cells as opposed to A-Raf. In vitro binding studies using purified Ras binding domains of Raf as well as in vivo bindings tests with full length molecules reveals significantly lower binding affinities of A-Raf to Ha-Ras as compared to other Raf isoforms. The Ras-binding interface of c-Raf differs from A-Raf by a conservative Arg to Lys exchange at residue 59 or 22 respectively. Mutational analysis reveals that this residue represents a point of isozyme discrimination: c-Raf-R59K binds Ha-Ras weaker than the wildtype, likewise A-Raf-K22R increases its affinity to Ha-Ras in vivo and in vitro. Differential binding affinities are reflected in downstream signaling. Immunecomplex kinase assays reveal that Ha-Ras mediated Raf activation is decreased for c-Raf-R59K and increased for A-Raf-K22R when compared to the respective wildtype forms. Thus our observations introduce a new level of isoform discrimination in Ras/Raf signaling as a functional consequence of a conservative amino acid exchange in the Ras binding domains.

Amino Acid Sequence↗