Staphylococcus epidermidis as a cause of bacteremia.

Staphylococcus epidermidis is a biofilm-producing commensal organism found ubiquitously on human skin and mucous membranes, as well as on animals and in the environment. Biofilm formation enables this organism to evade the host immune system. Colonization of percutaneous devices or implanted medical devices allows bacteria access to the bloodstream. Isolation of this organism from blood cultures may represent either contamination during the blood collection procedure or true bacteremia. S. epidermidis bloodstream infections may be indolent compared with other bacteria. Isolation of S. epidermidis from a blood culture may present a management quandary for clinicians. Over-treatment may lead to patient harm and increases in healthcare costs. There are numerous reports indicating the difficulty of predicting clinical infection in patients with positive blood cultures with this organism. No reliable phenotypic or genotypic algorithms currently exist to predict the pathogenicity of a S. epidermidis bloodstream infection. This review will discuss the latest advances in identification methods, global population structure, pathogenicity, biofilm formation, antimicrobial resistance and clinical significance of the detection of S. epidermidis in blood cultures. Previous studies that have attempted to discriminate between invasive and contaminating strains of S. epidermidis in blood cultures will be analyzed.

Interactions of uroseptic Escherichia coli with renal (A-498) and gastrointestinal (HT-29) cell lines.

We investigated the ability of Escherichia coli isolated from septic patients with urinary tract infection (UTI) to translocate through the gastrointestinal (GI) tract of the same patients using cell-culture models. Forty-seven hospitalized patients with urosepsis were included in this study. E. coli was isolated from their urine and blood (total 94 isolates) and investigated for genetic relatedness and interaction with the cell lines A-498 and HT-29. An initial comparison of the strains isolated from urine and blood showed that 44 out of 47 patients (94 %) had identical strains in their blood and urine. The blood isolates adhered to both cell lines, although their rate of adherence to A-498 cells was significantly higher than that to HT-29 cells (5.8±3.8 per cell vs 2.8±1.9; P<0.0001). The rate of translocation in A-498 cells was also significantly higher after 120 min (8.7×10(5) vs 2.9×10(5); P = 0.0006). Three non-identical blood isolates were unable to translocate in HT-29 cells, indicating that host immune factors might be more important than bacterial ability to translocate the GI epithelium in these patients. Our data showed that blood isolates from uroseptic patients are able to adhere to and translocate through both cell lines. This suggests that E. coli in patients with UTI may translocate from either the GI tract or the urinary tract, hence questioning the assumption that the urinary tract is the only source of septicaemia in these patients.

Expansive spread of IncI1 plasmids carrying blaCMY-2 amongst Escherichia coli.

Escherichia coli is a leading cause of urinary tract infections. One of the most common antibiotic classes used to treat such infections is the ß-lactams, including cephalosporins. Resistance to the third-generation cephalosporins can be caused by production of extended-spectrum ß-lactamases (ESBLs) or plasmid-mediated AmpC ß-lactamases. The most commonly reported AmpC ß-lactamase in E. coli is CMY-2. Plasmid-mediated CMY-2 has been frequently reported in E. coli and Salmonella sp. from food-producing animals. This study aimed to elucidate the molecular characteristics of clinical E. coli isolates carrying plasmids encoding CMY-2. A total of 67 CMY-2-producing E. coli were characterised by clonal analysis and phylogenetic typing. Characterisation of the plasmids carrying blaCMY-2 included replicon typing, plasmid profiling, plasmid transferability and sequencing of the blaCMY-2 genetic environment. As a result, E. coli producing CMY-2 was found to be highly polyclonal. The majority of CMY-2-producing E. coli belonged to phylogenetic group D. IncI1 plasmids were predominant among those carrying blaCMY-2 (96%). Restriction analysis revealed a single IncI1 plasmid carrying blaCMY-2 to be predominant and present in different clones of E. coli. IS1294-ISEcp1 complex or ISEcp1 that was truncated by IS1294 was the predominant insertion sequence upstream of blaCMY-2. The homogeneous genetic environment of blaCMY-2 observed among different strains of E. coli strongly suggests horizontal transfer of this IncI1, blaCMY-2-carrying plasmid. In summary, horizontal plasmid transfer plays a major role in the spread of blaCMY-2 in E. coli.

Efficacy of some colloidal silver preparations and silver salts against Proteus bacteria, one possible cause of rheumatoid arthritis.

There has been increased interest in the role of anti-Proteus antibodies in the aetiology of rheumatoid arthritis (RA) and whether chemotherapeutic agents active against Proteus species might reduce the risk and/or exacerbations of RA. We examined the in vitro antibacterial effects of ten different silver preparations which were either ionic silver [Ag(I)] solutions or nanoparticulate silver (NPS) (Ag(0)) suspensions against ATCC and two wild (clinical) strains of Proteus. The data establish the low minimum inhibitory concentration and minimum bactericidal concentration of all the silver formulations tested against these four Proteus strains. In a pilot study, a potent NPS preparation ex vivo showed long-lasting anti-Proteus activity in a normal human volunteer.

The ecology of antibiotic use in the ICU: homogeneous prescribing of cefepime but not tazocin selects for antibiotic resistant infection.

BACKGROUND: Antibiotic homogeneity is thought to drive resistance but in vivo data are lacking. In this study, we determined the impact of antibiotic homogeneity per se, and of cefepime versus antipseudomonal penicillin/ß-lactamase inhibitor combinations (APP-ß), on the likelihood of infection or colonisation with antibiotic resistant bacteria and/or two commonly resistant nosocomial pathogens (methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa). A secondary question was whether antibiotic cycling was associated with adverse outcomes including mortality, length of stay, and antibiotic resistance. METHODS: We evaluated clinical and microbiological outcomes in two similar metropolitan ICUs, which both alternated cefepime with APP-ß in four-month cycles. All microbiological isolates and commensal samples were analysed for the presence of antibiotic-resistant bacteria including MRSA and P. aeruginosa. RESULTS: Length of stay, mortality and overall antibiotic resistance were unchanged after sixteen months. However, increased colonisation and infection by antibiotic-resistant bacteria were observed in cefepime cycles, returning to baseline in APP-ß cycles. Cefepime was the strongest risk factor for acquisition of antibiotic-resistant infection. CONCLUSIONS: Ecological effects of different ß-lactam antibiotics may be more important than specific activity against the causative agents or the effect of antibiotic homogeneity in selection for antibiotic resistance. This has important implications for antibiotic policy.

Persistence of multiple antibiotic resistant strains of Acinetobacter baumannii carrying class 1 integron in a hospital setting.

Forty-nine strains of multiresistant Aceinetobacter baumannii isolated from intensive care unit patients in Royal Brisbane and Women Hospital (RBWH) between 2001 and 2003 and four epidemiologically unrelated strains from three other hospitals were tested (n = 53) for their genetic relatedness using pulsed-field gel electrophoresis (PFGE) and for the presence of different classes of integrons. With PFGE, these strains were divided into three common (C) but closely related types (i.e., C1, C1a, and C1b) and eight single (S) types (S1-S8). C1 contained 40 isolates, while C1a and C1b contained 5 and 2 isolates, respectively. All isolates from Royal Brisbane and Women Hospital (RBWH) were resistant to 12 or more antibiotics. Four common pattern of antibiotic resistance (PAR) was observed among the isolates. The dominant PAR contained 39 strains from RBWH, isolated during 2000 (n = 6), 2001 (n = 16), and 2002 (n = 17) and were resistant to 14 antibiotics. Of these, 36 strains (92%) had identical PAR/PFGE types. Class 1 integrase genes were detected in all of the 53 isolates with 5 isolates also having class 2 integrase gene. No class 3 integrase gene was detected among the isolates. Our data suggest the presence of a dominant and persistent clone of multiresistant A. baumannii strain carrying class 1 integron in this hospital setting.

Streptococcus bovis bacteraemia: identification within organism complex and association with endocarditis and colonic malignancy.

AIM: To identify Streptococcus bovis bacteraemia episodes and their clinical associations, including differences in associations by S. bovis biotypes (or species). METHODS: The study was performed at Princess Alexandra Hospital, Brisbane. Streptococcus bovis blood culture results for 1999-2006 were retrieved. Patient data including diagnosis and investigations were retrospectively obtained from clinical records and compared with the microbiological result, including S. bovis biotype/species. RESULTS: Twenty evaluable S. bovis bacteraemia episodes were identified. Ten were S. bovis biotype I (Streptococcus gallolyticus subspecies gallolyticus) and 10 S. bovis II. For S. bovis I infections, six patients had a diagnosis of infective endocarditis. Nine had assessment for colonic pathology and all had malignant or premalignant colonic lesions. Of patients with S. bovis II infections, two were diagnosed with endocarditis and six had a hepatobiliary source of infection. Of five patients assessed in this group, three had premalignant colonic lesions. CONCLUSIONS: Endocarditis and hepatobiliary infections were the main causes of S. bovis bacteraemia. Endocarditis was diagnosed in the majority of S. bovis I bacteraemias and all patients assessed in this group had premalignant/malignant colonic lesions. Determining S. bovis biotype/species provides information on likely clinical associations of bacteraemia episodes.

Ethanol lock therapy to treat tunnelled central venous catheter-associated blood stream infections: results from a prospective trial.

In order to assess the efficacy of 70% ethanol locks in addition to antibiotic therapy to treat tunnelled central venous catheter-associated bloodstream infections, a pilot study of 19 patients was performed prospectively using ethanol locks for 5 d in addition to antibiotic therapy to treat tunnelled central venous catheter-associated bacteraemia. 12 patients had mono-microbial infections and 7 had polymicrobial isolates. 17 of 19 patients completed ethanol lock therapy. 15 of 17 patients completing ethanol lock therapy had no recurrence of the original organism and retained their catheter for a median of 36 and an average of 47 d following initiation of ethanol lock therapy. These results demonstrate the safety and potential efficacy of this technique against a broad range of potentially virulent organisms. The intervention was acceptable to both staff and patients with no significant side-effects. These preliminary results from our prospective pilot study suggest that ethanol lock therapy is safe and easily integrated into clinical practice, and may have utility in treating central venous catheter-associated infections, avoiding removal of catheters in patients requiring long-term venous access.

Surveillance culture utility and safety using low-volume blind bronchoalveolar lavage in the diagnosis of ventilator-associated pneumonia.

BACKGROUND AND OBJECTIVES: Surveillance cultures may improve the prediction of ventilator-associated pneumonia (VAP) and empirical antibiotic selection. This study examined the utility and patient safety of blind, non-protected, low-volume mini-bronchial lavage (BM-BAL) surveillance cultures in predicting VAP. METHODOLOGY: A prospective, cohort study was performed in a large general intensive care unit. BM-BALs were collected within 12 h of admission then thrice weekly. Each BM-BAL was screened by Gram staining for intracellular organisms and then quantitatively cultured. VAP was diagnosed using the Clinical Pulmonary Infection Score. The concordance for isolates from the BM-BAL was assessed against concurrently collected endotracheal aspirates (EA). RESULTS: Four hundred and twelve patients requiring a minimum of 48 h of mechanical ventilation were enrolled. Fifty patients developed 58 episodes of VAP. Concordant pathogens were found in 85% of BM-BAL specimens collected 2 days prior to VAP onset. Their antibiograms were stable over the preceding 4 days. The isolation of pathogens with colony counts >or=10(4) cfu/mL from BM-BAL performed 2 days prior to the clinical onset of VAP had a sensitivity of 84%, specificity of 50%, positive predictive value of 31% and a negative predictive value of 93% for predicting the development of VAP. BM-BAL WCC, quantification of bacterial growth and the percentage of intracellular organisms were not helpful in predicting VAP diagnosis. CONCLUSIONS: BM-BAL surveillance cultures are well tolerated and useful in predicting the pathogens and their antibiograms causing VAP. Diagnostic specimen collection at the time of VAP onset is still required as surveillance cultures may be negative even one day prior to VAP onset.

The antimicrobial effect of heparin on common respiratory pathogens.

AIM: The mucolytic, anticoagulative, anti-inflammatory and neo-angiogenic properties of inhaled heparin may benefit patients with burns and cystic fibrosis. We assessed the antibacterial effects of unfractionated heparin. METHODS: Stored clinical isolates of Acinetobacter baumannii (n =4), Candida albicans (n = 5), Haemophilus influenzae (n =5), Klebsiella pneumoniae (n =4), methicillin-resistant Staphylococcus aureus (n=3), Pseudomonas aeruginosa (n = 2), and Streptococcus pneumoniae (n = 7) were subcultured on horse blood agar, incubated at 35 degrees C overnight, then inoculated into trypticase soy broth to a density of 1 McFarland standard. Dilutions of unfractionated heparin (containing 250- 7500 U) and 100 microL of the 1.0 McFarland standard broth were incubated at 35 degrees C overnight in microtitre plates and then subcultured on horse blood agar using 1 microL standard loops. Colonies (representing viable organisms) were counted. RESULTS: Heparin produced dose-dependent growth inhibition of three of seven S. pneumoniae isolates (complete inhibition at 2500U dose per 200 microL) and one of five H. influenzae isolates (complete inhibition at 7500 U dose per 200 microL), but no inhibition of other isolates. CONCLUSIONS: Unfractionated heparin is unlikely to have antibacterial effects because of its unpredictable inhibition of growth of common respiratory pathogens.

Incubation time required for neonatal blood cultures to become positive.

AIM: We aimed to determine the laboratory detection time of bacteraemia in neonatal blood cultures, and whether this differed by: organism; samples deemed to represent true bacteraemia versus contaminants; and blood cultures collected from an infant <48 h of age (early) or >or=48 h of age (late). METHODS: A retrospective audit of all positive blood cultures collected from neonates in the Grantley Stable Neonatal Unit, Royal Women's Hospital, Brisbane, between 1 January 2000 and 31 December 2004 was undertaken. The bacteraemia detection method used was the BacTAlert system with Peds bottles. RESULTS: Two hundred and three positive blood cultures were included in the analysis. One hundred and sixteen (57%) were deemed septicaemia, 87 (43%) were deemed contaminants. The median (interquartile range) time to positivity for positive blood cultures deemed septicaemia and contaminants were 15.9 (11.6, 22.2) and 30.2 (20.4, 43.9) h, respectively. Fifty-six (28%) positive blood cultures were collected when infants were <48 h of age and 147 (72%) were collected in infants >or=48 h of age. Post hoc analysis revealed that the time to positivity for early septicaemia was 13.7 (11, 16.7) h; early contaminant was 25.2 (19.2, 33.8) h; late septicaemia was 17.2 (12.2, 23.4) h; and late contaminant was 37.9 (21.7, 51.2) h. The time to positivity for: Group B streptococcus was 9.3 (8.2, 11.0) h; Escherichia coli was 11.3 (10.0, 13.5) h; and coagulase-negative staphylococci was 28.9 (20.5, 41.2) h. CONCLUSION: The incubation time for positive blood cultures significantly differs by organism type and whether they are considered early or late septicaemia versus contaminants. We recommend that: infants who are <48 h of age at the time of blood culture collection, who remain clinically well and have negative cultures 36 h after the initial collection can safely have their antibiotic treatment ceased; infants who are >or=48 h of age at the time of collection should continue antibiotic treatment for at least 48 h before cessation is considered.

Cough and reflux esophagitis in children: their co-existence and airway cellularity.

BACKGROUND: There are no prospective studies that have examined for chronic cough in children without lung disease but with gastroesophageal reflux (GER). In otherwise healthy children undergoing flexible upper gastrointestinal endoscopy (esophago-gastroscopy), the aims of the study were to (1) define the frequency of cough in relation to symptoms of GER, (2) examine if children with cough and reflux esophagitis (RE) have different airway cellularity and microbiology in bronchoalveolar lavage (BAL) when compared to those without. METHODS: Data specific for chronic cough (> 4-weeks), symptoms of GER and cough severity were collected. Children aged < 16-years (n = 150) were defined as 'coughers' (C+) if a history of cough in association with their GER symptoms was elicited before BAL were obtained during elective esophago-gastroscopy. Presence of esophagitis on esophageal biopsies was considered reflux esophagitis positive (E+). RESULTS: C+ (n = 69) were just as likely as C- (n = 81) to have esophagitis, odds ratio 0.87 (95%CI 0.46, 1.7). Median neutrophil percentage in BAL was significantly different between groups; highest in C+E- (7, IQR 28) and lowest in C-E+ (5, IQR 6). BAL positive bacterial culture occurred in 20.7% and were more likely present in current coughers (OR 3.37, 95%CI 1.39, 8.08). Airway neutrophilia (median 20%, IQR 34) was significantly higher in those with BAL positive bacterial cultures than those without (5%, 4; p = 0.0001). CONCLUSION: In children without lung disease, the common co-existence of cough with symptoms of GER is independent of the occurrence of esophagitis. Airway neutrophilia when present in these children is more likely to be related to airway bacterial infection and not to esophagitis.

A prospective, randomized trial of rifampicin-minocycline-coated and silver-platinum-carbon-impregnated central venous catheters.

OBJECTIVE: Central venous catheters are the predominant cause of nosocomial bacteremia; however, the effectiveness of different antimicrobial central venous catheters remains uncertain. We compared the infection rate of silver-platinum-carbon (SPC)-impregnated catheters with rifampicin-minocycline (RM)-coated catheters. DESIGN: A large, single-center, prospective randomized study. SETTING: Twenty-two-bed adult general intensive care unit in a large tertiary metropolitan hospital in Brisbane, Australia (2000-2001). PATIENTS: Consecutive series of all central venous catheterizations in intensive care unit patients. INTERVENTIONS: Randomization, concealment, and blinding were carefully performed. Catheter insertion and care were performed according to published guidelines. Blood cultures were taken at central venous catheter removal, and catheter-tip cultures were performed by both roll-plate and sonication techniques. Pulsed field gel electrophoresis was used to establish shared clonal origin for matched isolates. MEASUREMENTS AND MAIN RESULTS: Central venous catheter colonization and catheter-related bloodstream infection were determined with a blinded technique using the evaluation of the extensive microbiological and clinical data collected and a rigorous classification system. Six hundred forty-six central venous catheters (RM 319, SPC 327) were inserted, and 574 (89%) were microbiologically evaluable. Colonization rates were lower for the RM catheters than SPC catheters (25 of 280, 8.9%; 43 of 294, 14.6%; p=.039). A Kaplan-Meier analysis that included catheter time in situ did not quite achieve statistical significance (p=.055). Catheter-related bloodstream infection was infrequent for both catheter-types (RM 4, 1.4%; SPC 5, 1.7%). CONCLUSIONS: The SPC catheter is a clinically effective antimicrobial catheter; however, the RM catheter had a lower colonization rate. Both catheter types had low rates of catheter-related bloodstream infection. These results indicate that future studies will require similar rigorous methodology and thousands of central venous catheters to demonstrate differences in catheter-related bloodstream infection rates.

Double-heater-wire circuits and heat-and-moisture exchangers and the risk of ventilator-associated pneumonia.

OBJECTIVE: To compare the incidence of ventilator-associated pneumonia (VAP) in patients ventilated in intensive care by means of circuits humidified with a hygroscopic heat-and-moisture exchanger with a bacterial viral filter (HME) or hot-water humidification with a heater wire in both inspiratory and expiratory circuit limbs (DHW) or the inspiratory limb only (SHW). DESIGN: A prospective, randomized trial. SETTING: A metropolitan teaching hospital's general intensive care unit. PATIENTS: Three hundred eighty-one patients requiring a minimum period of mechanical ventilation of 48 hrs. INTERVENTIONS: Patients were randomized to humidification with use of an HME (n=190), SHW (n=94), or DHW (n=97). MEASUREMENTS AND MAIN RESULTS: Study end points were VAP diagnosed on the basis of Clinical Pulmonary Infection Score (CPIS) (), HME resistance after 24 hrs of use, endotracheal tube resistance, and HME use per patient. VAP occurred with similar frequency in all groups (13%, HME; 14%, DHW; 10%, SHW; p=0.61) and was predicted only by current smoking (adjusted odds ratio [AOR], 2.1; 95% confidence interval [CI], 1.1-3.9; p=.03) and ventilation days (AOR, 1.05; 95% CI, 1.0-1.2; p=.001); VAP was less likely for patients with an admission diagnosis of pneumonia (AOR, 0.40; 95% CI, 0.4-0.2; p=.04). HME resistance after 24 hrs of use measured at a gas flow of 50 L/min was 0.9 cm H2O (0.4-2.9). Endotracheal tube resistance was similar for all three groups (16-19 cm H2O min/L; p=.2), as were suction frequency, secretion thickness, and blood on suctioning (p=.32, p=.06, and p=.34, respectively). The HME use per patient per day was 1.13. CONCLUSIONS: Humidification technique does not influence either VAP incidence or secretion characteristics, but HMEs may have air-flow resistance higher than manufacturer specifications after 24 hrs of use.

Sensitivity of respiratory bacteria to lignocaine.

AIM: Lignocaine, a topical anaesthetic agent, is generally used in variable concentrations usually between 2% and 4% on the vocal cords prior to flexible bronchoscopy and bronchoalveolar lavage (BAL) procedures. The aim of this study was to investigate whether 2% or 1% lignocaine significantly inhibits the growth of organisms commonly found in the respiratory tract, in particular Streptococcus pneumoniae. METHOD: In order to determine the antibiotic effect of lignocaine on lower respiratory tract flora, five different organisms were examined in vitro using well diffusion, disc diffusion and microbroth dilution against 1% and 2% concentrations of lignocaine. RESULTS: Antimicrobial activity could not be detected using the well diffusion and the disc diffusion methods, as lignocaine failed to diffuse through the media. The microbroth dilution method showed reproducible bactericidal effect of these respiratory isolates against Streptococcus pneumoniae, Moraxella catarrhalis and Haemophilus influenzae at 2% concentration. Lignocaine 2% showed no growth inhibition against Pseudomonas aeruginosa and Candida albicans. Lignocaine 1% also partially inhibited S. pneumoniae. CONCLUSION: As lignocaine shows significant inhibition of respiratory pathogens such as Streptococcus pneumoniae even at a concentration of 1%, the lowest concentration possible should be used for flexible bronchoscopy and BAL to maximise the chance of recovery of these organisms.

Barrier properties and cost implications of a single versus a double wrap for storing sterile instrument packs.

BACKGROUND: Materials for wrapping sterile items continue to evolve, but evaluation of such products under clinical conditions is rare. The purpose of the current study was to test a new product before introducing it to the hospital's sterilizing processing unit. METHODS: Four hundred packs containing 1199 items were prepared. Half were wrapped in linen and Kimguard sterile wrap (Kimberley-Clark Australia Pty, Ltd; Queensland, Australia), and half were wrapped in Kimguard One-Step sterile wrap (Kimberley-Clark). They were stored on shelves in 4 areas in the hospital. Items from the packs were periodically tested in the laboratory to evaluate shelf life. Time of wrapping was measured on a series of 50 packs (25 using each product), wrapped by 1 experienced person. These were unwrapped by an operating room nurse, and, again, the process was timed. RESULTS: Bacteria were cultured from 20 (1.7%) of the 1157 test items. There were no differences on this measure between the 2 products (P = .64). Coagulase-negative Staphylococcus was the most frequent isolate, accounting for 40% of the positive results. The average time taken to wrap the test tray with the double wrap was 56.4 seconds compared with 32.4 seconds with the single wrap (P < or = .000). Unwrapping the single pack (5.02 seconds) was also faster than unwrapping the double-wrap pack (6.92 seconds; P = .000). CONCLUSIONS: Wrapping sterile items using Kimguard one-step sterile wrap carries no greater risk of bacterial contamination than double-wrap methods and may lead to significant cost savings in both labor (time to wrap) and consumables (linen and recycling costs).

Cough quality in children: a comparison of subjective vs. bronchoscopic findings.

BACKGROUND: Cough is the most common symptom presenting to doctors. The quality of cough (productive or wet vs dry) is used clinically as well as in epidemiology and clinical research. There is however no data on the validity of cough quality descriptors. The study aims were to compare (1) cough quality (wet/dry and brassy/non-brassy) to bronchoscopic findings of secretions and tracheomalacia respectively and, (2) parent's vs clinician's evaluation of the cough quality (wet/dry). METHODS: Cough quality of children (without a known underlying respiratory disease) undergoing elective bronchoscopy was independently evaluated by clinicians and parents. A 'blinded' clinician scored the secretions seen at bronchoscopy on pre-determined criteria and graded (1 to 6). Kappa (K) statistics was used for agreement, and inter-rater and intra-rater agreement examined on digitally recorded cough. A receiver operating characteristic (ROC) curve was used to determine if cough quality related to amount of airway secretions present at bronchoscopy. RESULTS: Median age of the 106 children (62 boys, 44 girls) enrolled was 2.6 years (IQR 5.7). Parent's assessment of cough quality (wet/dry) agreed with clinicians' (K = 0.75, 95%CI 0.58-0.93). When compared to bronchoscopy (bronchoscopic secretion grade 4), clinicians' cough assessment had the highest sensitivity (0.75) and specificity (0.79) and were marginally better than parent(s). The area under the ROC curve was 0.85 (95%CI 0.77-0.92). Intra-observer (K = 1.0) and inter-clinician agreement for wet/dry cough (K = 0.88, 95%CI 0.82-0.94) was very good. Weighted K for inter-rater agreement for bronchoscopic secretion grades was 0.95 (95%CI 0.87-1). Sensitivity and specificity for brassy cough (for tracheomalacia) were 0.57 and 0.81 respectively. K for both intra and inter-observer clinician agreement for brassy cough was 0.79 (95%CI 0.73-0.86). CONCLUSIONS: Dry and wet cough in children, as determined by clinicians and parents has good clinical validity. Clinicians should however be cognisant that children with dry cough may have minimal to mild airway secretions. Brassy cough determined by respiratory physicians is highly specific for tracheomalacia.

An in vitro study of the anti-microbial efficacy of a 1% silver sulphadiazine and 0.2% chlorhexidine digluconate cream, 1% silver sulphadiazine cream and a silver coated dressing.

UNLABELLED: Burn sepsis is a leading cause of mortality and morbidity in patients with major burns. The use of topical anti-microbial agents has helped improve the survival in these patients. There are a number of anti-microbials available, one of which, Silvazine (1% silver sulphadiazine (SSD) and 0.2% chlorhexidine digluconate), is used only in Australasia. No study, in vitro or clinical, had compared Silvazine with the new dressing Acticoat. This study compared the anti-microbial activity of Silvazine, Acticoat and 1% silver sulphadiazine (Flamazine) against eight common burn wound pathogens. METHODS: Each organism was prepared as a suspension. A 10 microl inoculum of the chosen bacterial isolate (representing approximately between 10(4) and 10(5) total bacteria) was added to each of four vials, followed by samples of each dressing and a control. The broths were then incubated and 10 microl loops removed at specified intervals and transferred onto Horse Blood Agar. These plates were then incubated for 18 hours and a colony count was performed. RESULTS: The data demonstrates that the combination of 1% SSD and 0.2% chlorhexidine digluconate (Silvazine) results in the most effective killing of all bacteria. SSD and Acticoat had similar efficacies against a number of isolates, but Acticoat seemed only bacteriostatic against E. faecalis and methicillin-resistant Staphylococcus aureus. Viable quantities of Enterobacter cloacae and Proteus mirabilis remained at 24h. CONCLUSION: The combination of 1% SSD and 0.2% chlorhexidine digluconate (Silvazine) is a more effective anti-microbial against a number of burn wound pathogens in this in vitro study. A clinical study of its in vivo anti-microbial efficacy is required.