Hand carriage of gram-negative bacilli and Staphylococcus aureus

Postoperative Wound Infections Following Cardiac Surgery: Significance of Contaminated Cases Performed in the Preceding 48 Hours

Postoperative wound infections following open heart cardiac surgery increased markedly after hospital relocation (7 of 77 v; 4 of 320; p = .0007). Of the multiple identified risk factors, significant patient and procedural association included prolonged operative time of infected patients (384 minutes ± 115 SD v 318 ± 67, p = .025) and operation in a room used within the previous 48 hours for a contaminated case (4/7 infected v 10/67 not infected; p = .023). Several defects were discovered in the air handling system. After appropriate changes, the infection rate decreased in the next 12 months (1 of 109; p < .02). Other concurrent surgical wound infection rates remained unchanged suggesting that defective air handling may have impacted only on the open heart cardiac surgery patients. Preceding contaminated surgery and prolonged operative time were associated with postoperative wound infections in cardiac surgery.

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.

A near-fatal case of sepsis with an antibiotic-resistant organism complicating a routine transrectal prostate biopsy in a health care worker

A 58-year-old physician with an elevated prostate specific antigen developed severe septic shock following a repeat transrectal prostate biopsy despite standard preoperative prophylactic protocol. This case highlights the significance of harbouring antibiotic-resistant bacteria and the risk of previous quinolone exposure. We believe this case may herald a rare but potentially serious consequence of increasingly common antibiotic resistance and that high-risk patients should be studied to determine their likelihood of carrying antibiotic-resistant flora in their genitourinary/gastrointestinal tract.

Stool colonization with vancomycin-resistant enterococci in healthcare workers and their households

OBJECTIVE

To determine the prevalence of stool colonization with vancomycin-resistant enterococci (VRE) among healthcare workers (HCWs) and their families.

DESIGN

Prospective assessment of fecal colonization with VRE.

SETTING

A 603-bed, tertiary-care teaching hospital.

PARTICIPANTS

Healthy volunteers recruited from hospital employees and their households were screened to exclude pregnancy, diabetes mellitus, immunosuppressive disorders, and recent use of antimicrobials.

INTERVENTION

Self-obtained stool swabs were used to obtain cultures. Isolated enterococci were screened for vancomycin resistance and species were identified. Intra-household isolates were genotyped using pulsed-field gel electrophoresis (PFGE).

RESULTS

The participants (n = 228; age range, 28 days to 80 years) were from 137 households with and 91 without employees who had contact with patients. Enterococcus species were isolated from 127 stool specimens (55.7%). VRE were detected in 12 individuals, representing 6 E. casseliflavus, 5 E. faecium, and 1 E. gallinarum. VRE were more commonly isolated in employees who had contact with patients (5 of 52 vs 0 of 40; relative risk [RR], 1.9; 95% confidence interval [CI95], 1.5 to 2.2; P = .07) and their household members (10 of 137 vs 2 of 91; RR, 3.3; CI95, 0.7 to 14.8; P = .13). In 2 households (2 adults in a physician's household and an adult plus a child in a nurse's household) PFGE analysis demonstrated identical intra-household strains of vancomycin-resistant E. faecium.

CONCLUSIONS

VRE colonization was found in 5.3% of screened stools and was more prevalent in HCWs who had contact with patients and their households. Identical PFGE patterns between 2 employees who had contact with patients and their household members demonstrated probable intra-household spread. Although the mode of acquisition was uncertain, the association with employees who had contact with patients suggests possible occupational sources. These findings demonstrate the spread of VRE within the household and implicate occupational risk for its acquisition.

Hygiene of the skin: when is clean too clean?

Skin hygiene, particularly of the hands, is a primary mechanism for reducing contact and fecal-oral transmission of infectious agents. Widespread use of antimicrobial products has prompted concern about emergence of resistance to antiseptics and damage to the skin barrier associated with frequent washing. This article reviews evidence for the relationship between skin hygiene and infection, the effects of washing on skin integrity, and recommendations for skin care practices.

Preliminary analysis of the transmission dynamics of nosocomial infections: stochastic and management effects

A simple mathematical model is developed for the spread of hand-borne nosocomial pathogens such as Staphylococcus aureus within a general medical-surgical ward. In contrast to previous models a stochastic approach is used. Computer simulations are used to explore the properties of the model, and the results are presented in terms of the pathogen's successful introduction rate, ward-level prevalence, and colonized patient-days, emphasizing the general effects of changes in management of patients and carers. Small changes in the transmissibility of the organism resulted in large changes in all three measures. Even small increases in the frequency of effective handwashes were enough to bring endemic organisms under control. Reducing the number of colonized patients admitted to the ward was also an effective control measure across a wide range of different situations. Increasing surveillance activities had little effect on the successful introduction rate but gave an almost linear reduction in colonized patient-days and ward-level prevalence. Shorter lengths of patient stay were accompanied by higher successful introduction rates, but had little effect on the other measures unless the mean time before detection of a colonized individual was large compared to the mean length of stay. We conclude that chance effects are likely to be amongst the most important factors in determining the course of an outbreak. Mathematical models can provide valuable insights into the non-linear interactions between a small number of processes, but for the very small populations found in hospital wards, a stochastic approach is essential.

The effects of 'in-use' surgical handwashing on the pre- and postoperative fingertip flora during cardiothoracic and orthopaedic surgery

Two operating teams (25 persons) were followed for two months with fingerprint samples taken preoperatively; before and after 'in-use' surgical handwashing; and immediately postoperatively, with and without surgical gloves. The mean time for handwashing for the cardiothoracic team (CT) was 2 min and for the orthopaedic team (OT) was 3.5 min. A closer observation of 10 persons revealed a great individual variation in washing techniques, in spite of standard guidelines. The CT team performed eight, and the OT team nine sterile operations with an average duration of 3 h and 20 min and 2 h and 40 min, respectively. Surgical handwashing resulted in fingertip sterility in 111/118 (94.1%) cases; in 61/66 (92.4%) samples from the surgeons and in 50/52 (96.2%) samples from the assistants. Postoperative fingerprinting with gloves on showed sterile conditions in 85/91 (93.4%) samples; 57/59 (96.6%) from the surgeons and 28/32 (87.5%) from the assistants. Immediately after removal of the gloves, 43/67 (64.2%) of fingerprint samples from the surgeons and 13/48 (27.1%) from the assistants were still sterile. Coagulase-negative staphylococci (CNS) and Bacillus species predominated in fingerprint samples. Of the 105 CNS strains tested, 11.4% were methicillin resistant. Only five strains of Staphylococcus aureus were isolated; in 4/5 cases from the OT. This study illustrates that in spite of standard guidelines, there is great individual variation in surgical handwashing. However, in most instances, the bacteria are eradicated from the fingertips. Even after surgery for 2-3 h, there may still be a residual effect of the hand disinfecting agent in half of the cases.

Gram-negative bacteria. The challenge of preventing cross-infection in hospital wards: a review of the literature

Gram-negative bacteria are responsible for a high proportion of nosocomial infections, particularly among the critically ill and those in hospital for long periods. Colonization (asymptomatic carriage on the skin) occurs before the emergence of overt clinical infection (appearance of the signs and symptoms of disease) and is therefore worth reducing. Spread is principally via the hands of staff, so handwashing is the chief method of prevention. Gram-negative bacteria survive best in a moist environment and are more readily transferred via damp than dry surfaces; hands and equipment should therefore be kept as dry as possible. Good skin can also help prevent cross-infection as Gram-negative bacteria colonize damaged skin more readily than if it is in good condition.

Nurses' hands as vectors of hospital-acquired infection: a review

Hospital-acquired infections (HAI) are notorious for the manner in which they complicate the course of the original illness, increase costs of hospital stay and delay recovery. This review will briefly outline the problems presented by HAI in developed countries and present evidence that Staphylococcus aureus and gram negative bacilli, the main causative agents, reach susceptible patients via the contact rather than airborne route, predominantly on the hands of hospital staff. Good hand hygiene could help reduce the economic burden and patient distress caused by HAI, but there is evidence that it is infrequently and poorly performed by nurses, the health care staff most frequently in continuous contact with patients. Possible reasons are explored in an attempt to identify strategies to improve hand hygiene.

Investigations into the efficacy of different procedures for surgical hand disinfection between consecutive operations

In order to examine whether thorough surgical hand disinfection (handwashing plus hand disinfection) between consecutive operations is necessary, tests were carried out simulating normal clinical conditions. The tests were performed according to the guidelines for the evaluation of disinfection procedures of the German Society for Hygiene and Microbiology. Surgical hand disinfection was as follows: handwashing with soap without antimicrobial additives and subsequent 5-min disinfection with 60% n-propanol. This was followed by simulated operations of 30 or 120 min duration with a 30-min break between operations, during which half of the test group kept on the surgical gloves, while the other half removed them. The second surgical hand disinfection was done without prior handwashing by 50% of the test group. The disinfection time was reduced from 5 to 1 min by 50% of the test group. The results were evaluated by means of explorative data analysis and inductive statistical methods. Removing the surgical gloves during the interoperative break did not result in significantly higher numbers of colony forming units (cfu) compared with retaining the gloves. This was also the case after a subsequent handwashing. At the second surgical hand disinfection, after a simulated operation of 60 min duration (including break), there was no significant difference in the numbers of cfus between the test group who had washed their hands and those who had not. Reducing the disinfection time from 5 min to 1 min was not associated with a significant increase in the number of cfus. However, after a simulated operating time of 150 min (including the break), the second surgical hand disinfection with handwashing resulted in a significantly lower number of microorganisms than disinfection alone. In half the tests, the numbers of cfu were significantly lower when the test group disinfected their hands for 5 min rather than 1 min.

Outbreaks of infection with methicillin-resistant Staphylococcus aureus on neonatal and burns units of a new hospital

Multiple introductions of methicillin-resistant Staphylococcus aureus (MRSA) strains occurred to a new hospital in Hong Kong. Two years of clinical microbiological surveillance of the resulting outbreaks was combined with laboratory investigation by phage and antibiogram typing, and plasmid profiling. The outbreaks on the special care baby (SCBU) and burns (BU) units were studied in detail, and colonization of staff and contamination of the environment were investigated. MRSA were spread by the hands of staff on the SCBU, where long-term colonization of dermatitis was important, but were probably transmitted on the BU by a combination of the airborne, transient hand-borne and environmental routes. Simple control measures to restrict hand-borne spread on the SCBU were highly effective, but control was not successful on the BU.

Cleansing of hands with emulsion--a solution to skin problems of hospital staff?

In this study of hand cleansing, nursing staff with skin problems used emulsion followed by rinsing with water, while control groups, with or without skin problems, used liquid soap and water. Clinical evaluation of the without skin problems, used liquid soap and water. Clinical evaluation of the skin by a dermatologist, as well as by self-assessment, suggested that when the staff with skin problems used emulsion their skin was in better condition than that of controls with similar skin problems. This favourable effect on skin was later confirmed in extended use of emulsion for hand cleansing in other hospital wards. Objective evaluation of skin condition with biophysical measurements was unsuccessful. Emulsion cleansing of the hands seems to offer a favourable alternative to washing with soap and water, especially for persons with skin problems.

The efficacy of several new handwashing agents for removing non-transient bacterial flora from hands

Forty subjects participated in a study of four handwashing agents evaluated for their efficacy in removing non-transient bacteria: 70% isopropanol, 0.05% stabilized iodine, 4% chlorhexidine gluconate, and 1% para-chloro-meta-xylenol. Each subject performed a non-medicated handwash to remove transient flora. Afterwards, three consecutive experimental handwashes were performed using a 10-second contact time, and a fourth handwash employed a 1-minute contact time. Quantitative post-handwash cultures were obtained using the sterile bag technique incorporating an effective agent neutralizer. Significant mean log10 reductions were documented for chlorhexidine gluconate, but only after the third (P = .05) and fourth (p = .004) handwash; however, the total log10 reduction was less than 1.0 for any single agent. Subsequently, three evaporative handwash agents, including 70% isopropanol, 0.5% chlorhexidine in 70% isopropanol, and a 60% isopropanol formulation containing evaporative retardants, were tested in 14 subjects. Contact time was prolonged to the point of evaporation prior to culturing. Four consecutive post-handwash cultures were obtained after performing a baseline pre-handwash culture. When compared with the other two evaporative agents, the 60% isopropanol formulation demonstrated significant mean log10 reductions for each handwash (p less than or equal to .03), with a total log10 reduction of 2.9 over all four handwashes (p = .0001). The brief contact time incorporated in our handwashing technique reflects clinical usage patterns. The marked bacterial reduction demonstrated by the 60% isopropanol formulation warrants further study.

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

Whereas infections of the skin per se comprise only a fraction of all institutionally-acquired infections, the skin has become one of the most important reservoirs of nosocomial pathogens in the hospital. Professor Noble has provided a scholarly review of the increasing importance of the major constituents of the cutaneous microflora as nosocomial pathogens and what we know of their epidemiology. Unfortunately, the empiricism and limited scientific data which underlie essential infection control measures in this area, particularly in regard to cutaneous antisepsis and handwashing, is almost incongruous in an era in which controlled clinical trials have dominated most other areas of medicine. The numerous outbreaks traced to contaminated antiseptics and disinfectants over the past two decades, stand as mute testimony to the inadequate investigative attention this area has received.

Hand carriage of aerobic gram-negative rods may not be transient

In order to determine whether hand carriage of aerobic Gram-negative rods is continuous we used the glove-handwash technique to sample the hands of two groups (four each) of health care workers with normal hands (surgical intensive care unit, medical ward) and one group (four) with hand dermatitis (HD) and a group (five) of control subjects -- secretaries with no exposure to patients. Each subject was sampled repeatedly over three to six weeks. The mean number of samples for each group was 25.2, 23.2, 19.8 and 25.8 respectively. The HD group had more samples positive for aerobic Gram-negative rods than did the other two groups of health care workers while the control group had more samples positive than any of the three health care groups. Using various typing schemes and the following definition of continuous carriage (the isolation of an organism of the same serotype, pyocin type or biotype from more than two handwash samples) we found that 4 of 11 subjects from whom Klebsiella pneumoniae was isolated carried this organism continuously; 2 of 3 carried Pseudomonas aeruginosa continuously and 4 of 5 of the control subjects carried the same biotype of Enterobacter agglomerans continuously. We conclude that continuous hand carriage of aeroic Gram-negative rods is common and, among health care workers, those with hand dermatitis carry Gram-negative rods more frequently and in greater numbers than health care workers without hand dermatitis.

Hand carriage of aerobic Gram-negative rods by health care personnel

A quantitative culture technique (hand washed in a glove containing broth for 30 s) was used to determine the frequency of hand carriage of aerobic Gram-negative rods by various groups of health care workers and 104 control subjects. Overall, 31% of health care workers carried aerobic Gram-negative rods on their hands compared to 59% of control subjects (P < 0.001). Enterobacter agglomerans accounted for 40% of the isolates, and other Enterobacter spp. 7%. Other organisms included Acinetobacter calcoaceticus 21%, Serratia spp. 11%, Klebsiella spp. 10%, Moraxella spp. 3%, Pseudomonas spp. 3%, Proteus spp. 1.5%, Escherichia coli 1%; Morganella morganii, Citrobacter freundii, Aeromonas sp. and an isolate that was not speciated accounted for 0.5% each. We conclude that endemic hand carriage of aerobic Gram-negative rods by health care personnel is common, but significantly less than that of control subjects. Enterobacter agglomerans is found so frequently on the hands of control subjects that it must be considered part of the normal hand flora.

A survey of infection in an intensive care unit. "Forewarned is forearmed"

The infection (36%) and mortality rates (28%) were investigated in 433 patients admitted to a Respiratory Intensive Care Unit. It was found that the mortality rate was higher (45%) in the infected group than in the non-infected group (19%) and particularly so in patients who had had intra-abdominal surgery or who remained in the unit for longer than a week.

Handwashing and antiseptic-containing soaps in hospital

Two aspects of handwashing in hospital were considered. A study was carried out to examine the contamination of bar soap and containers, and the use of antiseptic soaps in reducing the resident flora of the skin. Swabs were collected from soap dishes on six wards and from a bacteriology laboratory on four consecutive days. The unmedicated bar soap was replaced by bar soap containing 2.5% povidone-iodine, and further swabs were collected over a period of seven days. Ninety-two isolates from 48 samples were obtained when unmedicated bar soap was used, and nine isolates from 42 samples when povidone-iodine (Betadine) soap was substituted. The number of organisms recovered when povidone-iodine soap was used was much reduced, and Pseudomonas spp were recovered in low numbers on only one occasion. Six laboratory workers took part in a study to compare bar soap with other agents-povidone-iodine soap, povidone-iodine surgical scrub, povidone-iodine alcoholic solution, chlorhexidine surgical scrub, and alcoholic chlorhexidine. Samples were collected after standard washes and after surgical gloves had been worn for 90 minutes. The effect of multiple washes was assessed by samples collected after six washes with the agent under study (three per day) followed by 90 minutes wearing surgical gloves. The average percentage reduction in normal flora obtained indicated that alcoholic chlorhexidine was superior to the other agents.

Failure of hand disinfection with frequent hand washing: a need for prolonged field studies

In a prolonged field trial a 4% chlorhexidine digluconate detergent scrub (Hibiscrub(R)), that had earlier proved to be an effective hand disinfectant, was studied in hospital wards. Finger tips were found to harbour more bacteria than the hand dorsum and the samples collected from them yielded more information on the bacteriological and dermatological effects of hand disinfectants in practice.In wards with a relatively low hand-washing frequency (less than 20 times in 8 hours) the bacteriological results resembled those obtained by in-use tests with volunteers. In the neonatal unit where the hand washing frequency was remarkably high, even occasionally over 100 times/8 h shift, an increase in the bacterial colony counts of the majority of the staff was recorded both before and after hand washing already after using the preparation for 1 week. Age, occupation and hand-washing frequency all correlated with the bacteriological results. Twenty-seven out of 37 persons complained of side effects such as wounds of finger tips and redness or heavy drying of the skin. Wounds, particularly on finger tips, resulted in the failure of disinfection. An increase in bacterial counts was sometimes noted without any dermatological or subjective changes. Drying of the skin was complained of less often when no increase in skin bacteria occurred.After the changeover of washing practice to a detergent followed by a rinse with spirit solution containing chlorhexidine and glycerol a decrease was recorded in the bacterial counts. It is concluded that more attention should be paid to long-term testing of hand washing and disinfection methods to ensure optimum final results in practice. It is obvious that the knowledge obtained from short time in-use testing cannot be applied to all conditions of use.