Hygienic interventions to decrease deep sternal wound infections following coronary artery bypass grafting

BACKGROUND

The department of Cardiothoracic Surgery at Uppsala University Hospital has 25 beds in one to four patient rooms and an operating suite consisting of five operating rooms with ultraclean air. Around 700 open heart (250 isolated coronary artery bypass grafting, CABG) operations are performed annually. In 2009, the numbers of deep sternal wound infections (DSWIs) increased to unacceptable rates despite existing hygienic guidelines.

AIM

To show how root cause analysis (RCA) followed by quality improvement interventions reduced the rate of DSWI after CABG surgery.

METHODS

Only isolated CABG patients requiring surgical revision due to DSWI were included. Swabs and tissue biopsies were taken during surgical revision and analysed with standard methods. DSWIs were registered prospectively according to US Centers for Disease Control and Prevention definitions. RCA for infection was performed between September 2009 and April 2010. Interventions based on results of the RCA and on nationally recommended practices were concluded in April 2010, and thought to have taken full effect by July 1st, 2010. Air was actively sampled at ≤0.5m from the sternal incision.

FINDINGS

DSWI incidence rates per CABG operations decreased from 5.1% pre intervention to 0.9% post intervention. Wound cultures pre intervention grew Staphylococcus aureus 27.1% and coagulase negative staphylococcus (CoNS) 47.1%, post intervention S. aureus 23.1% and CoNS 30.8%. Air counts did not exceed 5cfu/m(3).

CONCLUSION

When the aetiology of an error is multifactorial, RCA engaging both the medical professions and the infection control team is a potential tool to map causes leading to adverse events such as healthcare-associated infections. A systematic quality improvement intervention based on the RCA may reduce the number of deep sternal wound infections after CABG surgery.

Different trends in antibiotic resistance rates at a university teaching hospital

OBJECTIVES

To investigate long-term trends in antibiotic resistance of common bacterial species isolated at a university hospital and in its intensive care units (ICUs).

METHODS

Levels of antibiotic resistance of common bacterial pathogens were investigated at the Karolinska Hospital during the 12-year period 1988-99. Resistance rates were analyzed for the entire hospital, as well as for ICUs combined.

RESULTS

At the Karolinska Hospital, we found increased ciprofloxacin resistance among Escherichia coli isolates, from 0% in 1991 to 11% in 1999. In the ICUs, the corresponding increase was from 0% to 4.8% during the same period. Co-trimoxazole resistance levels increased from 7.5% to 14%, with lower levels for the ICUs. For ampicillin, cefuroxime, and gentamicin, the levels of resistance were similar in the whole hospital and in the ICUs. Among Pseudomonas aeruginosa isolates, imipenem resistance was higher in the ICUs. For ciprofloxacin, resistance increased from 2.5% in 1991 to 13% in 1999 in the whole hospital, with similar figures for the ICUs.

CONCLUSION

The resistance rates at the Karolinska Hospital were still generally low, but were increasing for some antibiotic-microbe combinations. The results emphasize the importance of including all sectors of a hospital in resistance surveillance studies, and also the value of long surveillance periods.

Risk factors for nosocomial intensive care infection: a long-term prospective analysis

BACKGROUND

To identify risk factors for nosocomial infection in intensive care and to provide a basis for allocation of resources.

METHODS

Long-term prospective incidence study of risk factors for nosocomial infection in the surgical-medical intensive care unit of a university hospital.

RESULTS

A total of 2671 patients were admitted during four years, and 562 of 574 patients staying >48 h were observed during 4921 patient days (median length of stay 5 days, range 2-114). Of these, 196 (34%) patients had 364 nosocomial infections after median 8-10 days, an infection rate of 14/100 admissions. Infection prolonged length of stay 8-9 days and doubled the risk of death. The infections were 17% blood stream, 26% pneumonias, 34% wound, 10% urinary tract and 13% other infections. The incidence of bloodstream infection declined significantly during the study years, from 12% to 5%. In multiple regression analysis, the important variables for infection were central venous catheter, mechanical ventilation, pleural drainage and trauma with open fractures. High age, immunosuppression and infection on admission did not influence the risk of acquiring infection. Trauma patients constituted 24% of the study population. Trauma with open fractures increased the risk of infection more than twice (P=0.003), mainly due to wound infections.

CONCLUSION

Trauma cases, with open fractures, were the patients most at risk of infection, despite low disease severity scores. Resources to prevent nosocomial infection should be allocated to these patients.

A test for cleaning and disinfection processes in a washer-disinfector

Disinfection processes such as heat, aldehydes or alcohols kill vegetative microorganisms but do not necessarily remove other organic contamination. Organic residues impair the result of low-temperature sterilisation processes. Heat-stable organic residues may give rise to clinical symptoms in the patient. Standards are available in Britain and in Sweden for the examination of cleaning processes in washer-disinfectors. The test substances are artificial soil or blood. These standards are based on visual inspection of instruments or equipment. They cannot be used for examination of tubular instruments, nor can they be quantified. For validation of cleaning procedures a simple quantifiable method, which can be performed in an infection control laboratory is needed. We have used suspensions in horse blood of Enterococcus faecalis bacteria and Bacillus subtilis spores to test disinfection and cleaning in a washer-disinfector. Instruments used for laparoscopic surgery were contaminated with a blood bacteria suspension containing 10(7) organisms/ml and then dried and processed in a washer-disinfector using a regular process. Remaining microbial contamination was cultured quantitatively. Nineteen objects were investigated in 10 experiments each. Cleaning, measured as log reduction >5-6 of B. subtilis, was achieved on surfaces that were adequately in contact with the water flow in the machine. Disinfection (and cleaning) measured as log reduction >5-6 of E. faecalis was successful at all points examined. The test method is simple and quantifiable, and can be used to evaluate and to improve cleaning and disinfection processes.

[Task and task time should dictate the choice of gloves in health care services]

Worldwide consumption of medical gloves increased during the 1980's due to the recognized risk of cross infections in medical and dental care. In Stockholm County Council around 1 million pairs of surgical gloves and 18 millions pairs of examination gloves are purchased per year. In the following paper different glove materials and types are presented and also regulations on use and purchase. The protective capacity of gloves and contact hypersensitivity reactions are also discussed and advice is provided on glove usage.

Preoperative gentamicin eye drops and chlorhexidine solution in cataract surgery. Experimental and clinical results

PURPOSE

1) To evaluate the effects on the conjunctival flora of gentamicin ophthalmic eye drops 0.3%, given four times in 45 minutes, and a conjunctival rinse with 10 ml chlorhexidine 0.05% solution. 2) To investigate retrospectively the rate of endophthalmitis after cataract operations when these antimicrobials were applied preoperatively.

METHODS

Seventy-six patients undergoing standard phacoemulsification operations were enrolled in the experimental part of the study. Cultures were taken preoperatively, 5 minutes after prophylaxis with either chlorhexidine or gentamicin. To assess the combined effects of chlorhexidine and gentamicin, cultures were taken after the cataract operation. Hospital charts were reviewed for cases of endophthalmitis in 1994 and 1995, when this prophylactic protocol was used at the St Erik's cataract surgery department.

RESULTS

The conjunctival microflora was significantly suppressed by chlorhexidine rinsing alone (p = 0.001), while no other significant anti-bacterial effects were observed with the experimental prophylaxis. The endophthalmitis rate was 32/12. 806 operations (0.25%).

CONCLUSIONS

Topical rinsing with chlorhexidine solution suppresses conjunctival flora in the short term. Combined topical chlorhexidine and gentamicin prophylaxis does not eliminate postoperative endophthalmitis caused by gram-positive bacteria.

The effect of a 1-hour training program on the incidence of bacteremia in pediatric patients receiving parenteral nutrition

The effect of a 1-hour nurse training program on the frequency of bacteremia in patients receiving parenteral nutrition was evaluated in a pediatric tertiary center. All of the nurses had previous instruction on aseptic techniques in nursing school. The current program focused on aseptic management of intravenous catheters and implanted subcutaneous ports in patients receiving parenteral nutrition (PN). One hundred eighty-four nurses had a 1-hour training session in groups of three to five. The frequency of bacteremia in children receiving PN was not reduced (9.2% versus 8.9%), and there was no significant difference in time from the start of PN to the diagnosis of bacteremia (P = 0.31). The authors conclude that a 1-hour training session for the nursing staff was not sufficient. It is suggested that staff training for prevention of bloodstream infections associated with intravascular devices should cover a wider range of topics and take place over a longer period of time.

Spread of coagulase-negative staphylococci during cardiac operations in a modern operating room

BACKGROUND

Coagulase-negative staphylococci cause 33% to 62.5% of wound infections after cardiac operations. The aim of this study was to investigate the sources of coagulase-negative staphylococci in the sternal wound.

METHODS

Twenty operations performed in zonal ventilated operating rooms were investigated prospectively. Cultures were taken from all persons present in the room, the sternal wound, and the air. Isolates macroscopically judged to be coagulase-negative staphylococci were metabolically classified, and similar isolates were investigated by pulsed-field gel electrophoresis.

RESULTS

Bacterial counts in the operating room air were very low. Wound contamination was found in 13 of 20 operations. Six wound isolates could be traced, three to the patients' sternal skin, one to the patient's groin, one to the surgeon's nose, and one to the surgeon's arm and forehead and the assistant's nose. Three operating field air cultures could be traced to the scrubbed theatre staff. The single case of superficial sternal wound infection was caused by Staphylococcus aureus, which was not isolated from the wound at operation.

CONCLUSIONS

In an ultraclean environment, bacteria in the sternal wound originated from the patients' own skin and from the surgical team.

Protein depositions on one hydrocephalus shunt and on fifteen temporary ventricular catheters

Biomaterials are commonly used in modern medicine. Proteins are adsorbed to the surface of the biomaterial immediately after insertion. This report demonstrates the presence of adsorbed proteins in one infected cerebrospinal shunt from a child with hydrocephalus and on fifteen temporary ventricular catheters from adult patients with spontaneous or traumatic brain injuries. Depositions of vitronectin, fibrinogen and thrombospondin-fibronectin to some extent--on the shunt surface was imaged by field-emission scanning electron microscopy. Vitronectin, fibronectin, fibrinogen, and thrombospondin on the ventricular catheters were shown with radio-actively labelled antibodies. Furthermore, protein adsorption from human cerebrospinal fluid to heparinized and unheparinized polymers was studied under flowing conditions in vitro. On heparinized polymer, significantly reduced levels of vitronectin, fibronectin, and thrombospondin were exposed, as measured after 4 hours in vitro perfusion. After 24 hours perfusion, the differences in protein exposition between heparinized and unheparinized polymers were substantially reduced.

Surface heparinization of central venous catheters reduces microbial colonization in vitro and in vivo: results from a prospective, randomized trial

OBJECTIVE

To evaluate in vitro and in vivo the efficacy of covalent end point-attached heparin to single-lumen polyurethane central venous catheters in reducing microbial adherence and colonization.

DESIGN

In vitro study: A controlled bench study. In vivo study: A prospective, randomized, double-blind, clinical trial.

SETTING

Intensive care unit in a 1200-bed teaching hospital.

INTERVENTIONS

In vitro study: Adhesion of 17 radiolabeled clinical isolates of Staphylococci to catheters was examined in vitro. In vivo study: The outcome of heparinized and control catheters was compared in vivo in patients receiving long-term parenteral nutrition. Fifty-five adult patients were prospectively, blindly randomized to heparinized or control central venous catheters. The catheters, removed on clinical grounds, were analyzed with semiquantitative and quantitative cultures. Blood cultures were done at catheter removal.

MEASUREMENTS AND MAIN RESULTS

In vitro study: Coagulase-negative Staphylococci adhered less in vitro to heparinized catheters than to control catheters (p < .05). In vivo study: Among 32 central venous catheters, or patients who completed the study, catheter-associated bacteremia or fungemia was observed in five patients in the control group (n = 19) and in no patient with a heparinized catheter (n = 13) (p = .047). Four of 13 catheters in the heparin group were colonized compared with 14 of 19 in the control group (p = .03). Coagulase-negative Staphylococci were the most frequent microorganisms in both groups. The numbers of organisms found on colonized catheters were larger in the control group than in the heparin group.

CONCLUSIONS

Covalent end point surface heparinization appears to have a great impact on both in vitro and in vivo bacterial colonization of central venous catheters. Such heparinization can be a practical and economical approach to the prevention of catheter-associated bacteremia or fungemia.

Typing of coagulase-negative staphylococci from peritonitis in CAPD-patients by the PhP-CS system and REA

Coagulase-negative staphylococci (CNS) were the most common bacteria causing peritonitis in patients treated with continuous ambulatory peritoneal dialysis (CAPD). In order to investigate if the same clone was responsible for the peritonitis in the different patients and if the exit site was the source of infection we followed 68 patients on CAPD for 2 years. During this period 9 patients had 12 episodes of peritonitis caused by CNS. Cultures were taken from exit site and peritoneal fluid in all patients at peritonitis and during the first study year at monthly intervals. In each culture up to 10 isolates of CNS were randomly collected and frozen. All 437 CNS isolates from the patients with CNS peritonitis were typed using a biochemical typing method and 41 isolates identical by this method were further discriminated by a DNA fingerprinting method. Identical strains were in no case isolated from different patients, indicating that no virulent strain was spread between the patients. The isolates causing the peritonitis were never found at the exist sites before the first day of the peritonitis in any patient. In only two patients was the same strain found at the exit site and in the peritoneal fluid on the first day of peritonitis. It thus seems that no virulent clone of CNS was infecting the patients and we found no evidence of CNS at the exit site causing the peritonitis.

Colonization with coagulase-negative staphylococci in two neonatal units

Episodes of septicaemia due to coagulase-negative staphylococci (CNS) were more frequent in a level III than in a level II neonatal unit in Stockholm, Sweden. Colonization with CNS during the first 2 weeks of life was investigated in 10 infants from each unit. As the use of antibiotics differed between the two units, the aim was to correlate colonization and antimicrobial resistance patterns to antibiotic usage. Antimicrobial susceptibility of CNS to isoxazolylpenicillins, co-trimoxazole, erythromycin, clindamycin, chloramphenicol and gentamicin was determined. Selected isolates were typed with restriction endonuclease analysis of plasmid DNA and of genomic DNA. Infants were frequently colonized with multiple strains and species of CNS, and transmission of strains from patient to patient occurred within the unit. Qualitative and quantitative differences in antibiotic use were not correlated with colonization. The prevalence of resistant isolates, mostly of Staphylococcus haemolyticus, was higher in the level II unit with lower use of antibiotics. Staphylococcus epidermidis, which is generally more virulent, prevailed in the level III unit, where there were more severely ill children and invasive procedures were more frequently performed.

An outbreak of Klebsiella oxytoca septicemias associated with the use of invasive blood pressure monitoring equipment

Seven cases of septicemia with piperacillin-resistant Klebsiella oxytoca (PRKO) occurred at 2-monthly intervals in a thoracic surgery intensive care unit. All PRKO isolates were serotyped, and phenotyped with a biochemical typing system. Only one patient in the unit was found to be colonized in stool or respiratory tract with PRKO, and this strain was different from the septicemia strains in phenotype though not in serotype. Environmental cultures, from humidifiers, oxygenators, pressure transducers, etc. were negative. PRKO of the epidemic phenotype was recovered from several non-patient transducer domes. The outbreak ended when transducer heads were disinfected and the use of non-patient domes was abolished.

Characterization of Klebsiella oxytoca septicaemia isolates resistant to aztreonam and cefuroxime

Eleven clinical isolates of Klebsiella oxytoca from Stockholm hospitals were found to be resistant to aztreonam and cefuroxime, but susceptible to cefotaxime, ceftazidime and imipenem. Resistance could be overcome by combining the beta-lactams with the inhibitor clavulanic acid. Crude beta-lactamase preparations from the isolates inactivated aztreonam and cefuroxime rapidly. By isoelectric focusing, a single common beta-lactamase of pI 5.25 was detected. The K. oxytoca isolates belonged to three subgroups, based on their plasmid profiles and Bg/II restriction endonuclease digestion of plasmid DNA. It was concluded that resistance to aztreonam and cefuroxime in these isolates was conferred by a beta-lactamase distinct from TEM-1, TEM-2 and SHV-1, but possibly derived from TEM-like enzymes.

Routine semiquantitative cultures and central venous catheter-related bacteremia

Semiquantitative cultures were compared with blood cultures during one year in order to see if the routine use of a semiquantitative catheter culture method (SQC) in unselected patients can detect or predict infection associated with central venous catheters. Catheter infection, i.e. greater than or equal to 15 colony forming units (cfu) per plate, occurred in 137 of 542 catheter tips (25%), mainly with coagulase-negative staphylococci. Catheter-associated bacteremia occurred in 17 of 93 cases (18%) where blood cultures had been drawn. In 15 of these, the catheter tip grew greater than or equal to 15 cfu. The predictive value for bacteremia of a positive SQC was only 21%. SQC is not a suitable method for the detection of catheter-associated bacteremia, but may be an indicator of the standard of central venous catheter hygiene.

Characterization of beta-lactam-resistant Klebsiella oxytoca isolated in a neonatal intensive care unit

The occurrence of Klebsiella oxytoca resistant to ampicillin, piperacillin, aztreonam and cefuroxime in a neonatal intensive care unit, including two cases of septicemia, was shown to consist of a spread on three consecutive occasions caused by three different biochemical Klebsiella oxytoca phenotypes. All isolates, except six surface isolates from one infant belonging to phenotype 1, were sensitive to cefotaxime (MIC 0.5-4 mg/l) and ceftazidime (MIC 0.25-1 mg/l). Isolates of phenotypes 1 and 2 produced a beta-lactamase with an isoelectric point of 5.5 and isolates of phenotype 3, a beta-lactamase with an isoelectric point of 7.9. The beta-lactamases of all three phenotypes hydrolysed benzylpenicillin and more slowly cephalothin. All phenotype 1 isolates carried a 2.9 Md plasmid and most isolates also a 36 Md plasmid. All phenotype 2 isolates carried a 4.8 Md plasmid and one isolate also a 30 Md plasmid. The phenotype 3 isolates carried only one 85 Md plasmid.

Preoperative antibiotics and capsular contracture in augmentation mammaplasty

The main drawback with augmentation mammaplasty using implants is capsular contracture. The cause of this complication is still unknown. Silicone particles, hematoma, and bacterial contamination are some of the etiologic factors discussed. In this randomized, double-blind study on 76 breast-augmented women, 50 percent of the patients had preoperative prophylaxis with benzylpenicillin and dicloxacillin. Bacteria samples were taken intraoperatively. The number of negative cultures increased significantly with antibiotic prophylaxis. In four follow-ups during the first postoperative year, the rate of contractures was evaluated by subjective and objective methods. The results showed no statistically significant difference between the placebo and the antibiotic group with respect to the incidence of capsular contracture.

Methicillin-resistant Staphylococcus aureus in two burn units: clinical significance and epidemiological control

Routine isolation adequately controlled MRSA strains in two burns units with a restrictive antibiotic policy. Ventilation control and more rigorous change of clothing offered no further advantage. No carriers among staff were found, but some suffered minor skin lesions that were the source of further MRSA spread. Spread of MRSA from the unit to other parts of the hospital was prevented by early identification of colonized patients and by restricting patient and staff movement.

Serum levels of cloxacillin and benzylpenicillin in adults undergoing open-heart surgery

Serum levels of cloxacillin and benzylpenicillin were monitored in 35 consecutive adult patients undergoing elective open-heart surgery. Serial serum samples were analyzed during a 24-hour period. After oral intake of cloxacillin and phenoxymethylpenicillin on the preceding evening, very low concentrations remained in serum at the start of operation. Such preoperative medication is inappropriate. Intravenously administered cloxacillin (2 g) and benzylpenicillin (3 g) appeared to be adequate during the first 4 hours of surgery, as the serum half-life of the drugs was twice as long in the patients as in healthy adults, but repetition of the doses is recommended for further antibiotic protection during surgery.

Acute atrophic glossitis after open-heart surgery

The problem of Candida infections has become important in connection with transplant surgery and immunosuppression. To clarify the source of the postoperative acute atrophic glossitis (AAG) commonly seen in our department of cardiac surgery, 33 patients admitted for coronary artery bypass or valve replacement underwent clinical and microbiologic investigation before and after operation. None showed signs of AAG preoperatively, but 12 had cultures positive for Candida albicans, and in all 12 AAG appeared postoperatively. Six of the 21 patients with preoperatively negative cultures likewise had postoperative AAG. All 18 affected patients responded well to local nystatin treatment. No patient had disseminated candidiasis.

Plasmid analysis as an epidemiological tool in neurosurgical infections with coagulase-negative staphylococci

Coagulase-negative staphylococci isolated from blood or spinal fluid during a period of 1 year in a department of neurosurgery, were analysed by biotyping, antibiotic resistance pattern and plasmid profiles. Altogether 41 isolates from 19 patients were studied. About 90% of the isolates were Staphylococcus epidermidis. The antibiotic resistance pattern seemed to be closely related to antibiotic usage in the unit. Most common was resistance to penicillin (63%), trimethoprim-sulphamethoxazole (49%) and cloxacillin (39%) while resistance to gentamicin was seen in only one strain. In several cases species and antibiograms were identical in isolates from different patients. Plasmid pattern analysis could then be used for identification of different strains. In one instance, plasmid pattern and restriction enzyme analysis confirmed that two patients probably were infected by the same strain.

Antibiotic usage in surgery in a large teaching hospital

A prevalence study of the antibiotic usage in the surgical departments at the Karolinska Hospital, Stockholm, showed that 126/517 hospitalized patients (24%) received antibiotics and that 100/306 operated patients (33%) received antibiotics. 44 (44%) of the operated patients were given their antibiotics as prophylaxis and 46 (37%) of all patients receiving antibiotics were given them as prophylaxis. Antibiotics were administered intravenously to 35 (28%) patients, orally to 75 (60%), and topically to 16 patients (13%) (eye department only). The most commonly used drugs in prophylaxis were isoxazolylpenicillins and trimethoprim-sulphonamide while cephalosporins accounted for a minor part. In therapy the most commonly used drug was isoxazolylpenicillin, followed by ampicillin derivatives, metronidazole, tetracyclines, trimethoprim-sulphonamide and cephalosporins. The pattern of antibiotic usage differed markedly between departments.

Antibiotic prophylaxis in pacemaker surgery: a prospective double blind trial with systemic administration of antibiotic versus placebo at implantation of cardiac pacemakers

In a double blind clinical trial, 106 consecutive patients scheduled for pacemaker implantation were randomly assigned either to a systemic prophylaxis group (SPG) (to be given flucloxacillin) or to a control group who would be given a placebo (CPG). The SPG group received 2 g IV flucloxacillin 1 hour before the operation, then 1 g perorally every 8 hours for the next five days. In the CPG group, placebo infusions and tablets were given at the same schedule. There were a total of 106 patients (SPG 52, CPG 54) who met the criteria of the study. Of these, 102 patients (SPG 50, CPG 52) completed a follow-up of 7-35 months. Infection of the pacemaker system was not diagnosed in any patient in either group. Tissue fluid was drawn 24 hours postoperatively from the pacemaker pocket for culture and for determination of pocket antibiotic concentration. The mean flucloxacillin concentration of pocket fluid from 23 patients in the SPG was 7.5 micrograms/ml. The bacteriological cultures were positive in 9/32 patients in the SPG group and in 10/34 patients in the CPG group. This study suggests that antibiotic prophylaxis need not routinely be given at implantation of permanent pacemaker systems.

Masks: a ward investigation and review of the literature

The use of masks was related to the acquisition from patients of beta-haemolytic streptococci and Staphylococcus aureus in the nose/throat of staff in a burns unit. The study took place over 10 weeks; wearing multi-layer operating room masks for every visit to patient rooms had no effect on nose or throat carriage rates, although airborne dispersal from patients was high.

Bacteria in the female breast

Subclinical infection may play a role in capsular formation around silicone breast implants. To assess the possibility of antibiotic prophylaxis for prevention of capsular formation, knowledge of bacteria present in the female breast tissue and the resistance pattern of these bacteria is needed. Samples were taken from 25 patients (49 breasts) peroperatively during reduction mammaplasty with an impression pad method. The samples were placed in agar plates and incubated both aerobically and anaerobically. In more than 90% of the samples bacteria were found. The species of bacteria found were mainly Staphylococcus epidermidis and propionibacteria. These bacteria were sensitive to penicillin G and/or isoxapenicillin. It remains to be shown that prophylactic antibiotic treatment will decrease capsular formation following augmentation mammaplasty.

Rotavirus infections in newborns: an epidemiological and clinical study

An outbreak of rotavirus infections among newborns at Karolinska Hospital, Stockholm, which has been going on for greater than 2 years has been followed with clinical and epidemiological investigations. About one third of the babies born in the hospital were infected at the age of 3 days. The clinical symptoms were mild, 8.8% of the rotavirus positive babies had loose stools compared to 1.9% of those who did not excrete the virus. An epidemiological survey in the neonatal intensive care unit suggested that rotavirus was introduced into the unit by babies admitted from the obstetric wards. The main reservoir of rotavirus was the babies and rotavirus was not found among staff or mothers. In the beginning hygienic measures seemed to be effective but after some weeks the colonization rate again increased. Electropherotyping of samples collected during different periods showed that one single rotavirus electropherotype belonging to the subgroup 1 of human rotavirus was found throughout the outbreak.

A comparison between tracer gas and tracer particle techniques in evaluating the efficiency of ventilation in operating theatres

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Comparison of Staphylococcus aureus carriage and skin infection rates in hospital and office employees

The incidence of Staphylococcus aureus in the nose, throat and superficial wound infections of 99 office staff, 129 psychiatry staff and 115 surgical staff was studied over a 4-week period with the purpose of assessing the potential risk to hospital personnel of staphylococcal infection. Incidence rates, both average and cumulative, were essentially similar in the three groups but certain differences in the ecology of the staphylococcal phage groups were observed. Surgical staff appeared to have a more labile pattern of carriage. As in other Scandinavian studies throat carriage rates were high. Staphylococcal carriage seems largely to depend on individual characteristics rather than environmental factors.

Attempts to control clothes-borne infection in a burn unit, 2. Clothing routines in clinical use and the epidemiology of cross-colonization

Previous investigations have shown that cross-contamination in a burn unit is mainly clothes-borne. New barrier garments have been designed and tried experimentally. The aim of the present study was to investigate the effects of different clothing routines on cross-contamination. In a long-term study, the rates and routes of colonizations with Staphylococcus aureus, Streptococcus groups A, B, C, F, and G and Pseudomonas aeruginosa were examined. The exogenous colonization rates were, with S. aureus 77%, with Streptococcus species 52% and with Ps. aeruginosa 32%. The colonization rate with Ps. aeruginosa was higher in patients with larger burns. Patients dispersed Streptococcus and Ps. aeruginosa as well as S. aureus into the air of their rooms in considerable amounts, but dispersers were not more important as sources of cross-colonization than non-dispersers. In comparison of clothing routines, there was no difference in overall colonization rates. The newly designed barrier garment that was made from apparently particle-tight material did not reduce the transfer of bacteria from patient to patient. A less rigid routine than that previously used did not increase the risk of cross-contamination. A thorough change of barrier dress after close contact nursing delayed the first exogenous S. aureus colonization from day 6 to day 14 after admission. This routine might be recommended for clinical use. Otherwise, methods must be developed for adequate selection of materials intended for barrier garments.

An instrument for measuring bacterial penetration through fabrics used for barrier clothing

A new instrument has been designed to measure the penetration by rubbing of bacteria from cloth contaminated in the nursing of burn patients through fabrics designed for barrier garments. Most fabrics tested dry reduced the transfer of bacteria from the source cloth to about 10%, irrespective of the results of air filter tests, which agrees with mock nursing results. When the fabrics were tested against a wet surface, the transfer of bacteria rapidly reached 100% if the fabrics had a high wettability, but was slower for fabrics with a low wettability. Through closely woven waterproofed cotton, transfer was 5--25%, but increased three- to four-fold after ten launderings, in line with the water absorption. Transfer through plastic-laminated material was less than 1%. The results suggest that barrier garments should be made either of plastic or of recently waterproofed closely woven cotton at points of contact between nurse and patient where the clothes may be wetted by bacteria-containing wound secretions.

Attempts to control clothes-borne infection in a burn unit, 3. An open-roofed plastic isolator or plastic aprons to prevent contact transfer of bacteria

An open-roofed plastic isolator was built in a single patient isolation room in a burn unit. It was designed to prevent contact contamination only, as this had been shown to be the important route of cross-colonization in the unit. To exclude any possible effect on airborne transfer of bacteria, the isolator was first examined by means of an airborne particle tracer of the same size as bacteria-carrying particles. Such experiments indicated that the isolator might prevent some transfer out of but not into the isolator. This was not confirmed in simulated nursing experiments nor in a patient study, where the air counts of bacteria were practically the same inside and outside the isolator wall. Two patients only were nursed in the isolator. Both patients acquired exogenous colonizations from other patients, one with Ps. aeruginosa and the other with S. aureus. Nursing in the isolator was difficult and staff-demanding. In simulated nursing experiments, plastic aprons and gauntlets as the only protective measures against contact contamination gave as much protection to a mock patient as did the isolator. S. aureus were released from nurses' clothes more easily during work with the isolator than in open nursing with aprons and gauntlets. In conclusion, the isolator did not seem to be a realistic alternative to impermeable clothes such as plastic aprons as a means of preventing clothes-borne cross-contamination between burn patients.

Isolation care of infection-prone burn patients

An experimental and clinical study of spread of colonisation between burn patients, and their susceptibility to infection, was performed. Burn patients' polymorphonuclear neutrophil granulocytes (PMN) functioned poorly, particularly during the second week after injury which coincided with maximum growth of bacteria in the burn wound. Patients with large burns often dispersed S. aureus and Ps. aeruginosa but also beta-hemolytic Streptococcus to the air of their rooms. Airborne transfer of these bacteria was practically eliminated by nursing in single isolation rooms with plenum ventilation. In such rooms, cross-contamination was carried mainly via clothes. Patients with small burns sometimes were important sources of such contamination although they dispersed little bacteria to the air. A thorough change of barrier dress after close contact nursing delayed the first exogenous S. aureus colonisation until after the time of greatest impairment in PMN functions. A further reduction in cross-contamination would be possible with barrier garments impermeable to fluids and bacteria on points of contact, as shown in experiments with plastic apron as protective dress. Measurements of penetration through fabrics of particles suspended in air, commercially used, did not correlate to the performance of garments made from the fabrics in experimental nursing and clinical use. Bacteria were shown to penetrate fabrics through rubbing, particularly when wet where the microcolonies present on the cloth were separated into smaller units. An instrument was designed which measured such penetration, and was used to select fabrics for barrier garments. Tightly fitting barrier garments increased the disperal of bacteria from clothes worn underneath them. The wearing of barrier garments should therefore be restricted to close contact nursing. An open-roofed plastic patient isolator was designed and built. It did not appreciably reduce cross-contamination and gave psychological and practical problems. It seemed not to be a realistic alternative to better protective garments in isolation rooms.

Attempts to control clothes-borne infection in a burn unit. I. Experimental investigations of some clothes for barrier nursing

Clothes-borne transmission is an important way of spread of infection from patient to patient which is not interrupted by common cotton gowns. New barrier garments were designed from spun-bonded olefin that, in particle penetration tests, was 100 times better as a filter than cotton cloth. Three designs, a gown, a loose coverall and a close overall, were compared with each other and with conventional cotton gowns in experimental exercise and nursing procedures. Staphylococcus aureus from burned patients were used as markers. The close coverall was 4-7 times better than the loose coverall or gown in preventing the soiling of clothes worn underneath it, but appeared to permit substantially more transfer from garments underneath it to a mock 'patient' and to the air than did the looser garments. A cotton gown reduced the soiling of clothes underneath it by more than 10 times and the contamination of a mock patient by more than 30 times as compared with no barrier garment. The close coverall further diminished the contamination of clothes but not the transfer to the patient. The possible mechanisms for the discrepancy between particle transmission tests annd experimental porcedures are discussed.