Skin as a source of nosocomial infection: directions for future research

A Causal Link Between Handwashing and Risk of Infection? Examination of the Evidence

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 (9.4/105citations/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.

Risk Factors for Postoperative Chest Wound Infections Due to Gram-negative Bacteria in Cardiac Surgery Patients

Gram-negative bacteria account for up to 35% of postoperative sternal wound infections (SWI) in patients undergoing cardiac surgery. Despite this, risk factors for Gram-negative SWI have not been investigated. The objective of this study was to define risk factors associated with Gram-negative SWI in patients undergoing cardiac surgery. 2590 patients undergoing cardiac surgery between 2002-2005 were prospectively monitored for development of SWI. Patient, operative, and post-operative risk factors were compared among patients that developed Gram-negative SWI and Gram-positive SWI to uninfected controls using univariate and multivariate analysis. A p < 0.05 was considered significant. Surgical site infections developed in 152 (5.9%) patients. Isolates were recovered from the sternum for 128 (5.0%) patients, from the leg donor site for 19 (0.73%) patients, and from the sternum and donor site for 5 (0.19%) patients. Gram-positive pathogens were isolated from 83 (3.3%) patients, Gram-negative pathogens from 42 (1.6%) patients, and mixed pathogens from 27 (1.0%) patients. Hospital admission greater than 48 hours before surgery (OR: 2.25; 95% CI: 1.11 - 4.58), ventilator-dependency preoperatively (OR: 5.32 95% CI: 2.22 - 12.75), and thoracentesis procedure postoperatively (OR: 3.71; 95% CI: 1.45 - 9.49) and diabetes (OR: 2.04; 95% CI: 1.17 - 3.55) were identified as significant risk factors for SWI due to Gram-negative bacteria using multivariate logistic regression. Diabetes, increased age, and peripheral vascular disease were identified as significant risk factors for SWI due to Gram-positive bacteria (p < 0.05, each). The risk factors associated with Gram-negative SWI differed significantly from those associated with Gram-positive SWI. Risk factors associated with Gram-negative SWI were identified. Unique interventions may be necessary to prevent Gram-negative SWI in cardiac surgery patients.

Parenteral nutrition as a risk factor for central venous catheter-related infection

BACKGROUND

The role of parenteral nutrition (PN) therapy as an independent risk factor for central venous catheter (CVC)-related infection in nonselected adult patients is not well established. The aim of this study was to evaluate PN as a risk factor for central venous catheter-related infection in nonselected adult patients in a general university hospital.

METHODS

Patients using central venous catheters, exposed or nonexposed to PN, were prospectively followed for development of central venous catheter-related infection.

RESULTS

One hundred fifty-three patients were studied; 28 developed central venous catheter-related infection. Patients with central venous catheter-related infection presented higher frequency of PN use than patients without infection (60.7 vs 34.4%; p = .010). Multivariate Cox analysis showed that PN (relative risk (RR) = 3.30; 95% confidence interval [CI], 1.30-8.34; p = .012) was the only risk factor for central venous catheter-related infection. Malnutrition (RR = 0.45; 95% CI, 0.15-1.34; p = .152), days of hospitalization before central venous catheter insertion (RR = 1.00; 95% CI, 0.98-1.02; p = .801), and sustained hyperglycemia (RR = 0.49; 95% CI, 0.98-1.21; p = .091) were not significant in the model. Multiple logistic regression revealed that mal-nutrition (odds ratio [OR] = 8.05; 95% CI, 1.85-35.03; p = .005), central venous catheter indication for surgical-related pathology (OR = 7.26; 95% CI, 2.51-21.04; p < .001), sustained hyperglycemia (OR = 4.34; 95% CI, 1.79-10.52; p = .001), and days of hospitalization before central venous catheter insertion (OR = 1.04; 95% CI, 1.01-1.07; p = .004) were associated with PN use after adjustment for Assessment Score Intervention System score (OR = 0.33; 95% CI, 0.14-0.80; p = .014).

CONCLUSIONS

PN therapy is an independent risk factor for central venous catheter-related infection in nonselected hospitalized adult patients.

Central venous catheter-related blood stream infections: incidence, risk factors, outcome, and associated pathogens

OBJECTIVE

To determine the incidence, risk factors, outcome, and pathogens of central venous catheter-related bloodstream infections (CVC-BSIs).

DESIGN

Prospective study.

SETTING

Escorts Heart Institute and Research Centre, New Delhi, India.

PARTICIPANTS

One thousand three hundred fourteen consecutive patients undergoing cardiac operations who were admitted to the intensive care unit with CVC.

INTERVENTIONS

All patients were assigned into CVC-BSI (n = 35) and non-CVC-BSI (n = 1,279) groups.

MEASUREMENT AND MAIN RESULTS

Of the 1,314 patients in the study, 35 (2.6%) had CVC-BSI. On univariate analysis, significant risk factors were use of multilumen catheters, coexistent infections, intra-aortic balloon counterpulsation (IABC), total ventilation hours, emergency surgery, acute physiology, age, chronic health evaluation score (APACHE II), and steroids. On multivariate analysis, duration of catheterization (24.5 +/- 10.9 v 6.1 +/- 3.2; p < 0.001), coexistent infections (57.11% v 2.61%; p < 0.001), IABC (77.1% v 4.1%; p = 0.005), and temperature (38.2 +/- 0.6 v 37.4 +/- 0.3; p < 0.001) were independent predictors of CVC-BSI. Pathogens isolated were Escherichia coli (47%), Acinetobacter species (11.7%), Enterobacter species (5.8%), Proteus species (5.8%), methicillin-resistant Staphylococcus species (11.7%), coagulase-negative Staphylococcus species (5.8%), and Candida (11.7%). The mortality rate in CVC-BSI was 22.9% as compared with 0.2% in non-CVC-BSI cases (p < 0.001).

CONCLUSION

By univariate analysis, the risk factors for CVC-BSI were use of multilumen catheters, duration of catheterization, total ventilation hours, IABC, emergency surgery, APACHE II score, coexistent infections, and steroids. On multivariate analysis, duration of catheterization, IABC, coexistent infections, and temperature were independent predictors of CVC-BSI. The mortality was increased with CVC-BSI.

Central venous catheters: choosing the most appropriate access route

Intravenous therapy and care is a complex and intricate area of practice, which is being subsumed into the core role of registered nurses. As more patients become recipients of a vascular access device (VAD), particularly those requiring intermediate to long-term central venous access, it is important to ensure that not only the device but also the most appropriate vein meets their clinical physiological and psychological needs. There is much research and literature on the insertion and care of central venous catheters (CVCs) as well as the detection and treatment of complications. However, apart from a few small studies comparing the performance of devices placed either in the subclavian or jugular veins, there is little to guide doctors or nurses as to which vein is preferable, if secondary complications are to be avoided. This article will describe a number of primary and secondary complications associated with both the subclavian and internal jugular veins and how these can be minimized by selecting the most appropriate vessel. The article concludes with the author's suggestions for correct patient assessment in order that the correct vein is utilized.

Skin flora of patients in Thailand

BACKGROUND

Studies taken from different hospitalized patient populations, environments, and geographic regions reveal differences in the numbers and species of organisms colonizing the skin. Our aim was to determine the types and amounts of skin flora, and examine the factors associated with variations in microbial skin flora in patients in Thailand.

METHOD

We studied 350 outpatients and 500 inpatients at Siriraj Hospital in Bangkok, Thailand. The skin at the forearm and the sternum of each patient was cultured by contact plate technique.

RESULTS

The number of skin flora colony-forming units (CFUs) were correlated to the site of sampling. There was a significant correlation of CFUs between samples from the forearm and the sternum in patients who were hospitalized (r = 0.6; P <.001) and in outpatients (r = 0.5; P <.001). The numbers of micro-organisms on the sternum was significantly greater than the number cultured from the forearm for all patients. Inpatients had significantly more organisms on the the forearm and sternum compared with outpatients. High counts (CFUs > 600) were found more frequently in patients who were hospitalized; had chronic obstructive pulmonary disease, diabetes mellitus, or autoimmune diseases; and were undergoing operation and receiving antibiotics. Acinetobacter spp and methicillin-resistant Staphyloccoccus aureus were found more frequently in patients who were hospitalized.

CONCLUSION

Skin flora of patients in tertiary care hospitals in Thailand has higher CFUs, and A baumannii is prevalent, especially in patients who are hospitalized.

Relationship between skin microbial counts and surgical site infection after neurosurgery

A prospective study was performed to describe the density of bacterial counts on the skin of neurosurgical patients and examine the association between total colony-forming unit (cfu) counts of skin flora at the operative site and surgical site infection (SSI). Two skin cultures were obtained, immediately before and after skin preparation, from the operative sites of 609 neurosurgical patients. SSI surveillance that used Centers for Disease Control/National Nosocomial Infection Surveillance definitions was performed. Predictors for high bacterial counts and SSI among craniotomies were analyzed by means of logistic regression. Neither pre- nor postpreparation counts were associated with SSI. Other SSI risk factors were obesity (relative risk [RR], 2.5), duration of surgery (RR, 1.3 for every additional 30 minutes) and age (RR, 0.7 for each additional 10 years). Duration of skin preparation was not correlated with postpreparation cfu counts. We were unable to detect an association between preoperative bacterial skin counts and SSI.

Handwashing practices and resistance and density of bacterial hand flora on two pediatric units in Lima, Peru

The handwashing practices and bacterial hand flora of 62 pediatric staff members of a teaching hospital in Lima, Peru, were studied. Handwashing followed patient contact 29.3% of the time (204/697 contacts). Mean duration was 14.5 seconds, and significant differences in practices were found by unit (rehydration or neonatal intensive care), type of staff member (nurses or physicians), and type and duration of patient contact. Mean count of colony-forming units was log10 5.87 +/- 0.41, with significant differences in density of flora found between patient care and kitchen staffs. There was no significant effect of handwashing on counts of colony-forming units. Significant differences were also found by unit and by staff position with regard to species isolated and antimicrobial resistance of isolates. A more efficacious and cost-effective form of hand hygiene and a more prudent use of antimicrobial agents are indicated.

Lack of care giver hand contamination with endemic bacterial pathogens in a nursing home

Prevalences of Clostridium difficile and multiply resistant Staphylococcus aureus (MRSA) were determined in nursing staff and residents of a 233-bed long-term care facility. Twenty of 38 (52.6%) patients in the long-term care ward and three of 69 (4.3%) in the skilled-nursing ward were colonized with MRSA; 16 of 48 (33%) patients in the long-term care ward and seven of 52 (13%) in the nursing home ward were colonized with C. difficile. None of the 79 staff members whose hands were cultured had chronic C. difficile hand carriage and MRSA was present on only three of 79 (3.9%). Over a 6-month period, 128,000 pairs of gloves were worn. Since C. difficile and MRSA are rarely present on washed hands of care providers, appropriate handwashing and gloving should make a significant contribution to reducing the spread of these agents in long-term care facilities.

The pathogenesis and epidemiology of catheter-related infection with pulmonary artery Swan-Ganz catheters: a prospective study utilizing molecular subtyping

To delineate the pathogenesis and epidemiology of catheter-related infection with Swan-Ganz pulmonary artery (PA) catheters, a prospective clinical study of hospitalized adult medical and surgical patients was done. Role of catheter material was assessed by randomizing insertions to heparin-bonded PA catheters made of polyvinylchloride or polyurethane. Sources of infection and pathogenesis were studied by culturing skin, the introducer, the PA catheter tip, all hubs, infusate from each lumen, and the extravascular portion of the PA catheter beneath the external protective plastic sleeve. Concordance between isolates from sources and infected catheters was determined by speciation, antibiogram, and for coagulase-negative staphylococci, plasmid profile analysis. Risk factors for infection were determined by stepwise logistic regression. Overall, 65 (22%) of 297 Swan-Ganz catheters showed local infection of the introducer (58 catheters) or the intravascular portion of the PA catheter (20 catheters); only two catheters (0.7%) caused bacteremia. Eighty percent of infected Swan-Ganz catheters (the introducer or PA catheter) showed concordance with organisms cultured from skin of the insertion site, 17% with a contaminated hub and 18% with organisms contaminating the extravascular portion of the PA catheter beneath the sleeve. Isolates from infected PA catheters were most likely to show concordance with concomitantly infected introducers (71%). Cutaneous colonization of the insertion site with greater than 10(2) cfu/10 cm2 (relative risk [RR] 5.5; p less than 0.001), insertion into an internal jugular vein (RR 4.3; p less than 0.01), catheterization greater than 3 days (RR 3.1; p less than 0.01), and insertion in the operating room using less stringent barrier precautions (RR 2.1; p = 0.03) were each associated with a significantly increased risk of catheter-related infection. The risk of bacteremic infection with Swan-Ganz catheters is now low, in the range of 1%, with reasonable care. Swan-Ganz catheters are vulnerable to contamination from multiple sources, but the patient's skin is the single most important source of organisms causing invasive infection, which in most cases involves the introducer rather than the PA catheter. Heavy colonization of the insertion site, percutaneous insertion in the internal jugular vein rather than subclavian vein, catheterization longer than 3 days, and insertion with less stringent barrier precautions significantly increase the risk of catheter-related infection. These findings hold promise for application to management of Swan-Ganz catheters and research in catheter design to reduce the risk of catheter-related infection.

Intermittent use of an antimicrobial hand gel for reducing soap-induced irritation of health care personnel

We evaluated the effects of an antimicrobial hand gel (containing 60% ethanol plus emollients) on skin condition when used as a supplement to handwashing. Volunteers washed their hands 10 times per day for 5 days with a bar soap. Between washings one hand was treated with 1.0 ml of the gel while the other hand was untreated. By the conclusion of the study the gel-treated hands exhibited significantly lower (p less than 0.05) photographic scores for cracking, scaling, and erythema (redness), the major symptoms of dry, irritated skin. The gel treatment also helped to maintain normal skin hydration levels as measured by transepidermal water loss and skin impedance. By reducing soap-induced irritation, an alcohol gel with the appropriate emollients can help eliminate a major deterrent to handwashing among health care personnel.

Guideline for use of topical antimicrobial agents

This Guideline is based on published data available at the time of writing. The ideal means for comparing performance of various antimicrobial agents is through the conduct of carefully designed, large-scale clinical trials. Recommendations contained in this Guideline are subject to modification as additional data become available. It particularly should be noted that the implementation of universal precautions or body substance isolation has resulted in marked increase in the use of gloves for direct patient contact. Whether there is an additional cost-benefit rationale for handwashing with an antimicrobial agent remains to be studied.

Central venous catheter infections

When used wisely, central venous catheters are capable of providing vital circulatory access in any patient with a remarkably low risk of infection or major complication. Tunneled silicone catheters are the route of choice for long-term or outpatient use, particularly for oncology or TPN patients; insertion of such a catheter should occur early in the hospitalization of a newly diagnosed patient on chemotherapy. The greatest experience has accrued with the cuffed silicone catheters (for example, Broviac), but the totally implantable devices (for instance, Port-a-cath) may become the device of choice in pediatric outpatients. For infants, small, percutaneously inserted noncuffed silicone catheters appear to offer the greatest safety. Among acute care patients, percutaneous plastic central venous catheters fulfill a vital role but represent an important source of infection. Scrupulous technique, the minimizing of manipulation, and a readiness to replace the catheter at any suggestion of trouble are important to achieving the best results. Within a given design, it is generally best to use the smallest diameter catheter capable of performing the desired tasks. However, on the basis of currently available data, there need be no hesitation to use a multilumen catheter if the care of the patient demands multiple access ports. The various silicone catheters can usually be left in place while infection is treated, although fungal and certain other infections are more likely to require catheter removal. Percutaneous plastic catheters should be removed or changed over a wire if infection is suspected; if tip culture of the removed catheter is positive, and the catheter was replaced over a wire, then the replacement catheter should be promptly removed.

Rituals in infection control: what works in the newborn nursery?

Two infection control practices common in the newborn nursery, handwashing and gowning, are compared with regards to historic origins, effectiveness, and extent of practice. The practice of handwashing is the direct result of efforts to prevent puerperal sepsis and has been shown to be effective in reducing neonatal risk of infection. Gowning has evolved from operating room practices and has been shown to be generally ineffective in reducing risk of infant infection. Nevertheless, gowning is practiced extensively and handwashing is often omitted. Such rituals need occasional reexamination so that those practices associated with maximum effectiveness receive appropriate attention.

Vertebral osteomyelitis due to Staphylococcus warneri attributed to a Hickman catheter

A patient with a long-term right atrial (Hickman) catheter developed vertebral osteomyelitis due to Staphylococcus warneri. Documentation of this event--to our knowledge previously unreported--was made possible by use of special studies including plasmid profiles of the coagulase-negative staphylococcal isolates.