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T A Wichelhaus

Publications and source records attributed to T A Wichelhaus.

At least 19 recordsLinked to original sources
PubMed2004

Antibacterial resistance of community-acquired respiratory tract pathogens recovered from patients in Germany and activity of the Ketolide Telithromycin: results from the PROTEKT surveillance study (1999-2000).

BACKGROUND: The Prospective Resistant Organism Tracking and Epidemiology for the Ketolide Telithromycin (PROTEKT) longitudinal global surveillance study examines the antibacterial susceptibility of community-acquired respiratory pathogens. METHODS AND RESULTS: Data from isolates collected in Germany in 1999-2000 in the PROTEKT study show that 8.3% of pneumococcal isolates (n = 325) had reduced susceptibility to penicillin and 2.2% were fully resistant. Erythromycin resistance was 15.7% overall and particularly high in Leipzig (31.6%). All penicillin- and erythromycin-resistant strains were inhibited by telithromycin (MIC < or =0.5 mg/l) and linezolid (MIC < or =2 mg/l). Beta-lactamase was produced by 3.2% of Haemophilus influenzae (9/284) and 89.5% of Moraxella catarrhalis strains (111/124). All Streptococcus pyogenes isolates (n = 87) were susceptible to penicillin, although 9.2% were resistant to macrolides. CONCLUSIONS: Penicillin resistance in Germany remains low; however, the prevalence of antimicrobial resistance among common respiratory pathogens is rising, particularly against macrolides. Continued surveillance is necessary to guide optimal empirical therapy, and new antimicrobials, like telithromycin, need to be developed with improved potency against target pathogens and low propensity for the development of resistance.

Anti-Bacterial Agents↗
PubMed2003

[Evidence-based antibiotic prophylaxis in aseptic orthopedic surgery].

Disagreement exists on the topic of antibiotic prophylaxis in aseptic orthopedic surgery. No evidence on the usefulness of prophylactic antibiotic administration exists with regard to non-complex aseptic surgeries without placement of osteosynthetic material. Likewise, no undisputed evidence exists on the usefulness of antibiotic prophylaxis with regard to aseptic orthopedic surgeries involving placement of osteosynthetic material. However, the majority of experts agree on antibiotic prophylaxis in the latter cases. In contrast clear evidence does exist regarding the usefulness of antibiotic prophylaxis with first- or second-generation cephalosporins for surgeries of the hip involving fracture treatment or prosthetic replacement. The prophylactic use of glycopeptides should be confined to cases of high MRSA or MRSE risk. Administration of prophylactic antibiotics should precede incision time by around 30 min and tourniquet inflation by at least 10 min. Antibiotic administration may be repeated in the OR when surgery lasts longer than 3 h. The use of local antibiotics in bone cement has not proven useful as a prophylactic measure.

Anti-Bacterial Agents↗
PubMed2002

Antimicrobial effectiveness of povidone-iodine and consequences for new application areas.

The microbicidal action spectrum of povidone-iodine (PVP-I) is broad - even after short onset times. Unlike local antibiotics and other antiseptic substances, no resistance develops. The high degree of bactericidal efficiency in respect of highly resistant gram-positive pathogenic micro-organisms, such as methicillin-resistant Staphylococcus aureus (MRSA) and enterococcus strains, is particularly significant for hospital hygiene. An in vitro study with 10 genotypically different MRSA isolates showed an optimum bactericidal effect (logarithmic reduction factor value >5) without protein load after just 30 s exposure and even in a dilution of Betaisodona solution (Mundipharma GmbH) of 1%. With protein load (0.2% albumin), the optimum in microbicidal effectiveness shifts to concentrations > or = 10% Betaisodona solution referring to an exposure time of 30 s. Since recent results are now also available on the toxicological safety of PVP-I preparations for the ciliated epithelium of the nasal mucosa and the good tolerability on skin and other mucous membranes is a known factor, a controlled clinical study is currently being carried out to eliminate colonizations of MRSA. Evidence has also recently been produced of the antiviral activity of PVP-I against herpes simplex, adeno- and enteroviruses, as well as its high degree of efficiency against Chlamydia. Hence alongside the classical fields of application, such as the disinfection of the skin and hands, mucosa antisepsis and wound treatment, there are also useful indications for the substance, i.e. rinsing of body cavities and joints and application to the eye.

Adenoviridae Infections↗
PubMed2001

In vitro activity of mezlocillin, meropenem, aztreonam, vancomycin, teicoplanin, ribostamycin and fusidic acid against Borrelia burgdorferi.

The in vitro susceptibility profile of Borrelia burgdorferi is not yet well defined for several antibiotics. Our study explored the in vitro susceptibility of B. burgdorferi to mezlocillin, meropenem, aztreonam, vancomycin, teicoplanin, ribostamycin and fusidic acid. Minimal inhibitory concentrations (MICs) and minimal borreliacidal concentrations (MBCs) were measured using a standardised colorimetric microdilution method and conventional subculture experiments. MIC values were lowest for mezlocillin (MIC(90), < or =0.06 mg/l) and meropenem (MIC(90), 0.33 mg/l). Vancomycin (MIC(90), 0.83 mg/l) was less effective in vitro. Borreliae proved to be resistant to aztreonam (MIC(90), >32 mg/l), teicoplanin (MIC(90), 6.6 mg/l), ribostamycin (MIC(90), 32 mg/l), and fusidic acid (MIC(90), >4 mg/l). The mean MBCs resulting in 100% killing of the final inoculum after 72 h of incubation were lowest for mezlocillin (MBC, 0.83 mg/l). This study gathered further data on the in vitro susceptibility patterns of the B. burgdorferi complex. The excellent in vitro effectiveness of acylamino-penicillin derivatives and their suitability for the therapy of Lyme disease is emphasised.

Anti-Bacterial Agents↗
PubMed2001

Rapid molecular typing of methicillin-resistant Staphylococcus aureus by PCR-RFLP.

OBJECTIVE: To establish a new, rapid, and reliable genotypic fingerprinting technique for methicillin-resistant Staphylococcus aureus (MRSA) typing in routine epidemiological surveillance. DESIGN: The method is based on polymerase chain reaction (PCR) restriction fragment-length polymorphism (RFLP) following HaeII digestion of simultaneously amplified parts of the protein A gene, the coagulase gene, and the hypervariable region adjacent to mecA. A total of 46 MRSA initial isolates were analyzed, including 14 isolates from five countries; the six German epidemic strains; 16 isolates from the Frankfurt metropolitan area, which were known to be heterogeneous by pulsed-field gel electrophoresis (PFGE); and 10 isolates obtained during three epidemics, all of which displayed an identical genotype. RESULTS: Restriction analysis by PCR-RFLP permitted discrimination of 10 of 14 international isolates, all six German epidemic strains, and 15 of 16 national isolates. It also confirmed the homogeneous character of the 10 outbreak isolates. CONCLUSIONS: This new and rapid PCR-RFLP typing method is an attractive tool in routine epidemiological surveillance. Its impressive characteristics are ease of performance and interpretation, while at the same time guaranteeing good discriminatory power, reproducibility, and typeability.

Bacterial Typing Techniques↗
PubMed2001

Elution characteristics of vancomycin, teicoplanin, gentamicin and clindamycin from calcium sulphate beads.

The in vitro release of vancomycin, teicoplanin, gentamicin and clindamycin from biodegradable calcium sulphate (CaSO(4)) carrier beads is described. All antibiotics showed prolonged release from the carrier beads, which was elevated during the first 24 h, with peak levels exceeding 2500 microg/bead. Doubling the antibiotic load of the beads revealed a more prolonged elution and a two-fold increase in antibiotic release. Local carrier-associated antibiotic treatment with CaSO(4) beads may prove to be effective in the management of chronic bone infections.

Anti-Bacterial Agents↗
PubMed2001

In vitro activities of fluoroquinolones against the spirochete Borrelia burgdorferi.

Little is known to date about the in vitro activity of fluoroquinolones against Borrelia species. Our study aimed at determining the in vitro activities of 15 quinolones against nine isolates of the Borrelia burgdorferi sensu lato complex in addition to one Borrelia valaisiana and one Borrelia bissettii tick isolate. For the determination of MICs, a standardized colorimetric microdilution method was applied. Determination of minimal borreliacidal concentrations providing 100% killing of the final inoculum (MBCs) after 72 h and time-kill experiments were performed by conventional culture in Barbour-Stoenner-Kelly medium in combination with dark-field microscopy. The rank order of potency on a microgram-per-milliliter basis for the substances with in vitro activity against B. burgdorferi was gemifloxacin (MIC at which 90% of the isolates tested are inhibited [MIC(90)], 0.12 microg/ml) > sitafloxacin (MIC(90), 0.5 microg/ml), grepafloxacin (MIC(90), 0.5 microg/ml) > gatifloxacin (MIC(90), 1 microg/ml), sparfloxacin (MIC(90), 1 microg/ml), trovafloxacin (MIC(90), 1 microg/ml) > moxifloxacin (MIC(90), 2 microg/ml), ciprofloxacin (MIC(90), 2 microg/ml) > levofloxacin (MIC(90), 4 microg/ml) > ofloxacin (MIC(90), 8 microg/ml), norfloxacin (MIC(90), 8 microg/ml) > fleroxacin (MIC(90), >16 microg/ml), and pefloxacin (MIC(90), 32 microg/ml) > nalidixic acid (MIC(90), 256 microg/ml). After 72 h of exposure, gemifloxacin was borreliacidal (100% killing) against the isolates investigated at a median MBC of 4 microg/ml. In the other compounds tested, median MBCs were higher (> or =8 microg/ml). Results of electron microscopy and time-kill studies clearly support an in vitro activity of some fluoroquinolones against borreliae. Our study demonstrates for the first time the enhanced in vitro effectiveness of some of the recently introduced 4-quinolones against B. burgdorferi.

Anti-Infective Agents↗
PubMed2000

Risk of Pseudomonas aeruginosa cross-colonisation in patients with cystic fibrosis within a holiday camp--a molecular-epidemiological study.

OBJECTIVE: A study on the molecular epidemiology of Pseudomonas aeruginosa in patients with cystic fibrosis (CF) from Germany (N = 18) and Israel (N = 12) is presented. The aim is to provide an answer to the question as to whether or not social contact outside the hospital environment involves a potential risk for person-to-person spread of this pathogen. METHODS: Sputa from German and Israeli patients were obtained while these were attending a holiday camp in Israel. The sputum samples were analysed with regard to Pseudomonas aeruginosa. Strains dissimilar in macroscopic appearance and/or antibiotic resistance patterns were genotyped using pulsed-field gel electrophoresis after digestion of genomic DNA with restriction endonuclease Spel. The genetic polymorphism of DNA fragment patterns of all strains (N = 146) was studied for their overall relatedness using a fingerprint software system. RESULTS: Most of the German patients (77.7%) were colonised persistently by a unique clonal type during the four-week screening period. Isolates obtained from Israeli patients displayed a very close clonal relationship and a higher antibiotic resistance as a result of preceding epidemic spread of certain clones before the camp. Additionally, isolates showing identical PFGE patterns were demonstrated once in a single male Israeli patient and in one female German patient, suggesting previous cross-colonisation. CONCLUSION: The occurrence of person-to-person spread through social contact in patients with CF is supported by our findings, but remains a rare event outside the hospital environment, provided appropriate hygienic measures are applied.

Adult↗
PubMed2000

[Significance of methicillin resistant S. aureus (MRSA) in geriatrics--epidemiology, therapy and management].

Methicillin-resistant S. aureus (MRSA) has become an important cause of severe infection in hospitalized patients all over the world. In Germany a significant increase of nosocomial infections due to MRSA has occurred during the last 10 years. Especially elderly patients with chronic illnesses are at increased risk of becoming colonized or infected with MRSA. This report focuses on epidemiology and therapy of MRSA, and on the recommendations concerning management and prevention of spread of MRSA in hospitals and nursing homes.

Aged↗
PubMed2000

New colorimetric microdilution method for in vitro susceptibility testing of Borrelia burgdorferi against antimicrobial substances.

A newly developed colorimetric microdilution method was used to analyze the activity of 12 antimicrobial agents against nine Borrelia burgdorferi isolates, including all three genospecies pathogenic for humans. In addition, in vitro antimicrobial resistance patterns of Borrelia valaisiana and Borrelia bissettii tick isolates were investigated. The applied test system is based upon color changes that occur in the presence of phenol red and result from the accumulation of nonvolatile acid produced by actively metabolizing spirochetes. After 72 h of incubation, minimal inhibitory concentrations (MICs) were determined from the decrease of absorbance by software-assisted calculation of growth curves. MIC values were lowest for azlocillin (MIC, < or = 0.125 microg/ml), ceftriaxone (MIC range, < or = 0.015-0.06 microg/ ml), and azithromycin (MIC range, < or = 0.015-0.06 microg/ml). Whereas tobramycin (MIC range, 8-64 microg/ml) exhibited little activity, spectinomycin (MIC range, 0.25-2 microg/ml) showed in vitro antimicrobial activity against Borrelia burgdorferi. The MICs of penicillin G for Borrelia afzelii isolates were ten times higher than those for Borrelia burgdorferi, Borrelia valaisiana, and Borrelia bissettii isolates (P<0.05) and 100 times higher than those for isolates belonging to the genospecies Borrelia garinii (P < 0.05). Further significant differences with respect to the MIC values of the other antimicrobial agents tested were not noted. The colorimetric microdilution method offered the advantages of reliability, reproducibility, and convenience and could handle large numbers of isolates and antibiotics.

Anti-Bacterial Agents↗
PubMed2000

Colorimetric in vitro susceptibility testing of penicillins, cephalosporins, macrolides, streptogramins, tetracyclines, and aminoglycosides against Borrelia burgdorferi isolates.

The spectrum of antibiotic susceptibility of Borrelia burgdorferi has been only partially defined. In the present study the effectiveness of 12 antimicrobials, belonging to six different antibiotic classes have been tested against Borrelia burgdorferi s.s. (N=3), Borrelia garinii (N=3), Borrelia afzelii (N=3), Borrelia valaisiana (N=1), and Borrelia bissettii (N=1) isolates. These isolates were analysed by a new standardised colorimetric minimal inhibitory concentration (MIC) method based upon colour changes that result from actively metabolizing spirochaetes after 72 h of incubation. Piperacillin (MIC90: 0.08 mg/l), ceftriaxone (MIC90: 0. 04 mg/l), cefotaxime (MIC90: 0.15 mg/l), azithromycin (MIC90: 0.015 mg/l), roxithromycin (MIC90: 0.05 mg/l) and quinupristin/dalfopristin (MIC90: 0.12 mg/l) gave the lowest MIC values. Minimal inhibibitory activity of amoxycillin (MIC90: 1.04 mg/l), cefixime (MIC90: 1.33 mg/l), cefoperazone (MIC90: 0.83 mg/l) tetracycline (MIC90: 0.29 mg/l) and minocycline (MIC90: 0.30 mg/l) was slightly lower, whereas borrelia were resistant to amikacin (MIC90: >128 mg/l). Mean minimal borreliacidal concentrations (MBCs) were representatively determined for piperacillin (MBC: 1.8 mg/l), ceftriaxone (MBC: 2.0 mg/l), azithromycin (MBC: 0.82 mg/ml), roxithromycin (MBC: 1.8 mg/l), quinupristin/dalfopristin (MBC: 5.0 mg/l), minocycline (MBC: 5.8 mg/l), and amikacin (MBC: >128 mg/l) by using conventional subculture for three weeks in combination with dark-field microscopy. B. garinii proved to be the most susceptible of the genospecies tested. Our study showed excellent in vitro antimicrobial activity of all classes of antibiotics tested, except the aminoglycosides and hence their suitability for therapy of Lyme disease.

Aminoglycosides↗
PubMed2000

Colonization with superantigen-producing Staphylococcus aureus is associated with increased severity of atopic dermatitis.

BACKGROUND: Atopic dermatitis (AD) is a chronic inflammatory skin disease associated with colonization of the skin with Staphylococcus aureus known to produce toxins with superantigen (SAg) activity. Besides T-cell activation these toxins induce T-cell skin homing in vitro. This may contribute to the observed induction or enhancement of skin inflammation. OBJECTIVE: The aim of this study was to determine whether colonization with SAg-producing S. aureus isolates modulates the intensity of AD. If so, it was of interest whether this may be primarily due to the toxins' effects as SAgs or as allergens. METHODS: In AD patients, healthy controls, and atopic controls SAg production by S. aureus isolated from skin or mucous membranes was investigated and correlated to the severity of the disease. Total IgE, SAg-specific IgE, and T-cell activation and recirculation markers were analysed and correlated with SAg production. RESULTS: Fifty-seven percent of S. aureus strains isolated from AD patients produced SAgs. This frequency was higher compared to healthy controls (33%). SAg production by S. aureus was correlated with a significantly higher scoring of AD (SCORAD index, 58 +/- 19 in SAg-producing vs 41 +/- 7 in non-SAg-producing germs; P < 0.05). However, the severity of the disease was not associated with sensitization against the SAgs staphylococcal enterotoxin A (SEA) and staphylococcal enterotoxin B (SEB). Furthermore, SAg production by S. aureus was inversely correlated with total IgE concentration (P < 0.05) and positively correlated with T-cell activation (as measured by HLA-DR and CD69 expression) and the expression of the T-cell skin homing phenotype cutaneous lymphocyte-associated antigen. CONCLUSION: SAg production by S. aureus is suggested to be associated with an increased severity of atopic dermatitis. Since SAg production was found neither exclusively in AD patients nor in all patients, other pathogenic factors may be additionally effective.

Adult↗
PubMed1999

Molecular characterization of rpoB mutations conferring cross-resistance to rifamycins on methicillin-resistant Staphylococcus aureus.

Mutations of the rpoB gene conferring resistance to rifampin were analyzed in 40 methicillin-resistant Staphylococcus aureus isolates obtained from six countries. Interestingly, the majority of clinical isolates showed multiple mutations within rpoB. The amino acid substitution 481His-->Asn was the most prevalent one, capable of conferring low-level resistance on its own. Cross-resistance to rifampin, rifabutin, and rifapentine was demonstrated for all mutants identified. The level of resistance to rifamycins correlated with both the mutation position and type of amino acid substitution.

Amino Acid Sequence↗
PubMed1999

Rapid detection of epidemic strains of methicillin-resistant Staphylococcus aureus.

Fifty methicillin-resistant Staphylococcus aureus (MRSA) initial isolates obtained from patients hospitalized in the orthopedic clinic of the Frankfurt University Hospital and 150 methicillin-sensitive Staphylococcus aureus (MSSA) isolates were investigated in this study to determine whether the Slidex Staph-Kit is capable of differentiating between MRSA and MSSA owing to its unique performance characteristics. The Slidex Staph-Kit is a combined latex hemagglutination test designed to detect clumping factor, protein A, and a specific surface immunogen for S. aureus. Clumping factor-positive strains cause erythrocytes sensitized with fibrinogen to hemagglutinate, thereby resulting in visible red clumps. S. aureus strains deficient in clumping factor agglutinate latex particles sensitized with specific antibodies against surface proteins of S. aureus, thereby resulting in visible white clumps. Our results demonstrate that white clumping has a 99% specificity as well as a 98% positive predictive value for MRSA. Clumping factor-negative MRSA, which have been reported to occur in several countries, are epidemic in the Frankfurt area and account for 80% of all MRSA initial isolates in the orthopedic clinic of the Frankfurt University Hospital. Genotyping of all MRSA isolates by macrorestriction analysis of chromosomal DNA revealed that 83% of clumping factor-negative MRSA are closely related to the "southern-German" epidemic strain. This is the first study demonstrating the Slidex Staph-Kit's capability for identifying epidemic clumping factor-negative S. aureus strains as methicillin resistant even prior to antimicrobial susceptibility testing.

Agglutination Tests↗