Cross-infection and its prevention

[Surgical scrub: evaluation of its adequacy for the prevention of biological risks in surgical procedures II: effectiveness of surgical scrub]

The study elaborated evaluation patterns of the components of the surgical scrub in hospitals of the district of São Paulo. The most important difficulty was the lack of rules and consent on the types of the fabrics, as a microbiological and contact with blood and other fluids barrier. However, it was possible to identify positive and problematic aspects. It was observed that the components are similar among the hospitals, considering the design and the way of fabrics production. Gloves were the ones with the best quality results, while shootweares were the worst. The most problematic aspect was referred to the acquisition controls and the re-use process of the components.

[Surgical scrub: evaluation of its adequacy in preventing biological risks in surgery: I. Its use in surgery]

The study elaborated approaches for adequate use of the surgical scrub and it evaluated, through systematized observation, the performance of the surgical team during the surgery. The adopted procedure was very valid, allowing to recognize positive and problematic aspects. Except the protecting glasses, all the other components of the surgical scrub were used. The subject located in the use form, where caps and masks were more problematic among anaesthesists and circulate nurses; apron and gloves among surgeons and, mainly, scrub nurses.

Salmonella senftenberg: a new pathogen in the burns ward

This is the first report of Salmonella senftenberg serovar outbreak in a burns unit. This unit admits about 2000 patients with major burn injuries annually. Routine sampling from wound swabs in December 1995 revealed S. senftenberg in a few samples following which a study was instituted from January to March 1996. Of 446 burn admissions during this period 80 patients were culture positive for S. senftenberg in wound swabs. The protocol for investigation included wound swabs on admission and then at biweekly interval, blood culture studies on clinically toxic patients, anti-microbial sensitivity studies, environmental sampling and hand swabs and stool cultures from about 50 staff members of the burns ward. No wound swab at the time of admission was positive for S. senftenberg. Environmental study and the study of staff members did not reveal any obvious source of the infection. S. senftenberg strains were sensitive to more than seven of the 11 anti-microbials tested at the beginning of the study but later 96.3% of the strains showed multidrug (more than three drugs) resistance. By April 1996 the isolates became negligible and later disappeared completely. The organism resurfaced again in March 1997 and the same study was instituted again on 413 admissions between March and May 1997. Fifty patients were culture positive for S. senftenberg. This time stool sample from one burn dresser tested positive for S. senftenberg. Interestingly, again at the beginning of the second outbreak the Salmonella strains were sensitive to 9 out of 11 anti-microbials tested, but later 96.11% strains became multidrug resistant. S. senftenberg strains showed maximum resistance to amoxycillin (97.5%) and minimum to chloramphenicol, tetracycline and cotrimoxazole (12%). It was noticed that Salmonella strains surfaced in wound swabs after 3-4 weeks of hospital stay. Forty-five out of 130 patients studied, in both the episodes, died due to septicemia. The majority of the patients who died had sustained > 60% TBSA burns. Blood cultures were done in 34/130 patients and eight yielded growth (2 S. senftenberg, 4 Klebsiella spp., and two Pseudomonas spp.)

Cross infection on a combined paediatric plastic surgery and burns unit: a clinical and microbiological audit

To try and determine any presence of cross-infection between patients, prospective screening of 226 consecutive admissions on our burns unit was performed by taking nose, throat and wound swabs. Infected wounds were also swabbed and a correlation was sought between the organisms cultured on screening swabs and those responsible for infection. We did not find any evidence of cross- infection occurring between the burns patients and the other categories of patients on the ward. Screening swabs were useful in detecting carriers, who were found to be more of a risk to themselves than to other patients on the unit.

Analysis of bacteriuria in patients with burns

A detailed analysis of bacteriuria in 148 aged patients with burns was made for a period of 2 years (1991-92), in order to determine the incidence of the urine infections they sustained, the sources and mechanisms of the infections and the impact on the course and outcome of the primary disease. Urine infection was found in 7.6 per cent (46 patients) of all patients treated for burns during the study period; 39.1 per cent were community acquired uroinfection (CAU) and 60.9 per cent were hospital acquired (HAU). In addition there were eight patients with bacteriuria, secondary to a generalized bacterial infection (GBI), and 11 with candiduria associated with massive antibacterial therapy. Leading causes of CAU were the common uropathogens: E. coli, Citrobacter and Proteus sp.; those of HAU were multiresistant hospital strains, characteristic of the Burns Clinic: Pseud. aeruginosa, Klebsiella sp., Acinetobacter sp. and Serratia sp. This study confirmed the role of transurethral catheterizations as factors associated with the development or exacerbation of chronic uroinfections, which increased the chances of non-survival, especially in aged people with concomitant chronic urological, nephrological or other underlying diseases. The causes of death in 20 patients with HAU, CAU, GBI and candiduria were analysed. The need for strict monitoring of burned patients at risk for uroinfection development and the need to take urgent preventive measures is emphasized.

Use of teicoplanin in community medicine

Administration of parenteral antibiotics to outpatients is increasingly used to reduce hospital costs, to reduce loss of earnings for the patient and to improve the quality of life in patients requiring prolonged antibiotic treatment. The glycopeptides are required for treatment of infections caused by methicillin resistant staphylococci and some enterococci, or for treatment of patients allergic to beta-lactam agents. For home therapy, teicoplanin has some advantages over vancomycin in that it requires only once-daily bolus administration, does not necessitate monitoring of serum concentrations and offers the choice of intravenous or intramuscular administration. Teicoplanin has been used to complete treatment of endocarditis at home in selected patients, streptococcal disease being the most suitable form of endocarditis for this treatment. In open trials, teicoplanin has been found effective in home therapy of osteomyelitis but, as with other agents, prolonged dosage can be associated with adverse effects. It has also been used for home treatment of infections of the respiratory tract, intravascular catheters and soft tissue. Despite its higher acquisition costs, teicoplanin is to be preferred over vancomycin because of the reduced administration and assay costs and fewer adverse effects.

Clustering of group A streptococcal infections on a burns unit: important lessons in outbreak management

In a 12-month period 37 patients and four members of staff on a burns unit were infected or colonized by Streptococcus pyogenes (Group A streptococcus). One patient became septicaemic and died. Serotyping revealed five distinct clusters against a low background level of infection. Infection control measures included isolation, screening of patients, staff and environment and the use of prophylactic antibiotics for uninfected patients. We discuss the role of staff and patient carriers and the environment as a continuing source of infection, and the importance of serotyping in outbreak epidemiology.

Factors influencing the performance of temporary skin substitutes

Advances in our knowledge of the wound healing process has led to the development of various synthetic skin substitutes, which when applied to the wound surface provide a microclimate conducive to healing. The requirements of an ideal temporary skin substitute are presented. This review also provides an updated account of the preclinical evaluation procedures utilized to assess these demands, particularly important parameters such as water vapour permeability, adherence to excised wound surface, oxygen permeability, mechanical properties, microbial permeability and exudate soaking capacity.

Infection control in a Third World burn facility

A study of wound colonization by bacteria in 49 consecutive admissions was conducted over a 2-month period in patients with burns at King Edward VIII and Clairwood Hospitals, Durban, neither of which possess proper burn units. Specimens for culture were collected from patients, staff and the environment. Bacteria most frequently isolated were Staph. aureus, Klebsiella spp., Ps. aeruginosa and Enterobacter spp. Cross-infection occurred due to breakdown of aseptic techniques. Staff hands and contaminated baths and benches were also implicated. Recommendations to reduce cross-infection are presented.

Preclinical evaluation of skin substitutes

The important requirements of a skin substitute such as water vapour permeability, adherence to the excised wound surface, oxygen permeability, mechanical properties, impermeability to micro-organisms and exudate soaking capacity have been highlighted. Two commercial synthetic skin substitutes, Bioclusive and Geliperm, have been used to establish the preclinical assessment procedures for skin substitutes. Two in vitro techniques, the 'Water Cup' and the 'Inverted Cup,' and two in vivo methods involving a 'Ventilated Hygrometer Chamber' system and an Evaporimeter have been employed to assess and compare the water vapour permeability of the skin substitutes under controlled conditions. An Evaporimeter, which is very simple to operate, provides more accurate results. A simple test has been designed to evaluate the early adherence of the skin substitutes to the excised wound surface of rats. The pulling force and the peeling force required to remove the membrane from the wound surface have been measured and these forces have been found to depend upon the composition of the membrane. An oxygen permeability cell has been fabricated which measures the dissolved oxygen permeability of the skin substitutes. The detection of oxygen is based on the electrocatalytic reduction of oxygen at the surface of a noble metal. The tensile properties of the skin substitutes have been measured by an International Standard procedure and both the skin prostheses are associated with some drawbacks. An in vitro method of testing the microbial permeability of the skin substitutes has been designed which simulates an oozing colonized wound that a skin substitute faces in cases of septicaemia. Both the test materials were impermeable to both bacteria and fungi and will provide an effective barrier. The effectiveness of the skin substitutes to absorb wound exudate from the wound surface has been evaluated by soaking the pieces of the membranes in water, plasma and serum and observing their weight gain. The soaking capacity depends upon the composition and nature of the material. The procedures developed have been employed to evaluate a hydrogel type synthetic skin substitute recently formulated in our laboratory.

AIDS: practising safe endoscopy

The emergence of HIV has provoked a widespread reappraisal of infection control practices in endoscopy units. Infection control practices should be applied to all patients alike without recourse to selection or screening. Although there has only been one reported instance of viral transmission at endoscopy, HIV could in theory be transmitted by a contaminated endoscope. Experience suggests that this is more likely to occur from damaged endoscopes, if an unsuitable disinfectant is used or endoscopes are not precleaned. In-use studies have shown that HIV contaminates endoscopes used on patients with AIDS, but in amounts too small to cause infection in tissue cultures. Cleaning in neutral detergent is extremely effective in removing contaminating micro-organisms, including HIV, from endoscopes. Aldehydes are the disinfectants of choice, but any disinfectant may fail if organic material is not removed by cleaning. After thorough cleaning, short disinfection times (e.g. four minutes) ensure inactivation of all relevant micro-organisms except Cryptosporidium and mycobacteria, although in practice even these organisms are likely to be reduced to non-pathogenic levels. Accidental needlestick injuries are the greatest hazard in the endoscopy suite; needles should not be resheathed and biopsy forceps must be handled with great care. The wearing of gloves should become second nature.

Streptococcus pyogenes: an outbreak on a burns unit

An outbreak of infection with Streptococcus pyogenes (Group A beta-haemolytic streptococcus) on a burns unit described. The control measures taken are outlined, and the route of spread of infection is discussed along with possible preventative measures.

AIDS and the lung. 1--AIDS, aprons, and elbow grease: preventing the nosocomial spread of human immunodeficiency virus and associated organisms

Epidemiological evidence indicates that transmission of human immunodeficiency virus (HIV) other than by direct inoculation or sexual contact is extremely rare. HIV has, however, been found on fibreoptic bronchoscopes used on patients with AIDS and there is a clear theoretical risk of transmission by bronchoscopy. Applied experiments have underlined the importance of cleaning equipment thoroughly and have shown the limitations of disinfection. Infection control policies should be revised to meet the following four basic requirements: (1) all precautions should apply to all patients alike--that is, whether infectious or not; (2) equipment should be cleaned thoroughly in detergent immediately after use to remove body secretions and reduce contamination; (3) staff who may be exposed to body secretions should wear simple barrier clothing routinely; and (4) contaminated bronchoscopes should be disinfected for 20 minutes in 2% alkaline glutaraldehyde after cleaning.

Colonization priority among Staphylococcus aureus strains--correlation with phage-type

We have studied the distribution of phage-type patterns among strains of Staphylococcus aureus isolated from patients in a burns unit. From 51 patients the same phage-type was isolated from succeeding swabs during the observation period. In 20 patients new types were introduced, but the original strain remained. In 23 patients the first strain was replaced by one other strain, in eight patients two or more. Strains of type 95 seemed to have a high colonization priority, whereas strains of group III had a low one. In 1986 phage-typing was performed on two or more S. aureus strains from the same patient, in 4561 instances. Recurrence of strains of the same phage-type pattern was demonstrated in 70% of the patients when the first and the fourth sample were compared. The "newer epidemic" strains of phage-type 95 and of the 94,96 complex had the highest percentage of recurrence (more than 80%) when adjacent samples were compared, and 68-69% when the first and the fourth sample were compared. The good colonization capacity of these strains might be one of the explanations why they occur frequently today although they are resistant only to penicillin.

Aeromedical transfer of burned patients: a review with special reference to European civilian practice

Inter-hospital transfer of a patient with a burn injury can usually be undertaken with confidence, even for non-medical reasons, as long as it is undertaken with care. Transfer by air has many advantages for the seriously burned patient provided that all potential risk factors are taken into account. There is a need to consider infection, the respiratory condition and the cardiovascular status of the patient. The possibility of other injuries should also be borne in mind. Early transfer requires careful but urgent planning if it is to be achieved, as is desirable, by days 3 or 4 postburn. Transfer during or at the end of the resuscitation phase, or in the convalescent phase when skin cover is well established, poses least problems. Plenty of sterile paraffin gauze, wool and crêpe bandages will be needed. Appropriate monitoring equipment and full cardiovascular and respiratory resuscitation facilities should be carried. Care should be taken in the selection of the medical and nursing personnel to accompany the patient, who should whenever possible have experience of burns as well as aviation medicine.

Nosocomial infection--the irreducible minimum

Prevalence surveys in different countries have shown that about 1 in 10 hospitalized patients at any one time have acquired an infection and the incidence of infection is usually about 3% to 5%. Can this infection rate be significantly reduced and is there an irreducible minimum below which further reduction cannot be obtained? Cross-infection could probably be almost eliminated by the use of plastic isolators or life islands, and endogenous infections reduced by the wider and more rational prophylactic use of topical and systemic antimicrobial agents, and possibly a range of vaccines. However, the use of these techniques on all patients would clearly be impractical and too expensive for use in the foreseeable future. Excessive isolation techniques would have a detrimental psychological effect on many patients. In addition, failure to eradicate the organisms of the normal flora might be associated with more infections caused by antibiotic-resistant bacteria, fungi and viruses which would be more difficult to treat. Even if organisms could be eradicated, morbidity and mortality might not be correspondingly reduced. Priorities must therefore be set on the most effective use of staff and finances. These not only involve a consideration of infection, but all areas of clinical practice, eg, costs of cardiac transplants and provision of geriatric facilities. It therefore seems likely that little additional finance will be available for control of infection, other than possibly for transmissible infections with high mortality such as AIDS.