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Biomedical subjects

C H Webb

Publications and source records attributed to C H Webb.

At least 19 recordsLinked to original sources
PubMed1999

Implications of endotracheal tube biofilm for ventilator-associated pneumonia.

OBJECTIVE: To determine the relationship between, and antibiotic resistance of, endotracheal tube (ET) biofilm and pulmonary pathogens in ventilator-associated pneumonia (VAP). SETTING: General intensive care units in two university teaching hospitals. DESIGN: The microbiology of ET biofilm and tracheal samples from patients with and without VAP were compared. For individual patients, matching pairs of pathogens were confirmed as identical and characterised for antibiotic susceptibility. PATIENTS: 40 intensive care unit patients - 20 with VAP, 20 without VAP as control. The duration of intubation (median and range) was 6.5 days (3-17) and 5 days (2-10), respectively. MEASUREMENTS AND RESULTS: Samples of tracheal secretions were taken during ventilation for bacteriological culture. Following extubation, ETs were examined for the presence of biofilm. Isolates of high pathogenic potential included Staphylococcus aureus, enterococci, Enterobacteriaceae, pseudomonads and Candida spp. Where the same microorganism was found on tracheal and ET samples by phenotyping, these were confirmed as identical by genotyping and characterised for antibiotic susceptibility in both the free floating and biofilm forms. Seventy per cent of patients with VAP had identical pathogens isolated from both ET biofilm and tracheal secretions. No pairing of pathogens was observed in control patients (p < 0.005). Susceptibility data for these pairs show that the ET acts as a reservoir for infecting microorganisms which exhibit significantly greater antibiotic resistance than their tracheal counterparts. CONCLUSION: This investigation provides further evidence for the role of ET biofilm in VAP. The difficulty in eradicating an established microbial biofilm using antibiotics implies that increased attention must be directed towards modification of the ET to prevent or substantially reduce biofilm formation.

Adolescent↗
PubMed1998

Closed tracheal suctioning systems and infection control in the intensive care unit.

Closed tracheal suction catheters offer a number of microbiological advantages over the conventional single-use suction catheters. Intensive care staff, however, have experienced difficulties such as pooling of the catheter irrigation saline within the connectors, and hand contamination from condensate which escapes via the irrigation port. Using a descriptive survey design we quantified how frequently these problems occurred. Over an eight-week period, staff completed 923 survey forms. Hand contamination from condensate was reported in 61% of responses. Rinsing the catheter after use was ineffective in 39% of responses, and 70% reported pooling of the saline in the swivel and ventilator connectors. Forty-five percent of responses reported ineffective secretion removal. The infection implications for clinical practice are discussed.

Catheterization↗
PubMed1995

Contamination of multi-use closed tracheal suction catheters: an in-vitro study.

The use of closed multi-use tracheal suction systems in ventilated patients is increasingly popular as it offers a number of potential physiological and microbiological advantages. As the use of these systems has been associated with an increased prevalence of tracheal colonization, effective self-cleaning mechanisms employed in these catheters are necessary. Using an in-vitro model we assessed the degree of catheter colonization in two multi-use catheter systems; Stericath and Trach-Care. Fifty of each catheter type were tested for colonization with five challenge organisms: Staphylococcus aureus (NCTC 6571); Pseudomonas aeruginosa (NCTC 10662); Haemophilus influenzae type b; S. epidermidis (slime producer); and S. epidermidis (slime non-producer). All five challenge strains had colonized both catheter types after 24 h and all 100 catheter tips were colonized. The extent and density of colonization was variable and interspecies variation in the pattern of catheter colonization was observed. The mean colonized lengths of Stericath catheters was 10.9 +/- 1.4 cm and of Trach-Care 2.7 +/- 1.3 cm (P < 0.0001).

Bacteria↗
PubMed1995

Investigation of a nosocomial outbreak of Pseudomonas aeruginosa pneumonia in an intensive care unit by random amplification of polymorphic DNA assay.

From July to September 1993 in the intensive care unit of the Royal Victoria Hospital there were 10 cases of pneumonia associated with sputum culture of Pseudomonas aeruginosa. The isolates had an identical biotype and pyocine typing profile. The same strain of P. aeruginosa was recovered from the sink plug-hole in two rooms, and the tap handles and ventilator tubing in a third room. All strains were retrospectively typed by the random amplification of polymorphic DNA (RAPD) method using a 26-mer oligonucleotide primer, and were identical in profile. Recommendations to medical and nursing staff included secretion isolation precautions, terminal disinfection after patient discharge, use of disposable vinyl gloves by hospital staff for all body substance contacts, thorough handwashing with 4% chlorhexidine gluconate before and after dealing with all patient contacts, and prompt, appropriate antibiotic treatment for P. aeruginosa pneumonia. RAPD is a simple and effective method to determine the relatedness of P. aeruginosa isolates, and typing results are available within a single working day; thus dramatically increasing its clinical relevance over existing molecular methods.

Bacterial Typing Techniques↗
PubMed1993

Market penetration of new drugs in one United Kingdom region: implications for general practitioners and administrators.

OBJECTIVE: To determine the use of new drugs in one United Kingdom region. DESIGN: Examination of data on prescribing of angiotensin converting enzyme inhibitors, new broad spectrum antibiotics, and H2 receptor antagonists. Calculation of number of defined daily doses prescribed each month. SETTING: All general practices in Northern Ireland. MAIN OUTCOME MEASURES: Drug use index and market share of each drug. RESULTS: During 1988-91 prescribing of angiotensin converting enzyme inhibitors increased by 126%, of H2 receptor antagonists by 46%, and of new antibiotics by 207%. The first drug on the market usually retained the largest market share. Use of oral antibiotics increased threefold irrespective of the reporting policy of the general practitioners' local laboratory. CONCLUSIONS: The increase in prescribing of these drugs seems to be greater than can be accounted for by an increase in patients with specific indications for these drugs. This suggests that the profession has not instituted effective checks to ensure that the legitimate promotion of new products does not lead to inappropriate and wasteful use.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1993

Helping the helpers: the development of a critical incident stress management team through university/community cooperation.

Prehospital emergency services personnel often are exposed to high levels of occupational stress. Besides chronic stress, they can be involved in critical incidents, which cause a well-recognized set of overwhelming emotional reactions. If these reactions are not addressed promptly, emergency responders and their families can suffer further emotional trauma, and this can impair the ability of responders to care for patients in the field. A critical incident stress management team has been established through cooperation between the Charleston Division of the West Virginia University Health Sciences Center and emergency personnel in Charleston, as well as the rural countries in southern West Virginia. This team provides preincident education and postincident interventions for firefighters, police, emergency medical services, and on occasion, hospital emergency department personnel. This team can serve as a model for other such teams to organize to deal with this growing problem in the health care delivery field.

Community Mental Health Services↗
PubMed1993

Selective decontamination of the digestive tract (SDD) does not prevent the formation of microbial biofilms on endotracheal tubes.

The purpose of selective decontamination of the digestive tract (SDD) is to eradicate potentially disease-producing micro-organisms from the oropharynx and gastro-intestinal tract of intensive care unit (ICU) patients, thereby reducing the incidence of nosocomial sepsis, particularly pneumonia. Microbial biofilms form on endotracheal (ET) tubes even when SDD is being administered and may represent a persistent focus for infection. The aim of this investigation was to determine the susceptibilities of organisms adherent to ET tubes to SDD antibiotics (amphotericin B, tobramycin and polymyxin) and to measure the concentrations of these agents in the tracheal aspirates of 11 patients who were being mechanically ventilated. Following extubation, a section was cut from the tip of each ET tube and any adherent microorganisms subsequently isolated were identified and their MICs determined. Samples of tracheal aspirate were obtained three hours after administration of the SDD regimen and the concentrations of the constituent antimicrobials were measured. Enterobacteriaceae were not recovered from any of the tubes but six strains of Staphylococcus aureus, three Pseudomonas spp., three enterococci and four yeasts were isolated. Wide variations in the concentrations of all antibiotics were observed and in many cases they were below the MICs for the organisms isolated. In particular, tobramycin concentrations were uniformly less than the median MIC for the S. aureus isolates and this may account for the predominance of Gram-positive bacteria adherent to the ET tubes. Microbial biofilms attached to these tubes may have a role in the pathogenesis of nosocomial pneumonia in ICU patients.

Amphotericin B↗
PubMed1992

Epidemiology of Pseudomonas aeruginosa in an intensive care unit using selective decontamination of the digestive tract.

Selective decontamination of the digestive tract (SDD) aims to reduce the rate of nosocomial infections in critical care patients. Pseudomonas spp. are common nosocomial pathogens and in this study isolates collected from patients and the environment during an SDD trial were examined. The study enrolled 161 SDD cases and 170 controls. Pseudomonads were isolated from 27% of SDD patients and 30% of controls. SDD partially suppressed colonization in the 'gastro-respiratory' mucosae but not in the rectum. A total of 108 isolates of pseudomonads were recovered from the environment. Resistance in rectal isolates was minimal but isolates from 'gastro-respiratory' sites showed increasing aminoglycoside resistance. Eighty-six per cent of aminoglycoside-resistant isolates from both patient groups and environment were pyocine type 1x. Episodes of infection were reduced in the SDD patients (6) compared with the controls (16), aminoglycoside-resistant strains being associated with zero episodes in SDD patients but with five in the control group.

Cross Infection↗
PubMed1992

Antibiotic resistance associated with selective decontamination of the digestive tract.

Selective decontamination of the digestive tract (SDD) appears to reduce infection, particularly pneumonia, in intensive care, and some patients benefit markedly. Gram-positive overgrowth and antibiotic resistance in both Gram-positive and Gram-negative organisms has been recorded. However, the clinical and epidemiological significance of these observations is still debated. Future studies will need to be of sufficient size and duration to provide good quality data on which the safety and efficacy of SDD can be properly judged.

Anti-Bacterial Agents↗
PubMed1992

Teicoplanin vs cephamandole for antimicrobial prophylaxis in prosthetic joint implant surgery: (preliminary results).

Infection following prosthetic joint implant jeopardizes the prosthesis and may lead to long-term locomotor disability. Interoperative antimicrobial prophylaxis can reduce the incidence of infectious complications. The comparative safety and efficacy of single-dose teicoplanin and four doses of cephamandole over a 24-hour period is currently being assessed in a single-blind, randomized concurrent study of patients who undergo first time hip or knee arthroplasty. Of 660 evaluated patients, 352 have received cephamandole and 308 teicoplanin. Two patients in each group had a surgical wound infection at 1 week after surgery. Reassessment 30 days postoperatively showed resolution of the infection in both of the teicoplanin patients and in one of the cephamandole patients. Proven or suspected infection involving other body systems occurred in 30 teicoplanin and 38 cephamandole patients at 1 week postoperatively and in 5 teicoplanin and 3 cephamandole patients 1 month after surgery. Adverse events occurred in 20 (5.1%) teicoplanin patients and 29 (7.1%) cephamandole patients. These preliminary results suggest that single-dose teicoplanin is a safe and effective prophylactic agent in prosthetic joint implant surgery.

Adolescent↗
PubMed1992

Five cases of Alcaligenes pseudobacteraemia.

A cluster of five cases of pseudobacteraemia due to the organism Alcaligenes denitrificans occurred in three hospital medical wards over a four week period. The same organism was isolated from four of twelve commercially prepared bottles for erythrocyte sedimentation tests. The most likely explanation for the outbreak is that the ESR bottles were filled prior to inoculation of blood culture bottles. The outbreak was brought to an end by advising on correct procedure.

Alcaligenes↗