Source strength as a measurement to define the ability of clean air suits to reduce airborne contamination in operating rooms.

BACKGROUND: Surgical site infections after total hip and knee replacement are linked to the quality of the operating room (OR) air. Applying tight occlusive clothing, effective ventilation and correct working methods are key concepts to obtain low bacterial concentrations in the OR air. The dry penetration test referred to in European standard EN 13795-2:2019 is a screening method for materials used in surgical clothing. Source strength, defined as the dispersal of bacteria-carrying particles from persons during activity, is a functional test of clothing systems and has been calculated in a dispersal chamber and in ORs. Results from both tests can be used when comparing surgical clothing systems. AIM: This study relates results of dry penetration tests to source strength values for five surgical clothing systems available on the Swedish market. METHODS: Experimental data are reported on the function of these products, expressed as source strength calculated from results in a dispersal chamber and in ORs during orthopaedic operations. FINDINGS: All materials tested with dry penetration ≤50 colony-forming units (cfu) had source strength values <3 cfu/s for one person in the dispersal chamber, whereas the material of one product when laundered >50 times had source strength in the dispersal chamber of up to 8 cfu/s. CONCLUSION: The dry penetration test could predict the performance of clean air suits of the same design, but more studies are needed to obtain a more valid correlation. Requirements of source strength should be included in standards.

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.

Hospital outbreak control requires joint efforts from hospital management, microbiology and infection control.

An outbreak of multidrug-resistant Klebsiella pneumoniae producing the extended-spectrum beta-lactamase CTX-M15 affected 247 mainly elderly patients in more than 30 wards in a 1000-bedded swedish teaching hospital between May 2005 and August 2007. A manual search of the hospital administrative records for possible contacts between cases in wards and outpatient settings revealed a complex chain of transmission. Faecal screening identified twice as many cases as cultures from clinical samples. Transmission occurred by direct and indirect patient-to-patient contact, facilitated by patient overcrowding. Interventions included formation of a steering group with economic power, increased bed numbers, better compliance with alcohol hand disinfection and hospital dress code, better hand hygiene for patients and improved cleaning. The cost of the interventions was estimated to be euro3 million. Special infection control policies were not necessary, but resources were needed to make existing policies possible to follow, and for educational efforts to improve compliance.

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.

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.

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.

[Task and task time should dictate the choice of gloves in health care services]. / Uppgiften och arbetets längd bör styra valet av handskar i vården.

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.

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.

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.

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.

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.