Evaluation of six PCR assays in combination with patient related data for the diagnosis of Clostridium difficile-associated infections.

BACKGROUND: The aim of this multicenter study was to establish a diagnostic algorithm using molecular methods for the diagnosis of C. difficile-associated infection (CDI). In addition patient specific data were taken into consideration for the interpretation of the results. METHODS: We compared the performance of six different commercially available PCR-tests, two toxin immunoassays, and a glutamat-dehydrogenase test by analysing liquid stool specimens from patients with suspected CDI. Toxigenic culture on CLO-agar was used as reference method. RESULTS: In total 250 stool specimens were collected at two study sites. 77 (30.8%) stool samples were culture-positive for toxigenic C. difficile. 173 (69.2%) specimens showed no growth of C. difficile. As a result, each of the PCR assays tested for C. difficile had a significantly higher sensitivity (94.8% - 100%) and NPV (97.6% - 100%) than the TOX-EIA with a sensitivity of 57.1% and NPV of 83.8%. Specificity of the PCR tests was 94.1% to 96.0% and PPV between 86.5% and 91.6%. The analysis of the patient data revealed a significant difference (p-value 0.0202) between toxin-positive and toxin-negative patients regarding prior antibiotic treatment, especially for cephalosporins. CONCLUSIONS: Our findings support the recommendation to restrict the use of antibiotics as a cornerstone in the prevention of CDI. We conclude that all of the PCR assays evaluated in this study can be applied in a diagnostic algorithm.

[Severe pneumococcal infections in the elderly - preventable by vaccination]. / Schwere Pneumokokkeninfektionen im Alter - impfpräventabel.

Elderly people are more susceptible to pneumococcal infections. Data in Germany from 2005-2010 shows that especially seniors are prone to develop serious complications such as sepsis. Women are obviously less affected than men. Most of the infections occurred during the winter months. The majority of isolates, i.e., about 80%, possess capsular polysaccharide antigens which are represented in the 23-valent vaccine. Consequently, it could be assumed that the severe complications ensuing long hospital stays and associated with a high mortality could have been avoided, if the elderly people would have been vaccinated, which, however, was only true in a small proportion (28%). Recently, a new conjugated vaccine was introduced to the market. In principle, several antibiotics are available for direct antibacterial treatment. All isolates are susceptible to cefotaxime as well as to ceftriaxone. Resistance to penicillin as well as ampicillin is very rare in Germany. The vast majority of isolates are susceptible to quinolones such as levofloxacin and moxifloxacin. Resistance to macrolides, for example to erythromycin, occurs to a certain extent but the percentage has been declining in recent years. Nevertheless, in many instances therapy is too late. Thus, prevention is of great importance.

[Laboratory survey on the incidence of Pneumocystis jirovecii - obviously a peculiar fungus, but also a rare pathogen?]. / Laborerhebung zur Häufigkeit von Pneumocystis jirovecii - Zwar ein besonderer Pilz, aber auch ein seltener Erreger?

Pneumocystsis jirovecii is a peculiar fungus for a variety of reasons. This opportunistic pathogen multiplies in humans only under certain conditions; a defect in the T-cell defense system creates a predisposition to this infection. In 2010 a data survey (IFT as well as PCR) from a few laboratories in Germany revealed 412 positive individuals. Even if only a few patients test positive for the colonization stage of this pathogen, the sheer number of individuals testing positive for other stages of infection indicate that the incidence of pneumocystosis in immunocompromised patients in Germany is underestimated.

[Pneumococcal sepsis in aged patients - implications for the vaccination of seniors against pneumococci]. / Pneumokokkensepsis im Alter - Implikationen für die Impfung alter Menschen gegen Pneumokokken.

In the years 2005-2010 pneumococci were isolated in the Limbach laboratory/Heidelberg from blood cultures of 1,085 patients. Obviously, older patients are more prone to these bacteria, since 66 % of the patients were older than 60 years. All isolates were susceptible to cefotaxime; 3 % of isolates were resistant to penicillin, 2 % were resistant to levofloxacin and 15 % were resistant to erythromycin. From 457 out of the isolates serotyping was achieved: more than 80 % of the isolates were covered by the 23-valent vaccine. This means that particularly old people should be vaccinated against pneumococci, because they will profit probably most from such preventive measurements.

Value of whole-body washing with chlorhexidine for the eradication of methicillin-resistant Staphylococcus aureus: a randomized, placebo-controlled, double-blind clinical trial.

BACKGROUND: Whole-body washing with antiseptic solution has been widely used as part of eradication treatment for colonization with methicillin-resistant Staphylococcus aureus (MRSA), but evidence for the effectiveness of this measure is limited. OBJECTIVE: To study the efficacy of whole-body washing with chlorhexidine for the control of MRSA. DESIGN: Randomized, placebo-controlled, double-blinded clinical trial. SETTING: University Hospital of Heidelberg and surrounding nursing homes. PATIENTS: MRSA carriers who were not treated concurrently with antibiotics effective against MRSA were eligible for the study. INTERVENTION: Five days of whole-body washing with either 4% chlorhexidine solution (treatment group) or with a placebo solution. All patients received mupirocin nasal ointment and chlorhexidine mouth rinse. The outcome was evaluated 3, 4, 5, 9, and 30 days after treatment with swab samples taken from several body sites. RESULTS: Of 114 patients enrolled in the study (56 in the treatment group and 58 in the placebo group), 11 did not finish treatment (8 from the treatment group and 3 from the placebo group [P=.02]). At baseline, the groups did not differ with regard to age, sex, underlying condition, site of MRSA colonization, or history of MRSA eradication treatment. Eleven patients were MRSA-free 30 days after treatment (4 from the treatment group and 7 from the placebo group [P=.47]). Only groin-area colonization was significantly better eradicated by the use of chlorhexidine. The best predictor for total eradication was a low number of body sites positive for MRSA. Adverse effects were significantly more frequent in the treatment group than in the placebo group (any symptom, 71% vs 33%) but were reversible in most cases. CONCLUSION: Whole-body washing can reduce skin colonization, but it appears necessary to extend eradication measures to the gastrointestinal tract, wounds, and/or other colonized body sites if complete eradication is the goal.

Evaluation of a single-locus real-time polymerase chain reaction as a screening test for specific detection of methicillin-resistant Staphylococcus aureus in ICU patients.

The aim of the present study was to determine the diagnostic value of a single-locus real-time polymerase chain reaction (PCR) recently proposed for rapid detection of methicillin-resistant Staphylococcus aureus (MRSA) from clinical samples (IDI-MRSA; Infectio Diagnostic, Sainte-Foy, Québec, Canada). This test, which was developed on the basis of studies of the sequence analysis of the mecA gene carried by staphylococcal cassette chromosome mec (SCCmec), was used to screen nasal swabs of 320 intensive care unit (ICU) patients at admission. The results were compared with those of conventional culture of swabs from several body sites. When compared with culture of swabs from the nose, throat, and wounds, the diagnostic values of the real-time PCR test from nasal swabs were as follows: 92.3% sensitivity, 98.6% specificity, 75.0% positive predictive value, and 99.6% negative predictive value. Fifteen (4.7%) samples could not be evaluated because the PCR reaction was inhibited, even after the samples were frozen and thawed for retesting. Culture of nasal swabs showed that 78 of the patients were colonized with methicillin-susceptible S. aureus. Unexpectedly, 4 (5.1%) of these samples gave false-positive results in the IDI-MRSA. These isolates were all single clones, as shown by pulsed-field gel electrophoresis and spa typing. Reliable results were obtained with the IDI-MRSA assay, even in a patient population with a low prevalence (approximately 4%) of MRSA and even when compared with swabs of different body sites. Nevertheless, further work is needed to reduce the inhibition rate of the PCR and to explain why false-positive results were obtained with methicillin-susceptible S. aureus.

Tissue and serum levofloxacin concentrations in diabetic foot infection patients.

OBJECTIVES: Levofloxacin has a high bioavailability and a broad antibacterial spectrum which covers the common pathogens found in acute and chronic diabetic foot infections. The purpose of our study was to determine the serum and tissue concentrations of levofloxacin when administered orally in patients with infected diabetic foot ulcers and to compare these values with microbiological findings. PATIENTS AND METHODS: Ten outpatients with diabetes and ulcerations of the lower extremity were included. All patients received oral levofloxacin therapy at a dose of 500 mg once daily. Wound tissue and serum samples were collected and levofloxacin concentrations determined by HPLC with fluorescence detection. Additionally, microbiological cultures were performed from swabs and debrided wound tissue, both before and after treatment. MICs of levofloxacin for all bacterial isolates were determined using the Etest. RESULTS: Following oral treatment with levofloxacin for an average of 10 +/- 3.8 days, all patients received debridement at the affected limbs. The levofloxacin concentrations in necrotic wound tissue were between 2.33-23.23 mg/kg and between 0.12-6.41 mg/L in serum. Tissue-to-serum ratios of levofloxacin concentrations for each patient were >1.0. The MIC values for all 17 initially isolated bacteria were < or = 2 mg/L. In half of our patients, fluoroquinolones were one of the few oral monotherapy options where the spectrum covered all initially isolated pathogens. CONCLUSION: Our data showed good tissue penetration of levofloxacin in diabetic foot ulcers. In combination with adequate surgical debridement, levofloxacin seems well suited to the treatment of skin structure infections of diabetics caused by susceptible organisms.

Tissue and serum concentrations of levofloxacin 500 mg administered intravenously or orally for antibiotic prophylaxis in biliary surgery.

OBJECTIVES: Levofloxacin is a third-generation fluoroquinolone with a broad spectrum of antibacterial activity, comprising enterobacteria, non-fermenters, Gram-positive cocci and some anaerobic species. Members of these species are common pathogens in acute and chronic cholecystitis. This suggests that levofloxacin may be used as peri-operative prophylaxis in gall-bladder surgery. The purpose of our study was to determine serum and tissue levels of levofloxacin in cholecystectomy patients following pre-operative dosing. PATIENTS AND METHODS: Patients with gall-bladder surgery were given levofloxacin 500 mg as a single dose either intravenously (iv) or orally pre-operatively, at the treating physician's decision. Gall-bladder tissue and serum samples were collected, and drug concentrations were determined by HPLC with fluorescence detection. Additionally, all tissue samples underwent routine microbiological diagnostics. MICs for aerobic isolates were determined using the Etest. RESULTS: A total of 61 patients (48 female, 13 male) were included. The medians of the levofloxacin concentrations in serum were 11.37 mg/L (iv) and 9.65 mg/L (oral), and in gall-bladder tissue they were 15.61 mg/kg (iv) and 17.93 mg/kg (oral). Eleven pathogens were isolated from gall-bladder samples. Post-operative wound infection was observed in two of the 61 patients. CONCLUSION: Our data suggest that levofloxacin may be considered for peri-operative prophylaxis in biliary tract surgery.