Comparison of microbiological contents of compressed air in two Danish hospitals. Effect of oil and water reduction in air-generating units

Compressed-air power tools in orthopaedic surgery: exhaust air is a potential source of contamination

OBJECTIVES

To determine if the exhaust from surgical compressed-air power tools contains bacteria and if the exhaust leads to contamination of sterile surfaces.

DESIGN

Bacteriologic study of orthopaedic power tools.

SETTING

Level I trauma center operative theater.

PATIENTS/PARTICIPANTS

None.

INTERVENTION

Part I. Exhaust from two sterile compact air drills was sampled directly at the exhaust port. Part II. Exhaust from the drills was directed at sterile agar plates from varying distances. The agar plates represented sterile surfaces within the operative field. Part III. Control cultures. A battery-powered drill was operated over open agar plates in similar fashion as the compressed-air drills. Agar plates left open in the operative theater served as controls to rule out atmospheric contamination. Random cultures were taken from agar plates, gloves, drills, and hoses.

MAIN OUTCOME MEASUREMENT

Incidence of positive cultures.

RESULTS

In Part I, all filters from both compressed-air drill exhausts were culture negative ( = 0.008). In Part II, the incidence of positive cultures for air drills number one and number two was 73% and 82%, respectively. The most commonly encountered organisms were, coagulase-negative Staphylococcus, and Micrococcus species. All control cultures from agar plates, battery-powered drill, gloves, and hoses were negative ( < 0.01).

CONCLUSIONS

Exhaust from compressed-air power tools in orthopaedic surgery may contribute to the dissemination of bacteria onto the surgical field. We do not recommend the use of compressed-air power tools that do not have a contained exhaust.

Evaluation of compressed air used in the dental operatory

BACKGROUND

The authors report the findings obtained when they quantitatively examined compressed air samples from air-water syringes located in different dental operatories at the Louisiana State University School of Dentistry fo r the presence of microbial contaminants.

METHODS

Streams of air of 30 seconds' duration from air-water syringes were forced through sterile modified stainless steel membrane filter holders (Millipore, Millipore Corp., Bedford, Mass.), each containing a membrane filter (average pore diameter = 0.45 micrometers). Each filter was aseptically removed, placed onto the surface of a Petri dish containing sheep blood agar and incubated under increased carbon dioxide tension at 37 C for 48 hours. The authors performed a count of the resultant microbial colonies, after which they microscopically examined the gram-stained organisms.

RESULTS

Bacteria were detected in 24 percent of the samples. The number of colonies observed on the filters varied among the dental units. The air from only one of the dental units sampled repeatedly was found to be free of bacterial contaminants. This contrasted with other units for which one or more samples were found to be positive for microorganisms. The majority of colonies observed were pigmented. Microscopic examination of organisms from representative colonies revealed that most were either gram-positive cocci or gram-negative diplococci and tetrads. The results of the one-sample t test were found to be significant (t = 5.6, df = 98, P = .0001). The 95 percent confidence interval was 0.15 to 0.32.

CONCLUSION

The results suggest that, at least statistically, a percentage of air lines will have bacteria present.

Minimizing the potential for nosocomial pneumonia: architectural, engineering, and environmental considerations for the intensive care unit

The development of pneumonia in seriously ill patients remains an important concern of intensive care medicine. The design of the intensive care unit will have a direct effect upon the potential for infection. Persons involved in this design should consider engineering and architectural elements that will ultimately contribute to lower rates of infection. These include components to regulate the atmosphere, such as ventilation systems and temperature and humidity controls. Sources of contaminated water and the amplification mechanisms need to be addressed and minimized in the final designs. Architectural elements such as treatment space and lighting encourage optimal patient management and workable staffing patterns. Personnel who treat seriously ill patients should be part of the planning and design process in the construction and renovation of intensive care facilities.