José Antonio Álvarez

Chlorhexidine is a better antiseptic than povidone iodine and sodium hypochlorite because of its substantive effect

BACKGROUND The present study compared both the antiseptic efficacy of sodium hypochlorite against that of chlorhexidine gluconate in isopropyl alcohol and the substantive effect of chlorhexidine, povidone iodine, and sodium hypochlorite. METHODS This was a 2-step study that included volunteers. In step 1, 4 skin areas were tested for bacteria in colony-forming units (CFU): 2 were controls to determine baseline bacteria or the effect of scrubbing, and 2 were treated with 10% hypochlorite or 2% chlorhexidine in isopropyl alcohol. Every subject was tested 4 times. The second step tested the substantive effect of 10% povidone-iodine and the aforementioned antiseptics. RESULTS For the first step, 30 volunteers were studied, resulting in 120 determinations for each control and antiseptic. No differences between chlorhexidine gluconate (median 115 CFU/cm(2)) and sodium hypochlorite (median 115 CFU/cm(2)) were found. Both antiseptics were significantly different from rubbing control (317 CFU/cm(2)) and basal control (606 CFU/cm(2)). Only chlorhexidine showed a substantive effect. CONCLUSION We consider that chlorhexidine gluconate in isopropyl alcohol, sodium hypochlorite, and povidone-iodine is equally effective for procedures that do not require a long action. However, chlorhexidine is desirable for procedures such as catheter insertion, skin preparation for surgery, or handwashing prior to surgery.

Stethoscopes as potential intrahospital carriers of pathogenic microorganisms

Stethoscopes can take part in the transmission of health care-associated infections. We cultured 112 stethoscopes by direct imprint on blood agar to estimate the prevalence of potentially pathogenic microorganisms. Forty-eight (47%) produced 50 potentially pathogenic microorganisms; from these, 43 (86%) were Staphylococcus aureus, of which 18 (42%) were methicillin-resistant S. aureus. We concluded that stethoscopes should be considered as potential fomites and must be disinfected routinely before and after each patient contact.

Antimicrobial activity of copper against organisms in aqueous solution: a case for copper-based water pipelines in hospitals?

BACKGROUND An association exists between water of poor quality and health care-associated infections. Copper shows microbiocidal action on dry surfaces; it is necessary to evaluate its antimicrobial effect against organisms in aqueous solution. OBJECTIVE The objective was to determine the in vitro antimicrobial activity of copper against common nosocomial pathogens in aqueous solution. METHODS Copper and polyvinyl chloride containers were used. Glass was used as control material. Fourteen organisms isolated from hospital-acquired infections, and 3 control strains were tested. Inocula were prepared by direct suspension of colonies in saline solution and water in each container tested. Bacterial counts in colony-forming units (CFU)/mL were determined at the beginning of the experiment; at 30 minutes; and at 1, 2, 24, and 48 hours. RESULTS Organisms in glass and polyvinyl chloride remained viable until the end of the experiment. Organisms in copper showed a reduction from more than 100,000 CFU/mL to 0 CFU/mL within the first 2 hours of contact (F > 4.29, P < .001). CONCLUSION Copper containers show microbiocidal action on organisms in aqueous solution. Copper may contribute to the quality of water for human use, particularly in hospitals.

Isopropyl alcohol is as efficient as chlorhexidine to prevent contamination of blood cultures

Background: False‐positive blood cultures can lead to unnecessary risks and misuse of antibiotics; to reduce rates of false‐positives, it would be useful to determine whether use of an antiseptic with a prolonged effect is required. Methods: Clinical study of efficacy (blinded and randomized) to compare the rate of blood culture contamination when skin antisepsis was performed with 70% isopropyl alcohol or 2% chlorhexidine gluconate in 70% isopropyl alcohol in 2 hospitals. Patients aged 16 years or older with suspected bloodstream infection who were allocated in the emergency room, internal medicine ward, or intensive care unit were included. Results: Five of 563 (0.9%) blood cultures from the isopropyl arm and 10 of 539 (1.9%) from the chlorhexidine arm were contaminated. No significant differences were observed among the rate of contamination (χ2 = 1.27; P = .3) or the relative risk of contamination (relative risk = 2.09; 95% confidence interval, 0.72‐6.07; P = .2). Conclusions: The rates of blood contamination were not different when isopropyl alcohol and chlorhexidine were compared. Isopropyl alcohol could be used for skin antisepsis before blood collection.

Decontamination of stethoscope membranes with chlorhexidine: Should it be recommended?

OBJECTIVE To determine differences in the recontamination of stethoscope membranes after cleaning with chlorhexidine, triclosan, or alcohol. METHODS Experimental, controlled, blinded trial to determine differences in the bacterial load on stethoscope membranes. Membranes were cultured by direct imprint after disinfection with 70% isopropyl alcohol, 1% triclosan, or 1% chlorhexidine and normal use for 4 hours. As a baseline and an immediate effect control, bacterial load of membranes without disinfection and after 1 minute of disinfection with isopropyl alcohol was determined as well. RESULTS Three hundred seventy cultures of in-use stethoscopes were taken, 74 from each arm. In the baseline arm the median growth was 10 CFU (interquartile range [IQR], 32-42 CFU); meanwhile, in the isopropyl alcohol immediate-effect arm it was 0 CFU (IQR, 0-0 CFU). In the arms cultured after 4 hours, a median growth of 8 CFU (IQR, 1-28 CFU) in the isopropyl alcohol arm, 4 CFU (IQR, 0-17 CFU) in the triclosan arm, and 0 CFU (IQR, 0-1 CFU) in the chlorhexidine arm were seen. No significant differences were observed between the bacterial load of the chlorhexidine arm (after 4 hours of use) and that of the isopropyl alcohol arm (after 1 minute without use) (Z= 2.41; P > .05). CONCLUSIONS Chlorhexidine can inhibit recontamination of stethoscope membranes and its use could help avoid cross-infection.

Chlorhexidine avoids skin bacteria recolonization more than triclosan

BACKGROUND We do not know whether differences exist between the residual effect of 2% chlorhexidine in 70% isopropyl alcohol when compared with 1% triclosan in 70% isopropyl alcohol. METHODS Using an analytic, longitudinal, controlled, and comparative experimental trial, with blinded measurements, we recruited healthy, adult volunteers from the University of Guanajuato who completed a stabilization phase of skin microbiota and had no history of skin allergies. Four 25-cm2 areas of the inner surface of the forearms were designated for study: unscrubbed control for establishing baseline bacterial counts, scrubbed control with tridistilled water, scrubbed with chlorhexidine, and scrubbed with triclosan. Quantitative cultures were taken of all the areas at 0, 3, and 24 hours, using agar plates with neutralizing agents. RESULTS A total of 135 healthy volunteers were tested. At 24 hours, the unscrubbed control counts were 288 CFU/cm2, whereas the scrubbed control counts were 96 CFU/cm2; 24 CFU/cm2 for chlorhexidine and 96 CFU/cm2 for triclosan (Kruskal-Wallis χ2H = 64.27; P <.001). CONCLUSIONS Chlorhexidine is the best antiseptic option when a prolonged antiseptic effect is needed; for instance, when implanting medical devices or performing surgical procedures.

Role of chlorhexidine bathing in infection control.

Cassir et al1 collected data to assess the impact of chlorhexidine daily bathing on the incidence of hospital-acquired infection. They concluded a significant reduction of the rates of infections related to medical devices and the infections caused by gram-negative bacilli. These findings contrast with a recent publication by Noto et al,2 inwhich the authors concluded in an apparent lack of benefit from chlorhexidine bathing. We would like to make 2 observations regarding these studies. First, authors of both studies state that unnecessary exposure may result in the development of reduced susceptibility to chlorhexidine, which they equate to resistance. Previously, Suwantarat et al,3 showed that the minimal inhibitory concentration and minimal bactericidal concentration of chlorhexidine are higher for some clinical isolates from units where chlorhexidine baths are used; typical susceptibility reduction goes for 1 or 2 dilutions (eg, 4-8 or 4-16 mg/mL). However, 2% chlorhexidine baths act at topical levels of 20,000 mg/mL; even at the very lowest concentration used for chlorhexidine (0.06%), the topical concentration is 600 mg/mL, which is orders of magnitude above the minimal inhibitory concentration or minimal bactericidal concentration. Then, the authors made the commonmistake of equalizing induced resistance to antibiotics (a common phenomenon) with induced resistance to antiseptics (a phenomenon that no one has been able to demonstrate). Second, contrary to Noto et al, Cassir et al found a significant reduction in the rate of hospital-acquired infection. This may be caused by the basal rate of hospital infections and the analysis of each kind of infection and the causing agents. In our view, the fractionated analysis of Cassir et al allows a better understanding of the effect of chlorhexidine baths in infection control. In hospitals where specific health careerelated infections are near elimination, it is not surprising that the use of chlorhexidine baths might be of little help and have a low benefit-cost ratio; chlorhexidine would still be a valid option for infection control in many hospitals with higher rates of infection. Although more research is needed, we believe that the study of Cassir et al shows more objectively the eventual role of chlorhexidine in infection control. The effects of chlorhexidine bathing on infection control may be mainly caused by a reduction in the rate of infections by gram-negative bacilli, which could be related not to the antiseptic effect of chlorhexidine itself, but just to avoiding contact of the medical devices with tap water. In a recent study on hospitals in Mexico, only 1 of 53 hospitals had an adequate concentration of chlorine in tap water4; under such conditions, disposable baths could be of much more benefit. Bed baths, however, remain prevalent in the idiosyncrasies of both nurses and patients, and chlorhexidine baths are unavailable or costly in many hospitals worldwide. References

Salvaging diabetic foot through debridement, pressure alleviation, metabolic control, and antibiotics

There is a fatalist perception of diabetic foot because the argument of “small‐vessel disease” prevails. This is the report of a cohort study of patients facing a formal recommendation for major foot amputation to assess how many can be saved with a conventional treatment, defined as debridement, pressure alleviation, metabolic control, and antibiotics. The primary efficacy measurement was the salvage of the limb at the follow‐up visit between 25 and 35 days after the first consultation. The secondary efficacy measurement was the subsequent epithelization of the ulcerative lesions, following patients for up to 270 days. The cohort consisted of 105 type 2 diabetic patients; 87 (83%) had severe lesions. A total of 71 patients (68%) required hospitalization. By the intention‐to‐treat analysis, 89 patients (85%) avoided major amputation. A total of 88 patients were evaluated for complete epithelization, reaching median success by day 120. Overall, 51 patients (49%) underwent minor amputations. It was concluded that there is a high rate of unnecessary major foot amputations, because a diabetic foot can be salvaged across the continuum of severity when patients receive care in a multidisciplinary wound clinic.

Scheduling a plan with delays in time: a CSP approach

In many realistic planning domains, the exact duration of actions is only known at the instant of executing the action. This is the case, for instance, of temporal domains where it is common to find external factors that cause a delay in the execution of actions. In this paper we present an approach to obtain a plan for a temporal domain with delays. Our approach consists in combining a planning process, from which a temporal plan is obtained, and a scheduling process to allocate (instantiate) such a temporal plan over a time line.