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C Wendt

Publications and source records attributed to C Wendt.

At least 37 records · Page 2Linked to original sources
PubMed1999

Validity of screening procedures for glycopeptide-resistant enterococci.

Screening agars containing different vancomycin concentrations and different susceptibility testing procedures were compared to determine their validity for the detection of glycopeptide-resistant enterococci (GRE). Direct streaking of rectal swabs over the surface of a commercially available agar (Enterococcosel; Becton Dickinson, Germany) containing 4 microg/ml and 16 microg/ml vancomycin was followed by incubation for 24 to 48 h. Susceptibility tests were done by microbroth dilution, disk diffusion, and the E test (AB Biodisk, Sweden). The microbroth dilution method according to National Committee for Clinical Laboratory Standards (NCCLS) was used as the gold standard for detection of GRE. Resistant and intermediately susceptible enterococcal isolates were differentiated to the species level. To detect resistance genes, the polymerase chain reaction was performed on all intermediately resistant isolates, on all isolates of VanB phenotype, and on 30% of isolates of VanA phenotype. Screening agar containing 4 microg/ml vancomycin displayed high sensitivity (97.6%) but only low specificity (35%) for the detection of GRE. Screening agar containing 16 microg/ml vancomycin had a high specificity of 89.3% and only a slightly lower sensitivity (92.7%) than the screening agar containing 4 microg/ml vancomycin. For the disk diffusion test, a breakpoint of < 16 mm yielded the optimal combination of sensitivity (98.8%) and specificity (99.6%). Both sensitivity and specificity of the E test for GRE detection were 100%. However, the E test is too expensive for testing of all enterococci. In conclusion, the combination of an inexpensive screening agar with either the E test or the disk diffusion test constitutes a valid and cost-effective method for the detection of GRE from screening specimens.

Colony Count, Microbial↗
PubMed1999

Efficacy of hand disinfectants against vancomycin-resistant enterococci in vitro.

Vancomycin-resistant enterococci (VRE) may be spread within a hospital via the contaminated hands of the healthcare worker. Effective hand disinfectants are necessary to break chains of transmission. We determined the bactericidal activity of 1-propanol, chlorhexidine digluconate (0.5 and 4%). Sterillium (45% 2-propanol, 30% 1-propanol and 0.2% mecetronium etilsulphate), Skinsept F (70% 2-propanol, 0.5% chlorhexidine digluconate and 0.45% hydrogen peroxide) and Hibisol (70% 2-propanol and 0.5% chlorhexidine gluconate) against 11 clonally distinct enterococcal isolates in a quantitative suspension test. Four isolates were vancomycin susceptible, four were vanA and the remainder vanB positive. Eight isolates were identified as Enterococcus faecium, two as Enterococcus faecalis and one as Enterococcus gallinarum. The investigator was blinded to the species and the genotype. Four parallel experiments were carried out for each isolate, each preparation, each dilution and each reaction time. 1-Propanol (60%), Sterillium, Skinsept F and Hibisol were all highly bactericidal after 15 and 30 s against VRE and vancomycin-susceptible enterococci (VSE) with reduction factors (RF) > 6.4, even in dilution of 50% (v/v). No significant difference was observed between vanA isolates, vanB isolates and VSE. Chlorhexidine digluconate (0.5% and 4%) was found to be less bactericidal after 30, 60 and 300 sec (RF < or = 2.5). The vanB genotype isolates were found to be significantly more susceptible to chlorhexidine (0.5%) than the vanA isolates (60 sec; one-way ANOVA model; P = 0.05). After 300 sec the vanB genotype isolates were found to be significantly more susceptible to chlorhexidine (0.5%) than the other two genotype isolates (P = 0.016). The vanA isolates were found to be significantly more susceptible to chlorhexidine (4%) than the vanB isolates (300 s; P = 0.024). E. faecium was found to be less susceptible to chlorhexidine than E. faecalis at all concentrations and reaction times, but significant differences between RF were only observed at 60 sec for both chlorhexidine concentrations (P < 0.05; t-test for independent samples). Propanol is much more effective against enterococci than chlorhexidine and combination of the two may be useful in providing an immediate and long lasting effect.

Analysis of Variance↗
PubMed1999

Prevalence of colonization with vancomycin-resistant enterococci in various population groups in Berlin, Germany.

In order to prevent the spread of vancomycin-resistant enterococci (VRE), the epidemiology of this micro-organism must be defined. The prevalence of colonization with VRE in various population groups in Berlin was investigated and the risk factors associated with VRE colonization assessed. In a cross-sectional study, rectal swabs were taken from seven population groups (healthy students, outpatients, home nursing patients, normal care and critical care patients of a community hospital and university hospital). Every one completed a questionnaire (age, gender, previous hospital stays, antibiotic therapy). Rectal swabs were examined for the presence of normal gut flora and VRE. All VRE isolates were typed by pulsed-field gel electrophoresis (PFGE). VRE colonization prevalence ranged from 0.9% (students) to 4.2% (nursing-home patients) in non-hospitalized subjects; in hospitalized patients prevalence ranged from 1.8% (regular care ward of a community hospital) to 16.3% (ICU patients of a university hospital). Location (university hospital, OR = 3.5) and age (> or = 60 years, OR = 2.2) were independent risk factors for VRE colonization. Within one population group, isolates with identical PFGE patterns were found in up to three people; one strain was found in four subjects belonging to different groups. Our findings suggest that VRE are imported from the community into hospitals with subsequent spread within the institution.

Adult↗
PubMed1999

Molecular epidemiology of gram-negative bacteremia.

We did pulsed field gel electrophoresis (PFGE) and antibiotic susceptibility testing on 202 gram-negative isolates obtained from blood cultures between 1 January 1989 and 31 December 1993. Seventy-eight patients had at least two gram-negative isolates of the same species recovered from blood drawn one or more days apart and met the other study criteria. Twenty patients had only 1 bloodstream infection, 48 patients had 1 recurrence of bacteremia, and 10 patients had > 1 recurrence of bacteremia. Of 80 recurrences of bacteremia, 52 (65%) were relapses and 28 (35%) were reinfections. Seventy-eight percent of the episodes of bacteremia occurring < or = 300 days apart were relapses, and 100% occurring > 300 days apart were reinfections (P < .001). Organisms causing recurrent bacteremia were not more resistant than those causing initial episodes. In conclusion, most episodes of recurrent gram-negative bacteremia were relapses. Relapses and reinfections could not be distinguished only by the length of time between episodes or by antimicrobial susceptibility patterns.

Anti-Bacterial Agents↗
PubMed1999

Recurrent gram-negative bacteremia: incidence and clinical patterns.

Fifty-eight patients who had at least two episodes of gram-negative bacteremia were evaluated to define the epidemiology of recurrent bacteremia caused by these organisms. Thirty-two patients (55%) had single relapses, 16 (28%) had one reinfection, and 10 (17%) had more than one recurrence of bacteremia. Intravenous catheters were the most common probable source of bacteremia. Relapses occurred earlier after the initial episode than did reinfections (58 days vs. 292 days; P = .002). The duration of antibiotic therapy for the first episode was shorter for patients with relapses than for those with reinfections (13.9 days vs. 17.5 days; P = .046). Microorganisms causing recurrent bacteremic episodes were not unusually resistant to antimicrobial agents. Reinfections may be difficult to prevent because they are associated with the severity of the underlying illness, which may not improve. The frequency of relapses might be reduced by increasing the duration of antibiotic therapy and eliminating foci of infection.

Adolescent↗
PubMed1998

Epidemiology of polyclonal gram-negative bacteremia.

Polyclonal bacteremic episodes are caused by more than one genotype of the same species. We conducted a study to estimate the frequency and to describe the epidemiology of polyclonal Gram-negative bacteremia in our patient population. We reviewed the patients' medical records. We also did pulsed field gel electrophoresis on 66 Gram-negative isolates obtained from the 28 patients (29 episodes) who had more than one morphologically different isolate of the same Gram-negative species in a blood culture obtained between January 1, 1989 and December 31, 1993. Nine of 29 (31%) bacteremic episodes evaluated were polyclonal. The source of bacteremia was not significantly different among patients with polyclonal and monoclonal bacteremic episodes. Patients with polyclonal bacteremic episodes were younger and were more likely to have rapidly fatal diseases than were those with monoclonal bacteremic episodes; however, neither of these differences reached statistical significance. Patients with polyclonal bacteremic episodes were significantly more likely to have leukemia than were those with monoclonal bacteremic episodes (odds ratio = 18.67; 95% confidence interval, 1.92 to 255.80). Three of nine patients who had polyclonal bacteremia died compared with 2 of 19 patients who had monoclonal bacteremia (odds ratio = 4.25; 95% confidence interval, 0.41 to 50.80). Polyclonal Gram-negative bacteremia is more common than previously thought. Despite their younger age, patients with polyclonal bacteremic episodes were more likely to die than those with monoclonal bacteremic episodes. Thus, polyclonal bacteremia may be either an indicator or a risk factor for poor prognosis.

Adolescent↗
PubMed1998

Characterization of Bartonella henselae isolated from bacillary angiomatosis lesions in a human immunodeficiency virus-infected patient in Germany.

Infections with Bartonella (Rochalimaea) henselae can result in a variety of clinical entities, including bacillary angiomatosis in immunocompromised hosts. The fastidious nature of this bacterium has so far prevented the culture of many clinical isolates. We report the recovery of the first European B. henselae isolate associated with bacillary angiomatosis. The isolate was cultured in a frozen skin biopsy specimen from a human immunodeficiency virus (HIV)-infected patient and was characterized by means of biochemical, bacteriologic, immunologic, and molecular biological methods including pulsed-field gel electrophoresis. This strain was compared with two B. henselae strains isolated in the United States to determine the relationship between the isolates. We found that it was phenotypically and genotypically indiscernible from B. henselae Houston-1, a blood culture isolate from an HIV-infected patient in Houston. These data suggest that one B. henselae clone is associated with human infections in Europe and the United States.

AIDS-Related Opportunistic Infections↗
PubMed1998

Microbicidal activity of a new silver-containing polymer, SPI-ARGENT II.

The survival of three bacterial species and Candida albicans was studied on SPI-ARGENT II. The immediate recovery from silver-impregnated polymer and control polymer (1 cm2) was approximately 10(6) to 10(7) microorganisms. After incubation (37 degreesC) and neutralization of silver with horse serum (5%), surviving organisms were recovered. The survival of the microorganisms on the polymer was not found to be influenced by the silver implantation.

Anti-Infective Agents↗
PubMed1998

Survival of vancomycin-resistant and vancomycin-susceptible enterococci on dry surfaces.

We compared the abilities of Enterococcus faecium strains (three vancomycin-resistant enterococci [VRE] and five vancomycin-susceptible enterococci [VSE]) and Enterococcus faecalis strains (one VRE and 10 VSE) to survive under dry conditions. Bacterial suspensions of the strains were inoculated onto polyvinyl chloride and stored under defined conditions for up to 16 weeks. All strains survived for at least 1 week, and two strains survived for 4 months. A statistical model was used to distribute the 19 resulting survival curves between two types of survival curves. The type of survival curve was not associated with the species (E. faecalis versus E. faecium), the source of isolation (patient versus environment), or the susceptibility to vancomycin (VRE versus VSE). Resistance to dry conditions may promote the transmissibility of a strain, but VRE have no advantages over VSE with respect to their ability to survive under dry conditions.

Anti-Bacterial Agents↗
PubMed1997

[Breathing circuit exchange in intensive care. Once daily once weekly?].

UNLABELLED: In an investigation of infection control methods for respirator systems in 89 randomly selected German intensive care units as a part of the NIDEP study (Nosocomial Infections in Germany--Surveillance and Prevention), it was found that respirator systems were exchanged daily in about 50% of the intensive care units. However, Craven et al. found that changing circuits (including tubing and exhalation valve and the attached humidifier) every 24 h rather than every 48 h was independently associated with the occurrence of nosocomial pneumonia. On the basis of these results and recent studies, the current situation in the literature was analyzed in order to make recommendations for exchanging ventilator circuits. METHODS: Based on the extensive analysis of the literature by the Hospital Infection Control Practices Advisory Committee (HICPAC), we could limit our investigation to the years after 1994. A MEDLINE search was done, and abstracts from congresses of the past few years were considered. The main focus of the analysis was the development of pneumonia and not the contamination of the breathing circuit. The following methodological factors were analyzed for the most important published studies: design, applied definitions of pneumonia, sample size, comparability of study groups, inclusion and exclusion criteria. The results of the different studies were compared considering the potential bias factors. RESULTS AND DISCUSSION: There were nine prospective controlled studies on this topic. In all studies, the authors tried to investigate whether a longer interval between ventilator circuit exchange (more than 48 h) is safe or whether it is possible to leave the circuits unchanged (without using breathing filters). The design and results of the available studies were analyzed. The three most important studies were compared very carefully (Table 1 and 2), and a recommendation for infection control measures for ventilator circuits was made as a modification of the HICPAC guidelines. In addition, the device-associated pneumonia rates of ventilated intensive care patients in the NIDEP study were analyzed separately according to a daily or a 48-h or longer interval of ventilator circuit exchange. For patients with daily exchange, we found a device-associated rate of 17.4 per 1000 ventilator days and for those with longer intervals a rate of 7.9 per 1000 ventilator days. Only considering those patients without heat and moisture filters, the figures were 14.8 versus 6.1. These differences were not significant because of the small number of patients investigated. CONCLUSION: The available studies show clear advantages of not routinely exchanging the ventilator circuit, including tubing, exhalation valve and the attached humidifier, more often then every 7 days for an individual patient. Based on these findings, the current practice in most German intensive care units should be reevaluated.

Clinical Trials as Topic↗
PubMed1997

Survival of Acinetobacter baumannii on dry surfaces.

Acinetobacter spp. have frequently been reported to be the causative agents of hospital outbreaks. The circumstances of some outbreaks demonstrated the long survival of Acinetobacter in a dry, inanimate environment. In laboratory experiments, we compared the abilities of five Acinetobacter baumannii strains, three Acinetobacter sp. strains from the American Type Culture Collection (ATCC), one Escherichia coli ATCC strain, and one Enterococcus faecium ATCC strain to survive under dry conditions. Bacterial solutions of the 10 strains were inoculated onto four different material samples (ceramic, polyvinyl chloride, rubber, and stainless steel) and stored under defined conditions. We investigated the bacterial counts of the material samples immediately after inoculation, after drying, and after 4 h, 1 day, and 1, 2, 4, 8, and 16 weeks of storage. A statistical model was used to distribute the 40 resulting curves among four types of survival curves. The type of survival curve was significantly associated with the bacterial strain but not with the material. The ability of the A. baumannii strains to survive under dry conditions varied greatly and correlated well with the source of the strain. Strains isolated from dry sources survived better than those isolated from wet sources. An outbreak strain that had caused hospital-acquired respiratory tract infections survived better than the strains from wet sources, but not as well as strains from dry sources. Resistance to dry conditions may promote the transmissibility of a strain, but it is not sufficient to make a strain an epidemic one. However, in the case of an outbreak, sources of Acinetobacter must be expected in the dry environment.

Acinetobacter↗
PubMed1996

Comparative evaluation of an automated ribotyping system versus pulsed-field gel electrophoresis for epidemiological typing of clinical isolates of Escherichia coli and Pseudomonas aeruginosa from patients with recurrent gram-negative bacteremia.

Ribotyping and macrorestriction analysis of chromosomal DNA using pulsed-field gel electrophoresis (PFGE) are among the more useful molecular epidemiologic typing methods. Because these techniques are labor intensive, automation of one or more steps may allow clinical laboratories to apply molecular typing methods. We compared the recently developed automated ribotyping system, the RiboPrinter Microbial Characterization System (DuPont), with PFGE as a means of typing clinical isolates of E. coli and P. aeruginosa. A total of 22 E. coli and 24 P. aeruginosa were typed by both PFGE and the RiboPrinter. When compared with PFGE typing of E. coli and P. aeruginosa, the RiboPrinter was less sensitive in identifying different strains, particularly among the isolates of P. aeruginosa. The RiboPrinter was completely automated and allowed up to 32 isolates to be typed within an 8-hour period. The pattern of results obtained in this study suggests that a heirarchical approach to molecular typing using the RiboPrinter Microbial Characterization System plus PFGE might be feasible. The RiboPrinter Microbial Characterization System promises to be a very useful addition to the expanding molecular typing armamentarium.

Bacteremia↗
PubMed1995

[Field study to obtain Legionella-free water from showers and sinks of a transplantation unit by a system of water filters].

The efficiency of filters for elimination of Legionella was examined in a ten month field study. Showers and sinks of twelve patient rooms were equipped with nylon 66-polyamid filters. Before filtration the total number of colonies was very high with an arithmetical mean of 1131 cfu/ml. This could be reduced by filtration at the sinks (mean = 205 cfu/ml). After equipping showers with filters we found a significant increase in the total number of colonies (mean = 1961 cfu/ml). In non-filtered water we found Legionella in nearly 90% of the 648 samples, the concentration extended to 300 cfu/ml (mean = 51 cfu/ml). After filtration the concentration of Legionella was up to 280 cfu/ml in 7.3% of the 665 samples. We calculated a logistic regression model to examine the effects of the age of the filters and the duration of their use since the last sterilization. These parameters were calculated from the time of the break through or retrograde contamination with Legionella. There were clear differences between shower and sink filters. Assuming a 5% probability of break through or retrograde contamination with Legionella, the sink filters should be sterilized every 3 weeks without regards to the age of the filters. In contrast the shower filters may be used for 3 weeks if they are sterilized weekly. If weekly sterilization is not feasible they should be used for 2 weeks only. In our study it was not possible to achieve Legionella-free water by changing either the frequency of sterilization or the age of the filters.

Baths↗
PubMed1993

Role of mesenchymal cell death in lung remodeling after injury.

Repair after acute lung injury requires elimination of granulation tissue from the alveolar airspace. We hypothesized that during lung repair, signals capable of inducing the death of the two principal cellular elements of granulation tissue, fibroblasts and endothelial cells, would be present at the air-lung interface. Bronchoalveolar lavage fluid obtained from patients during lung repair induced both fibroblast and endothelial cell death, while fluid obtained at the time of injury or from patient controls did not. The mode of cell death for endothelial cells was apoptosis. Fibroblast death, while morphologically distinct from necrosis, also differed from typical apoptosis. Only proliferating cells were susceptible to the bioactivities in lavage fluid, which were trypsin sensitive and lipid insoluble. Histological examination of lung tissue from patients after lung injury revealed evidence of apoptotic cells within airspace granulation tissue. Our results suggest that cell death induced by peptide(s) present at the air-lung interface may participate in the remodeling process that accompanies tissue repair after injury.

Acute Disease↗
PubMed1992

Adenoid cystic carcinoma of the palate.

We reviewed the clinical records of 41 patients who received definitive treatment for adenoid cystic carcinoma arising from the palate. Tumors were divided into three categories depending on local extension and pattern of growth. Surgery, either alone or in combination with post-operative radiation therapy, yielded satisfactory local regional control of the cancer. Patients who had adenoid cystic carcinoma with diffuse microscopic spread into adjacent tissues had the highest propensity for the development of distant metastases.

Adult↗
PubMed1990

[Characterization of T lymphocyte defects in patients with Hodgkin's disease using enzyme chemical markers].

Patients suffering from lymphogranulomatosis were studied with respect to cellular immune deficiencies. For this purpose, mononuclear cells from venous blood were separated and subjected to analysis of lymphocyte markers. T-lymphocytes were enumerated by means of the sheep erythrocyte (SE) rosette test. T cell subpopulations were determined using enzyme cytochemical staining for dipeptidyl peptidase IV (DP IV) and unspecific acid alphanaphthylacetate esterase (ANAE). In 18 patients with M. Hodgkin a significant reduction in the T lymphocyte count in peripheral blood was found. This T cell defect is due to a selective decrease in the TM-subpopulation as identified by enzyme cytochemical markers DP IV and ANAE (focal reaction). From these results it is concluded that patients with lymphogranulomatosis have characteristic abnormalities in the immune system in the sense of a disturbed equilibrium of immune regulatory cells.

Adult↗