Search PubMed⌕ Search

Biomedical subjects

H Humphreys

Publications and source records attributed to H Humphreys.

At least 91 records · Page 5Linked to original sources
PubMed1996

Clinical and molecular aspects of the pathogenesis of Staphylococcus aureus bone and joint infections.

Staphylococcus aureus is an important cause of bone and joint infections. In recent years, significant changes in the incidence of septic arthritis and osteomyelitis have occurred. Haematogenous osteomyelitis is now less common during childhood, but secondary spread of infection to bone or joint from a contiguous site in adults is increasing in incidence. Infection introduced at the time of surgery or arising by the haematogenous route is a significant complication of prosthetic joint implantation, and the effect of bone cement on local immune function may be important in this setting. ALthough S. epidermis is a more common cause of prosthetic joint infection, S. aureus is more difficult to treat. S. aureus produces a number of extracellular and cell-associated factors, but it is unclear what role these have as virulence factors in vivo. Furthermore, it is difficult in animal models to simulate transient bacteraemia followed by non-fulminating septic arthritis or osteomyelitis, as occurs in the patient. Surface factors which may be important in pathogenesis include the cell wall (activates complement and stimulates cytokine release), capsular polysaccharide (promotes adhesion to host cell surfaces), collagen receptors and fibronectin-binding protein. Staphylococcal toxic shock syndrome toxin (TSST-1) and the enterotoxins are superantigens and have the potential to suppress plasma cell differentiation and antibody responsiveness. TSST-1-positive isolates have been shown to cause more severe joint infection in one animal model, but most other studies to date have focused on in-vitro rather than in-vivo effects. There is little evidence supporting a role for coagulase, lipase and the haemolysins in staphylococcal bone and joint infections. Despite the clinical importance of these infections, surprisingly little is known about pathogenesis at the cellular level. Future research should focus on the role of the host immune system in limiting spread of infection, and the expression of virulence factors in animal or other models incorporating isogenic mutant strains.

Arthritis, Infectious↗
PubMed1996

Comparison of rapid automated laser fluorescence analysis of DNA fingerprints with four other computer-assisted approaches for studying relationships between Acinetobacter baumannii isolates.

The relationships between isolates suggested by a novel DNA typing method (RAPD-ALFA) that combines randomly amplified polymorphic DNA with automated on-line laser fluorescence analysis of DNA fragments were compared with those suggested by four other computer-assisted typing strategies (biotyping, antibiogram typing, pulsed-field gel analysis of chromosomal fingerprints and arbitrarily-primed DNA amplification with three different primers) for 25 isolates of Acinetobacter baumannii obtained from 12 different hospitals in four countries over a period of 12 years. The results obtained by cluster analysis with two different software packages confirmed that the relationships suggested by RAPD-ALFA were robust and essentially similar to those suggested by the other more laborious computer-assisted typing methods. The technique of RAPD-ALFA appears to offer the possibility of routine on-line molecular identification and typing of isolates from particular hospital wards or units (e.g., intensive care units), and could, therefore, play a key role in the early recognition and prevention of outbreaks of infection.

Acinetobacter↗
PubMed1996

Comparison of bronchoalveolar lavage and catheter lavage to confirm ventilator-associated lower respiratory tract infection.

Lower respiratory tract infection (LRTI) is a well recognised complication of artificial ventilation in intensive care units (ICU). Ideally, specimens for microbiological analysis should be obtained during bronchoscopy, but this is not always possible. Therefore, the microbiological diagnosis of lower respiratory tract infection by broncho-alveolar lavage (BAL) obtained during bronchoscopy was compared with catheter lavage (CL) with a balloon-tipped catheter. Adult patients with clinical evidence of lower respiratory tract infection in an adult ICU were randomly assigned to undergo BAL followed by CL or vice versa. Forty ml of normal saline 0.9% were instilled and then aspirated with a flexible bronchoscope to obtain BAL. A similar volume was instilled and aspirated with a 12-gauge Foley balloon-tipped catheter to obtain a CL sample. The number of inflammatory cells, epithelial cells and organisms seen by microscopy were quantified. Culture results were semi-quantified and classified as negative, positive, equivocal or contaminated. Seventy-nine paired specimens were obtained from 66 patients, including specimens from 10 patients taken on two or more occasions. Only 20% of BAL and 16% of CL had one or more epithelial cells and bacteria were seen in 26 BAL and 21 CL specimens, respectively; 35% of BAL and CL specimens were positive and there was a discrepancy in the culture result in only two cases. Staphylococcus aureus was the pathogen isolated most frequently and polymicrobial lower respiratory infection was diagnosed on 10 occasions (15%). CL fluid is as reliable as BAL in diagnosing lower respiratory tract infection in ICU. This approach does not require bronchoscopic expertise and utilises convenient laboratory techniques.

Adolescent↗
PubMed1995

Usefulness of culture in the diagnosis of Clostridium difficile infection.

Between January and April 1993, culture for Clostridium difficile and a faecal cytotoxin assay were performed on 500 selected specimens. Isolates from culture-positive patients from whom faecal samples were cytotoxin negative were also examined in vitro for cytotoxin production. The significance of a positive culture result in the absence of faecal cytotoxin was assessed. Forty-one of the 500 specimens were toxin positive. In only 25 of these was Clostridium difficile examination specifically requested. Six of nine culture-positive cytotoxin-negative patients (11 specimens) had recently received antibiotics. In four of these, Clostridium difficile was considered to be of possible clinical significance. Culture and in vitro determination of toxin production of isolates may aid in the diagnosis of some additional cases, but cytotoxin detection remains the single optimal routine laboratory method for diagnosis.

Adult↗
PubMed1995

Survey of operating theatres in Great Britain and Ireland.

A survey of operating theatres in Great Britain and Ireland by postal questionnaire was undertaken to determine the number of non-ventilated theatres in use, the number of designated theatres for specialist surgery and how and when bacterial sampling is conducted. Replies were received from 147 centres covering 438 operating theatre suites. Eighty-seven (59%) centres contained three or fewer suites and only 32% did not have a designated theatre for any specialist surgery. One hundred and seventy-three (40%) theatre suites were built over 20 years ago and 28 non-ventilated theatres were identified, mainly used for minor surgery (e.g. removal of 'lumps'). Four percent of plenum and 9% of ultraclean theatres are never monitored bacteriologically and settle plates are used in 72 (49%) centres. This survey suggests there is some confusion over the indications for bacteriological monitoring and what constitutes acceptable standards. The use of non-ventilated theatres, except for the most minor of procedures, is of some concern and should be phased out.

Environmental Monitoring↗
PubMed1995

Clinical and epidemiological features of an outbreak of acinetobacter infection in an intensive therapy unit.

Sporadic examples of infection with multi-resistant Acinetobacter spp. have occurred in Nottingham hospitals since at least 1977, punctuated by more prolonged outbreaks involving larger numbers of patients, particularly those confined to the intensive therapy unit (ITU) with severe underlying disease. In the most recent outbreak, 11 patients were infected with multi-resistant Acinetobacter strains and 26 patients were colonised. Four of the infected patients died directly or indirectly from infection with multi-resistant Acinetobacter spp., either while in the ITU or after discharge to a general ward. The mean interval from admission to the first isolation of a multi-resistant Acinetobacter strain was 6.7 and 12.1 days in the infected and colonised groups, respectively. Multi-resistant Acinetobacter strains were isolated most frequently from the respiratory tract, and eight patients had probable or suspected pneumonia caused by a multi-resistant Acinetobacter sp. All infected patients were treated with imipenem, with or without an aminoglycoside, except one patient who died before a diagnosis of acinetobacter infection was confirmed. Multi-resistant Acinetobacter spp. were isolated from various environmental sites in the ITU, and patient and environmental isolates were found to be related closely by biotyping, antibiograms, pulsed-field gel electrophoresis of chromosomal fingerprints and ribotyping. The outbreak was controlled ultimately by transfer of infected or colonised patients to an isolation cubicle, cohort nursing, emphasis on the importance of hand washing before and after patient contact and when handling case notes, and the use of disposable aprons and gowns during patient contact.(ABSTRACT TRUNCATED AT 250 WORDS)

Acinetobacter↗
PubMed1994

Airborne dissemination of Burkholderia (Pseudomonas) cepacia from adult patients with cystic fibrosis.

BACKGROUND: Burkholderia (Pseudomonas) cepacia is an increasingly important pathogen in patients with cystic fibrosis but it is unclear how it spreads from patient to patient. A study was undertaken to determine whether B cepacia could be recovered from room air occupied by colonised adult patients with cystic fibrosis. METHODS: Air samples were obtained consecutively from an enclosed room or isolation cubicle before, during, and after occupation by six patients on nine occasions using a surface air sampler incorporating contact plates with selective medium. Settle plates were also used and sputum from five patients was cultured. RESULTS: B cepacia was recovered from room air during occupation by five of six patients, the number of bacteria ranging from 1 to 158 cfu/m3 (mean 32 cfu/m3). The number of bacteria isolated was greater when patients were coughing. B cepacia persisted in room air on four occasions after the patient left the room, on one occasion for up to 45 minutes. CONCLUSIONS: The isolation of B cepacia from the air of rooms occupied by colonised patients suggests that dissemination might occur by aerosol as well as by direct physical contact with patients or contaminated environmental sites.

Adult↗
PubMed1994

Effect of antibiotic treatment on inflammatory markers and lung function in cystic fibrosis patients with Pseudomonas cepacia.

BACKGROUND: The acquisition of Pseudomonas cepacia in patients with cystic fibrosis is associated with increasing deterioration in lung function and more frequent hospital admissions. Pseudomonas cepacia is usually resistant to several antibiotics in vitro, but the response of patients colonised with the organism has not been extensively studied in vivo. METHODS: A three month prospective study was performed to investigate the response of 14 Ps cepacia positive patients and 10 Ps cepacia negative patients to a two week course of intravenous antibiotics. All those who were Ps cepacia negative and six of the 14 Ps cepacia positive patients had Ps aeruginosa in their sputum which was sensitive to the prescribed therapy. The inflammatory markers C-reactive protein, white blood cell count, serum lactoferrin, neutrophil elastase/alpha 1-antitrypsin complex, and tumour necrosis factor alpha were measured at the start and end of each antibiotic course. RESULTS: The median (range) % improvement in baseline FEV1 and FVC following treatment in the group as a whole was 15.2% (-23.5% to 156.3%) and 23.9% (-36.8% to 232.7%) respectively. There was no statistical difference in improvement in lung function, body weight, or inflammatory markers between individuals who were Ps cepacia positive and those who were Ps cepacia negative. CONCLUSIONS: Patients who are Ps cepacia positive appear to respond as well to intravenous antibiotics as those who are Ps cepacia negative, despite having lower lung function and a bacterium in their sputum which is resistant in vitro to the antibiotics used.

Adult↗