[Do Multiplex PCR techniques displace classical cultures in microbiology?]. / Verdrängt Multiplex PCR den klassischen Kulturnachweis in der Mikrobiologie?

Multiplex PCR technologies progressively find their way in clinical microbiology. This technique allows the simultaneous amplification of multiple DNA targets in a single test run for the identification of pathogens up to the species level. Various pathogens of infectious diseases can be detected by a symptom-oriented approach clearly and quickly with high reliability. Essentially multiplex PCR panels are available for clarification of gastrointestinal, respiratory, sexually transmitted infections and meningitis. Today's offer from industry, university hospitals and large private laboratories of Switzerland is tabulated and commented.

Diagnostics as essential tools for containing antibacterial resistance.

Antibacterial drugs are overused and often inappropriately selected. This exacerbates drug resistance and exacts a high burden from acute respiratory tract, bloodstream, sexually-transmitted, diarrheal and other infections. Appropriate use of existing diagnostic tests, and developing better ones, could avert these costs and would avoid selective pressure from unnecessary antibacterial use. Product profiles of resistance-averting tests would specify WHO 'ASSURED' (Affordable, Sensitive, Specific, User-friendly, Rapid and Robust, Equipment-free and Deliverable) criteria and request susceptibility as well as etiological information. Advances in genomics, nanoscience, microfluidics and bioengineering, as well as innovative funding paradigms can help to overcome research and development barriers for such diagnostics if they are deliberately and forcefully applied. Rapid uptake of new tests requires timely translation of research on cost-benefit analyses into policy, value-based subsidies and reimbursements, as well as behavioral change of health care providers and users.

Prevention of severe Candida infections in nonneutropenic, high-risk, critically ill patients: a randomized, double-blind, placebo-controlled trial in patients treated by selective digestive decontamination.

OBJECTIVE: Infections caused by Candida spp. are a major cause of morbidity and mortality in critically ill patients and usually develop from endogenous colonization. We assessed the effectiveness of adding fluconazole to a selective digestive decontamination regimen to prevent candidal infections. DESIGN AND SETTING: We performed a prospective, randomized, double-blind, placebo-controlled trial among medical and surgical intensive care unit patients at a large university hospital. PATIENTS: All adult patients mechanically ventilated for at least 48 h with an expectation to remain so for at least an additional 72 h, and receiving selective decontamination of the digestive tract. INTERVENTIONS: Patients were randomly assigned fluconazole 100 mg daily (n=103) or placebo (n=101). MEASUREMENTS AND RESULTS: Candida infections occurred less frequently in the fluconazole group (5.8%) than in the placebo group (16%; rate ratio 0.35; Cl(95) 0.11-0.94). Some 90% of candidemia episodes occurred in the placebo group (rate ratio for fluconazole use 0.10; Cl(95) 0.02-0.74). The rate of treatment failure, development of candidal infection, or increased colonization, was 32% in the fluconazole group and 67% in the placebo group (P<0.001). Crude in-hospital mortality was similar in the two groups (39% fluconazole vs. 41% placebo). CONCLUSIONS: Prophylactic use of fluconazole in a selected group of mechanically ventilated patients at high risk for infection reduces the incidence of Candida infections, in particular candidemia.

Epidemiology of methicillin-resistant Staphylococcus aureus: results of a nation-wide survey in Switzerland.

OBJECTIVE: To assess the epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) in Switzerland. MATERIAL AND METHODS: One-year national survey of all MRSA cases detected in a large sample of Swiss healthcare institutions (HCI). Analysis of epidemiological and molecular typing data (PFGE) of MRSA strains. RESULTS: During 1997, 385 cases of MRSA were recorded in the 5 university hospitals, in 33 acute care community hospitals, and 14 rehabilitation or long-term care institutions. Half of the cases were found at the University of Geneva Hospitals where MRSA was already known to be endemic (41.1 cases/10,000 admissions). The remaining cases (200) were distributed throughout Switzerland. The highest rates (>100 cases/10,000 admissions) were reported from non-acute care institutions. Rates ranged from 3.3 to 41.1 cases/10,000 admissions for university hospitals (mean 15.5); 0.67 to 90.4 for community hospitals (mean 4.8), and 28.2 to 315 for non-acute care institutions reporting MRSA (mean 85.7). Forty percent of MRSA patients were infected, while 60% were only colonised. The leading infection sites were skin and soft tissue (21%), surgical site (15%), and the urinary tract (26%). Whereas in Eastern Swiss HCI most MRSA cases occurred in acute care hospitals (n = 47, 98%), rehabilitation and long-term care institutions accounted for an important number of the identified cases (n = 107, 38%) in Western Switzerland. CONCLUSION: Low rates of MRSA were still observed in Swiss HCI, despite one outlying acute care centre with endemic MRSA and some nonacute care institutions with epidemic MRSA. Rehabilitation and long-term care institutions contributed to a substantial proportion of cases in Western Switzerland and may constitute a significant reservoir. Overall, a national approach to surveillance and control of MRSA is mandatory in order to preserve a still favourable situation, and to decrease the risk of epidemic MRSA dissemination.

Pharmacokinetics and pharmacodynamics of oral beta-lactam antibiotics as a two-dimensional approach to their efficacy.

Pharmacokinetic and pharmacodynamic parameters are increasingly recognized as important determinants of the therapeutic efficacy of an antibiotic. For beta-lactam antibiotics, the most important determinant of the antimicrobial efficacy, and hence predictor of therapeutic efficacy, is the length of time that serum concentrations exceed the MIC. Dosing schedules for beta-lactam antibiotics should maintain serum concentrations above the MIC for the bacterial pathogen for at least 50% of the dosing interval to achieve therapeutic efficacy and prevent the development of resistance. This is a basic criterion for the clinical efficacy of beta-lactams. A combination of microbiological activity and pharmacokinetic characteristics was applied to calculate the time that serum antibiotic concentrations exceed the MIC for the major respiratory tract pathogens such as Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, Streptococcus pyogenes and Klebsiella pneumoniae. In contrast with some other oral beta-lactam antibiotics, cefpodoxime 200 mg bd maintains serum concentrations above the MIC for each organism for at least 50% of the dosing interval and may therefore be an attractive choice for empirical therapy of community-acquired lower respiratory tract infections.

European survey of glycopeptide susceptibility in Staphylococcus spp.

OBJECTIVE: To reassess the relative potencies of teicoplanin and vancomycin following several years of clinical usage. METHODS: The glycopeptide susceptibilities of clinical isolates of staphylococci collected from 70 hospitals in 1995 were determined using NCCLS (National Committee for Clinical Laboratory Standards) methods. RESULTS: In total, 2885 isolates of Staphylococcus aureus and 1480 isolates of coagulase-negative staphylococci were collected. S. aureus was significantly less susceptible to vancomycin (MIC50 1 mg/L) than teicoplanin (MIC50 0.5 mg/L), but the reverse was the case for S. haemolyticus and S. epidermidis. No S. aureus isolate was resistant (>/=32 mg/L) to either glycopeptide, but nine isolates of coagulase-negative staphylococci had an MIC of teicoplanin of 32 mg/L. Respiratory isolates of S. aureus were less susceptible to glycopeptides than those from other sites. Staphylococci from Belgium and Italy were less susceptible to teicoplanin than isolates from other countries. CONCLUSIONS: This European survey shows that in 10 years of clinical use there have been no major changes in the susceptibility of staphylococci to the glycopeptides.

Community-acquired methicillin-resistant Staphylococcus aureus isolated in Switzerland contains the Panton-Valentine leukocidin or exfoliative toxin genes.

Among 10 strains of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) isolated in 2002 from patients with skin infections, seven harbored the Panton-Valentine leukocidin gene, two harbored the exfoliative toxin A gene, and one harbored neither of these genes. CA-MRSA isolates producing a variety of exotoxins are currently spreading in the Swiss community.

Resistance to amikacin and gentamicin among Gram-negative bloodstream isolates in a university hospital between 1989 and 1994.

OBJECTIVE: To characterize antimicrobial resistance patterns to amikacin (AN) and gentamicin (GM) among Gram-negative bloodstream isolates and to determine the possible relationship between use of AN and GM and the occurrence of antibiotic resistance during a 6-year period. METHODS: Standard media and techniques of isolation and identification were used. Antimicrobial susceptibility testing was performed with the disk diffusion method and API rapid ATB E strips. Data on consumption of aminoglycosides were collected by the central hospital pharmacy and were expressed as daily defined doses. RESULTS: One thousand nine hundred and four bloodstream isolates were tested for AN and GM susceptibility between 1989 and 1994. Activities of AN and GM remained high during the study period against most isolates of Gram-negative bacteria. No relationship could be observed between the use of AN/GM and the rate of AN/GM resistance. Nosocomial Gram-negative bloodstream isolates showed a higher degree of resistance towards both AN (3.9% of all nosocomial isolates) and GM (7.9%) than community-acquired isolates (1.8% toward AN and 3.1% towards GM, respectively). There was a significant increase (P=0.004) in the risk of GM resistance in patients with nosocomial Gram-negative bacteremia detected more than 14 days after admission. The proportion of GM-susceptible Pseudomonas aeruginosa isolates decreased linearly from 97% for infections acquired between day 3 and day 10 following admission to 80% for bacteremia developing 30 days or more after admission (P=0.008). CONCLUSIONS: AN and GM remain highly active antimicrobial drugs for treatment of GNB in times of growing resistance to cephalosporins and fluoroquinolones.

Postneurosurgical meningitis due to Proteus penneri with selection of a ceftriaxone-resistant isolate: analysis of chromosomal class A beta-lactamase HugA and its LysR-type regulatory protein HugR.

We report on a case of a postneurosurgical meningitis due to ceftriaxone-susceptible Proteus penneri, with selection of a ceftriaxone-resistant isolate following treatment with ceftriaxone. The isolates presented identical patterns by pulsed-field gel electrophoresis and produced a single beta-lactamase named HugA with an isoelectric point of 6.7. The ceftriaxone-resistant isolate hyperproduced the beta-lactamase (increase in the level of production, about 90-fold). The sequences of the hugA beta-lactamase gene and its regulator, hugR, were identical in both P. penneri strains and had 85.96% homology with those of Proteus vulgaris. The HugA beta-lactamase belongs to molecular class A, and the transcriptional regulator HugR belongs to the LysR family.