Microbiologic sampling of the inanimate environment in U.S. hospitals, 1976-1977.

Data obtained in the first two phases of the Study on the Efficacy of Nosocomial Infection Control (SENIC Project) indicate that in 1975 three-quarters of U.S. hospitals performed environmental culturing on a routine basis; however, between 1970 and 1975, one-quarter had reduced the extent of environmental culturing permanently. Large hospitals (greater than or equal to 200 beds) and those with an infection control nurse who had completed a training course in hospital epidemiology were more likely to have reduced the extent of culturing. In 1976-1977 hospitals that performed such culturing collected an average of 500 environmental cultures per year, whereas larger hospitals and those with an infection control nurse collected significantly fewer cultures. Only 28 percent of the approximately two million environmental cultures collected in U.S. hospitals in 1975 were indicated by recommendations of the Centers for Disease Control and the American Hospital Association current at the time.

Measles outbreak in a pediatric practice: airborne transmission in an office setting.

In February 1981, a measles outbreak occurred in a pediatric practice in DeKalb County, GA. The source case, a 12-year-old boy vaccinated against measles at 11 1/2 months of age, was in the office for one hour on the second day of rash, primarily in a single examining room. On examination, he was noted to be coughing vigorously. Seven secondary cases of measles occurred due to exposure in the office. Four children had transient contact with the source patient as he entered or exited through the waiting room; only one of the four had face-to-face contact within 1 m of the source patient. The three other children who contracted measles were never in the same room with the source patient; one of the three arrived at the office one hour after the source patient had left. The risk of measles for unvaccinated infants (attack rate 80%, 4/5) was 10.8 times the risk for vaccinated children (attack rate 7%, 2/27) (P = .022, Fisher exact test, two-tailed). Airflow studies demonstrated that droplet nuclei generated in the examining room used by the source patient were dispersed throughout the entire office suite. Airborne spread of measles from a vigorously coughing child was the most likely mode of transmission. The outbreak supports the fact that measles virus when it becomes airborne can survive at least one hour. The rarity of reports of similar outbreaks suggests that airborne spread is unusual. Modern office design with tight insulation and a substantial proportion of recirculated ventilation may predispose to airborne transmission.

The role of the microbiology laboratory in surveillance and control of nosocomial infections.

The microbiology laboratory's rapid and consistent identification of nosocomial pathogens is a keystone in the surveillance and control of hospital-acquired infections. In addition, the laboratory serves as a source of expert consultation for clinicians and infection control personnel and as an "early warning center" for infection problems. In making its contributions to infection control most effective, the laboratory must recognize its capabilities and limitations, must insure that the materials and methods it uses and the specimens it processes meet high standards, must provide retrievable records, and must have a good working knowledge of microbiologic technics used to evaluate both endemic and epidemic infections. Moreover, because laboratory workers come into contact daily with potentially infectious specimens and isolates, the laboratory's contributions to infection control should also include the prevention and surveillance of laboratory-acquired infections.

Ventilation and air conditioning--a primer for nonengineers.

Some aspects of ventilation and air conditioning have been explained for infection control personnel who are not engineers. With more understanding of ventilation, infection control personnel may be able to communicate better with engineering personnel on this subject.

Recommendations for reducing risks of infection associated with suction collection procedures.

It is recognized that risks are incurred when health care workers contact various body fluids. The handling of suction collection equipment poses a risk because it is one way workers may come in contact with these fluids. Minimizing the risks associated with suction procedures can be accomplished if appropriate policies and procedures can be developed in health care facilities.

Handwashing practices for the prevention of nosocomial infections.

Handwashing is generally considered the most important procedure in preventing nosocomial infections, because many types of these infections may be caused by organisms transmitted on the hands of personnel. Personnel should wash their hands before and after significant contact with any patient. The risk of personnel acquiring transient hand carriage of organisms is usually greatest after contact with excretions, secretions, or blood; patients at greatest risk are those undergoing surgery, those with catheters, and newborn infants. Although handwashing with an antiseptic agent between patient contacts is theoretically desirable, handwashing with soap, water, and mechanical friction are sufficient ro remove most transiently acquired organisms. Antiseptic agents may produce excessively dry skin if used frequently, and any regimen of handwashing that leads to dermatitis negates the purpose of handwashing. We favor antiseptics for handwashing before surgery and other high-risk invasive procedures and in the care of newborn infants but prefer soap and water for other handwashing.

Microbial penetration of muslin- and paper-wrapped sterile packs stored on open shelves and in closed cabinets.

Microbial penetration of sterile packs was studied using single-wrap (two layers) muslin, double-wrap (four layers) muslin, and two-way crepe paper (single layer) to wrap 20 gauze sponges (2 by 2 inch). These packs were stored in the central sterile supply departments of two hospitals and processed for sterility at predetermined intervals. Microorganisms penetrated single-wrap muslin as early as 3 days and double-wrap muslin and single-wrap two-way crepe paper in 21 to 28 days stored in open shelves. The time required for microbial penetration was at least twice as long when closed cabinets were used. Single-wrap muslin packs stored in sealed, impervious plastic bags remained sterile for at least 9 months. All sterile materials in pervious wrappers should be handled as little as possible and then only with extreme care and caution. Closed cabinets offer more protection than open shelves, and single wrappers are not recommended.

Microbial penetration through three types of double wrappers for sterile packs.

Microbial penetration of sterile packs was studied by using double-wrap (two layers each) muslin, single-wrap (two layers) muslin inner covering with single-wrap (one layer) two-way crepe paper outer covering, and single-wrap (two layers) muslin inner covering with single-layer BAR-BAC wrappers to wrap 20 gauze sponges (2 by 2 in.). These packs were stored on open shelves of a central sterile supply department of a hospital and processed for sterility at weekly intervals. Microorganisms penetrated the double-wrap muslin as early as 28 days, the single-wrap muslin and single-wrap two-way crepe paper combination in 77 days, and the single-wrap muslin and single-layer BAR-BAC combination in 63 days.

Nosocomial pseudobacteremia. Positive blood cultures due to contaminated benzalkonium antiseptic.

Pseudomonas cepacia or Enterobacter species or both were isolated from blood cultures of 79 patients in a community hospital between April 1971 and March 1972. No common exposures other than venipuncture correlated with positive blood cultures. Pseudomonas cepacia, Enterobacter, and other Gram-negative enteric bacteria were cultured from aqueous benzalkonium chloride used for skin antisepsis prior to ordinary and blood culture venipuncture. Contamination of blood cultures by organisms from the antiseptic most likely accounted for positive cultures in 35 to 38 patients (92%) with P cepacia. The remaining three patients had repeated blood cultures positive for P cepacia and circumstantial clinical evidence of bacteremia; they may have contracted disease through exposure to the contaminated antiseptic. Substitution of an iodine-alcohol antiseptic abruptly reduced the isolation of P cepacia and Enterobacter.

Improved system for floor cleaning in health care facilities.

A new system has been developed for sanitizing floors in hospitals; this system replaces the traditional procedure of daily dusting and wet mopping with a disinfectant-detergent solution and periodic buffing . This new system relies on a sequence of procedures consisting of dust mopping using a chemically treated dust mop, machine buffing of a sprayed-on polymer treatment, and a second dust mopping . The effectiveness of the procedures was evaluated by means of surface sampling for bacterial contamination and air sampling for airborne bacteria and dust. The level of bacterial contamination on the floors was reduced by 93.6% by using the new system, compared with 79.8% by using the conventional process of dust mopping and wet mopping with a disinfectant solution. The levels of airborne bacteria during and after the individual procedures did not vary significantly from the initial level (123.6 CFU/per m3 of air). A survey of representative colonies from air samples revealed staphylococci, gram-positive bacilli, gram-positive diplococci, yeast cells, and infrequent gram-negative rods. The distribution at the conclusion of the sanitizing process was similar to that at the outset. Similarly, the levels of airborne dust measured during and after the individual procedures did not vary significantly from the initial level. When compared with the traditional method of cleaning by wet mopping , the new method was significantly more effective in removal of microbial contamination and required less labor.

Carpeting in hospitals: an epidemiological evaluation.

Epidemiological and microbiological studies were conducted in a hospital room with carpet (CR) and in one with carpet (NCR). Microbiological profiles were determined with specimens obtained from patients admitted to these rooms. Patient records were reviewed to note infection status and other case identities. Eleven-millimeter cylindrical core samples of carpet were obtained, and swab template techniques were used on the bare floor for subsequent enumeration and identification of contaminating microorganisms. In each sampling period, higher microbial counts per square inch (1 in(2) = ca 6.452 cm(2)) were measured for the carpet than for the bare floor. Recovery rates of Enterobacter spp., Klebsiella pneumoniae, and Escherichia coli were higher from carpet samples than from bare floor samples. Typable organisms (such as E. coli, Pseudomonas aeruginosa, K. pneumoniae, and Staphylococcus aureus) obtained from patients were also more frequently recovered from the carpet than from the bare flooring. Patients who stayed in the CR were shown to be colonized with the same types of organisms as those initially recovered from the carpet. However, no statistically significant differences were found in patients in the CR versus NCR in colonization with all typable and nontypable organisms first found on the floor. Disease in patients was found not to be associated with organisms found as contaminants of the carpet or the bare floor. Air above carpeting contained more consistent concentrations of organisms than air above the bare flooring.

Failure of Legionella pneumophila sensitivities to predict culture results from disinfectant-treated air-conditioning cooling towers.

The disinfection of cooling towers based on manufacturers' treatment protocols, as employed in units installed at various public gathering places in Dallas, Tex. (hotels, municipal auditorium), and at the city health department, was evaluated for effectiveness in controlling Legionella pneumophila and compared with previous laboratory studies. In specimens collected in September and December, 1978, L. pneumophila was isolated from 2 of 4 specimens from untreated cooling towers, 2 of 4 specimens from towers treated with agents deemed ineffective in earlier laboratory tests, 6 of 11 specimens from towers treated with putatively effective agents, and 0 of 4 specimens from towers treated with an agent unknown efficacy. These results suggest the need for further studies to identify biocidal agents effective in eliminating L. pneumophila from air-conditioning cooling towers.