Implementation and evaluation of an algorithm for isolation of patients with suspected pulmonary tuberculosis.

OBJECTIVE: To implement and evaluate an algorithm designed to assist in the consistent placement of patients with suspected pulmonary tuberculosis into negative-pressure isolation rooms (NPIRs). DESIGN: A standard algorithm was designed for the appropriate room placement of patients with suspected pulmonary tuberculosis using clinical, radiographic, and laboratory criteria and reported risk factors. A case-patient was defined as an inpatient who had at least one Mycobacterium tuberculosis culture-positive respiratory specimen from January 1, 1993, through December 31, 1994. Demographic, clinical, laboratory, case contact, and isolation and room placement data were collected prospectively on all case patients. SETTING: A 900-bed university teaching and referral center. RESULTS: During 1993 and 1994, 69 patients were evaluated for possible pulmonary tuberculosis, and 31 case-patients were identified. Of the 31 case-patients, 26 (84%) were placed on respiratory isolation in NPIRs, including 19 (61%) who were isolated within 24 hours of admission (1993, 14 of 20 [70%]; 1994, 5 of 11 [45%]). Seven case-patients (23%) were isolated in NPIRs following delays that ranged from 2 to 31 days (median, 9 days), and five case-patients (16%) never were isolated during admissions of from 3 to 28 days (median, 4 days). These 12 case-patients contributed a total of 136 patient-exposure days during their hospitalizations. Misclassification of patient risk status by user error delayed isolation of five (42%) of the 12 improperly isolated case-patients. CONCLUSIONS: The use of an algorithm incorporating radiographic, laboratory, and clinical criteria and reported risk factors may assist in the rapid isolation of patients with suspected pulmonary tuberculosis.

Infectious complications associated with temporary epidural catheters.

To identify cases of deep-tissue or local infection associated with temporary epidural catheters, we reviewed medical records from 1980 through 1992 and prospectively followed up patients with temporary epidural catheters from January 1993 through June 1993 who were hospitalized at a large, tertiary referral hospital. We identified seven cases of temporary epidural catheter-associated infection, including three cases of deep-tissue infection (paraspinal muscle abscess, epidural abscess, and meningitis) and four cases of local infection. The infections were diagnosed 2 days to 22 days following insertion of the epidural catheter. Staphylococcus aureus was isolated in four (57%) of the cases. All seven patients were treated with removal of the catheter and antimicrobial therapy; three patients also required surgical drainage for management of deep-tissue infection. Our findings emphasize the importance of daily inspection and prompt removal of temporary epidural catheters if infection is suspected.

Complications and survival of multilumen central venous catheters used for total parenteral nutrition.

In a prospective study of 879 triple-lumen catheters, 219 pulmonary artery catheters, 31 double-lumen and six single-lumen catheters used for the administration of total parenteral nutrition over a 1-year period, the overall complication rate was 12.5 per cent (14.7 complications per 1000 catheter-days) and the catheter-related sepsis rate 4.4 per cent (5.2 per 1000 catheter-days). The probability of development of catheter-related sepsis did not increase with the duration of catheterization. There were no differences in the rate of complications associated with 427 catheters changed by replacement at a new site compared with 159 lines changed over a guidewire. These data support the use of multilumen central venous catheters for the administration of total parenteral nutrition. They suggest that a routine weekly change of line is unnecessary; catheters should be changed only on the development of a complication. When it is required, a catheter should be changed by replacement over a guidewire.

Perioperative antibiotic prophylaxis and wound infection following breast surgery.

The effectiveness of perioperative antibiotic prophylaxis against wound infections following breast surgery was investigated by meta-analysis of published data from a randomized clinical trial and an observational data set, which included a total of 2587 surgical procedures, including excisional biopsy, lumpectomy, mastectomy, reduction mammoplasty and axillary node dissection. There were 98 wound infections (3.8%). Prophylaxis was used for 44% (1141) of these procedures, cephalosporins accounted for 986 (86%) of these courses of antibiotics. Prophylaxis prevented 38% of infections, after controlling for operation type, duration of surgery and participation in the randomized trial (Mantel-Haenszel Odds Ratio = 0.62, 95% confidence interval = 0.40-0.95, P = 0.03). There was no significant variation in efficacy according to operation type or duration. We conclude that antibiotic prophylaxis significantly reduces the risk of postoperative wound infection following these commonly performed breast procedures.

Prophylaxis against wound infection following herniorrhaphy or breast surgery.

The effect of perioperative antibiotic prophylaxis on definite wound infections was assessed for 3202 herniorrhaphies or selected breast surgery procedures. Patients were identified preoperatively and monitored for greater than or equal to 4 weeks. Thirty-four percent of patients (1077/3202) received prophylaxis at the discretion of the surgeon; 86 definite wound infections (2.7%) were identified. Prophylaxis recipients were at higher risk for infection, with a higher proportion of mastectomies, longer procedures, and other factors. Patients who received prophylaxis experienced 41% fewer definite wound infections (odds ratio [OR], 0.59; 95% confidence interval [CI], 0.35-0.99; P = .04) and 65% fewer definite wound infections requiring parenteral antibiotic therapy (OR, 0.35; 95% CI, 0.15-0.88; P = .02) after adjustment for duration of surgery and type of procedure. Additional adjustment for age, body mass index, the presence of drains, diabetes, and exposure to corticosteroids did not change the magnitude of this effect meaningfully. The effect of prophylaxis was similar for all procedures studied. In the absence of formal guidelines, surgeons at these institutions administered prophylaxis preferentially to patients at highest risk.

Antibiotic prophylaxis in clean surgery: peripheral vascular surgery, noncardiovascular thoracic surgery, herniorrhaphy, and mastectomy.

Studies published in the English-language literature on the use of prophylactic systemic antibiotics in vascular surgery, noncardiovascular thoracic surgery, mastectomy, and herniorrhaphy were reviewed. The effectiveness of antibiotic prophylaxis in preventing deep and superficial wound infections in peripheral vascular surgery appears to be well documented, especially if prophylaxis is directed against Staphylococcus aureus. In clean thoracic surgery the evidence is equivocal, and no studies have sufficient statistical power to eliminate the possibility even of a 50% reduction in incidence. In herniorrhaphy and mastectomy some evidence from a much more powerful study suggests that antibiotic prophylaxis may result in a decrease of up to 50% in wound infections, but whether these data can be generalized uncritically to all clean wounds is still a matter of debate. Accordingly, only guarded recommendations can be made regarding the use of prophylactic antibiotics in procedures associated with a very low risk of serious infection.

Perioperative antibiotic prophylaxis for herniorrhaphy and breast surgery.

We assessed the efficacy of perioperative antibiotic prophylaxis for surgery in a randomized, double-blind trial of 1218 patients undergoing herniorrhaphy or surgery involving the breast, including excision of a breast mass, mastectomy, reduction mammoplasty, and axillary-node dissection. The prophylactic regimen was a single dose of cefonicid (1 g intravenously) administered approximately half an hour before surgery. The patients were followed up for four to six weeks after surgery. Blinding was maintained until the last patient completed the follow-up and all diagnoses of infection had been made. The patients who received prophylaxis had 48 percent fewer probable or definite infections than those who did not (Mantel-Haenszel risk ratio, 0.52; 95 percent confidence interval, 0.32 to 0.84; P = 0.01). For patients undergoing a procedure involving the breast, infection occurred in 6.6 percent of the cefonicid recipients (20 of 303) and 12.2 percent of the placebo recipients (37 of 303); for those undergoing herniorrhaphy, infection occurred in 2.3 percent of the cefonicid recipients (7 of 301) and 4.2 percent of the placebo recipients (13 of 311). There were comparable reductions in the numbers of definite wound infections (Mantel-Haenszel risk ratio, 0.49), wounds that drained pus (risk ratio, 0.43), Staphylococcus aureus wound isolates (risk ratio, 0.49), and urinary tract infections (risk ratio, 0.40). There were also comparable reductions in the need for postoperative antibiotic therapy, non-routine visits to a physician for problems involving wound healing, incision and drainage procedures, and readmission because of problems with wound healing. We conclude that perioperative antibiotic prophylaxis with cefonicid is useful for herniorrhaphy and certain types of breast surgery.

AIDS. Implementation of universal blood and body fluid precautions.

The use of "universal blood and body-fluid precautions," or "universal precautions" to prevent the acquisition of blood-borne diseases in health care workers is now widely recommended. Such recommendations are soundly based on a number of biologic, psychologic, and administrative bases. Implementation of the program in an individual hospital is an imposing task, requiring administrative support and skill. A process for establishing initial definitions for the more ambiguous areas, and for administrative and educational support to all levels of care needs to be defined in advance, then put into effect. A wider definition of "universal precautions," which approaches the "Body Substance Isolation" system, is discussed. The use of a "task-classification" system, evaluating the risk inherent in specific tasks, may actually aid both the implementation and the acceptance of such a program.

Closed intravenous administration of gonadotropin-releasing hormone: safety of extended peripheral intravenous catheterization.

The use of pulsatile gonadotropin-releasing hormone is an effective means of inducing ovulation, but requires prolonged intravenous (IV) or subcutaneous administration. We hypothesized that the use of self-contained infusion pumps using fluids maintained in a closed system would permit safe peripheral IV administration of gonadotropin-releasing hormone, and possibly other hormones, over prolonged intervals. Thirty-eight female patients undergoing pulsatile IV gonadotropin-releasing hormone therapy were followed for 1958 catheter days (230 catheters). Catheters were removed for signs of local inflammation, at the completion of a treatment episode or, initially, at routine intervals of 7-10 days. There were no episodes of fever (temperature over 37.5C) and three episodes of local inflammation. The incidence of significant catheter-tip cultures was 11%, and none were associated with local inflammation. There were four positive blood cultures (2%), none associated with local or systemic signs of infection. We conclude that the use of a closed system of prolonged peripheral IV cannulation is relatively safe when combined with fastidious care of the catheter site and careful outpatient monitoring for long-term administration of pulsatile gonadotropin-releasing hormone.

Recognition of endemic and epidemic prosthetic device infections: the role of surveillance, the hospital infection control practitioner, and the hospital epidemiologist.

Surveillance as a means of identifying endemic and epidemic problems is an established and useful public health practice, which increasingly has been applied to the hospital population. The current practice of hospital infection control surveillance tends to concentrate on acute, in-hospital events. It will miss most longer-term prosthetic device infections, since they will often appear at a distance both in time and place. Currently, case report information is not reliably returned to the hospital or physician responsible for the implantation of the device. Since ongoing analysis of the epidemiologic patterns involved in these cases would seem useful, it is proposed that existing infection control units create, define, and maintain a system of net-working communication to return case data to the hospital of origin. This hospital could then combine these data with its own population data, in the hopes of generating useful epidemiologic information for the future.

Invasive aspergillus infection: possible non-ward common source within the hospital environment.

Six immunocompromised patients housed in widely separated portions of a hospital campus developed invasive aspergillosis during a single month. This represented a significant increase (P less than .001) in the number of cases observed over the 3 years which included this event (19 cases in 36 months). Epidemiological investigation suggested that this cluster of cases was due to a common source outbreak related to construction activity in a central radiology suite serving the hospital. Such non-ward exposures to nosocomial hazards are becoming increasingly important for immunosuppressed hosts.

Possible role of capillary action in pathogenesis of experimental catheter-associated dermal tunnel infections.

An animal model of vascular-catheter-associated dermal tunnel infections was developed to study the pathogenesis of such infections. Bacteria inoculated onto entry sites of catheters into skin could be identified by culture and Gram stain on the tips of plastic catheters (4 cm from the entry site) within 1 h of inoculation, whether the animal was inoculated at the time of insertion of the catheter or 1 week afterwards. Histological examination of dermal tunnels revealed that the introduction of bacteria preceded the development of tissue inflammation. Bacteria on entry sites of percutaneous catheters moved rapidly from the entry site into the dermal tunnel along the external catheter surface, perhaps suspended in a fluid phase and propelled by capillary action.

Microbial examination of kidney lithotripter tub water and epidural anesthesia catheters.

Kidney lithotripsy patients frequently receive epidural anesthesia via indwelling epidural catheters. In our hospital, patients are immersed in a tub of warm, continuously-flowing tap water. The epidural catheter-entry site is covered by a transparent occlusive dressing. To determine the risk of microbial colonization of the epidural catheter during lithotripsy, we performed quantitative cultures of tub water and semiquantitative cultures of catheters in 63 lithotripsy procedures. Most of the tub water organisms were typical tap water and skin flora isolates. Total colony counts were generally low with no significant progression during the course of serial procedures. Forty-two epidural catheters were cultured; 34 (81%) were sterile, 8 (19%) were colonized with small numbers of flavobacteria or coagulase-negative staphylococci. Only four catheters had organisms present on catheter segments covered by the transparent occlusive dressing (in each case there was a single colony forming unit per semiquantitative plate) and these organisms were probable contaminants. We conclude that with our current lithotripsy procedures, the risk for the development of epidural catheter-associated infection seems to be low.

Cryptosporidiosis in immunocompetent patients.

The intestinal protozoan cryptosporidium is known to cause diarrhea in immunocompromised patients, but few cases have been reported in detail in immunocompetent persons. During a 12-month period, we identified cryptosporidium in the stools of 43 immunocompetent patients. The numbers of cases were increased in those under 4 years old and in those from 30 to 39 years old. Of 30 index cases, 23 (77 per cent) were diagnosed in the late summer or the fall. Fifteen of the 43 patients (35 per cent) had other gastrointestinal pathogens, of which only Giardia lamblia was statistically associated with cryptosporidium. In the 28 patients in whom other gastrointestinal pathogens were not identified, the clinical manifestations were predominantly watery, nonbloody diarrhea and, less commonly, abdominal discomfort, anorexia, fever, nausea, and weight loss. The infection was self-limited in all 43 patients. Clustering of cases occurred in a day-care center and in two families. These clinical observations confirm worldwide findings and suggest that cryptosporidium is a relatively common nonviral cause of self-limited diarrhea in immunocompetent persons in the northeastern United States.

Rapid diagnosis of intravascular catheter-associated infection by direct Gram staining of catheter segments.

We conducted a study to determine the usefulness of the Gram stain in the detection of intravascular catheter-associated infection. A total of 330 intravascular catheters were prospectively collected from adults and children suspected of having such an infection. Semiquantitative solid-agar cultures of the distal catheter tip were correlated with blood cultures. Catheter-associated bacteremia occurred in 34 per cent of cases in which catheter tips were colonized (greater than or equal to 15 colonies per agar plate). There were no cases of catheter-associated bacteremia in patients with uncolonized catheters. Immediately after culture, whole catheter segments were stained by the Gram technique. Gram-negative and gram-positive bacteria and yeast were easily identifiable under oil immersion (X 1000), located predominantly on external catheter surfaces. Any catheter with at least one organism per 20 oil-immersion fields was designated as positive by Gram stain, but the majority of the 41 positive catheters had much larger numbers of organisms. The Gram stain of the catheter tip was 100 per cent sensitive and 96.9 per cent specific for the detection of catheter-tip colonization, with positive and negative predictive values of 83.9 and 100 per cent, respectively. We conclude that a Gram stain of the distal catheter tip is a simple, inexpensive, and accurate test for the rapid diagnosis of intravascular catheter-associated infection.

Risk of nosocomial infection with human T-cell lymphotropic virus III (HTLV-III).

Infection with human T-cell lymphotropic virus III (HTLV-III) is closely linked to the acquired immunodeficiency syndrome (AIDS). We evaluated the risk of nosocomial infection with HTLV-III by testing for antibodies to HTLV-III among hospital employees, including victims of needle-stick exposure, endoscopists, pathologists, and laboratory workers. Assays for antibody against the virus were performed by enzyme-linked immunosorbent assay and electrophoretic (Western blot) techniques. Although all 22 of our patients with AIDS and 6 of 7 with AIDS-related complex were found to have antibodies to HTLV-III when both assays were employed, none of the 85 employees with nosocomial exposure to specimens from patients with AIDS were positive for HTLV-III antibody. These studies must be regarded as preliminary, but they suggest that when current hospital isolation procedures are employed, the risk of nosocomial transmission of HTLV-III is low.

Fulminant hospital-acquired toxic shock syndrome.

Fatal toxic shock syndrome developed in a previously healthy 19-year-old man following arthroscopy. The fulminant presentation led to an initial diagnosis of pulmonary embolus. Toxic shock syndrome must now be considered in the differential diagnosis of cardiovascular catastrophes.