Airborne bacterial contamination during orthopedic surgery: A randomized controlled pilot trial.

STUDY OBJECTIVE: Several factors such as lack of unidirectional, turbulent free laminar airflow, duration of surgery, patient warming system, or the number of health professionals in the OR have been shown or suspected to increase the number of airborne bacteria. The objective of this study was to perform a multivariate analysis of bacterial counts in the OR in patients during minor orthopedic surgery. DESIGN: Prospective, randomized pilot study. SETTING: Medical University of Vienna, Austria. PATIENTS: Eighty patients undergoing minor orthopedic surgery were included in the study. INTERVENTIONS: Surgery took place in ORs with and without a unidirectional turbulent free laminar airflow system, patients were randomized to warming with a forced air or an electric warming system. MEASUREMENT: The number of airborne bacteria was measured using sedimentation agar plates and nitrocellulose membranes at 6 standardized locations in the OR. MAIN RESULTS: The results of the multivariate analysis showed, that the absence of unidirectional turbulent free laminar airflow and longer duration of surgery increased bacterial counts significantly. The type of patient warming system and the number of health professionals had no significant influence on bacterial counts on any sampling site. CONCLUSION: ORs with unidirectional turbulent free laminar airflow, and a reduction of surgery time decreased the number of viable airborne bacteria. These factors may be particularly important in critical patients with a high risk for the development of surgical site infections.

Effectiveness of preventive measures for hemato-oncologic patients undergoing stem cell transplantation during a period of hospital construction.

BACKGROUND: Aspergillus spp are ubiquitous spore-forming fungi. Construction work, renovation, demolition, or excavation activities within a hospital or in surrounding areas increase the risk for aspergillus infection in susceptible patients and are the main cause of nosocomial aspergillus outbreaks. METHODS: We investigated the efficacy of infection control measures on the frequency of fungal infection among hemato-oncologic patients undergoing stem cell transplantation during excavation and construction work of an adjacent hospital building. Clinical isolates from these patients obtained before and during the excavation and construction period were analyzed. Preventive measures consisted in the implementation of a multibarrier concept to protect these patients from fungal infection. RESULTS: There was no record of any clinical isolate of Aspergillus spp in the observation period before the beginning of the groundwork. However, 3 clinically significant isolates of Aspergillus spp were detected in respiratory tract specimen of 2 patients after the beginning of excavation and demolition work, which were found to be community acquired. CONCLUSION: Although our data cannot demonstrate the efficacy of infection control measures during construction work, it can be concluded that excavation work close to immunocompromised patients is safe if a bundle of preventive measures is implemented before groundwork.

Impact of different-sized laminar air flow versus no laminar air flow on bacterial counts in the operating room during orthopedic surgery.

BACKGROUND: This study investigated the influence of the size of unidirectional ceiling distribution systems on counts of viable microorganisms recovered at defined sites in operating room (ORs) and on instrument tables during orthopedic surgery. METHODS: We compared bacterial sedimentation during 80 orthopedic surgeries. A total of 19 surgeries were performed in ORs with a large (518 cm × 380 cm) unidirectional ceiling distribution (colloquially known as laminar air flow [LAF]) ventilation system, 21 procedures in ORs with a small (380 cm × 120 cm) LAF system, and 40 procedures in ORs with no LAF system. Bacterial sedimentation was evaluated using both settle plates and nitrocellulose membranes. RESULTS: Multivariate linear regression analysis revealed that the colony-forming unit count on nitrocellulose membranes positioned on the instrument table was significantly associated only with the size of the unidirectional LAF distribution system (P < .001), not with the duration of the surgical intervention (P = .753) or with the number of persons present during the surgical intervention (P = .291). CONCLUSION: Our findings indicate that simply having an LAF ventilation system in place will not provide bacteria-free conditions at the surgical site and on the instrument table. In view of the limited number of procedures studied, our findings require confirmation and further investigations on the ideal, but affordable, size of LAF ventilation systems.

Clinical impact of antimicrobial resistance in European hospitals: excess mortality and length of hospital stay related to methicillin-resistant Staphylococcus aureus bloodstream infections.

Antimicrobial resistance is threatening the successful management of nosocomial infections worldwide. Despite the therapeutic limitations imposed by methicillin-resistant Staphylococcus aureus (MRSA), its clinical impact is still debated. The objective of this study was to estimate the excess mortality and length of hospital stay (LOS) associated with MRSA bloodstream infections (BSI) in European hospitals. Between July 2007 and June 2008, a multicenter, prospective, parallel matched-cohort study was carried out in 13 tertiary care hospitals in as many European countries. Cohort I consisted of patients with MRSA BSI and cohort II of patients with methicillin-susceptible S. aureus (MSSA) BSI. The patients in both cohorts were matched for LOS prior to the onset of BSI with patients free of the respective BSI. Cohort I consisted of 248 MRSA patients and 453 controls and cohort II of 618 MSSA patients and 1,170 controls. Compared to the controls, MRSA patients had higher 30-day mortality (adjusted odds ratio [aOR] = 4.4) and higher hospital mortality (adjusted hazard ratio [aHR] = 3.5). Their excess LOS was 9.2 days. MSSA patients also had higher 30-day (aOR = 2.4) and hospital (aHR = 3.1) mortality and an excess LOS of 8.6 days. When the outcomes from the two cohorts were compared, an effect attributable to methicillin resistance was found for 30-day mortality (OR = 1.8; P = 0.04), but not for hospital mortality (HR = 1.1; P = 0.63) or LOS (difference = 0.6 days; P = 0.96). Irrespective of methicillin susceptibility, S. aureus BSI has a significant impact on morbidity and mortality. In addition, MRSA BSI leads to a fatal outcome more frequently than MSSA BSI. Infection control efforts in hospitals should aim to contain infections caused by both resistant and susceptible S. aureus.

Bacterial contamination of anesthesia machines' internal breathing-circuit-systems.

BACKGROUND: Bacterial contamination of anesthesia breathing machines and their potential hazard for pulmonary infection and cross-infection among anesthetized patients has been an infection control issue since the 1950s. Disposable equipment and bacterial filters have been introduced to minimize this risk. However, the machines' internal breathing-circuit-system has been considered to be free of micro-organisms without providing adequate data supporting this view. The aim of the study was to investigate if any micro-organisms can be yielded from used internal machines' breathing-circuit-system. Based on such results objective reprocessing intervals could be defined. METHODS: The internal parts of 40 anesthesia machines' breathing-circuit-system were investigated. Chi-square test and logistic regression analysis were performed. An on-site process observation of the re-processing sequence was conducted. RESULTS: Bacterial growth was found in 17 of 40 machines (43%). No significant difference was ascertained between the contamination and the processing intervals. The most common contaminants retrieved were coagulase negative Staphylococci, aerobe spore forming bacteria and Micrococcus species. In one breathing-circuit-system, Escherichia coli, and in one further Staphylococcus aureus were yielded. CONCLUSION: Considering the availability of bacterial filters installed on the outlet of the breathing-circuit-systems, the type of bacteria retrieved and the on-site process observation, we conclude that the contamination found is best explained by a lack of adherence to hygienic measures during and after re-processing of the internal breathing-circuit-system. These results support an extension of the re-processing interval of the anesthesia apparatus longer than the manufacturer's recommendation of one week. However, the importance of adherence to standard hygienic measures during re-processing needs to be emphasized.

A matched prospective cohort study on Staphylococcus aureus and Escherichia coli bloodstream infections: extended perspectives beyond resistance.

BACKGROUND: Bacteremias caused by Staphylococcus aureus and Escherichia coli are among the most common bloodstream infections (BSIs) in adults. The aim of the study was to investigate risk factors for infection and clinical outcomes of bacteremias caused by S aureus or E coli. METHODS: We conducted a 1-year matched prospective cohort study including 150 patients with BSI caused by susceptible or resistant S aureus or E coli and 300 controls without BSI caused by these organisms. RESULTS: Of the 150 episodes of bacteremia, 37% were caused by S aureus (including 5 cases of methicillin-resistant S aureus [MRSA]) and 63% were caused by E coli (including 9 cases of extended-spectrum beta lactamase [ESBL]-producing E coli). We identified 4 independent risk factors for acquisition of S aureus bacteremia (emergency, peripheral or central vascular catheter, renal disease) and 6 risk factors for E coli bacteremia (emergency, peripheral or central vascular catheter, malignancy, cytoreductive or immunosuppressive therapy). Both types of bacteremia were associated with an increased length of hospital stay compared with controls. We observed a 5-fold increase in the 30-day mortality rate for bacteremias due to S aureus, and a 2-fold increase in BSI caused by E coli. The in-hospital mortality rate was increased by 6-fold for S aureus and by 3-fold for E coli. CONCLUSION: Longer hospitalization periods and increased mortality of bacteremias caused by S aureus or E coli, irrespective of susceptibility, implicate controlling for risk factors at an early stage.

Evaluation of the decontamination efficacy of new and reprocessed microfiber cleaning cloth compared with other commonly used cleaning cloths in the hospital.

BACKGROUND: The aim of this study was to investigate the decontamination capacity of 4 different types of cleaning cloths (microfiber cleaning cloth, cotton cloth, sponge cloth, and disposable paper towels) commonly used in hospital in their ability to reduce microbial loads from a surface used dry or wet in new condition. All of the cloths except disposable paper towels were also compared after 10 and 20 times of reprocessing, respectively, at 90 degrees C for 5 minutes in a washing machine. METHODS: Staphylococcus aureus (ATCC 6538) and Escherichia coli (ATCC 8739) were used as test organisms. Test organisms were then added to a test soil (6% bovine serum albumin and 0.6% sheep erythrocytes) resulting in a controlled concentration of 5 x 10(7) colony-forming units per milliliter in the final test suspension. Standardized tiles measuring 5 x 5 cm were used as test surface. RESULTS: Microfiber cloths showed the best results when being used in new condition. However, after multiple reprocessing, cotton cloth showed the best overall efficacy. CONCLUSION: We therefore suggest that the choice of the cleaning utilities should be based on their decontamination efficacy after several reprocessings and recommend the establishment of strict and well-defined cleaning and disinfection protocols.

[History of ether in the 18th century: George-Louis Lesage's system of corpuscules ultramondains]. / Zur geschichte des Athers im 18.Jahrhundert. George-Louis Lesages system der corpuscules ultramondains.

The article presents an account of Lesage's theory of corpuscules ultramondains and ether. It shows that essential attributes of the antique concept of ether still belong to his speculative physics. In accordance with this concept, Lesage understood the corpuscules ultramondains as subtle celestial matter and carriers of the primordial movements in the universe which were characterised by their proximity to the divine. On the other hand, Lesage was engaged in the contemporary debate concerning the problem of causa gravitatis. His position turns out to be halfway between dynamic corpuscularity and mechanistic physics. With the former he shared the rejection of vortex theories and the adherence to the corpuscular theory of light and the nutshell theory, with the latter the rejection of action at-a-distance and forces inherent to matter. Contrary to the accusation that he plagiarised Fatio de Duillier's theory of gravitation, it is shown that Lesage formulated a gravitational mechanism essentially different to Fatio's. Lesage used the term ether for the theory of chemical affinities. His attempt to reduce them to gravitational force failed. The complexity of chemical phenomena could not be mastered theoretically by reduction to a uniform natural force.