Wound contamination with endogenous bacterial scalp flora plays an important role in the pathogenesis of postoperative neurosurgical infections. To assess the effect of preoperative antiseptic shampoos on the emergence of resident scalp flora during surgery and subsequent wound contamination, we randomized 151 neurosurgical procedures into four study groups: group A—preoperative shampoos with chlorhexidine, surgical scalp preparation with chlorhexidine; group B-no shampoos, surgical preparation with chlorhexidine; group C-shampoos with iodophor, surgical preparation with iodophor; group D-no shampoos, surgical preparation with iodophor. Quantitative cultures of the scalp were obtained preoperatively and at the end of surgery, and qualitative wound cultures were taken prior to wound closure. Group A had the lowest concentration of bacteria on the scalp both preoperatively and postoperatively (median range = 30 [0-5.7 × 105] and 0 [0-2.5 x 103] respectively). Group A also had significantly fewer positive postoperative scalp cultures (29%) than groups B (51%), C (58%), and D (53%) (P<0.05), as well as fewer positive wound cultures (20% v 25%, 42%, and 30% respectively). A density of bacteria on the scalp of > 102/4cm2 best predicted the presence of bacteria in the wound. Repeated preoperative shampoos with chlorhexidine reduce intraoperative emergence of resident skin flora and subsequent contamination of the wound.

Nosocomial infection rates were computed for 5,031 patients at an oncology center during a 20-month period. Twelve percent of the patients developed nosocomial infections, accounting for a total of 802 infections. The overall incidence of nosocomial infections during this study period was 6.27 infections per 1,000 patient days. The highest incidence of nosocomial infections was found in patients having acute myelogenous leukemia (30.49 infections per 1,000 patient days); bone and joint cancer (27.27 infections per 1,000 patient days); and liver cancer (26.58 infections per 1,000 patient days). The respiratory tract was the most common site of infection, followed by blood-stream, surgical wound, and urinary tract infections. Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, and coagulase-negative staphylococci were most frequently implicated as pathogens. The distribution of specific types of infection according to underlying malignancy was also tabulated. These data provide nosocomial infection rates, common pathogens, and sites of infection for cancer patients, thus assisting in directing appropriate therapy for these patients.

Between March 1984 and February 1986, ten patients admitted to a spinal cord injury/stroke rehabilitation unit became bacteriuric with a strain of Serratia marcescens resistant to ampicillin, cephalothin, cefoxitin, ticarcillin, cotrimoxazole, gentamicin, and tobramycin. All the patients were catheterized, and in most, bacteriuria was asymptomatic. The organism was also recovered from their hospital environment (sinks, toilets, urine-collecting basins). Analysis of total plasmid content of multiresistant isolates revealed the presence of two plasmids (7 kilobase, 25.5 kilobase), not found in aminoglycoside susceptible strains of Serratia marcescens. Restriction endonuclease analysis and Southern hybridization (DNA probe: 25.5 kilobase plasmid) verified that these plasmids were identical. The 25.5 kilobase plasmid was purified, introduced by transformation into an Escherichia coli strain C recipient, and was found to mediate resistance to gentamicin and tobramycin. The emergence of multiresistant Serratia marcescens coincided with an increase in antibiotic usage on the ward. The reservoir seemed to be the urinary tracts of asymptomatic catheterized patients and their contaminated hospital environment.

To examine evidence of a causal link between handwashing and risk of infection, a review of published literature from 1879 through 1986 was conducted. In the 107 years studied, 423 articles specifically related to handwashing were found. Articles were categorized as studies to evaluate products (50.8%), review articles (29.1%), behavioral studies (10.9%), methodologie studies (2.8%), studies linking handwashing to infection and other (3.1%). There was an increase in the proportion of handwashing articles published in the 1980s with the rate (9.4/105 citations/year) being almost double that of any other period studied. Nonexperimental and experimental studies related to handwashing were reviewed and evidence for a causal association evaluated. Except for specificity, all the elements for causality, including temporality, strength, plausibility, consistency of the association, and dose response were present. It was therefore concluded that emphasis on handwashing as a primary infection control measure has not been misplaced and should continue.

Peritoneal dialysis has been successfully used in treating patients with end stage renal disease (ESRD) for approximately 40 years. Peritoneal infections are a frequent consequence of this procedure which has diminished its acceptance by physicians and patients alike. Since the development of an improved access catheter and automated dialysate delivery devices, peritoneal analysis has been gaining widespread acceptance as an alternative to hemodialysis in the treatment of patients with ESRD. Despite the improvement in the peritoneal dialysis systems, peritonitis continues to be a major complication for adult and pediatric patients undergoing continuous ambulatory peritoneal dialysis (CAPD).:‘-’ Although most patients have from less than one to four peritonitis episodes per year, some patients have no episodes of' peritonitis or have a significantly high occurrence (greater than four episodes) of peritonitis. Several reports have indicated that two thirds of the total number of ‘peritonitis episodes is due to gram-positive bacteria. Gram-negative bacteria accounts for approximately 15% and fungal infections account for less than 5%.

For years, Infection Control Practitioners have been asked to identify the “ultimate” hospital::: disinfectant. Health care personnel seem to want a multipurpose product; one that can he used for handwashing for, instrument disinfection and for cleaning the commode. Simply stated, there is not one product that call successfully do all three. Antiseptic solutions, which are approved by the Food and Drug Administration are for use on skin (ie, handwashing and skirt preparation whereas disinfectants are for use in the inanimate environment and are approved by the Environmental Protection Agency.

There are two classifications of' disinfectants housekeeping disinfectants and instrument disinfectants. Housekeeping disinfectants are generally low-level disinfectants, and quartenary ammonium compounds or phenol-based solutions are the most common. Instrument disinfectants are high-level disinfectants such as glutaraldehydes and chlorine dioxide.

As with all human endeavors, medical care in any setting has observable and occult benefits and risks. The methods of study of these facets of medical care have become known as “clinical epidmiology.”

This article is the introduction to a new series entitled “Topics in Clinical Epidemiology.” The authors are practicing clinicians, one as director of the Quality Assurance department and the other as director of the Hospital Epidemiology department, both at a large tertiary teaching hospital. The series will attempt, in the fashion of the old shoe leather epidemiologist, to reflect those problems and interactions which are the realities of our current practice milieu and experience. That this collection of manuscripts will be presented in an infection control periodical reflects the journal's and the authors' perspective that the same epidemiological techniques that have made infection control clinically successful and cost-effective can be used to reduce noninfectious hazards of medical care, and to enhance the diagnostic and therapeutic benefits of modern medical management.