Forty percent to 60% of antimicrobial agents administered in hospitals without effective antimicrobial review and control programs are not needed. Excessive use of antimicrobial agents in the hospital promotes colonization of patients with resistant organisms, needlessly exposes them to the risk of an adverse drug reaction, and increases the cost of care. A gradated antimicrobial utilization review program is presented that determines hospital usage, develops guidelines for appropriate cost-effective drug administration, provides several options for implementation, and monitors outcome so that measures can be modified for specific situations. The techniques used are basic epidemiologic measures currently used to assess hospital infections.

Disease outbreaks involving public whirlpools have been reported frequently since their use has become popular in recent years. Because public whirlpools are often used by persons who have only transient contact, infections resulting from their use are difficult to identify, and published reports probably represent only a small portion of a larger public health problem. Most published outbreaks have reported Pseudomonas aeruginosa contamination of the whirlpool as a result of failure to operate the pool according to recommended practices. Maintaining the microbiologic quality of whirlpool water and preventing infection absolutely require regular operation and maintenance, including monitoring and record keeping by qualified personnel.

The role of the pulmonary function (PF) laboratory and PF testing equipment in the transmission of infections has not been established. Although microorganisms have been cultured from parts of in-use pulmonary function testing equipment, a relationship between equipment contamination and transmission of infection or colonization has not been documented. Nosocomial outbreaks of respiratory infections, eg, influenza, tuberculosis, and legionellosis have been described, but transmission of the microorganisms has not been shown to be more likely in the PF laboratory or with PF testing equipment than in other areas in the hospital or with other hospital equipment. Unlike nebulizers, which have been implicated in epidemic and endemic nosocomial gram-negative bacterial infections, PF machines do not generate aerosols. PF testing equipment is thus built without provision for easy machine disassembly and disinfection, except for parts that routinely come in contact with mucous membranes or secretions (eg, mouthpieces, valves, and some tubings).

The growing popularity of heated pools, especially whirlpools and hot tubs, has been accompanied by increasingly frequent oubreaks of an illness produced by Pseudomonas aeruginosa. The illness usually includes folliculitis, pruritic skin rash, and/or otitis externa and occasionally mastitis and systemic symptoms. Although usually self-limited, rare severe cases have been described. Motel and hotel whirlpools are most often implicated as the source of outbreaks. The relative importance of pool conditions and the bacteriology of P. aeruginosa in the pathogenesis of this illness remain to be elucidated. Implementing CDC Guidelines for public spas and hot tubs seem the most reasonable way of reducing the risk of large outbreaks. Prevention of cases arising from home hot tubs or whirlpools will be very difficult and may depend on extensive public education or the development of simple, inexpensive and effective disinfection systems.

Eight cases of sternal/mediastinal infection due to Enterobacter species were seen in postoperative cardiac patients during 1980 to 1981. The attack rate was 14.5% (8/55), compared to 3.7% (2/54) for an identical period in 1979 to 1980 (p<0.05). Cases varied in severity from fulminant, acute bacteremic infections (one death) to less severe wound infection. Late complications or recurrences were not seen. There was a hospital-wide increase, relative to all other gram-negative bacillary isolates, in Enterobacter laboratory isolations, but no increased rate of infection in any other specific surgical condition.

No personnel, materials, or techniques were associated with the outbreak, and all but two environmental cultures were negative. Case-control analysis suggested that surgical complications and prophylactic cephalosporins were associated with infection. Prospectively, an additional 85 cardiac surgery patients had increased Enterobacter skin/wound colonization following perioperative prophylaxis with cephalosporin antibiotics. After introduction of barrier isolation and restriction of contacts no further mediastinitis occurred in 100 subsequent cardiac surgery patients. This study indicates that Enterobacter may be major pathogens causing post-cardiac-surgery infection not prevented by cephalosporin prophylaxis.

Medical patients receiving IV therapy were randomly assigned to one of two IV tubing change groups. One group had a 48-hour tubing change and the other had no tubing change for the remainder of the cannula placement. A daily IV fluid specimen was processed microbiologically. To complete the study, a minimum of 3 continuous days of therapy and three fluid specimens was required. There were two contaminated specimens, one in each tubing change group. The contamination rate in the 48-hour change group was 0.87% and 0.96% in the no change group. The rate difference of 0.09% has a 95% confidence interval (−0.035 to +0.036) which includes zero. Survival analysis also revealed no significant difference in the cumulative probability of survival, however the mean duration of continuous tubing use of 4.3 days in the no change group and 1.8 days in the 48 hour change group were significantly different (p<0.05). The cumulative probability of surviving contamination free was 0.988 in the 48-hour group and 0.987 in the no-change group. We conclude that it is safe to change IV tubing at intervals up to but not exceeding 4 days.

Although the mode of transmission of L. pneumophila is as yet unclear, the hot water distribution system has been shown to be the reservoir for Legionella within the hospital environment. In this report we identify a previously unrecognized reservoir for L. pneumophila within the hospital environment, ie, the cold water dispensers of hospital ice machines. The cold water dispensers of 14 ice machines were cultured monthly over a 1-year period. Positive cultures were obtained from 8 of 14 dispensers, yielding from 1 to 300 CFU/plate. We were able to link the positivity of these cold water sites to the incoming cold water supply by recovering L. pneumophila from the cold water storage tank, which is directly supplied by the incoming municipal water line. This was accomplished by a novel enrichment experiment designed to duplicate the conditions (temperature, sediment, stagnation, and continuous seeding) of the hot water system. Our data indicate that significant contamination of cold water outlets with L. pneumophila can occur. Although no epidemiologic link to disease was made, the fact that the primary source of a patient's drinking water is from the ice machines warrants further investigation of these water sources as possible reservoirs.

Recent clinical experience has added Mycobacterium fortuitum and Mycobacterium chelonei to the expanding list of nosocomial pathogens. These rapidly growing mycobacteria were first isolated 80 years ago from frogs (M. fortuitum) and sea turtles (M. chelonei). Obtained occasionally from human sources as early as 1904, they were generally regarded as commensals in man. Friedmann was so convinced of the non-pathogenicity of M. chelonei that he introduced the “turtle vaccine” as a means of preventing and treating tuberculosis. Contemporary medical literature firmly establishes these organisms as human pathogens with particular importance in nosocomial infections.

Resuscitation bags at the bedside of 12 intubated ICU patients with known culture positive sputum were evaluated as possible reservoirs of pathogenic bacteria. As oxygen was constantly flowing into the bags, sampling of gas continuously emitted from the exhalation valve assembly was sampled to detect if a bacteria-laden aerosol was being created. Positive cultures were obtained from 75% of the valves and 25% of the aerosol samples. In those patients with gram-negative bacteria in their sputum, 71% of the valves and 29% of the gas samples were positive for the same organisms. Various methods to control this possible contributing factor to nosocomial infection in the ICU are discussed.

The antibiotic resistance of Klebsiella pneumoniae isolates from 12 medical centers worldwide, over a 1- to 6-year period, were tested. Clinical isolates of K. pneumoniae were resistant to ampicillin and carbenicillin. Resistance to other antibiotics was less frequent with isolates of K. pneumoniae from 5 of 6 US centers than with those from 6 centers outside the US. In nearly all of the centers, resistance to sulfamethoxazole-trimethoprim, gentamicin, tobramycin, or chloramphenicol was more frequent in isolates of K. pneumoniae than in those of Escherichia coli, while the reverse was true for resistance to tetracycline. Resistance to multiple antibiotics declined gradually in isolates of K. pneumoniae at one center, but rose abruptly again with dissemination of a new plasmid.

Due to sporadic infections attributed to contaminated multiple-dose medication vials (MDV), some authorities have suggested discarding all MDV within 24 hours. We inoculated 11 commonly used medications with suspensions of 10 bacterial species previously associated with contaminated parenteral solutions and determined microbial persistence at both room and refrigerator temperature. At 22°C, atropine, curare, folic acid, NPH insulin and triamcinolone did not allow microbial persistence beyond 4 hours. Lidocaine and heparin were sterile by 24 hours. Regular insulin, immune serum globulin, and myochrysine allowed persistence for up to 7 days. At 4°C, bacterial persistence was significantly prolonged for all medications including those MDV requiring refrigeration. No organisms proliferated; however, F. meningosepticum and P. maltophilia were particularly persistent at both temperatures. The risk of persistent MDV contamination appears to be dependent upon specific pharmaceutical, microbe and storage temperature interactions. Recommendations for the refrigeration of MDV medications may require reevaluation on a product-by-product basis.

A retrospective study of 204 patients culture positive for methicillin-resistant Staphylococcus aureus compared infected and colonized patients. Seventy-eight patients were colonized and never developed infection (C), 24 were colonized and subsequently infected (C➧I), and 102 patients had 1 or more nosocomial infections with MRSA at time of first culture (I). The most prevalent sites of infection were wound (26.5%) and bloodstream (20.7%), whereas the respiratory tract and surgical wounds were both frequent sites of colonization. Stepwise discriminant analysis found the most important factors in differentiating likelihood of colonization vs. infection were recent prior hospitalization, history of wound debridement, and number of invasive procedures. Ten percent of (C) died and 25.5% of (I) died. MRSA contributed to death in 57.6% of the (I) deaths (p<.05). These results underscore the importance of differentiating (C) vs. (I) in hospitals where MRSA is endemic so that early specific treatment may be initiated. Risk factors for infection should be discriminated from those for acquisition of the organism.

A statistical algorithm was used to identify potentially important clusters among nosocomial infections reported each month by 7 community hospitals. Epidemiologic review and on-site investigations distinguished outbreaks of clinical disease from factitious clusters. In 1 year, 8 outbreaks were confirmed. They involved 82 patients—approximately 2% of patients with nosocomial infections and 0.09% of all discharges. One true outbreak occurred for every 12,000 discharges—at least 1 outbreak per year for the average community hospital. Five (63%) outbreaks were recognized independently by the hospitals' infection control personnel. Four (50%) resolved spontaneously; the hospitals' own control measures were necessary in 2; and 2 resolved only after an outside investigation. Organized surveillance appears necessary to detect some outbreaks, and control measures are needed to stop many. Since, however, outbreaks account for such a small proportion of nosocomial infections, infection control programs should be sufficiently staffed and managed so that most of the effort is directed toward the surveillance and control of endemic infection problems, but with adequate resources remaining to respond to outbreaks when they occur.

Klebsiella pneumoniae causes serious epidemic and endemic nosocomial infections. We conducted a literature review to characterize the epidemiology of epidemic K. pneumoniae outbreaks. Eighty percent of the outbreaks (20/25) involved infections of the bloodstream or urinary tract. Person-to-person spread was the most common mode of transmission, and nearly 50% of the outbreaks occurred in neonatal intensive care units. No one serotype predominated, and no association was found between serotype and either the site of infection or the antimicrobial susceptibility pattern.

We used data reported to the Centers for Disease Control (CDC) by hospitals participating in the National Nosocomial Infections Study (NNIS) to describe the epidemiology of endemic K. pneumoniae infections. In die 8-year period from 1975 through 1982 the nosocomial K. pneumoniae infection rate was 16.7 infections per 10,000 patients discharged. The rate of infection at medical school-affiliated hospitals was significantly greater than at nonaffiliated hospitals; furthermore, the rate of infection at large affiliated hospitals was greater than at small affiliated hospitals. The rate of infection varied by service, with the highest rate found on the medicine service. During the 8-year period, 184 deaths were caused by nosocomial K. pneumoniae infections (184 deaths/16,969 infections, case-fatality ratio 1.1%), with higher ratios in pediatrics (5%) where there was a 12% mortality in children infected with an aminoglycoside-resistant strain.

All patients at the new British Columbia's Children's Hospital with chickenpox or Herpes zoster are nursed with appropriate precautions in single-bed rooms provided with negative pressure ventilation. Over a period of 1 year, no nosocomial infections were detected on follow-up of 110 susceptible patients who had been on wards at the same time as six cases of chickenpox and one immunocompromised patient with cutaneous dissemination of Varicella zoster. In a preceding study at the previous hospital, with similar staff, control measures, and patient population, in an isolation facility without negative pressure ventilation, nosocomial infections occurred in seven out of 41 susceptible patients who were on the same ward as two patients with chickenpox. These findings suggest that a simple negative pressure ventilation system without air locks is a useful adjunct in the control of cutaneous Varicella infections.

An outbreak of rubella in a large metropolitan hospital is described. Nineteen cases among employees and three secondary cases in family members occurred. Nosocomial cases occurred among the 3,900 employees of an adult medical-surgical unit where a voluntary program of rubella immunization was in effect. No cases occurred among the 1,400 employees of the women's and pediatric units with mandatory policies, despite interfacility and community exposure. Ten pregnant women were among the 377 contacts of the cases. Five were sero-negative to rubella. Two who developed clinical rubella, one asymptomatic sero-conversion and one other, all elected to terminate their pregnancies. The remaining woman, exposed in her third trimester delivered a normal infant. We conclude a policy requiring new employees to be rubella immune is more effective in preventing nosocomial rubella than a voluntary program and is desirable in view of the potential consequences of an outbreak to pregnant employees.