Blood drawn through valved catheter hub connectors carries a significant risk of contamination

Infection Control became concerned when bloodstream infection (BSI) rates increased after implementing a needleless valved hub connector. During a 21-month period three different needleless catheter hub connectors were evaluated by quantitatively culturing blood drawn through hub connectors that would have ordinarily been discarded (DBC). DBC drawn through Clearlink™ catheter hub connectors were found to be twice as likely to be positive as DBC drawn through Clave® or Q-syte™ hub connectors (P < 0.04). DBC grew pathogens 46% of the time and skin organisms 54% of the time. Patients with positive DBC were three times more likely to meet Centers for Disease Control (CDC) BSI criteria by DBC cultures than by physician-ordered blood cultures (CBC; P < 0.001). For patients growing pathogens in DBC, 64% had no CBC drawn, the average temperature was lower than for patients with pathogens in CBC (99.3 ± 1.5 ve 100.6 ± 1.9, P = 0.015), and 92% of discharged patients (11 out of 12) were not treated with an antibiotic active against the DBC pathogen. Drawing BC through a catheter hub connector carries a risk of false-positives that could increase BSI rates by up to 3-fold. Further work is necessary to evaluate this concern.

Nasal carriage of Staphylococcus aureus among patients receiving allergen-injection immunotherapy: associated factors and quantitative nasal cultures

OBJECTIVE

To compare the prevalence of nasal Staphylococcus aureus carriage among outpatients receiving allergen-injection immunotherapy with the prevalence among healthy controls and to determine predictors of nasal S. aureus carriage.

DESIGN

Survey.

SETTING

Allergy clinic of a university hospital.

PARTICIPANTS

A volunteer sample consisting of 45 outpatients undergoing desensitization therapy and 84 first- and second-year medical students.

RESULTS

The nasal S. aureus carriage rate was significantly higher among patients (46.7%) than among students (26.2%; P=.019). In a multivariate model adjusted for age and gender, the presence of atopic dermatitis or eczema was the only independent predictor of nasal S. aureus carriage (odds ratio [OR], 4.4; 95% confidence interval [CI95], 1.2-16.0; P=.02). The only other participant characteristic associated with nasal S. aureus carriage was immunotherapy with allergen injections (OR, 1.98; CI95, 0.7-6.0), but this association did not reach statistical significance (P=.23). The probability of nasal S. aureus carriage was 88.9% for patients receiving allergen injections and having atopic dermatitis or eczema, and 36.1% for patients receiving allergen injections without atopic dermatitis or eczema.

CONCLUSIONS

Patients undergoing desensitization have a higher nasal carriage rate of S. aureus. However, factors other than the regular use of needles, and in particular abnormalities related to the atopic constitution of these patients, may predispose this population for S. aureus carriage.

Can antibiotic-resistant nosocomial infections be controlled?

Three decades ago infection-control programmes were created to control antibiotic-resistant nosocomial infections, but numbers of these infections have continued to increase, leading many to question whether control is feasible. Meticillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci were major problems during the 1990s. Many hospitals have tried antibiotic control but with limited efficacy against these pathogens. Studies of antibiotic restriction, substitution, and cycling have been promising, but more definitive data are needed. Increased compliance with hand hygiene would help but is unlikely to control this problem alone as a result of frequent contamination of other surfaces even when hands are cleansed and high transmission rates when hand hygiene is neglected. For 17 years, the Centers for Disease Control and Prevention have recommended contact precautions for preventing nosocomial spread of important antibiotic-resistant pathogens. Many studies confirm that this approach works when sufficient active-surveillance cultures are undertaken to detect the reservoir for spread. However, most healthcare facilities have not yet tried this approach.

Prolonged antimicrobial activity of a catheter containing chlorhexidine-silver sulfadiazine extends protection against catheter infections in vivo

The present study evaluated in vitro and in vivo a new chlorhexidine (C)-silver sulfadiazine (S) vascular catheter (the CS2 catheter) characterized by a higher C content and by the extended release of the surface-bound antimicrobials. The CS2 catheter was compared with a first-generation, commercially available CS catheter (the CS1 catheter). The CS2 catheter produced slightly smaller zones of inhibition (mean difference, 0.9 mm [P < 0.001]) at 24 h against Staphylococcus aureus and five other microorganisms by several different methodologies. However, in a rabbit model, both CS catheters were similarly efficacious in preventing a catheter infection when the rabbits were inoculated with 10(4) to 10(7) CFU of S. aureus at the time of catheter insertion. The CS2 catheter retained its antimicrobial activity significantly longer in vitro and in vivo (half-lives exceeded 34 and 7 days, respectively) and was also significantly more efficacious in preventing a catheter infection when 10(6) CFU of S. aureus was inoculated 2 days after catheter implantation (P < 0.001). These results suggest that prolonged anti-infective activity on the external catheter surface provides improved efficacy in the prevention of infection.

Guidelines for the management of intravascular catheter-related infections

These guidelines from the Infectious Diseases Society of America (IDSA), the American College of Critical Care Medicine (for the Society of Critical Care Medicine), and the Society for Healthcare Epidemiology of America contain recommendations for the management of adults and children with, and diagnosis of infections related to, peripheral and nontunneled central venous catheters (CVCs), pulmonary artery catheters, tunneled central catheters, and implantable devices. The guidelines, written for clinicians, contain IDSA evidence-based recommendations for assessment of the quality and strength of the data. Recommendations are presented according to the type of catheter, the infecting organism, and the associated complications. Intravascular catheter-related infections are a major cause of morbidity and mortality in the United States. Coagulase-negative staphylococci, Staphylococcus aureus, aerobic gram-negative bacilli, and Candida albicans most commonly cause catheter-related bloodstream infection. Management of catheter-related infection varies according to the type of catheter involved. After appropriate cultures of blood and catheter samples are done, empirical i.v. antimicrobial therapy should be initiated on the basis of clinical clues, the severity of the patient's acute illness, underlying disease, and the potential pathogen(s) involved. In most cases of nontunneled CVC-related bacteremia and fungemia, the CVC should be removed. For management of bacteremia and fungemia from a tunneled catheter or implantable device, such as a port, the decision to remove the catheter or device should be based on the severity of the patient's illness, documentation that the vascular-access device is infected, assessment of the specific pathogen involved, and presence of complications, such as endocarditis, septic thrombosis, tunnel infection, or metastatic seeding. When a catheter-related infection is documented and a specific pathogen is identified, systemic antimicrobial therapy should be narrowed and consideration given for antibiotic lock therapy, if the CVC or implantable device is not removed. These guidelines address the issues related to the management of catheter-related bacteremia and associated complications. Separate guidelines will address specific issues related to the prevention of catheter-related infections. Performance indicators for the management of catheter-related infection are included at the end of the document. Because the pathogenesis of catheter-related infections is complicated, the virulence of the pathogens is variable, and the host factors have not been well defined, there is a notable absence of compelling clinical data to make firm recommendations for an individual patient. Therefore, the recommendations in these guidelines are intended to support, and not replace, good clinical judgment. Also, a section on selected, unresolved clinical issues that require further study and research has been included. There is an urgent need for large, well-designed clinical studies to delineate management strategies more effectively, which will improve clinical outcomes and save precious health care resources.

Guidelines for the management of intravascular catheter-related infections

These guidelines from the Infectious Diseases Society of America (IDSA), the American College of Critical Care Medicine (for the Society of Critical Care Medicine), and the Society for Healthcare Epidemiology of America contain recommendations for the management of adults and children with, and diagnosis of infections related to, peripheral and nontunneled central venous catheters (CVCs), pulmonary artery catheters, tunneled central catheters, and implantable devices. The guidelines, written for clinicians, contain IDSA evidence-based recommendations for assessment of the quality and strength of the data. Recommendations are presented according to the type of catheter, the infecting organism, and the associated complications.

Intravascular catheter-related infections are a major cause of morbidity and mortality in the United States. Coagulase-negative staphylococci,Staphylococcus aureus, aerobic gram-negative bacilli, andCandida albicansmost commonly cause catheter-related bloodstream infection. Management of catheter-related infection varies according to the type of catheter involved. After appropriate cultures of blood and catheter samples are done, empirical iv antimicrobial therapy should be initiated on the basis of clinical clues, the severity of the patient's acute illness, underlying disease, and the potential pathogen (s) involved. In most cases of nontunneled CVC-related bacteremia and fungemia, the CVC should be removed.

"Cloud" health-care workers

Certain bacteria dispersed by health-care workers can cause hospital infections. Asymptomatic health-care workers colonized rectally, vaginally, or on the skin with group A streptococci have caused outbreaks of surgical site infection by airborne dispersal. Outbreaks have been associated with skin colonization or viral upper respiratory tract infection in a phenomenon of airborne dispersal of Staphylococcus aureus called the "cloud" phenomenon. This review summarizes the data supporting the existence of cloud health-care workers.

In vitro zones of inhibition of coated vascular catheters predict efficacy in preventing catheter infection with Staphylococcus aureus in vivo

This report summarizes data from 35 rabbit model experiments investigating the relationship between in vitro anti-infective catheter coating zones of inhibition and in vivo efficacy. The rabbit model studies involving 15 anti-infective coatings demonstrate an inverse correlation between the sizes of zones of inhibition of Staphylococcus aureus and both the quantity of Staphylococcus aureus removed from the catheter and the risk of a purulent infection. The review of seven previously published clinical trials reveals that the use of anti-infective coated catheters, efficacious in the rabbit model, was associated with a higher success rate than the use of uncoated catheters in preventing both Staphylococcus aureus catheter colonization (odds ratio: 1.28; 95% confidence interval: 0.84-1.93) and Staphylococcus aureus catheter-related bloodstream infection (odds ratio: 3.07; 95% confidence interval: 0.98-9.60) in humans. These findings strongly suggest a correlation between zones of inhibition and in vivo efficacy. In vitro zones of inhibition may serve as a useful screening test for evaluating new anti-infective coatings.

Education of physicians-in-training can decrease the risk for vascular catheter infection

BACKGROUND

Procedure instruction for physicians-in-training is usually nonstandardized. The authors observed that during insertion of central venous catheters (CVCs), few physicians used full-size sterile drapes (an intervention proven to reduce the risk for CVC-related infection).

OBJECTIVE

To improve standardization of infection control practices and techniques during invasive procedures.

DESIGN

Nonrandomized pre-post observational trial.

SETTING

Six intensive care units and one step-down unit at Wake Forest University Baptist Medical Center, Winston-Salem, North Carolina.

PARTICIPANTS

Third-year medical students and physicians completing their first postgraduate year.

INTERVENTION

A 1-day course on infection control practices and procedures given in June 1996 and June 1997.

MEASUREMENTS

Surveys assessing physician attitudes toward use of sterile techniques during insertion of CVCs were administered during the baseline year and just before, immediately after, and 6 months after the first course. Preintervention and postintervention use of full-size sterile drapes was measured, and surveillance for vascular catheter-related infection was performed.

RESULTS

The perceived need for full-size sterile drapes was 22% in the year before the course and 73% 6 months after the course (P < 0.001). The perceived need for small sterile towels at the insertion site decreased reciprocally (P < 0.001). Documented use of full-size sterile drapes increased from 44% to 65% (P < 0.001). The rate of catheter-related infection decreased from 4.51 infections per 1000 patient-days before the first course to 2.92 infections per 1000 patient-days 18 months after the first course (average decrease, 3.23 infections per 1000 patient-days; P < 0.01). The estimated cost savings of this 28% decrease was at least $63000 and may have exceeded $800000.

CONCLUSIONS

Standardization of infection control practices through a course is a cost-effective way to decrease related adverse outcomes. If these findings can be reproduced, this approach may serve as a model for physicians-in-training.

Neutrophil chemotaxis on silicone and polyurethane surfaces

Silicone vascular catheters have a greater risk of infection and produce greater inflammation in vivo and greater complement activation in vitro than other vascular catheter polymer materials. This study investigated whether polymorphonuclear leukocyte (PMNL) chemotaxis under agarose on silicone surfaces is different than on polyurethane (PU). Glass slides were coated with silicone and PU by use of a constant-speed dipping apparatus. Chemotaxis (3 h) in response to (10-7 mL) FMLP, zymosan-activated serum, and fresh serum (100%) was greater on silicone than on PU (P<.05). Polyclonal antibody to C5a blocked >50% of the movement toward serum (P<.05). Serum in the PMNL well significantly decreased chemotaxis toward FMLP on silicone (P<.05) but not on PU. These findings suggest that excessive complement activation by silicone may interfere with chemotaxis, but further work is necessary to determine whether this is relevant to an increased risk of catheter-related infection.

Minocycline and ethylenediaminetetraacetate for the prevention of recurrent vascular catheter infections

Three patients with recurrent vascular catheter-related bacteremia were successfully treated by allowing a solution of minocycline and ethylenediaminetetraacetate (EDTA) to dwell in the lumen of the indwelling catheter or by coating polyurethane catheters with minocycline/EDTA and flushing the lumen daily with the same solution. In vitro and in vivo experiments showed that minocycline/EDTA may have broad-spectrum antimicrobial activity, may have optimal anticoagulant activity, and may be highly efficacious in preventing catheter colonization.

Microbial interactions with catheter material

The use of central venous catheters to deliver parenteral nutrition therapy is often complicated by infection. The original source of these infections has been debated but it appears that organisms colonizing the skin or those contaminating the catheter hub are most often responsible. Before forming a biofilm, an organism must first successfully attach to a surface. To do this, microbes have evolved strategies that allow them to adhere to surfaces and evade forces that would favor their detachment. Once a biofilm is formed on a catheter, the organisms are relatively safe from a host immune response and antibiotics. In this review, what is known about these interactions is discussed.

The risk of peripheral vein phlebitis associated with chlorhexidine-coated catheters: a randomized, double-blind trial

OBJECTIVE

To evaluate the risk of phlebitis associated with chlorhexidine-coated polyurethane catheters in peripheral veins.

DESIGN

A randomized, double-blinded trial comparing chlorhexidine-coated polyurethane catheters with uncoated polyurethane catheters.

SETTING

A university hospital.

PATIENTS

Adult medicine and surgery patients.

INTERVENTIONS

Certified registered nurse anesthetists or an infusion team consisting of nurses and physicians inserted the catheters. Catheter insertion sites were scored twice daily for evidence of phlebitis. At the time catheters were removed, a quantitative blood culture was performed, and catheters were sonicated for quantitative culture.

RESULTS

Of 221 evaluable catheters, phlebitis developed in 18 (17%) of 105 coated catheters, compared to 27 (23%) of 116 uncoated catheters (relative risk [RR], 0.74; 95% confidence interval [CI95], 0.43-1.26; P = .32). By survival analysis, chlorhexidine-coated catheters had a lower risk of phlebitis during the first 3 days (P = .06), but not when all catheters were considered in both patient groups (P = .31). In the absence of catheter colonization, the incidence of phlebitis was 21% (16/76) and 24% (20/86) for coated and uncoated catheters, respectively (P = .85), whereas in the presence of catheter colonization, the incidence of phlebitis was 14% (1/7) and 80% (4/5) for coated and uncoated catheters, respectively (RR, 0.18; CI95, 0.03-1.15; P = .07).

CONCLUSION

The risk of phlebitis in the presence of catheter colonization was 82% lower for chlorhexidine-coated polyurethane catheters compared to otherwise identical uncoated catheters.

Diagnosis of triple-lumen catheter infection: comparison of roll plate, sonication, and flushing methodologies

In a recent clinical trial, 248 triple-lumen catheters were removed from patients in an intensive care unit, and their tip and subcutaneous segments were cultured by both the sonication and roll plate methods; for 191 of these catheters, flush cultures of all three catheter lumens were also performed. Previously published quantitative endpoints were used to define significant catheter colonization. By using a composite index as a definition of colonization (any of the seven types of cultures meeting quantitative criteria), sonication of the subcutaneous segment was the most sensitive at detecting colonization (58%), followed by sonication of the catheter tip (53%). Sonication of both the subcutaneous and tip segments was 20% more sensitive than sonication of an adjacent catheter segment by the roll plate method (P < 0.05). The greater sensitivity of the sonication method could be attributed to its greater ability than the roll plate method to detect catheter lumen colonization (82 versus 57%, respectively; P = 0.01). A greater number of positive catheter segment cultures were found for colonized catheters from patients with associated bacteremia than for colonized catheters from patients without bacteremia (57 versus 37%; P = 0.004), making any culture method more likely to identify them. For catheters with significant colonization of only one site, the localization was as follows: 36.7% subcutaneous segment, 36.7% catheter lumen, and 26.6% tip segment. These findings suggest that the current practice of culturing a single segment of a central vascular catheter is inadequate and needs to be reexamined. They further suggest that initial colonization of the catheter lumen and tip segments may be more important than previously thought and may require a change in thinking of strategies designed to prevent catheter infection.

Surveillance for infections associated with vascular catheters

Intravascular devices are the source of most primary bloodstream infections. Unfortunately, there are few studies that demonstrate how surveillance for catheter-related infection should be done. This article attempts to provide infection control personnel with information necessary to develop such surveillance.

Gamma radiation-sterilized, triple-lumen catheters coated with a low concentration of chlorhexidine were not efficacious at preventing catheter infections in intensive care unit patients

In a randomized, double-blind trial, gamma radiation-sterilized, chlorhexidine-coated triple-lumen catheters were compared with uncoated control catheters for their ability to prevent catheter infection in 254 intensive care unit patients. The chlorhexidine coating was not efficacious, and a rabbit model demonstrated that reduction of chlorhexidine activity by gamma radiation sterilization was the likely explanation for the failure.

A cloud adult: the Staphylococcus aureus-virus interaction revisited

BACKGROUND

Nasal carriage of Staphylococcus aureus is common among health care workers, but outbreaks caused by such carriers are relatively uncommon. We previously reported outbreaks of S. aureus skin infections that affected newborn infants and were attributed to an S. aureus nasal carrier who had had an associated upper respiratory tract infection (UR) during the outbreak period.

OBJECTIVE

To investigate the contribution of a nasal methicillin-resistant S. aureus (MRSA) carrier (physician 4) who contracted a URI to an outbreak of MRSA infections that involved 8 of 43 patients in a surgical intensive care unit during a 3-week period.

DESIGN

An epidemiologic study of an outbreak of MRSA infections and a quantitative investigation of airborne dispersal of S. aureus associated with an experimentally induced rhinoviral infection.

SETTING

A university hospital.

PARTICIPANTS

43 patients in a surgical intensive care unit and 1 physician.

MEASUREMENTS

Molecular typing was done, and risk factors for MRSA colonization were analyzed. Agar settle plates and volumeric air cultures were used to evaluate the airborne dispersal of S. aureus by physician 4 before and after a rhinoviral infection and with or without a surgical mask.

RESULTS

A search for nasal carriers of MRSA identified a single physician (physician 4); molecular typing showed that the MRSA strain from physician 4 and those from the patients were identical. Multivariate logistic regression analysis identified exposure to physician 4 and duration of ventilation as independent risk factors for colonization with MRSA (P < or = 0.008). Air cultures showed that physician 4 dispersed little S. aureus in the absence of a URI. After experimental induction of a rhinovirus URI, physician 4's airborne dispersal of S. aureus without a surgical mask increased 40- fold; dispersal was significantly reduced when physician 4 wore a mask (P < or = 0.015).

CONCLUSIONS

Physician 4 became a "cloud adult," analogous to the "cloud babies" described by Eichenwald and coworkers who shed S. aureus into the air in association with viral URIs. Airborne dispersal of S. aureus in association with a URI may be an important mechanism of transmission of S. aureus.

Contribution of vascular catheter material to the pathogenesis of infection: the enhanced risk of silicone in vivo

There is currently very little information to suggest that polymer materials used to make vascular catheters differ in their risk of infection. A rabbit model of subcutaneous Staphylococcus aureus infection was used to determine the relative risk of infection associated with silicone, polyurethane, polyvinylchloride, and Teflon catheters. Seven days after catheter implantation and inoculation with S. aureus, catheters were observed for gross purulence and quantitatively cultured. Silicone catheters were found to have a greater risk of grossly apparent infection (purulence) and a greater number of organisms removed from catheters by quantitative culture than the other three catheter materials (P < .01). The risk of infection associated with silicone catheters decreased (P < .05) if the S. aureus inoculation was delayed for 2 days or if the catheters were preincubated in the subcutaneous space prior to insertion. The histology of the inflammatory response around the four catheter materials was evaluated at either 2 or 7 days after catheter insertion with or without S. aureus inoculation. Silicone catheters had greater associated inflammation (P < .05) with or without S. aureus inoculation. These results suggest that silicone catheter materials may have unique properties that increase the risk of infection after implantation. Further studies should be done to understand the mechanism(s) of these observations.

Subcutaneous, catheter-related inflammation in a rabbit model correlates with peripheral vein phlebitis in human volunteers

In the development of a polyurethane vascular catheter with anti-infective properties, it became desirable to develop a measure of tissue inflammation. This was investigated in a rabbit model by implanting uncoated catheters and catheters coated with heparin (HEP), chlorhexidine (CH), or CH/HEP in the subcutaneous space with or without 10(4) Staphylococcus aureus. At intervals of 2, 4, and 7 days after implantation, animals were sacrificed; tissue blocks containing catheters were removed and preserved with formaldehyde; and sections were stained with hematoxylin and eosin. Using a histologic index, 240 sections (10 for each experimental condition) were evaluated by two investigators blinded to experimental conditions. Uncoated catheters or catheters coated with CH alone had a lower histologic index (less inflammation) than catheters coated with HEP alone or CH/HEP (P < .05). When catheters were inoculated with S. aureus, those coated with CH, with or without HEP, had a lower histologic index than uncoated catheters (P < .05). Next, 30 volunteers had a control catheter inserted in a vein in one forearm and a catheter coated with either CH alone or CH/HEP in a vein in the other forearm. After 96 h of observation there was a greater risk of phlebitis associated with CH/HEP catheters than control catheters (P < .05), and no difference in the risk of phlebitis between CH catheters and control catheters (P = 0.43). Thus, the amount of inflammation around the catheter in the subcutaneous space of rabbit correlated with the risk of peripheral vein phlebitis.

Natural history of bloodstream infections in a burn patient population: the importance of candidemia

Because of a perceived increase in Candida bloodstream infections in our burn unit, we retrospectively reviewed all the microbiologic data and the medical records of 209 patients with burns admitted during a 42-month period. Twice weekly burn wound cultures demonstrated that Candida species were the tenth most frequently isolated organisms (69/191 patients, 36%). Despite the low frequency of isolation from burn wounds, Candida species were the most common organisms found in blood cultures and urine cultures. Of 49 patients with positive blood cultures, 16 (33%) had clinically significant culture growth of yeasts: Candida albicans, 12; Candida parapsilosis, 2; Candida tropicalis, 1; and Torulopsis glabrata, 1. Patients with candidemia were more likely than patients with blood culture growth of other organisms to have burn wound cultures that grew Candida (15/16 vs 21/33, p = 0.02), larger burns (61% vs 38%, p < 0.001), and death (63% vs 27%, p = 0.02). Multivariate analysis demonstrated that the total number of blood cultures with microorganism growth and large burn size were the greatest independent risk factors for candidemia. These data demonstrate that yeasts are pathogens of major importance in patients with burns, suggesting that in patients with burns who have suspected sepsis and large burn injury or a previous bacteremia, strong consideration should be given to administration of amphotericin B initiation of empiric antibacterial therapy.

Efficacy of antibiotic-coated catheters in preventing subcutaneous Staphylococcus aureus infection in rabbits

Vascular catheters coated with antiinfective compounds were evaluated as to their ability to prevent Staphylococcus aureus catheter infection in a rabbit model. Zones of inhibition of agar surface-plated S. aureus demonstrated the following hierarchy: dicloxacillin and clindamycin were each better than fusidic acid or chlorhexidine, which were better than ciprofloxacin, cefotaxime, or cefuroxime. In vivo half-lives of inhibitory activity for clindamycin and dicloxacillin were 5.6 and 17.7 h, respectively, with apparent first-order kinetics. Chlorhexidine disappeared in vivo with apparent two-compartment kinetics: first-compartment t1/2, 16.8 h; second-compartment t1/2, 115.6 h. In a rabbit model, dicloxacillin, clindamycin, fusidic acid, and chlorhexidine decreased the risk of infection compared with uncoated control catheters (P < .05). For dicloxacillin, clindamycin, and chlorhexidine, this was true even if the S. aureus inoculation was delayed 48 or 96 h after catheter implantation. These data suggest that vascular catheters with antiinfective coatings should be investigated further in hospitalized patients.

Vancomycin is not an essential component of the initial empiric treatment regimen for febrile neutropenic patients receiving ceftazidime: a randomized prospective study

The use of vancomycin as part of the initial antibiotic therapy of febrile neutropenic patients has become a controversial issue. Some studies support its incorporation in the initial regimen, and others suggest that vancomycin can be added later. We examined this issue in a prospective, randomized trial. We randomized 127 febrile neutropenic patients to receive either ceftazidime alone or ceftazidime plus vancomycin as the initial empiric antibiotic treatment. We added vancomycin to the ceftazidime arm of the study when fever persisted after 96 h of monotherapy, when new fever occurred after this time, or when a moderately ceftazidime-resistant gram-positive bacterium was isolated. Each of these regimens had similar initial response rates, similar durations of initial fever, similar frequencies of new fever during therapy, similar microbiological cure rates, similar superinfection rates, and similar survival rates. We observed more renal and cutaneous toxicities in patients receiving vancomycin and ceftazidime as initial therapy. We conclude that ceftazidime is appropriate as initial therapy for febrile neutropenic patients and that the addition of vancomycin is appropriate when fever persists after 4 days of monotherapy or when fever recurs following an initial response.

Outbreak of Candida bloodstream infections associated with retrograde medication administration in a neonatal intensive care unit

An outbreak of candidemia involving five infants receiving total parenteral nutrition in the neonatal intensive care unit was investigated. Cultures of the intravenous fluids demonstrated that the retrograde medication syringe fluids were significantly more likely to be contaminated with Candida than were other fluids being administered to the infants (p less than 0.001). Candidemia was significantly associated with total parenteral nutrition (p = 0.04) and retrograde medication administration (p = 0.02). A survey of nursing practice found that reuse of the retrograde syringes was the most likely cause of contamination. Molecular typing showed that the strains of Candida albicans that were isolated from the bloodstream were also found in the retrograde syringes and that at least three strains of C. albicans and one strain each of Candida tropicalis and Candida parapsilosis were involved. In vitro growth curves demonstrated that Candida species had a selective growth advantage versus bacteria in the total parenteral nutrition fluid. An in vitro simulation of the retrograde medication administration system suggested that the outbreak probably developed after the frequency of changing intravenous tubing was decreased from every 24 hours to every 72 hours. The outbreak was terminated by using syringes only once and resuming intravenous tubing changes every 24 hours. Retrograde medication administration in association with total parenteral nutrition may increase the risk of Candida line infection.

Infected radial artery pseudoaneurysms occurring after percutaneous cannulation

During a ten-month period in 1988 at our institution, we identified three infected radial artery pseudoaneurysms (RAPAs) associated with arterial lines. A retrospective chart review to 1983 identified three additional cases, all occurring in 1986. In the six-year period of 1983 through 1988, during which approximately 12,500 radial artery catheters were placed, the incidence of RAPA formation was 6/12,500 (0.048 percent). Five of the six cases were associated with Staphylococcus aureus infection. The duration of radial artery cannulation was significantly longer in patients who developed a pseudoaneurysm (12.5 days) than in those patients who did not suffer this complication (4.3 days). Patients in whom infected RAPAs occurred also tended to be older (mean, 71.6 years) than the average age (54 years) for all patients admitted to the intensive care unit (ICU). They also tended to have long stays in the ICU prior to development of RAPA, the shortest stay being 11 days and the average being 51 days. Risk factors for the development of this complication may include advanced age, longer duration of catheterization and hospitalization, and infection with S aureus.

Quantitative tip culture methods and the diagnosis of central venous catheter-related infections

The diagnostic usefulness of two quantitative catheter culture methods was compared in a prospective study of central venous arterial catheters. The roll-plate method followed by sonication was used to culture 177 catheters from 85 patients, and the sonication method was used to culture 136 catheters from 68 patients. All patients were evaluated for catheter-related infections. Catheter-related infections were associated with greater than or equal to 100 colony-forming units (CFU) isolated from catheter tips by either roll plate (p = 0.01) or sonication (p less than 0.001). The sensitivity, specificity, and positive and negative predictive values of greater than or equal to 10(3) CFU by roll plate for catheter-related septicemia were 56%, 97%, 63%, and 96% compared with 93%, 95%, 76%, and 99%, respectively, for the same level by sonication. For central venous and arterial catheters, the sonication method can distinguish infection from contamination and is superior to the roll-plate method in that it may offer a more sensitive and predictive alternative in the diagnosis of catheter-related septicemia.

Uncontrolled nosocomial rotavirus transmission during a community outbreak

Between Jan. 11 and March 31, 1983, 60 pediatric patients were diagnosed with rotavirus gastroenteritis. Of these cases 24 were community acquired, 29 were nosocomial, and 7 were of undetermined origin. Despite intensive infection control efforts, nosocomial transmission continued as long as patients with community-acquired cases were admitted. The use of disinfectants and germicides that were ineffective against rotavirus may have contributed to the continued nosocomial spread during a community outbreak.

Annual tuberculin skin testing of employees at a university hospital: a cost-benefit analysis

The usefulness of routine annual tuberculin skin testing (purified protein derivative [PPD]) of hospital employees has been questioned. Between 1984 and the end of 1987 the PPD conversion rates of hospital employees at a university and psychiatric hospital in North Florida were compared. The number of employees in both hospitals were almost equal and compliance with the annual testing was more than 95%. In the psychiatric hospital tuberculosis screening of patients was practiced on admission and annually thereafter. Although no unsuspected smear-positive tuberculosis patients were diagnosed in the psychiatric hospital as compared to four in the university hospital, the annual conversion rates of employees were 0.42% and 0.13%, respectively (p greater than 0.001). However, the ratios of these conversion rates to the incidence of tuberculosis in the counties where these hospitals are located respectively were similar (20.0 vs 24.3, p = 0.7). The community seems be the major source of the PPD conversion. At the university hospital more than +70,000 was spent on the annual PPD testing to discover 15 converters; nine had no or minimal contact with patients and only two complied with isoniazid (INH) prophylaxis. Annual PPD testing is not cost effective in hospitals with a low annual conversion rate among its employees and with low tuberculosis case rates in the hospital and the surrounding community.

Efficacy of dicloxacillin-coated polyurethane catheters in preventing subcutaneous Staphylococcus aureus infection in mice

In a mouse model, dicloxacillin-coated polyurethane catheters or control (uncoated) catheters were placed subcutaneously and then Staphylococcus aureus was inoculated at the time of insertion, 24 or 48 h later. The in vivo half-life of the antibiotic was 11 to 16 h. When 10(5) CFU of S. aureus were inoculated at the time of catheter insertion, dicloxacillin-coated catheters kept the number of S. aureus removed from catheters by sonication below 10(2) CFU at 12, 24, 48, and 96 h after inoculation compared with titers greater than 10(3.5) CFU for control catheters (P less than 0.05). When S. aureus was inoculated 24 h after catheter insertion, control catheters averaged greater than 10(2) CFU of S. aureus removed compared with less than 10(1.5) CFU for the dicloxacillin-coated catheters (P less than 0.05). No difference was found between coated and control catheters when S. aureus was inoculated 48 h after catheter insertion, but S. aureus titers averaged less than 10(2) CFU for all experimental groups. Our data suggest that in mice, regional prophylaxis of S. aureus subcutaneous space infection is feasible with catheters coated with dicloxacillin and that the presence of antibiotic is only necessary for the first 24 to 48 h.

The importance of nosocomial transmission of measles in the propagation of a community outbreak

In late January 1985, a measles outbreak occurred at a community hospital in Columbia county, Florida. The outbreak spread throughout the county and to two neighboring counties (Alachua and Marion), resulting in 79 cases with a 29% hospitalization rate. Hospitals represented the site with the highest frequency of transmission. At the Alachua county hospitals, where strict respiratory isolation measures were taken, no secondary cases occurred among hospitalized patients. Two independent risk factors existed for hospitalization: measles exposure in a hospital setting (P less than 0.05) and nonvaccination (P less than 0.001). Of the total measles cases, 24% were under the age of 16 months and 47% of those aged 16 months or older had a history of appropriate vaccination. Columbia county, which experienced 86% of the cases, had a 5% frequency of unvaccinated students compared to 0.6% frequency at Alachua (P less than 0.001) where only 10% of the cases occurred. This outbreak demonstrates the role of uncontrolled nosocomial transmission of measles in the propagation of a community outbreak.

Comparison of cefpimizole with cefotaxime and penicillin G for treatment of uncomplicated gonorrhea

One hundred sixteen patients (92 men and 24 women) with suspected uncomplicated gonorrhea were randomized in a double-blind manner to receive intramuscular treatment with 1.0 g of cefpimizole, 1.0 g of cefotaxime, or 4.8 x 10(6) units of aqueous procaine penicillin G (APPG) with 1 g of oral probenecid. Seventeen percent were nonassessable (cultures negative, co-existing syphilis, etc.). Infection sites in 96 assessable patients were urethra (78), cervix (17), pharynx (two), and rectum (two). Of 52 patients treated with cefpimizole, 46 (88%) were bacteriologically cured, as compared with 100% (24 of 24) treated with APPG (P = 0.18) and 90% (18 of 20) treated with cefotaxime (P greater than 0.20). On a weight basis the in-vitro activity of cefpimizole against Neisseria gonorrhoeae was similar to that of APPG. Pain at the injection site was reported by 52% of patients treated with cefpimizole as compared with 27% of those given cefotaxime (P = 0.008) and 17% of those given APPG (P = 0.002). No major organ toxicity was found with cefpimizole, cefotaxime, or APPG. Thus, for acute uncomplicated gonorrhea cefpimizole is similar in efficacy to cefotaxime and APPG but has a higher frequency of pain at the injection site.

Vascular-access infections in hospitalized patients

Vascular catheters are a common source of nosocomial infections, although many of these infections are potentially preventable. A long duration of catheterization, multiple catheter manipulations, the inexperience of some inserters, use of transparent plastic dressings, violations of aseptic technique, the use of multilumen catheters, and inadequate sterilization of reusable pressure transducers all increase the risk of these infections. The only interventions that have been proved to reduce the risk are standardized insertion and maintenance technique by an intravenous-therapy team, preinsertion skin preparation with chlorhexidine gluconate, and the use of topical antibiotics at the insertion site. The goal of the physician should be to prevent catheter infection, because the treatment of established infection can be difficult and costly. Treatment must be individualized for each patient on the basis of the clinical presentation and the causative organism.

Impact of air filtration on nosocomial Aspergillus infections. Unique risk of bone marrow transplant recipients

Bone marrow transplant recipients were found to have a 10-fold greater incidence of nosocomial Aspergillus infection than other immunocompromised patient populations (p less than 0.001) when housed outside of a high-efficiency particulate air (HEPA) filtered environment. Multivariate analysis demonstrated that number of infections, age, and graft-versus-host disease severe enough to require treatment were independent risk factors for development of nosocomial Aspergillus infection in this group. The use of whole-wall HEPA filtration units with horizontal laminar flow in patient rooms reduced the number of Aspergillus organisms in the air to 0.009 colony-forming units/m3, which was significantly lower than in all other areas of the hospital (p less than or equal to 0.03). No cases of nosocomial Aspergillus infection developed in 39 bone marrow transplant recipients who resided in this environment throughout their transplantation period compared with 14 cases of nosocomial Aspergillus infection in 74 bone marrow transplant recipients who were housed elsewhere (p less than 0.001). Thus, although bone marrow transplant recipients had an order-of-magnitude greater risk of nosocomial Aspergillus infection than other immunocompromised hosts, this risk could be eliminated by using HEPA filters with horizontal laminar airflow.

Factors affecting colonization and dissemination of Candida albicans from the gastrointestinal tract of mice

Male ICR Swiss mice (2 to 3 months old) were fed Candida albicans in their drinking water for 3 days, followed by no treatment, antibiotics in their drinking water (daily), or immunosuppressants given by intraperitoneal injection (two to three times weekly) over a 3- to 4-week period. The organs of animals were processed to determine the numbers of C. albicans and total aerobic bacteria per g of tissue. Untreated animals had mean Candida counts during the 1-month period of 10(2.3) CFU/g of cecum. Animals in six of eight antibiotic-treated groups had mean cecal Candida counts higher than those of control animals (P less than 0.05), with clindamycin-gentamicin producing the highest counts (10(4.7) CFU/g). Cyclophosphamide produced counts (10(4.3) CFU/g) which were higher (P less than 0.05) than those resulting from methotrexate (10(3.0) CFU/g) or steroid (10(2.7) CFU/g) treatment. Cyclophosphamide-clindamycin-gentamicin treatment was associated with the highest (P less than 0.05) levels of Candida colonization (10(6.5) CFU/g). Mice receiving immunosuppressants plus clindamycin-gentamicin were more likely to disseminate C. albicans than were mice receiving antibiotics alone (P less than 0.001). Our findings suggest that colonization of the guts of mice by C. albicans can be facilitated by manipulating the aerobic, anaerobic, or both types of gut flora. The combined effect of immunosuppressants on both Candida gut colonization and dissemination appears multifactorial and deserves further investigation.

Influence of sterile protective sleeves on the sterility of pulmonary artery catheters

Eighty-seven pulmonary artery catheters (PACs) with sterile protective sleeves were placed into 69 surgical ICU patients by one of the following two methods: through an introducer placed in a new, percutaneous site or by exchanging an indwelling catheter for an introducer. On removal, 5-cm catheter segments from the catheter tip and from within the introducer and sleeve, peripheral blood, and blood drawn from the PAC distal port were cultured quantitatively. Sleeve segment cultures were sterile if catheterization was less than 48 h and had been accomplished through a new percutaneous site. The risk of growing greater than 10(3) colonies on the tip and introducer segment increased to greater than 30% when PACs were left in over 96 h. The incidence of catheter-related bacteremia (CRB), defined as the simultaneous growth of identical organisms from the blood and the PAC tip, was 5.3% but may have been underestimated. CRB was associated with the use of corticosteroids (p = .009) and with cultures from any PAC segment growing more than 10(3) colonies (p less than .01). Although our data suggest that the use of the sterile protective sleeve is associated with a low risk of colonization, further study will be required to delineate the relationship between the use of protective sleeves and CRB.

Outbreak of staphylococcal infection in two hospital nurseries traced to a single nasal carrier

In late January and early February 1983, an outbreak of skin infections (7 of 145 infants) caused by a penicillin/erythromycin resistant strain of Staphylococcus aureus (SA), phage type 3A/3C, occurred in our newborn nursery. A week following the first cluster of infections, another nursery outbreak due to SA with the same antibiogram occurred in a nearby community hospital (11 of 114 infants). Subsequently, a second cluster of infections with the same SA was identified at our nursery. The epidemic strain was carried in the anterior nares of a single nurse who worked at both hospital nurseries on alternate weeks. Investigation revealed that the nurse had an upper respiratory tract infection during each of these outbreaks--simulating "a cloud baby." No further infections have occurred since this nurse was treated and her SA nasal carrier state eliminated.

Acquired immune deficiency syndrome. A perspective for the medical practitioner

AIDS is a new disease process with complications and management problems unlike anything ever seen before. An attempt has been made to summarize the available information about its various clinical presentations and how to manage them. Subjects covered will include associated malignancies, infections, transmissibility, prodromal states, and infection control issues.

An outbreak of infections with Acinetobacter calcoaceticus in burn patients: contamination of patients' mattresses

During a 21-month period Acinetobacter calcoaceticus was the most common organism causing infections in a university burn center. Forty-three of 103 patients admitted became infected with this organism. Risk factors associated with burn wound colonization with Acinetobacter included larger burns and Foley catheter use; however, only a longer duration of hospitalization was an independent discriminator of colonization. Infection-control measures, including strict isolation and closure and repainting of the burn unit, did not prevent the transmission of Acinetobacter. An investigation found that wet mattresses served as environmental reservoirs of Acinetobacter. This finding led to a policy of discarding each patient's mattress on the day of the patient's discharge from the burn unit. Life table analysis demonstrated that this intervention led to a reduced risk of burn wound colonization with Acinetobacter (P less than .05) and ultimately resulted in the complete elimination of the organism from the burn unit.

Nonurban male homosexuals: epidemiologic, immunologic and virologic characteristics

Twenty asymptomatic male homosexuals living in North Carolina were evaluated looking at epidemiologic, immunologic and virologic characteristics. In ten subjects selected for inhalant nitrite use a significantly higher frequency of multiple drug abuse and a trend toward greater sexual promiscuity was found in comparison with ten nonnitrite users. None of the 20 subjects had chronic lymphadenopathy. Cytomegalovirus (CMV) was not found in urine, blood or throat washings, but was found in 29% of the subjects' semen specimens--a finding that was significantly linked (P less than .05) to the presence of CMV IgM antibody in serum. There were no abnormal helper lymphocytes: suppressor T lymphocyte ratios (all greater than 1.3) and lymphocyte mitogen stimulations were not different from heterosexual controls in contrast to frequent abnormalities reported in male homosexuals in metropolitan areas. If these immunologic findings are reproducible, they may be important in understanding why the Acquired Immunodeficiency Syndrome has clustered in large cities.

Transmission of hepatitis A by transfusion of blood products

The transmission of hepatitis A by blood products has been thought to occur rarely or not at all. By measuring IgM antibody to hepatitis A virus, we diagnosed a case of hepatitis A transmitted by the transfusion of a unit of fresh frozen plasma. Since the commercial availability of methods for measuring IgM antibody to hepatitis A, four other well-defined cases of hepatitis A transmitted by blood products have been reported in the literature. We detail our case and the natural history and importance of this clinical entity.

Environmental study of a methicillin-resistant Staphylococcus aureus epidemic in a burn unit

During an outbreak of infections caused by methicillin-resistant (MR) Staphylococcus aureus in our burn unit, we conducted an extensive 10-week study to define the environmental epidemiology of the organism. The inanimate environment in patient rooms and adjacent areas was examined by using volumetric air samplers and Rodac plates. Airborne and surface level contamination with MR S. aureus was quantitated, and overall, MR S. aureus comprised 16, 31, and 40% of all bacterial growth from air, elevated surfaces, and floor surfaces, respectively. Mean air, elevated surface, and floor surface MR S. aureus contamination in rooms of MR S. aureus-infected burn patients were 1.9 MR S. aureus per ft3 (ca. 0.028 m3), 20 MR S. aureus per Rodac plate and 48 MR S. aureus per Rodac plate, respectively. Peak patient room environmental contamination levels were 6.9 MR S. aureus per ft3 of air, 70 MR S. aureus per Rodac plate per elevated surface and 138 MR S. aureus per Rodac plate per floor surface. Environmental contamination levels in the adjacent work areas were considerably lower than in infected patient rooms. There was ample opportunity for contamination of personnel through the inanimate environment in this unit.

A three-year study of nosocomial infections associated with Pseudomonas aeruginosa

During a 3-year study period in a university teaching hospital, 417 nosocomial infections associated with Pseudomonas aeruginosa were documented in 321 patients. The overall rate of P. aeruginosa nosocomial infection was 5.3 cases per 1,000 patients. Residence on the surgery or medicine service, advanced patient age, and exposure to the burn, surgery, or medicine intensive care units correlated with higher rates of infection. The most common sites for P. aeruginosa infection were the lower respiratory tract, urinary tract, blood stream, and surgical wounds. Nosocomial P. aeruginosa lower respiratory tract and blood stream infections were significantly associated with exposure to certain intensive care units, whereas P. aeruginosa urinary tract infections more commonly occurred on the neurology and neurosurgery services. Results of live antigen serotyping showed that serotype 6 was most common, followed by serotypes 1 and 11. Serotype 6 correlated with resistance to carbenicillin, gentamicin, and tobramycin, and serotype 11 correlated with resistance to carbenicillin. Two-thirds of the isolates tested were sensitive to carbenicillin, gentamicin, and tobramycin, but 13.2% were resistant to all three of these drugs. P. aeruginosa isolates resistant to all three drugs were associated with urinary tract infections.

Infections associated with subclavian Uldall catheters

During a 12-month period, the use of a subclavian vein Uldall catheter (UC) for hemodialysis or plasmapheresis in 27 patients was studied prospectively. Ten patients had ten UC site infections. Organisms associated with these infections included Staphylococcus epidermidis (five), Staphylococcus aureus (four), Proteus mirabilis (two), and Enterococcus (one). The four S aureus infections occurred 1, 2, 4, and 9 days after UC insertion, whereas the five S epidermidis infections occurred 6, 17, 17, 26, and 97 days after insertion. Five patients had associated bacteremias; in one of these patients, the bacteremia was the major cause of death. The incidence of UC site infection and bacteremia based was higher than the incidence of infection reported with any other type of vascular access for hemodialysis. Further studies are necessary to define whether the UC should be routinely employed for temporary vascular access.

Pharmacokinetics of intravenous chloramphenicol sodium succinate in adult patients with normal renal and hepatic function

The pharmacokinetics of chloramphenicol (CAP) and total chloramphenicol succinate (CAPS) were studied in eight hospitalized adult patients with normal renal and hepatic function receiving intravenous chloramphenicol sodium succinate therapy. The steady-state peak concentrations of CAP (8.4-26.0 micrograms/ml) occurred at an average of 18.0 min (range 5.4-40.2) after cessation of the chloramphenicol sodium succinate infusion. Unhydrolyzed CAPS prodrug, representing 26.0 +/- 7.0% of the dose, was recovered unchanged in the urine indicating that the bioavailability of CAP from a dose of intravenous chloramphenicol succinate is not complete. A pharmacokinetic model was developed for simultaneous fitting of CAP and CAPS plasma concentration data. Pharmacokinetic parameters determined by simultaneous fitting were: V, 0.81 +/- 0.18 liters/kg; t1/2, 3.20 +/- 1.02 hr; CLB, 3.21 +/- 1.27 ml/min/kg for chloramphenicol; and V, 0.38 +/- 0.13 liters/kg; t1/2, 0.57 +/- 0.12 hr; CLB, 7.72 +/- 1.87 ml/min/kg for total chloramphenicol succinate.