Prevalence of MRSA in South Australian nursing homes.
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Biomedical subjects
Publications and source records attributed to D L Gordon.
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The results of four urinary albumin methods used to identify patients with early diabetic renal disease were compared using random urine samples from healthy and diabetic patients. These methods were the Beckman Array and Behring BNAI immunonephelometric methods, the Dade aca particle-enhanced turbidimetric inhibition immunoassay method, and the INCSTAR SPQ immunoturbidimetric method. The albumin/creatinine ratio reference interval was found to be 2-20 mg albumin/g creatinine (mg/g) for the Array and 3.5-27.5 mg/g for the aca method. All four methods were compared using urines from a group of diabetic and nondiabetic patients. The BNAI, SPQ and Array methods compared well with one another while the aca demonstrated a positive bias of almost 60% at the 30 mg/g and 300 mg/g levels with certain lots of reagent and calibrator. Calibrator cross-over experiments demonstrated that some of the positive bias of the aca method could be accounted for by calibrator differences.
Complement factor H (fH) regulates activation of the alternative pathway of C, reducing the amount of C3b deposited on sialic acid-rich surfaces. Heparin binding has been used as a model for examining the sialic acid-binding characteristics of fH. We have previously shown that of the 20 short consensus repeat (SCR) modules of fH, SCR 7 contains an important heparin binding site, but other SCRs also play a role in heparin binding. To localize the other sites, we prepared recombinant truncated and SCR deletion mutants of fH and tested them by heparin-agarose affinity chromatography. The 5 C-terminal SCRs were found to contain a heparin binding site as an SCR 7 deletion mutant of the N terminal 15 SCRs did not bind heparin, but a construct consisting of SCRs 16-20 was shown to bind heparin. Double deletion of SCRs 7 and 20 from fH abrogated binding to heparin, indicating that SCR 20 contains a heparin binding site. This finding was confirmed with the observation that attachment of SCR 20 to a group of nonbinding SCRs produced a heparin-binding protein. A protein consisting of SCRs 19 and 20 did not bind heparin, whereas SCRs 18-20 did, indicating that, although SCR 20 contains a heparin binding site, at least two nonspecific adjacent SCRs are required. fH-related protein-3 (FHR-3) possesses an SCR homologous to SCR 7 of fH and bound heparin, whereas FHR-4, which lacks such an SCR, did not. Thus, fH contains two separate heparin binding sites, which are located in SCRs 7 and 20.
This report presents an infant in whom a unique case of chylous ascites developed after blunt abdominal trauma. Unfortunately, this case was complicated by Pseudomonas peritonitis, likely from a distant source. Our patient was treated medically and had a good overall outcome.
Fatigue is a frequently reported symptom by persons with HIV infection and one that has an adverse impact on activities of daily living and overall quality of life. Although the concept of fatigue has been studied extensively and discussed in the literature, little is known about the experience of fatigue by persons with HIV infection. A hermeneutic phenomenological study was conducted to investigate the subjective experience of HIV-associated fatigue and to describe the management of fatigue in the context of daily life. In-depth interviews were done with 10 adult patients of an outpatient HIV/AIDS clinic. Thematic analysis identified three concerns that represented the meaning of fatigue for the participants. The first concern was 'Fatigue as a signal of AIDS'. A second concern was 'The mind, the body, the social experience of fatigue'. The third concern was 'Choosing ways to live with fatigue and addiction'. The findings provide insights for nursing practice regarding the subjective meaning of fatigue for patients with HIV and the need for nurses to explore this topic with patients.
Infection with marine bacteria is uncommon. A patient with systemic lupus erythematosus who developed concurrent infection with Shewanella putrefaciens and Mycobacterium marinum (M. marinum) is described. After bathing leg ulcers in sea water, severe cellulitis of the left leg with necrotic areas and extensive bullae developed. Infection due to S. putrefaciens was confirmed and a long course of hospitalization, oral ciprofloxacin and skin grafting was required. During hospitalization subcutaneous nodules developed on the other leg. Biopsy revealed acid-fast bacilli and culture grew M. marinum. These lesions responded to rifampicin and cotrimoxazole. Patients with leg ulcers, peripheral vascular disease, diabetes, or receiving immunosuppressive drugs may acquire unusual infections after salt water exposure.
Streptococcus pyogenes evades complement by binding the complement-regulatory protein factor H (fH) via the central conserved C-repeat region of M protein. However, the corresponding binding region within fH has not previously been precisely localized. fH is composed of 20 conserved modules called short consensus repeats (SCRs), each of which contains approximately 60 amino acids. A series of fH truncated and deletion mutants were prepared, and their interaction with M6 protein was examined. The M protein binding site was initially localized to SCRs 6 to 15 as demonstrated by ligand dot blotting, chemical cross-linking, and enzyme-linked immunosorbent assay. SCR 7 was then shown to contain the M protein binding site, as a construct consisting of the first seven SCRs bound M protein but a construct containing the first six SCRs did not bind. In addition, deletion of SCR 7 from full-length fH abolished binding to M protein. SCR 7 is known to contain a heparin binding domain, and binding of fH to M6 protein was almost totally inhibited in the presence of 400 U of heparin per ml. These results localize the M6 protein binding site of fH to SCR 7 and indicate that it is in close proximity to the heparin binding site.
The 5' flanking region of human factor H was cloned using nested polymerase chain reaction (PCR) and the promoter finder method. A total of 1.2 kb has been sequenced and a number of putative regulatory elements identified including glucocorticoid response elements cAMP responsive element, HTF-1, and acute phase signal sequences. A 717 b.p. fragment was cloned into a CAT reporter vector and transfected into HeLa cells. A series of truncations from the 5' end of this fragment were also cloned into the CAT vector. Analysis of CAT activity of the cell lysates showed that the region from -699 to +18 is likely to contain promoter elements for the factor H gene as it was able to drive transcription of the CAT gene.
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Surface polyanions such as sialic acid and heparin are thought to enhance the binding of complement factor H (fH) to C3b deposited on particles and cell surfaces, thereby reducing complement activation. fH contains 20 short consensus repeat (SCR) domains, and it has been proposed that SCR 13 contains a heparin binding site. We used recombinant proteins to determine the heparin binding site on fH. Full-length fH (H20) and truncated and SCR deletion mutant proteins were cloned and expressed in Chinese hamster ovary cells. Supernatants were applied to heparin-agarose affinity columns to determine their binding and elution profiles. Deletion of SCR 13 from H20 did not prevent heparin binding nor alter its salt elution profile, indicating that SCR 13 does not contain an essential heparin binding site. We found that SCR 7 contains a heparin binding site, as SCRs 1 through 7 were the smallest truncated proteins to bind heparin (89 +/- 3%). Furthermore, deletion of SCR 7 from a protein containing SCRs 1 through 9 reduced heparin binding, whereas deletion of SCR 6 did not (17 +/- 13 vs 81 +/- 13%; p = 0.02). It is likely that other heparin binding sites exist within SCRs 10 through 20; an SCR 7 deletion mutant of H20 eluted earlier than H20, but still showed >99% binding to immobilized heparin. SCR 13 does not contain such a site because a double deletion of SCRs 7 and 13 from H20 showed >97% heparin binding and had an elution profile smilar to that of a single deletion of SCR 7.
Thrombospondin is a trimeric glycoprotein that has several known functions, including roles in platelet aggregation, phagocytosis and an inhibitor of angiogenesis. Typically the molecule is isolated from platelet secretate by heparin affinity followed by sizing chromatography. In this study, purity is analysed by 7.5% SDS-PAGE under reducing conditions when thrombospondin monomers run as a band at around 180 kDa. Under nonreducing conditions of 7.5% SDS-PAGE, thrombospondin does not penetrate beyond the stacking gel; however, under these conditions a major contaminating band can be seen which, upon reduction, merges into the thrombospondin band. Further purification of this contaminating protein was achieved by DEAE chromatography and it was identified as Factor H by peptide sequencing and immunoblotting. Factor H function was demonstrated by the ability of the protein to function as a cofactor in the Factor-I-mediated cleavage of C3b. Since Factor H has several known functions, such contamination could confound functional studies of thrombospondin thus purified and a pre-elution step of the heparin affinity column is recommended.
Enterococcus spp. are becoming increasingly important nosocomial pathogens. They are intrinsically resistant to most antibiotics, and effective therapy depends primarily on the penicillins, vancomycin and the aminoglycosides. Under antibiotic selection pressure they have developed high level resistance to these agents, and the first vancomycin-resistant enterococcal infection in Australia was described recently. The vancomycin-resistance genes are of particular concern because of their potential to transfer to other gram-positive organisms. The prevention and control of resistant enterococci is a major challenge that is best met by a combination of active infection control measures and restriction of broad-spectrum antibiotic use.
BACKGROUND: There is increasing resistance to commonly used antibiotics, including third generation cephalosporins, and an increasing cost burden. AIMS: To assess the appropriateness of prescribing of third generation cephalosporin antibiotics in a tertiary teaching hospital. METHODS: Prescriptions of third generation cephalosporins (ceftriaxone, cefotaxime and ceftazidime) to inpatients were identified prospectively by the Hospital Pharmacy Department for a six week period during May-June 1994. Clinical data and indications were obtained from patient records and, when necessary, by interviewing the prescriber and by patient assessment. Criteria for appropriate prescribing were according to nationally accepted criteria outlined in the 1994-95 Antibiotic Guidelines handbook. All inpatients who were prescribed a third generation cephalosporin at Flinders Medical Centre for the duration of the audit period were eligible. This included medical, surgical, paediatric, obstetric and gynaecology inpatients. RESULTS: Sixty-five per cent of prescriptions for third generation cephalosporins were judged appropriate, 31% inappropriate and 4% doubtful. Inappropriate use was found particularly in the treatment of respiratory tract infections and abdominal sepsis, and in surgical prophylactic use. CONCLUSION: Third generation cephalosporin prescribing in a tertiary care teaching hospital is frequently inappropriate, as judged against widely available Australian guidelines.
The mechanism by which Burkholderia pseudomallei is resistant to lysis by human serum is unknown but may include interference with complement activation, effective opsonization, or complement-mediated lysis. We investigated the interaction of B. pseudomallei with complement in the presence and absence of specific antibody to determine potential mechanisms of serum resistance. We demonstrated rapid activation and consumption of complement by B. pseudomallei which, in the absence of specific antibody, occurred predominantly via the alternative pathway. Complement activation was associated with deposition of the opsonically active C3b and iC3b fragments on the bacterial surface. C5b-9, detected on the bacterial surface after opsonic periods of 1 to 60 min, was susceptible to elution by 1 M NaCl, indicating that resistance to complement-mediated lysis may result from deposition of the membrane attack complex in a nonmicrobicidal location. To define the role of opsonins, we investigated the ability of polymorphonuclear leukocytes (PMNL) to phagocytose B. pseudomallei. Phagocytosis of bacteria by PMNL, and the observed oxidative response, was significantly increased by opsonization of organisms with complement and/or specific antibody. Despite opsonophagocytosis by PMNL and the production of an oxidative response, no significant bacterial killing was observed.
Factor H, a regulator of complement activation, contains 20 short consensus repeat (SCR) domains common among the family of C3b/C4b-binding proteins. Chinese hamster ovary cells transfected with cDNA corresponding to the N-terminal tryptic fragment of factor H (containing SCR 1-5 and part of SCR 6) secreted protein with cofactor activity for factor I-dependent cleavage of C3b. A series of deletion mutants, each lacking one of the first five SCR, were constructed, and the supernatants of transfected Chinese hamster ovary cells were tested for cofactor activity. Supernatants of Chinese hamster ovary cells transfected with SCR 1, SCR 4, and SCR 5 deletion mutants retained cofactor function, although the SCR 1 deletion had reduced cofactor activity. Deletion of SCR 2 or 3 totally abolished cofactor activity. Expression and functional analysis of SCR units 1-3, 2-3, and 2-4 demonstrated that the SCR 1-3 unit is sufficient for cofactor activity, but SCR 1-4 is required for full activity. For assays involving cell protection, a construct linking SCR 1-5 to the glycosyl-phosphatidylinositol anchor of decay-accelerating factor was prepared, and stable transfectants were obtained. These cells were protected against complement-mediated cytotoxicity, similarly to decay-accelerating factor- and membrane cofactor protein-transfected cells. These studies define the complement regulatory domains in factor H and suggest that the general complement functional unit for C3 convertase regulation involves three or four consecutive SCR units.
OBJECTIVES: To describe the likely causes of ischemic stroke in a population of young adults and to report the influence of strict algorithms on the diagnosis of the likely cause of stroke in this cohort. DESIGN: Between July 1, 1977, and January 1, 1993, we registered 329 young adults with ischemic stroke in our registry. Diagnostic studies were selected on a case-by-case basis. Presumed causes of stroke were determined using clinical information and the results of diagnostic tests. In each case, a second causative diagnosis was made using the criteria developed for a large clinical trial. SETTING: Patients referred to the Division of Cerebrovascular Diseases in the Department of Neurology at the University of Iowa Hospitals and Clinics, Iowa City, by physicians in Iowa and adjacent states. PATIENTS: Three hundred twenty-nine young adults (182 men and 147 women) aged 15 to 45 years with ischemic stroke; 102 persons, 48 men and 54 women, were aged 30 years or younger. RESULTS: Cerebral arteriography was performed in 227 cases, and the findings were abnormal in 146. Transthoracic echocardiography revealed abnormalities in 82 of 221 patients examined. We identified approximately 60 different disorders that were presumed to be the cause of stroke. There were no major changes in the frequency of subtype diagnoses between the first 144 patients and the subsequent 185. Use of strict diagnostic criteria increased the number of cases of stroke of undetermined etiology (from 45 to 113), and the number attributed to large artery atherosclerosis declined from 71 to 32. CONCLUSIONS: The causes of ischemic stroke in young adults are numerous. Because treatment options in this group are influenced by a presumed cause, an evaluation on a case-by-case basis is warranted. Our experience suggests that a likely cause will be detected in most cases and that a regimented battery of tests may not be required. If strict diagnostic criteria are used, the diagnosis of stroke of undetermined etiology considerably increases. While such strict criteria are important in clinical trials that test new interventions, the value of the application of such methodologies to an unusual population, such as stroke in young adults, needs clarification. In particular, the usefulness of categorizing a stroke as undetermined when two or more possible causes are identified needs to be explored.
Nasopharyngeal aspirates and throat swab specimens were compared in a polymerase chain reaction (PCR)-based test for Mycoplasma pneumoniae. The pathogen was detected in 50% and 45% of throat swab specimens and aspirates, respectively. However, in specimens negative for Mycoplasma pneumoniae by PCR, amplification inhibitors were detected in 0% and 36% of throat specimens and aspirates, respectively. Further investigations confirmed that no throat specimens, but one-quarter of aspirates, are likely to be rejected for containing inadequate respiratory material or excess amplification inhibitors. Because rejection of most of the unsuitable specimens is possible only after PCR, the use of aspirates is less cost-effective. This, and the reluctance to subject patients to aspiration, make the aspirate an inferior specimen for detection of Mycoplasma pneumoniae by PCR.
An in-house polymerase chain reaction (PCR) test using ribosomal RNA gene primers was compared with chlamydia antigen detection (DIF) and culture for the detection of Chlamydia trachomatis. Five hundred and forty-eight fresh (unstored) genital swabs and 174 urines (collected at the same time) from patients attending a sexually-transmitted diseases clinic were examined. PCR, DIF and culture detected chlamydia in 43, 35 and 42 swabs respectively from the 43 resolved positive cases. The specificity on the resolved negative specimens was 100% for each of the tests. From the urines, PCR and DIF detected the organism in 16 and 15 cases respectively of the 23 resolved positive males tested but in only 2 and 3 cases respectively of the 9 resolved positive females tested. Specificities were 100% in all cases. Both of the non-culture tests manifested problems with urine due to inhibitory activity (in PCR test) or excessive debris (in DIF test) in about 5% of the specimens. Culture of the urines yielded sensitivities of 40% in the males and 22% in the females. Overall PCR was more sensitive than either culture or DIF on both urethral and cervical swabs and urines. The urines yielded less than three-quarters the number of positives that was obtained from the swabs and were considered to be an unsatisfactory specimen for chlamydial diagnosis. It is concluded that PCR is a satisfactory alternative to culture on genital swabs and may be preferable in situations where the viability of the organisms is in question. DIF remains useful because of its speed and simplicity but is insufficiently sensitive to be relied upon by itself.