The effect of antibacterial agents on the flora of the skin

Comparative efficacy of three antiseptics as surgical skin preparations in dogs

OBJECTIVE

To compare the antimicrobial efficacy of a 2% chlorhexidine gluconate and 70% ethanol solution (CG+A) with that of F10 Skin Prep Solution (F10) and electrochemically activated water (EAW) when used as a surgical preparation in canine patients.

STUDY DESIGN

Prospective randomized clinical study.

SAMPLE POPULATION

One hundred sixteen dogs presented for ovariohysterectomy.

METHODS

Dogs were randomly divided into 1 of the 3 antiseptic groups (CG+A, F10, EAW). Skin samples with replicating organism detection and counting plates were taken at 4 different perioperative sites and time intervals (postskin preparation, postskin antisepsis, 2 hours after the second sample, and at the end of surgery) during ovariohysterectomies performed by students. The colony forming unit (CFU) counts from each sample were quantified according to the level of bacterial contamination. Zero CFU was defined as no contamination, 1-12 CFU was defined as low contamination, and greater than 12 CFU was defined as high contamination. The 3 antiseptics were compared with respect to the level of contamination.

RESULTS

There was no difference in the level of colonization between the antiseptics at the first sampling time (P = .454). However, the level of contamination for CG+A was lower compared with F10 and EAW at the second, third, and fourth sampling times (P =  .001, P =  .01, P =  .02, respectively).

CONCLUSION

CG+A was more effective at achieving a zero CFU count and low levels of contamination compared with F10 and EAW for surgical preparation in dogs undergoing ovariohysterectomy.

CLINICAL SIGNIFICANCE

This study does not provide evidence to support the use of F10 and EAW instead of CG+A for the surgical skin preparation of dogs undergoing ovariohysterectomy.

Hospitals as factories of medical garbage

Over the course of the twentieth century, as hospitals cleaned up, they came to produce more and more rubbish. Beginning in the 1970s and gaining pace in the 1980s and 1990s, single-use plastic items (syringes, blood bags, tubing) saturated everyday medical practice across the globe. This essay brings the question of plastic to bear upon the longer history of twentieth century sanitary science. The widespread adoption of single-use disposable medical plastics consolidated a century's worth of changes in medical hygiene. As strange as it may seem today, the initial uptake of medical plastics was not driven primarily by concerns about hygiene. Plastic began as a mid-century technology of convenience and durability. It was not until the end of the twentieth century that it morphed into a powerful symbol and instrument of medical hygiene. Today, both patients and practitioners have embraced plastic as an indispensable technology of clean medicine. The procession of single-use medical plastics through everyday medicine now comprises a constant, if disposable, infrastructure of medical hygiene. This new processional infrastructure of disposable hygiene has produced another, albeit unintended, consequence. This new regime has exponentially increased hospitals' material outputs. In so doing, plastic has refigured the ecologies of everyday medicine. Plastic hygiene has rendered hospitals factories of medical garbage.

Effect of Hand Antisepsis Agent Selection and Population Characteristics on Surgical Site Infection Pathogens

BACKGROUND

Selection of a pre-operative hand antisepsis agent has not been studied in relation to surgical site infection (SSI) culture data. In our hospital, we introduced an alcohol-based hand rub (ABR) in 2012 as an alternative to traditional aqueous surgical scrubs (TSS). It was the goal of this study to review any effect of this implementation on SSI pathogen characteristics. In addition, we sought to compare our SSI culture data with available National Healthcare Safety Network (NHSN) data. We hypothesized that SSI pathogens and resistant isolates are affected by surgical hand antisepsis technique.

METHODS

Data collected prospectively between 2007 and 2014 were retrospectively analyzed for two time periods at the Veterans Affairs Boston Healthcare System (VABHS): Before ABR implementation (TSS group) and after (ABR group). Pathogen distribution and pathogenic isolate resistance profiles were compared for TSS and ABR, and similar comparisons, along with procedure-associated SSI comparisons, were made between VABHS and NHSN. All VABHS data were interpreted and categorized according to NHSN definitions.

RESULTS

Compared with TSS (n = 4,051), ABR (n = 2,293) had a greater rate of Staphylococcus aureus (42.6% vs. 38.0%), Escherichia coli (12.8% vs. 9.9%), Pseudomonas aeruginosa (8.5% vs. 2.8%), and Enterobacter spp. (10.6% vs. 2.8%), and a lower rate of Klebsiella pneumoniae/K. oxytoca (4.3% vs. 8.5%) cultured from superficial and deep SSIs (p < 0.05). Of the S. aureus isolates, 35.0% and 44.4% were resistant to oxacillin/methicillin (MRSA) in ABR and TSS, respectively (p = 0.06). Looking at all SSIs, coagulase-negative staphylococci and K. pneumoniae/K. oxytoca at VABHS (4.0% and 10.4%, respectively) accounted for the biggest difference from NHSN (11.7% and 4.0%, respectively). Aside from MRSA, where there was no difference between VABHS and NHSN (42.9% vs. 43.7%, respectively; p = 0.87), statistically significant (p < 0.05) differences were observed among multi-drug-resistant K. pneumoniae/K. oxytoca (0% vs. 6.8%, respectively) and Escherichia coli (10.0% vs. 1.6%, respectively), as well as among extended-spectrum cephalosporin-resistant K. pneumoniae/K. oxytoca (4.8% vs. 13.2%, respectively) and Enterobacter (58.3% vs. 27.7%, respectively). VABHS had a greater proportion of SSIs in abdominal and vascular cases than did NHSN (48.6% vs. 22.5% and 13.2% vs. 1.5%, respectively). Overall, these differences were significant (p < 0.05).

CONCLUSIONS

The TSS and ABR groups differed in the distribution of pathogens recovered. Those differences, along with SSI pathogen distribution, pathogenic isolate resistance profiles, and procedure-associated SSIs between VABHS and NHSN, warrant further investigation.

Update on Surgical Principles and Equipment

The diversity implicit in exotic animal surgery requires a tailored approach to optimize successful outcomes. Outlined is information on patient preparation, instrumentation, hemostatic techniques, and magnification as it pertains to the exotic animal. Application of topical antiseptic solutions and judicious removal of pelage and feathers will decrease bacterial load during patient preparation. The use of specific barrier protection ensures proper aseptic technique and enables optimal patient monitoring. Magnification combined with a focal light source enhances visual acuity, allowing for better use of delicate instrumentation and identification of anatomic structures.

A test procedure for evaluating surgical hand disinfection

A technique for assessing the immediate and prolonged efficacy of surgical scrubs and alcoholic hand rubs is described. A mean baseline count is obtained from all volunteers and logarithmic reductions in resident skin flora immediately after one or more applications, and after wearing gloves for 3 h, are measured. Loose-fitting surgical gloves are used for sampling resident flora. Preparations were applied using a standard technique for 2 min, apart from one test with 70% isopropanol (IPA) in which the application time was 30 s. Two studies are described, one of which compared four chlorhexidine scrubs, and the second 70% IPA, 7.5% povidone-iodine scrub, 2% triclosan cleanser and unmedicated bar soap. In spite of their constituent similarity, the four chlorhexidine scrubs varied considerably in efficacy and user acceptability. A 2 min application of 70% IPA was the most effective treatment, and gave log10 reductions of 1.65 for immediate and 1.58 for prolonged effect. This was marginally more effective than a 30 s application, but the difference was not significant. 'Hibiscrub' was the most effective aqueous formulation and gave reductions of 1.01 for immediate effect and 1.16 for prolonged effect. The test described could be used by reference centres and manufacturers to assess the efficacy of new and existing surgical hand disinfection formulations.

The effect of surgical handwashing routines on the microbial counts of operating room nurses

Many factors may affect the efficiency of handwashing techniques. This study examined two interdependent factors: the time taken to wash the hands and the type of antiseptic solution used. A 3-minute initial scrub and 30-second consecutive scrub regimen was compared with a current standard regimen of a 5-minute initial scrub and a 3-minute consecutive scrub. Chlorhexidine gluconate 4% and povidone-iodine 7.5% were the antiseptics used in the two regimens. The sample (n = 34) was drawn from nurses employed in the operating room suite of a 950-bed hospital. Chlorhexidine gluconate was found to be responsible for lower numbers of colony-forming units of bacteria than povidone-iodine. The duration of the scrub had no significant effect on the numbers of bacteria when povidone-iodine was used. The optimal regimen was found to be the 5-minute initial and 3-minute consecutive scrubs with chlorhexidine gluconate.

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.

Reduction in amputation stump infection by antiseptic pre-operative preparation

The prevalence of ischaemic or infective delayed wound healing in amputations for peripheral vascular disease may vary from 18 to 40%. A prospective trial to test the efficacy of 12 h pre-operative preparation with 10% povidone-iodine was performed in a 1-year period, during which time 80 consecutive amputations were performed on 73 patients. Accrual to the treatment arm was incomplete and was principally due to extreme nursing shortages. Failure of randomization resulted in the study being analysed as if it were retrospective. Infection occurred in 14 (23%) of unprepared limbs but was not found in any of the 19 prepared limbs (P less than 0.05). Infection occurred in 11 of 34 unprepared limbs which had distal ulcers or moist gangrenous lesions; however, 15 prepared limbs which had similar distal lesions had no infection (P less than 0.025). The reduction of wound breakdown and infection resulted in a significant reduction in hospitalization prior to commencement of prosthetic fitting (P less than 0.001). Pre-operative antiseptic preparation played an important role in the reduction of infection following amputation for peripheral vascular disease, particularly for those patients whose amputation was required because of contaminated peripheral ischaemic lesions. However, these preliminary results should be confirmed by further study.

In vivo standardization of cutaneous bactericidal activity of antiseptics by using monoxenic hairless mice

This study was designed to investigate the bactericidal activities of antiseptics on the cutaneous flora of hairless mice monoxenic to Staphylococcus epidermidis, Staphylococcus aureus, or Pseudomonas aeruginosa in vivo. A standardized method for testing such antiseptics to compare their bactericidal effectiveness in humans in described. Seven antiseptics belonging to seven different chemical groups (iodine derivatives, alcohols, mercury compounds, quaternary ammonium salts, biguanides, phenols, and carbanilides) were used as recommended by the manufacturers (conditions of contact or prolonged contact time followed by washing with distilled water). Germfree hairless mice were infected with various bacterial strains by gastric intubation, producing levels of about 10(3) CFU/cm2 of skin. The antiseptic under test was placed on the right or left side of the ventral region. The contralateral side served as a control. In order to standardize the method, a number of crucial parameters were carefully controlled: the amount of antiseptic applied, the area of skin treated, the duration of treatment, and the washing procedure. Skin samples were obtained by cutaneous biopsy, which effectively removed all the bacteria along with the sample. The bacterial populations were counted before and after application of the antiseptic. Reductions of between 0.5 and 1.9 log units were obtained; these are comparable to those observed in humans. The standardization of our procedure and the use of animals with a strictly controlled flora eliminated much of the variability and sources of error inherent in human studies. This model could be of value for the study of resistant bacterial strains responsible for nosocomial infections and for investigations of damaged skin.

Hand disinfection: a comparison of various agents in laboratory and ward studies

The efficacy of 14 handwashing or disinfectant preparations was compared in laboratory tests on staff volunteers. The test organism, Escherichia coli, was applied to the fingertips and log reductions (LR) were measured following treatment with the test agent and control preparations (70% isopropanol and non-medicated bar soap). Alcoholic preparations, particularly n-propanol and isopropanol were the most effective showing LRs of 3.1-3.8. Chlorhexidine (LR 2.9) and povidone-iodine detergent preparations were significantly more effective than non-medicated soap (LR 2.1), but triclosan products were not. In addition the residual effect of several of these formulations was assessed after 10 applications by comparing the survival of E. coli on the fingertips over a 32-min period. This number of handwashes compares favourably with those recorded during an 8 h nursing shift. Chlorhexidine-detergent consistently showed the best residual activity. Alcoholic formulations showed little or no residual effect. The survival studies show that on the whole gram-positive organisms (Staphylococcus aureus and Candida albicans) survive better on the skin than Gram-negative bacilli (GNB). However, it would seem that GNB which are considered to be residents (Acinetobacter calcoaceticus and Enterobacter spp.) survive much better than many other GNB (Pseudomonas aeruginosa, E. coli and Proteus vulgaris). The Klebsiella species varied in survival times. Random sampling of ward staff hands showed that contamination with S. aureus and GNB was greater in dermatological and general wards than in an isolation unit, where handwashing or disinfection was carried out after every patient contact. No cross-infection occurred in the isolation ward during periods of study in which 70% alcohol, chlorhexidine-detergent and non-medicated soap were used.

Gram-negative bacilli as nontransient flora on the hands of hospital personnel

The possibility that gram-negative bacilli (GNB) are part of the nontransient flora on hands was examined by using a broth rinse technique to detect low titers of GNB after a hygienic hand wash with soap and water. A total of 100 nurses who had direct patient contact and 40 controls without patient contact had a similar rate of recovery of GNB (46 and 55%, respectively). GNB persisted on the hands of 10 nurses throughout five successive hand washes with soap and water. Hand cultures were obtained daily from 12 nurses before and after a work shift in a surgical intensive care unit. GNB were recovered from 57% of individuals before patient contact and from only 24% after the work shift. Nontransient GNB on the hands of hospital personnel are a potential reservoir for hospital strains, and patient contact is not an obvious source for the acquisition of nontransient GNB.

Wound infection after cesarean section

A prospective multicenter study of 1,032 cesarean sections was performed to identify risk factors for postoperative wound infection. The overall rate of wound infection was 6.6% (3.8% in elective cases and 7.5% following nonelective operations), with considerable interhospital variation. Obesity was recognized as a patient-related risk factor, while risk factors inherent to the obstetric situation were duration of ruptured membranes prior to operation, fetal and labor monitoring by intrauterine devices, and omission of the use of plastic draping and redisinfection of the skin before closure. Logistic regression analysis was used to estimate the influence of these factors on the probability of wound infection. Certain risk factors associated with and over-represented in nonelective operations would explain the increased infection rates in these, and the observed interhospital variations did not differ from the expected rates when the distribution of other risk factors was considered.

Nosocomial infection--the irreducible minimum

Prevalence surveys in different countries have shown that about 1 in 10 hospitalized patients at any one time have acquired an infection and the incidence of infection is usually about 3% to 5%. Can this infection rate be significantly reduced and is there an irreducible minimum below which further reduction cannot be obtained? Cross-infection could probably be almost eliminated by the use of plastic isolators or life islands, and endogenous infections reduced by the wider and more rational prophylactic use of topical and systemic antimicrobial agents, and possibly a range of vaccines. However, the use of these techniques on all patients would clearly be impractical and too expensive for use in the foreseeable future. Excessive isolation techniques would have a detrimental psychological effect on many patients. In addition, failure to eradicate the organisms of the normal flora might be associated with more infections caused by antibiotic-resistant bacteria, fungi and viruses which would be more difficult to treat. Even if organisms could be eradicated, morbidity and mortality might not be correspondingly reduced. Priorities must therefore be set on the most effective use of staff and finances. These not only involve a consideration of infection, but all areas of clinical practice, eg, costs of cardiac transplants and provision of geriatric facilities. It therefore seems likely that little additional finance will be available for control of infection, other than possibly for transmissible infections with high mortality such as AIDS.

The bactericidal activity of aqueous disinfectants applied on living tissues

Thirteen antiseptic aqueous solutions intended for the disinfection of living tissues were compared in regard to their microbicidal effectiveness towards. Staphylococcus aureus and Pseudomonas aeruginosa. Six antiseptics, which contain boric acid, eosine, hydrogen peroxide or an organic mercury compound as the active substance, did not fulfil the requirements of the preliminary in vitro test. The seven other preparations were examined in a practical test, in which bactericidal activity was assessed on artificially contaminated intact skin after exposures of 15 s and 60 s. The most active solution appeared to be 0.5% tosylchloramide sodium, followed by 0.05% chlorhexidine with 0.5% cetrimide. The other preparations, namely 0.05% chlorhexidine without cetrimide, 0.245% chloroxylenol, 0.04% clorofene, 10% povidone-iodine and 0.2% tosylchloramide sodium, were less active in this practical test.

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.