Zinc-Impregnated Mesh for Abdominal Wall Repair Reduces Infection in a Rat Model of Peritonitis.

BACKGROUND: The objective of this study was to assess whether a zinc-impregnated polypropylene mesh (ZnMesh) has better antibacterial properties in a contaminated environment compared with a regular polypropylene mesh. MATERIALS AND METHODS: Thirty-eight Wistar Han rats underwent cecal ligation and puncture to induce peritonitis 24 h before implantation of an intraperitoneal ZnMesh or a regular polypropylene mesh. Primary outcome was the number of colony forming units (CFU) per sample (mesh and abdominal wall). Secondary outcomes were macroscopic (incorporation of mesh, abscesses, and adhesions on mesh surface) and histological (inflammatory cell reaction, mesh-specific parameters, and collagen deposition) parameters. All outcomes were evaluated after 30 and 90 d. RESULTS: After 30 d, no significant difference in CFU per sample was present between the ZnMesh and control groups. After 90 d, a lower number of CFU per sample was present in the ZnMesh group compared with the control group (trypticase soy agar with 5% sheep blood: 0 log10 CFU/sample IQR: 0-1.40 versus 1.58 log10 CFU/sample IQR: 0-4.30, P = 0.012; MacConkey: 0 log10 CFU/sample IQR: 0-2.65 versus 1.18 log10 CFU/sample IQR: 0-4.04, P = 0.438). After 90 d, the percentage of adhesions on mesh surface was significantly higher in the ZnMesh group (95% IQR: 60%-100% versus 50% IQR: 23%-75%, P = 0.029). No differences were seen in other macroscopic outcomes or histology. CONCLUSIONS: A significantly lower number of CFU per sample was found in the ZnMesh group after 90 d. After 30 d, no statistically significant differences in CFU per sample were seen. This result suggests that the ZnMesh group has better antibacterial properties in a contaminated environment. However, this is at the cost of a significantly higher percentage of adhesions.

Seasonal changes in indoor airborne fungal concentration in a hematology ward.

Invasive fungal disease (IFD) is an important infectious complication of hematological disorders, especially in hematopoietic stem cell transplantation recipients. Evidences suggest seasonal and/or geographical variations in the airborne fungal counts and a relationship between those counts and the incidence of IFD. We evaluated the concentrations of indoor airborne fungi quantitated over the course of one year in a hematology ward in Japan. In January, April, July, and October, fixed volumes of air samples were obtained by an air sampler in a hematology ward not equipped with a high-efficiency particulate air filter and incubated in fugal cultures. Samples were also obtained from a protective environment in the same ward and were evaluated. The number of fungal colonies per 50 L of sampled air was highest in October (median 2.25 (range, 0.2-7.0)), which was significantly higher than those in the other three months (0.1 (range, 0-1.0) in January; 0 (0-0) in April; 0.55 (0-2.5) in July; P < 0.01)). Commonly identified pathogens included Penicillium and Cladosrporium species, but Aspergillus species was detected only in July and October samples. These results suggest a seasonal variation in indoor airborne fungal concentrations in Japan, which could affect the epidemiology of IFD.

Risk factors and outcomes of culture-proven acute Coccidioides spp. infection in San Diego, California, United States.

BACKGROUND: Coccidioides spp. are dimorphic fungi endemic to parts of the United States, Mexico, Central and South America. Infection can cause a range of disease from self-limited acute pneumonia to severe disseminated disease. METHODS: We performed a retrospective chart review of medical records of cases of culture-proven acute coccidioidomycosis at the University of California San Diego between 1 April 2015 and 31 December 2019 and described the demographics, risk factors and outcomes of these cases. RESULTS: Over the study period, fifteen evaluable cases of culture-proven acute coccidioidomycosis were identified. Of these, 87% (13/15) had traditional risk factors for coccidioidomycosis infection while two lacked known risk factors, including one patient with cirrhosis and one with chronic hepatitis C infection. Seven of fifteen (47%) had primary coccidioidomycosis of the lungs without dissemination and 7/15 (47%) disseminated disease. Of those with disseminated disease, 6/7 (86%) had either high-risk ethnicity or blood type as their only risk factor. At 90 days, 11/15 (73%) were alive, 3/15 (20%) deceased and 1/15 (7%) lost to follow-up. Of those not alive at 90 days, 1/3 (33%) had disseminated disease and 2/3 (67%) primary coccidioidomycosis, both on immunosuppressive therapy. DISCUSSION: Coccidioides spp. infection occurs in a variety of hosts with varying underlying risk factors, with the majority in our cohort overall and 86% with disseminated disease lacking traditional risk factors for invasive fungal infection other than ethnicity and/or blood phenotype. Clinicians should be aware of these non-traditional risk factors in patients with coccidioidomycosis infection.

Characterization of Escherichia coli possessing the locus of heat resistance isolated from human cases of acute gastroenteritis.

The purpose of this study was to identify Escherichia coli isolates obtained from patients experiencing acute gastroenteritis that possess the locus of heat resistance (LHR) and characterize their heat resistance upon exposure to temperatures of 60 °C and 71 °C. From a collection of 613 clinical E. coli strains, 3 heat resistant E. coli isolates were identified. Two of the 3 isolates were stx1 positive; no isolates possessed stx2 as determined by qPCR. D60-values of heat resistant isolates all exceeded 10.20 min with one isolate's D60-values ranging from 20.46 to 72.47 min. The presence of 4% additional NaCl significantly increased D60-values of 2 clinical isolates. Cell reductions of heat resistant isolates in ground beef patties grilled to 60 °C and 71 °C remained above 2.8 and 4.9 log CFU/mL, respectively, compared to reductions of 6.1 log CFU/mL and greater in heat sensitive E. coli. Constitutive expression of novel Clp protease ClpK, encoded on open reading frame 3 of the LHR, was identified in all heat resistant isolates by SDS-PAGE and peptide mass fingerprinting. This data is the first to report heat resistant E. coli possessing the LHR involved in clinical infection, highlighting the potential threat of heat resistant enteric pathogens on food safety.

Microbial study of household hygiene conditions and associated Listeria monocytogenes infection risks for Peruvian women.

OBJECTIVES: To develop an exposure and risk assessment model to estimate listeriosis infection risks for Peruvian women. METHODS: A simulation model was developed utilising Listeria monocytogenes concentrations on kitchen and latrine surfaces in Peruvian homes, hand trace data from Peruvian women and behavioural data from literature. Scenarios involving varying proportions of uncontaminated, or 'clean', surfaces and non-porous surfaces were simulated. Infection risks were estimated for 4, 6 and 8 h of behaviours and interactions with surfaces. RESULTS: Although infection risks were estimated across scenarios for various time points (e.g. 4, 6, 8 h), overall mean estimated infection risks for all scenarios were ≥ 0.31. Infection risks increased as the proportions of clean surfaces decreased. Hand-to-general surface contacts accounted for the most cumulative change in L. monocytogenes concentration on hands. CONCLUSIONS: In addition to gaining insights on how human behaviours affect exposure and infection risk, this model addressed uncertainties regarding the influence of household surface contamination levels. Understanding the influence of surface contamination in preventing pathogen transmission in households could help to develop intervention strategies to reduce L. monocytogenes infection and associated health risks.

OBJECTIFS: Développer un modèle d'exposition et d'évaluation des risques pour estimer les risques d'infection par la listériose chez les femmes péruviennes. MÉTHODES: Un modèle de simulation a été développé en utilisant des concentrations de Listeria monocytogenes sur la surface des cuisines et des latrines dans des foyers péruviens, des données de traces de mains de femmes péruviennes et des données comportementales de la littérature. Des scénarios impliquant différentes proportions de surfaces non contaminées ou «propres¼ et de surfaces non poreuses ont été simulés. Les risques d'infection ont été estimés pour 4, 6 et 8 heures de comportements et d'interactions avec les surfaces. RÉSULTATS: Bien que les risques d'infection aient été estimés pour tous les scénarios à différents moments (par ex. à 4, 6 ou 8 heures), les risques d'infection globaux moyens estimés pour tous les scénarios étaient ≥ 0,31. Les risques d'infection augmentaient à mesure que les proportions de surfaces propres diminuaient. Les contacts entre la main et les surfaces générales contribuent pour le plus de changement cumulatif de la concentration de L. monocytogenes sur les mains. CONCLUSIONS: En plus de comprendre comment les comportements humains affectent l'exposition et le risque d'infection, ce modèle a traité des incertitudes quant à l'influence des niveaux de contamination des surfaces ménagers. Comprendre l'influence de la contamination de surface dans la prévention de la transmission d'agents pathogènes dans les ménages pourrait aider à développer des stratégies d'intervention pour réduire l'infection à L. monocytogenes et les risques associés pour la santé.

Statistical Package for Growth Rates Made Easy.

Growth rates are an important tool in microbiology because they provide high throughput fitness measurements. The release of GrowthRates, a program that uses the output of plate reader files to automatically calculate growth rates, has facilitated experimental procedures in many areas. However, many sources of variation within replicate growth rate data exist and can decrease data reliability. We have developed a new statistical package, CompareGrowthRates (CGR), to enhance the program GrowthRates and accurately measure variation in growth rate data sets. We define a metric, Variability-score (V-score), that can help determine if variation within a data set might result in false interpretations. CGR also uses the bootstrap method to determine the fraction of bootstrap replicates in which a strain will grow the fastest. We illustrate the usage of CGR with growth rate data sets similar to those in Mira, Meza, et al. (Adaptive landscapes of resistance genes change as antibiotic concentrations change. Mol Biol Evol. 32(10): 2707-2715). These statistical methods are compatible with the analytic methods described in Growth Rates Made Easy and can be used with any set of growth rate output from GrowthRates.

Robust fit of Bayesian mixed effects regression models with application to colony forming unit count in tuberculosis research.

Early bactericidal activity of tuberculosis drugs is conventionally assessed using statistical regression modeling of colony forming unit (CFU) counts over time. Typically, most CFU counts deviate little from the regression curve, but gross outliers due to erroneous sputum sampling are occasionally present and can markedly influence estimates of the rate of change in CFU count, which is the parameter of interest. A recently introduced Bayesian nonlinear mixed effects regression model was adapted to offer a robust approach that accommodates both outliers and potential skewness in the data. At its most general, the proposed regression model fits the skew Student t distribution to residuals and random coefficients. Deviance information criterion statistics and compound Laplace-Metropolis marginal likelihoods were used to discriminate between alternative Bayesian nonlinear mixed effects regression models. We present a relatively easy method to calculate the marginal likelihoods required to determine compound Laplace-Metropolis marginal likelihoods, by adapting methods available in currently available statistical software. The robust methodology proposed in this paper was applied to data from 6 clinical trials. The results provide strong evidence that the distribution of CFU count is often heavy tailed and negatively skewed (suggesting the presence of outliers). Therefore, we recommend that robust regression models, such as those proposed here, should be fitted to CFU count.

Perception and Practice of HIV/AIDS Counseling and Testing Among Secondary School Adolescents in Ogun Waterside Local Government Area, Ogun State, Southwest Nigeria.

A large proportion of Nigerian adolescents are sexually active and the country has one of the highest HIV prevalence among youths globally. This study was done to assess the perception and practice of HIV/AIDS counseling and testing (HCT) among secondary school adolescents in a rural community in Southwest Nigeria. A cross-sectional descriptive study was carried out using multistage sampling method. The results showed that despite high level of HCT awareness, majority of the adolescents (62.9%) had negative attitude toward it. The practice of HCT was poor among majority of the respondents as less than 15% of the adolescents had ever done HCT. This study recommends that adolescents should be better informed on the locations of the health centers within the community and services rendered by them. Peer education on HCT should also be intensified in schools to promote positive healthy sexual lifestyles among adolescents.

Microbiological quality of pastrami and associated surfaces at the point of sale in Kayseri, Turkey.

OBJECTIVE: The aim of this study is to trace the possible relations between the hygienic status of slicing utensils and the microbiological quality of pastrami. STUDY DESIGN: A total of 75 pastrami retail markets were visited in Kayseri, Turkey, where the pastrami (a ready-to-eat meat product) is commonly produced and consumed. Sliced pastrami, the cutting board and knife surface swabs were collected from each pastrami retail point to trace possible sources of contamination. METHODS: Samples were analysed for the presence of total viable counts (TVC), total coliforms, Escherichia coli, members of Enterobacteriaceae, Staphylococcus aureus and Listeria spp. In addition, pastrami samples were analysed for sulphite-reducing Clostridium spp. and Toxoplasma gondii. RESULTS: When compared with the target values of related literatures, a total of 6 (8%) pastrami samples were found unsatisfactory as a result of TVC (5.3%), Enterobacteriaceae (5.3%), E. coli (2.6%), S. aureus (2.6%), Listeria spp. (2.6%) and Listeria monocytogenes (1.3%) contaminations. No T. gondii positivity was observed among the pastrami samples. None of the cutting board and knife surface swabs were found to harbour TVC level >103 cfu/cm2, E. coli and L. monocytogenes. For the total coliforms, 7 (9.3%) and 5 (6.6%) of cutting board and knife surface swabs were found to exceed the target value (<2.5 cfu/cm2), respectively. No statistically significant correlation was detected between the organisms on pastrami and slicing utensils indicating that pastrami were not cross-contaminated by the contact surfaces. CONCLUSION: More emphasis needs to be placed for training of food handlers and to apply good hygienic practices at the point of pastrami sale. The conditions at retail points must be monitored and inspections should be tightened to protect public health.

No Evidence of Increased Infection Risk with Forced-Air Warming Devices: A Systematic Review.

INTRODUCTION: Forced-air warming devices have been reported to present a potential risk for surgical site infections (SSIs) and periprosthetic joint infections. Due to a lack of consensus, we reviewed the infection risk of forced-air warming devices. MATERIALS AND METHODS: A systematic literature review was performed, evaluating overall infection risk and bacterial load. A total of eight studies reporting outcomes from 1,965 subjects were included. RESULTS AND CONCLUSIONS: There is no current evidence in the orthopaedic literature that forced-air warming devices translate to increased SSIs. Accordingly, these devices should continue to be used for the maintenance of intraoperative normothermia.

Vancomycin-resistant enterococci colonization among dialysis patients: a meta-analysis of prevalence, risk factors, and significance.

BACKGROUND: Vancomycin-resistant enterococci (VRE) have become important nosocomial pathogens causing outbreaks worldwide. Patients undergoing dialysis represent a vulnerable population due to their comorbid conditions, frequent use of antibacterial agents, and frequent contact with health care settings. STUDY DESIGN: Systematic review and meta-analysis of cross-sectional studies of screening for VRE colonization. SETTING & POPULATION: Patients receiving long-term dialysis treatment. SELECTION CRITERIA FOR STUDIES: We performed a systematic literature search of PubMed and EMBASE databases to identify studies performing screening for VRE colonization among dialysis patients. PREDICTOR: Region, recent use of vancomycin or other antibiotics, previous hospitalization. OUTCOMES: (1) VRE colonization and (2) rate of VRE infection among colonized and noncolonized individuals. Relative effects were expressed as ORs and 95% CIs. RESULTS: We identified 23 studies that fulfilled the inclusion criteria and provided data for 4,842 dialysis patients from 100 dialysis centers. The pooled prevalence of VRE colonization was 6.2% (95% CI, 2.8%-10.8%), with significant variability between centers. The corresponding number for North American centers was 5.2% (95% CI, 2.8%-8.2%). Recent use of any antibiotic (OR, 3.62; 95% CI, 1.22-10.75), particularly vancomycin (OR, 5.15; 95% CI, 1.56-17.02), but also use of antibiotics other than vancomycin (OR, 2.92; 95% CI, 0.99-8.55) and recent hospitalization (OR, 4.55; 95% CI, 1.93-10.74) significantly increased the possibility of a VRE-positive surveillance culture. Colonized patients had a significantly higher risk of VRE infection (OR, 21.62; 95% CI, 5.33-87.69) than their noncolonized counterparts. LIMITATIONS: In 19 of 23 studies, a low percentage of dialysis patients (<80%) consented to participate in the screening procedure. 4 of 8 studies in which patients were followed up for more than 1 month reported VRE infections and only 5 of 23 studies provided extractable data for antibiotic consumption prior to screening. CONCLUSIONS: VRE colonization is prevalent in dialysis centers. Previous antibiotic use, in particular vancomycin, and recent hospitalization are important predicting factors of colonization, whereas the risk of VRE infection is significantly higher for colonized patients.

Prevalence of oropharyngeal antibiotic-resistant flora among residents of aged care facilities: a pilot study.

Residents in 11 long-term care facilities, and presenting to a single tertiary hospital site, were sampled to estimate prevalence of oropharyngeal colonization with resistant Gram-negative bacteria. From 124 residents, only one isolate (0.8%; 95% confidence interval 0.0%, 4.4) was multi-resistant (an extended-spectrum ß-lactamase producing Escherichia coli) indicating that different treatment recommendations for respiratory infections in this population may not be justified.

[STUDY OF THE IMPACT OF CERTAIN ENVIRONMENTAL FACTORS ON THE VIABILITY OF THE SALMONELLA BACTERIA IN WATER FOR THE DETECTION OF ITS EPIDEMIC POTENTIAL].

Salmonella from the tail water of the Don river was shown to be detected in 31.4% of samples with an average index of 23.5. Under experimental conditions, revealed long-term survival of Salmonella in the water exceeded in most of the experiments terms of preservation of E. coli and E. faecalis. The calculated high level of microbial risk of emergence of intestinal infections suggests the possibility ofwater route ofsalmonellosis.

Study of the effect of post-packaging pasteurization and argon modified atmosphere packaging on the sensory quality and growth of endogenous microflora of a sliced cooked meat product.

The objective of this work was to study the effect of post-packaging pasteurization on the sensory quality and growth of natural microorganisms during refrigerated storage (6 °C) of a cooked meat product considering two packaging atmospheres based on mixture of typical gases (CO(2)/N(2) (22/78%) and novel gases (CO(2)/Ar (17/83%)). Growth of lactic acid bacteria was significantly different between samples with and without post-packaging pasteurization, showing a growth rate >0.44 and equal to 0.28 log cfu/day, respectively. For samples with post-packaging pasteurization, atmosphere CO(2)/Ar resulted in a lower growth of lactic acid bacteria and a better sensory quality. Overall, samples without post-packaging pasteurization did not show a significant reduction of sensory quality during storage time (121 days) while samples with post-packaging pasteurization showed deterioration in their sensory quality. Further investigation is needed to obtain more definitive conclusions about the effect of post-packaging pasteurization and argon-based packaging atmospheres on cooked meat products.

[Measurement of genital mycoplasma concentration by using a microbiological and molecular-biological methods].

AIM: Establishment of ratios that would allow to execute recalculation of mycoplasma concentration from CFU/ml and/or CCU/ml into units obtained during PCR analysis--geq/ml. MATERIALS AND METHODS: Pure cultures of Mycoplasma hominis, Ureaplasma parvum and Ureaplasma urealyticum were studied by cultural and molecular-biological methods with quantitative evaluation. Studies of initial cultures as well as series of 10-fold dilutions were carried out. 32 experiments in total were carried out. RESULTS: Ratio between geq/ml and CFU/ml for M. hominis was 3.5; geq/ ml and CCU/ml ratio--4.4. Ratio between geq/ml and CCU/ml for U. parvum was 7.1; for U. urealyticum--11.2. CONCLUSION: Ratios between indexes obtained during quantitative study of pure genital micoplasma cultures by using 2 methods were established.

Non-stochastic sampling error in quantal analyses for Campylobacter species on poultry products.

Using primers and fluorescent probes specific for the most common food-borne Campylobacter species (Campylobacter jejuni and Campylobacter coli), we developed a multiplex, most probable number (MPN) assay using quantitative PCR (qPCR) as the determinant for binomial detection: i.e., number of p positive pathogen growth responses out of n = 6 observations each of 4 mL (V) per dilution. Working with media washes of thrice frozen-thawed chicken pieces which had been spiked with known levels of C. jejuni and C. coli, we found that about 20% of the experiments had a significant amount of error in the form of either greater than 25% MPN calculation error (Δε) and/or a low apparent recovery rate (R less than 1 = MPN observed ÷ CFU spiked). Assuming such errors were exacerbated by an excessively small n, we examined computer-generated MPN enumeration data from the standpoint of stochastic sampling error (Δ) and found that such binomial-based assays behaved identically to Poisson-based methods (e.g., counting data) except that fewer technical replicates (n) appeared to be required for the same number of cells per test volume (µ). This result implies that the qPCR detection-based MPN protocol discussed herein should accurately enumerate a test population with a µ ≥ 1 using n = 6 observations per dilution. For our protocol, this equates to ≥ 8 cells per 400-500 g of sampled product. Based on this analysis, the error rate we saw in spiked experiments (where µ >> 1) implied a non-stochastic source. In other experiments we present evidence that this source was, at least in part, related to the cell concentration step (i.e., centrifugation). We also demonstrate that the error rate lessened (from ~38% to ~13%) at lower Campylobacter levels (µ ≤ 40) as would most likely exist in nature. Using this protocol, we were able to quantify 14 to 1,226 MPN per 450 g of naturally contaminated chicken for skinless pieces and 11 to 244 MPN per 450 g for wings, breasts, legs, and thighs (skin on) whereupon about 50% of the 29 samples tested negative for both species. Four of these chicken wash samples did have substantially lower Campylobacter levels (1 to 6 MPN per 450 g) which might be better enumerated using a larger n. However, we established that the limit of quantification of this protocol diminishes for n > 6 because one is ever more diluting the sample, or lessening V, to achieve the requisite n.

Distribution of vibrio species in shellfish and water samples collected from the atlantic coastline of south-east Nigeria.

Crayfish, lobster, and sea-water samples collected from five fishing islands on the Atlantic coast-Bight of Biafra (Bonny)-belonging to Ibaka Local Government Area of Akwa-Ibom State of Nigeria were bacteriologically evaluated on thiosulphate citrate bile-salt sucrose (TCBS) agar for Vibrio load and pathotypes. Mean log10 Vibrio counts of 7.64+/-2.78 cfu/g (in crayfish), 5.07+/-3.21 cfu/g (in lobster), and 3.06+/-2.27 cfu/mL (in sea-water) were obtained in rainy season (June-July) while counts in the dry season (November-December) were 6.25+/-1.93 cfu/g, 5.99+/-1.54 cfu/g, and 3.84+/-1.78 cfu/mL respectively. The physicochemical measurements (temperature, pH, and total dissolved solutes) of the sea-water did not vary significantly in the two seasons across all five islands. Vibrio species isolated were Vibrio cholerae (both O1 and non-O1 serotypes), V parahaemolyticus, V vulnificus, V mimicus, and V fluvialis. Both Ogawa and Inaba subtypes of V cholerae O1 serotype were found. In addition, the Hikojima subtype, which had not been previously reported in the region, was isolated in two samples. The results show that these Vibrio species are endemic in the area.

A comparison of test statistics for the recovery of rapid growth-based enumeration tests.

This paper considers five test statistics for comparing the recovery of a rapid growth-based enumeration test with respect to the compendial microbiological method using a specific nonserial dilution experiment. The finite sample distributions of these test statistics are unknown, because they are functions of correlated count data. A simulation study is conducted to investigate the type I and type II error rates. For a balanced experimental design, the likelihood ratio test and the main effects analysis of variance (ANOVA) test for microbiological methods demonstrated nominal values for the type I error rate and provided the highest power compared with a test on weighted averages and two other ANOVA tests. The likelihood ratio test is preferred because it can also be used for unbalanced designs. It is demonstrated that an increase in power can only be achieved by an increase in the spiked number of organisms used in the experiment. The power is surprisingly not affected by the number of dilutions or the number of test samples. A real case study is provided to illustrate the theory.

Dressing disruption is a major risk factor for catheter-related infections.

OBJECTIVE: Major catheter-related infection includes catheter-related bloodstream infections and clinical sepsis without bloodstream infection resolving after catheter removal with a positive quantitative tip culture. Insertion site dressings are a major mean to reduce catheter infections by the extraluminal route. However, the importance of dressing disruptions in the occurrence of major catheter-related infection has never been studied in a large cohort of patients. DESIGN: A secondary analysis of a randomized multicenter trial was performed in order to determine the importance of dressing disruption on the risk for development of catheter-related bloodstream infection. MEASUREMENTS AND MAIN RESULTS: Among 1,419 patients (3,275 arterial or central-vein catheters) included, we identified 296 colonized catheters, 29 major catheter-related infections, and 23 catheter-related bloodstream infections. Of the 11,036 dressings changes, 7,347 (67%) were performed before the planned date because of soiling or undressing. Dressing disruption occurred more frequently in patients with higher Sequential Organ Failure Assessment scores and in patients receiving renal replacement therapies; it was less frequent in males and patients admitted for coma. Subclavian access protected from dressing disruption. Dressing cost (especially staff cost) was inversely related to the rate of disruption. The number of dressing disruptions was related to increased risk for colonization of the skin around the catheter at removal (p < .0001). The risk of major catheter-related infection and catheter-related bloodstream infection increased by more than three-fold after the second dressing disruption and by more than ten-fold if the final dressing was disrupted, independently of other risk factors of infection. CONCLUSION: Disruption of catheter dressings was common and was an important risk factor for catheter-related infections. These data support the preferential use of the subclavian insertion site and enhanced efforts to reduce dressing disruption in postinsertion bundles of care.

Legionella on board trains: effectiveness of environmental surveillance and decontamination.

BACKGROUND: Legionella pneumophila is increasingly recognised as a significant cause of sporadic and epidemic community-acquired and nosocomial pneumonia. Many studies describe the frequency and severity of Legionella spp. contamination in spa pools, natural pools, hotels and ships, but there is no study analysing the environmental monitoring of Legionella on board trains. The aims of the present study were to conduct periodic and precise environmental surveillance of Legionella spp. in water systems and water tanks that supply the toilet systems on trains, to assess the degree of contamination of such structures and to determine the effectiveness of decontamination. METHODS: A comparative pre-post ecological study was conducted from September 2006 to January 2011. A total of 1,245 water samples were collected from plumbing and toilet water tanks on passenger trains. The prevalence proportion of all positive samples was calculated. The unpaired t-test was performed to evaluate statistically significant differences between the mean load values before and after the decontamination procedures; statistical significance was set at p ≤ 0.05. RESULTS: In the pre-decontamination period, 58% of the water samples were positive for Legionella. Only Legionella pneumophila was identified: 55.84% were serogroup 1, 19.03% were serogroups 2-14 and 25.13% contained both serogroups. The mean bacterial load value was 2.14 × 10(3) CFU/L. During the post-decontamination period, 42.75% of water samples were positive for Legionella spp.; 98.76% were positive for Legionella pneumophila: 74.06% contained serogroup 1, 16.32% contained serogroups 2-14 and 9.62% contained both. The mean bacterial load in the post-decontamination period was 1.72 × 10(3) CFU/L. According to the t-test, there was a statistically significant decrease in total bacterial load until approximately one and a half year after beginning the decontamination programme (p = 0.0097). CONCLUSIONS: This study indicates that systematic environmental surveillance could be a useful approach for assessing the risk of exposure to Legionella bacteria, which still represents a public health threat. According to the study results, an environmental surveillance programme, followed by decontamination procedures where necessary, would decrease the total bacterial count, protecting the health of travellers and workers.