Demonstration of a functional variant of chloramphenicol acetyltransferase in Haemophilus influenzae.

Seven clinical isolates of chloramphenicol-resistant Haemophilus influenzae were studied. The products of chloramphenicol inactivation by chloramphenicol acetyltransferase (CAT) were identified by high performance liquid chromatography. The sole product in H. influenzae is a single monoacetyl compound, whereas variants of CAT isolated from other chloramphenicol-resistant bacteria usually produce both monoacetyl and diacetyl chloramphenicol metabolites. The chloramphenicol resistance gene was found to reside on a 65-kb plasmid which, in five of the six cases studied, appeared to be integrated into the host cell chromosome.

An investigation of the spread of gentamicin resistance in a district general hospital.

A cluster of infections caused by gentamicin-resistant gram-negative bacilli in a District General Hospital was investigated. The plasmids coding for gentamicin resistance in the infecting organisms and in isolates obtained from the ward environment and from the faeces of patients and staff were characterised. Six plasmids encoding gentamicin resistance were recognised amongst the organisms causing infection. Two of the plasmids were found in different serotypes of the same species and one plasmid was found in different genera. Three of the plasmids present in the organisms causing the infections were also present in the inanimate environment or in the bowel flora of patients and these also were found in different serotypes of the same species and in different genera.

Relationship between sexual intercourse and urinary-tract infection in women attending a clinic for sexually transmitted diseases.

The prevalence of urinary-tract infection (UTI), diagnosed by examination of a single midstream urine from sexually active women was found to be 6.4%. Significant bacteriuria was most common in women who presented within 24 h of coitus but was not related to the number of sexual partners. UTI occurred significantly more often in women who presented within 4 days of intercourse than in women seen after a longer interval. Whether frequency of intercourse affects the prevalence of UTI remains to be determined.

Intelligent systems: how can they help?

Expert systems are a branch of the computer science of artificial intelligence. Their ability to mimic experts by applying their domain knowledge has led to the construction of a number of medical applications. A brief resumé of the structure and the processes involved in constructing knowledge-based expert systems is given. Reasons are given for the failure of these successful programs to be widely implemented. It is to be expected that improvements in other areas of artificial intelligence will make them more widely acceptable to the non-expert.

The origin of coagulase-negative staphylococci isolated from blood cultures.

The source of coagulase-negative staphylococci (CNS) isolated from blood cultures and thought to be contaminants was investigated over a two month period. Isolates recovered from swabs taken from patients, doctors and laboratory staff were compared with the blood culture patient isolate in an attempt to identify the source of contamination. Six hundred and ninety-six blood culture sets were received of which 28 were contaminated with CNS. Nineteen of these blood cultures had sufficient data to be included in this study. Six were matched to isolates from the patient's skin and none to the medical or laboratory staff. Major differences in the antibiograms were seen between the patients, medical and laboratory staff. Organisms from patients and medical staff were more likely to have multiple antibiotic resistances. It appears that the most important source of CNS contamination of blood cultures processed in a semi-automated manner is the patient's own skin flora.

Assessment of the Axicare human milk pasteuriser (CM80).

The performance of the Axicare human milk pasteurizer was evaluated under different load conditions. The design criteria for pasteurisation specified that milk should be held at 63 degrees C for 30 min. The holding time at this temperature was insufficient if bottles of milk frozen at -20 degrees C were placed into the machine as directed, after the water-bath preheating phase. However, if the machine was loaded with frozen bottles before the whole cycle was commenced, adequate thawing and warming to holding temperature was achieved in sufficient time for satisfactory pasteurization. The pasteurizer gave consistent and adequate temperature and time conditions. The seals on three types of bottles tested tended to leak during the pasteurization cycle but no method of avoiding this problem was established.

A comparison of the morbidity associated with occlusive and non-occlusive dressings applied to peripheral intravenous devices.

In a non-randomized controlled study of the effects of an occlusive polymer dressing on the morbidity associated with intravenous (iv) cannulation, it was found that the polymer dressing adversely affected the rate of cannula tip colonization, but that this could not be generally related to an increased risk of thrombophlebitis. A strong association was found between Staphylococcus aureus colonization and thrombophlebitis. It is proposed that the materials, method of manufacture and the use to which the cannula is put are more important in the genesis of the minor complications of iv cannulation than the type of dressing.

Dermal absorption of isopropyl alcohol from a commercial hand rub: implications for its use in hand decontamination.

Isopropyl alcohol-containing hand rubs are widely used in healthcare for hand decontamination. Ten healthy adult volunteers applied a commercially available isopropyl alcohol-containing hand rub to their hands every 10 min over a 4 h period. Blood isopropyl alcohol levels were measured at the beginning and end of the study. At the end of the study, measurable blood isopropyl alcohol levels (range 0.5-1.8 mg/l) were recorded in nine subjects. We confirmed that isopropyl alcohol could be absorbed through the intact skin of adult humans. The social and medical implications are discussed.

The Second National Prevalence Survey of infection in hospitals: methodology.

This paper describes the methods used to perform a very large multicentred prevalence survey of infection in hospitals. Infection control teams were trained centrally to use a standardized questionnaire and agreed definitions to collect prevalence data on a portable computer. The study was coordinated from a single centre and the analysis performed by the statistics department at Central Public Health Laboratory, Colindale, London. The survey included 157 centres throughout England and Wales, Scotland and all Ireland. The survey was carried out as a joint venture by members of The Hospital Infection Society, The Public Health Laboratory Service and the Infection Control Nurses' Association of the British Isles and was organized by a Steering Committee.

An evaluation of the Hamo LS-76 washing, drying and disinfecting machine for anaesthetic equipment.

This report evaluates a machine designed to wash, disinfect and dry anaesthetic equipment. Following adjustments to the program these objectives could be reliably achieved within a reasonable time. Multifunction machines should be considered for future use in Sterile Service Departments, although a careful assessment of the workload capacity should be made before purchase.

The use of the wound scoring method 'ASEPSIS' in postoperative wound surveillance.

For the purposes of wound surveillance programmes and clinical trials, a wound scoring method, ASEPSIS, makes assessment of wound sepsis more objective and reproducible by allotting points both for the appearance of the wound in the first week and for the clinical consequences of infection. ASEPSIS was compared with other definitions of wound infection in 1029 surgical patients and its suitability for surveillance and detection of risk factors were examined. Satisfactory healing was recorded in 867 patients, disturbance of healing in 74 and minor, moderate and severe wound infection in 41, 24 and 23 patients respectively. An ASEPSIS score over 20 points was more sensitive and as specific as the presence of pus as an indicator of changes in management resulting from infection. Multiple regression analysis of ASEPSIS scores indicated that operation type, ward, degree of contamination, age, body mass index, and preoperative stay in hospital were significant risk factors. In matching 52 infected patients with uninfected controls, any wound score over 10 points was associated with a significant delay in discharge from hospital (median 3 days, P less than 0.0005).

Preoperative screening cultures in the identification of staphylococci causing wound and valvular infections in cardiac surgery.

Cultures of nasal or presternal swabs form part of the routine preoperative screening of patients on the cardiac surgical ward. During a trial of antibiotic prophylaxis in 314 patients, preoperative isolates of Staphylococcus aureus and coagulase-negative staphylococci were compared with strains associated with postoperative sternal wound breakdown (24 patients) and prosthetic valve endocarditis (3 patients). Morphology, antibiotic sensitivity pattern, plasmid analysis and phage typing were used to differentiate strains. In only three cases of wound infection and one of prosthetic valve endocarditis were pathogenic staphylococci not distinguishable from preoperative isolates. The collection of superficial swabs for this purpose before cardiac surgery is therefore unlikely to be cost effective.

Prevalence of lower respiratory tract infections in hospitalized patients in the United Kingdom and Eire--results from the Second National Prevalence Survey.

During 1993 and 1994, the Hospital Infection Society conducted its Second National Prevalence Survey of infections in patients in British hospitals. The prevalence rates for hospital-acquired (HA) and community-acquired (CA), lower respiratory tract infections (LRTIs) were 2.4% and 6.1%, respectively; this shows an increase over that reported in the First National Prevalence Study. The prevalence rate of HA infections for ventilated patients was 18.6%. The prevalence was greater in males, odds ratio (OR, 95% CI) for HA-LRTIs (1.4, 1.1-1.6) and CA-LRTIs (1.2, 1.1-1.3) than in females. In the case of both HA-LRTIs and CA-LRTIs, there was an increase in prevalence in patients with age >75 years, (HA-LRTIs 1.7, 1.3-2.2; CA-LRTIs 1.7, 1.0-2.7). Results of multivariable logistic regression analysis showed an increased risk of HA-LRTIs in patients who had a nasogastric tube (3.6, 2.3-3.6), were ventilated (2.3, 1.6-3.2), trauma patients (2.2, 1.5-3.0), chronic obstructive airway disease (COAD), (1.9, 1.5-2.3), a tracheostomy (1.9, 1.3-2.7), prior blood transfusion (1.5, 1.2-1.8), smokers (1.4, 1.1-1.6) or on systemic corticosteroid therapy (OR 1.3, 1.1-1.6). Community-acquired LRTIs were positively associated with cystic fibrosis (33.7, 19.1-59.3), HIV (9.8, 6.5-14.8), COAD (4.8, 3.8-4.8), systemic corticosteroid therapy (2.5, 2.2-2.8), tracheostomy (1.8, 1.1-2.9), males (1.2, 1.1-1.3) and smoking (1.2, 1.1-1.4).

The assessment of the risk of cross-infection with a multi-use nasal atomizer.

Atomizers working on the Venturi principle are used by otolaryngology departments in the UK to spray cocaine and other local anaesthetic and vasoconstricting solutions into the nasal cavities. These devices are rarely cleaned, nor is the cocaine in the reservoir changed between patients. This study aimed to assess the risk of cross-infection with such an atomizer of the Down's design. Nutrient broth from a sterile atomizer was sprayed into the nasal cavities of 12 healthy volunteers on three occasions, the tip of the nozzle was withdrawn between sprays into the right nostril, but not between sprays into the left. On each occasion the tip of the nozzle, a nutrient broth rinse of the inner tube of the nozzle and the residue of broth in the reservoir of the atomizer were cultured and the colonies compared with those from a nasal swab collected previously. The results show transmisson of bacteria from the nasal vestibule on to the tip, into the nozzle and into the reservoir of the atomizer. Examination of the minimum inhibitory concentration values of 10% cocaine with and without Nipasept preservative indicated poor antibacterial properties. We conclude that the use of an atomizer on more than one patient poses a risk of cross-infection, and recommend their replacement with a single-use disposable nasal atomizer.

The Second National Prevalence Survey of infection in hospitals--overview of the results.

This study was designed to assess the overall prevalence of infection among the patients in hospitals in the UK and the Republic of Ireland. Patient data were collected and entered directly into a portable Olivetti (A12 notebook) computer with a custom-designed program (Epi-Info version 5.01). The statistical analysis was performed using the Statistical Package for Social Sciences software (SPSS). In all, 37,111 patients from 157 centers were studied, and a mean hospital acquired infection (HAI) prevalence rate of 9.0% (range 2-29%) was calculated. HAI rates were higher in teaching hospitals (11.2%) than in non-teaching hospitals (8.4%) P < 0.001. Four major sites of infections--infections of the urinary tract (23.2%), surgical-wound infections (10.7%), lower-respiratory tract (22.9%) and skin infections (9.6%)--accounted for 66.5% (2559 of 3848) of the total infections identified.

Antibiotics on urethral catheter withdrawal: a hit and miss affair.

Globally, millions of patients undergo urethral catheterization every year. Our objective was to study the current use of prophylactic antibiotics on urinary catheter withdrawal. A questionnaire (N = 300) was sent to healthcare professionals involved in the management of patients with urinary catheters (consultant microbiologists, infection control nurses, consultant urologists, specialist nurses in urology, continence advisers and consultants in the care of older people). The questionnaire asked about their use of prophylactic antibiotics on the withdrawal of a urethral catheter. Sixty percent of healthcare professionals advocated the use of antibiotics for either all or selected groups of patients. The remainder did not. The use of prophylactic antibiotics varied among different groups. Of the healthcare professionals who used antibiotics, the majority cited more than one reason for their use (prevent bacteraemia, avoid an infection in a prosthesis or urinary tract infection). The course and type of antibiotic used varied. Our study has shown diversity in practice that is of concern. At present, just over one-half of patients with urinary catheters are being given antibiotics, although there is no evidence to suggest that such an intervention confers any benefit. If benefits do not exist, these patients are being exposed to the harm of antibiotics and providers are incurring costs unnecessarily. A formal trial to address this issue is urgently needed.

Safety and efficacy of caffeine-augmented ECT in elderly depressives: a retrospective study.

Prior studies have shown that in younger depressives undergoing ECT whose seizure durations declined despite maximum settings on three different ECT devices, pretreatment with caffeine lengthened seizures and resulted in clinical improvement. Caffeine (half life, 140-270 minutes) was well tolerated even in patients with pre-existing cardiovascular disease. The purpose of this retrospective study was to determine the safety and efficacy of caffeine augmented ECT in elderly depressed patients. The charts of 14 elderly depressives (average age 75.6, range 59-83; 2 males, 12 females) who received caffeine-augmented ECT were reviewed. Patients pre- and post-ECT medications, blood pressure, pulse, and seizure times (cuff and EEG) for each ECT performed were noted. The following conclusions were drawn from our study: (1) Caffeine definitely increases the seizure length and was useful in our setting when the energy settings could not be increased anymore. (2) Caffeine augmentation inconsistently causes an increase in pulse rate, on average, in the elderly. (3) Caffeine inconsistently produces an increase in mean arterial pressure. (4) Caffeine did not consistently produce an increase in the maximum rate-pressure product. We conclude from this study that caffeine-augmented ECT is safe and effective in increasing seizure duration in the elderly. However, more research needs to be done to determine optimal dosing and tolerability.

The acute exanthem associated with seroconversion to human T-cell lymphotropic virus III in a homosexual man.

An illness characterised by fever, arthralgia, myalgia, a macular erythematous rash, a sore throat and the appearance of atypical lymphocytes in the blood film is described in a 27-year-old homosexual man. There was serological evidence that this illness was due to the human T-cell lymphotropic virus Type III.

Effectiveness of intradermal hepatitis B immunization of hospital staff.

Three doses of hepatitis B vaccine were administered via an intradermal route to 316 health service staff. One month after the final dose, 89.9% of subjects had antibodies to hepatitis B surface antigen at levels of 10 IU/l or greater. A programme of hepatitis B immunization based upon the intradermal route is substantially less expensive than one using an intramuscular technique, and can enable health authorities to provide protection for increased numbers of staff without diverting resources from other programmes of health care.

Impact of changes in Clostridium difficile diagnostic testing on detection of C. difficile infection and all England mandatory surveillance data.

Following the report of the Centre for Evidence-based Purchasing, which suggested poor performance of Clostridium difficile testing kits, revised guidance was issued by the Department of Health (England) recommending a two-test algorithm. The aim of this study was to survey English National Health Service (NHS) diagnostic microbiology laboratories using an electronic questionnaire to investigate changes in laboratory procedures in response to the guidance and model the impact these changes had on national and locally reported data. It was found that 24% of laboratories had changed testing procedures and there was no evidence of an overall effect on the English mandatory surveillance data used for performance management. It was shown that there could be an impact on an individual NHS Trust's case numbers, and a simple model for Trusts to predict these changes in C. difficile laboratory diagnosis was developed. There was also evidence of the use of variable sample selection criteria, which could affect the positive and negative predictive values of local testing.