Comparative evaluation of the detection rate, workflow and associated costs of a multiplex PCR panel versus conventional methods in diagnosis of infectious gastroenteritis.

Introduction. Infectious gastroenteritis is a common reason for consulting a physician. Although most cases of gastrointestinal illness are self-limiting, the identification of the etiologic pathogen by stool specimen analysis is important in cases of more severe illness and for epidemiological reasons.Due to the broad range of causative pathogens, the conventional examination of a stool specimen is labour-intensive and usually requires different diagnostic methods. Multiplex PCR tests [e.g. BioFire Gastrointestinal (GI) Panel] allow the rapid detecting of up to 22 pathogens in one test.Hypothesis. Using a multiplex PCR panel to test stool specimens for infectious gastroenteritis pathogens can improve the detection rate, reduce the time-to-result and hands-on time and lower the costs of a microbiology laboratory.Aim. This study was aimed at evaluating the detection rate, the workflow and associated costs of stool specimen management using the BioFire GI Panel versus conventional methods.Methodology. Stool specimens were evaluated prospectively during the routine operation. Pathogen detection rate, hands-on time, time-to-result and material and personnel costs were determined for the BioFire GI Panel and conventional methods-the latter based on physician request and excluding viral testing.Results. Analysing 333 specimens collected between 2019 and 2020, the detection rate of enteropathogens was significantly higher with a positivity rate of 39.9 % using the multiplex PCR panel compared with 15.0 % using the conventional methods. The BioFire GI Panel presented results in a median time of 2.2 h compared with 77.5 h for culture and 22.1 h for antigen testing, noting that no tests were performed at weekends except for toxinogenic Clostridioides difficile. Based on list prices, the BioFire GI Panel was nine times more expensive compared with conventional methods, whereas hands-on-time was significantly lower using the BioFire GI Panel.Conclusion. Multiplex PCR panels are valuable tools for laboratory identification of infectious agents causing diarrhoea. The higher costs of such a multiplex PCR panel might be outweighed by the higher detection rate, ease of handling, rapid results and most likely improved patient management. However, these panels do not provide information on antimicrobial susceptibility testing. Therefore, if this is necessary for targeted therapy or if outbreak monitoring and control is required, specimens must still be cultured.

[Systemic and local antibiotic therapy of conservative and operative treatment of spondylodiscitis]. / Systemische und lokale Antibiotikatherapie bei konservativ und operativ behandelten Spondylodiszitiden.

An evidence-based recommendation for a standardized antibiotic therapy of spondylodiscitis has not yet been published. Crucial for conservative therapy is the verification of the causative organism and an appropriate antibiotic therapy. Intravenous antibiotic therapy should be administered for 2-3 weeks and a switched to oral administration for 6-12 weeks is then possible. If an empirical antimicrobial therapy is required a combination of ciprofloxacin and clindamycin, alternatively a combination of cefotaxim and flucloxacillin is recommended. Surgical removal of the infection by extensive debridement with stabilization and filling the resulting bone defect is desirable. Under the perception of a high local dose of antibiotic the defect filling with a mixture of cancellous bone and antibiotic-loaded hydroxyapatite and calcium sulfate is advisable.

Antimicrobial Activity of Ceftolozane-Tazobactam, Ceftazidime-Avibactam, and Cefiderocol against Multidrug-Resistant Pseudomonas aeruginosa Recovered at a German University Hospital.

Multidrug-resistant (MDR) Pseudomonas aeruginosa increasingly causes health care-associated infections. In this study, we determined the activity of ceftolozane-tazobactam, ceftazidime-avibactam, and cefiderocol against 223 MDR P. aeruginosa clinical isolates recovered from 2013 to 2017 at the University Hospital Frankfurt by using MIC test strips. Furthermore, we evaluated the presence of genes encoding major ß-lactamases, such as VIM, IMP, NDM, GIM, SPM, and KPC; the extended spectrum ß-lactamase (ESBL)-carbapenemase GES; and the virulence-associated traits ExoS and ExoU, as in particular ExoU is thought to be associated with poor clinical outcome. For MDR P. aeruginosa isolates, the MIC50/MIC90 values of ceftolozane-tazobactam, ceftazidime-avibactam, and cefiderocol were 8/>256 mg/L, 16/>256 mg/L, and 0.25/1 mg/L, respectively. Cefiderocol showed the highest susceptibility rate (97.3%) followed by ceftazidime-avibactam (48.4%) and ceftolozane-tazobactam (46.6%). In 81 (36.3%) isolates, carbapenemase gene blaVIM was detected, and in 5 (2.2%) isolates, blaGES was detected (with a positive association of exoU and blaVIM). More than half of the isolates belong to the so-called international P. aeruginosa "high-risk" clones, with sequence type 235 (ST235) (24.7%) being the most prevalent. This study underlines that ceftolozane-tazobactam, ceftazidime-avibactam, and cefiderocol are important options for the treatment of infections due to MDR P. aeruginosa, with cefiderocol currently being the most active available antipseudomonal ß-lactam agent. According to our clinical experience, the outcome of cefiderocol therapy (8 patients) was favorable especially in cases of MDR P. aeruginosa-associated complicated urinary tract infections. IMPORTANCE After testing ceftolozane-tazobactam, ceftazidime-avibactam, and cefiderocol against a collection of 233 multidrug-resistant (MDR) Pseudomonas aeruginosa, we showed that cefiderocol is the most active antipseudomonal ß-lactam agent (susceptibility rates were 46.6%, 48.4%, and 97.4%, respectively). The most prevalent one was sequence type 235 (ST235) (24.7%), followed by ST244, ST175, and ST233, with all belonging to the top 10 P. aeruginosa high-risk clones with worldwide distribution. Our data indicate that during surveillance studies special attention should be paid to the MDR and highly virulent VIM- and ExoU-producing variant of ST235. Furthermore, in the case of infections caused by carbapenemase-producing MDR P. aeruginosa, cefiderocol is the preferred treatment option, while outcomes of complicated urinary tract infections and hospital-acquired pneumonia with cefiderocol were favorable.

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.

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.

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.

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.

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.

Removal of PCR inhibitors by silica membranes: evaluating the Amplicor Mycobacterium tuberculosis kit.

The effectiveness of PCR inhibitor removal by silica membranes in combination with the Amplicor Mycobacterium tuberculosis kit was analyzed for 655 respiratory and nonrespiratory specimens. The overall inhibition rate was reduced from 12.5%, when applying the Amplicor kit alone, to 1.1% with the addition of silica membrane DNA purification.

[Significance of methicillin resistant S. aureus (MRSA) in geriatrics--epidemiology, therapy and management]. / Bedeutung des Methicillin-resistenten S. aureus (MRSA) in der Geriatrie--Epidemiologie, Therapie und 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.

[Pathogen detection in blood culture. Contamination, colonization or infection]. / Keimnachweis in der Blutkultur. Kontamination, Kolonisation oder Infektion.

Sepsis is a severe and life-threatening disease that requires a rapid and reliable diagnosis. The detection of microorganisms in blood culture and the results of in vitro anti-microbial susceptibility testing are prerequisites for a directed and cost-effective antimicrobial therapy. Microbiological results are difficult to interpret if contamination of the blood culture with colonizing or environmental germs cannot be ruled out. The source of contamination is predominantly inappropriate withdrawal of blood. Occasionally, contamination of blood cultures occurs in the laboratory. A potentially relevant blood culture result is already indicated by the isolated pathogen itself. In addition, a short time between the collection of blood and the isolation of the microorganism as well as the detection of the same pathogen in several blood cultures even more suggest a clinically relevant result.

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.

[Evidence-based antibiotic prophylaxis in aseptic orthopedic surgery]. / Perioperative Antibiotikaprophylaxe bei aseptischen Eingriffen in der Orthopädie.

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.

Clonal heterogeneity, distribution, and pathogenicity of methicillin-resistant Staphylococcus aureus.

Four thousand eighty-eight Staphylococcus aureus isolates obtained from patients hospitalised in a university clinic and four community hospitals over a period of one year were screened for methicillin resistance. A resistance rate of 5% was detected among initial isolates. Distribution of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive Staphylococcus aureus showed an increased prevalence of MRSA in clinically significant specimens such as blood, central venous catheter tips, bronchial secretions, and wound secretions. Typing of 110 MRSA strains (initial isolates) by macrorestriction analysis of chromosomal DNA revealed 26 different genotypes that could be divided into five epidemic and 21 sporadic strains. More than 50% of all isolates belonged to one type that was confirmed to be closely related to the "southern-German" epidemic strain. Production of virulence factors such as enterotoxin A-D and toxic shock syndrome-toxin 1 among MRSA strains (initial isolates) occurred in ten of 26 different MRSA types. A strong correlation between genotype and toxin production was demonstrated.

[Antibacterial effectiveness of povidone-iodine (Betaisodona) against highly resistance gram positive organisms]. / Antibakterielle Wirksamkeit von Polyvidon-lod (Betaisodona) auf hochresistente grampositive Erreger.

Antiseptics that are locally applicable gain in significance due to their reliable microbicidal effectiveness and especially due to the rising incidence of highly resistant bacteria. This is because systemically applied antibiotics are not sufficient in eradicating superficial mucodermal bacteria and locally applied antibiotics can cause new resistance rapidly. The aim of this study was to demonstrate the microbicidal effectiveness of Poly(1-vinyl-2-pyrrodlidon)-iodine (PVP-iodine) against ten genotypical different methicillin resistant Staphylococcus aureus-(MRSA-) and five Enterococcus faecium-strains in a quantitative suspension test. The effectiveness of PVP-iodine with protein load (0.2% and 2% albumin) was tested against three MRSA strains. Without any protein load best microbicidial activity (KRt-value > 5) was obtained with concentrations in the range between 1-10% of the original Betaisodona solution after 30s exposure time. With protein load (0.2% albumin) the optimum in microbicidal effectiveness shifts to concentrations > or = 10% Betaisodona solution referring to an exposure time of 30s. With a protein load up to 2% albumin and an exposure time of 30s the bactericidal activity of the undiluted Betaisodona solution is already satisfying, while the 10% solution is not active till an exposure time of 5 min. Summing up PVP-iodine is recommended as a local mucodermal antiseptic against highly resistant gram positives.

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.

[Methicillin-reistant Staphylococcus aureus: risk factors for infection-colonization and clonal heterogeneity in intensive care units]. / Methicillin-resistenter Staphylococcus aureus: Risikofaktoren der Infektion/Kolonisation und Klonale Heterogenität des Erregers auf einer Intensivstation.

PURPOSE: The aim of this study was to determine the risk factors associated with colonisation/infection by methicillin-resistant Staphylococcus aureus (MRSA) and to demonstrate the chain of infections by genotyping of all MRSA isolates. METHODS: A total of 6143 microbiological samples from 1753 patients was obtained at a surgical ICU of Frankfurt University hospital during 1995. RESULTS: MRSA was detected in 1.6% of patients and three members of staff (3.3%). Typing of these 31 MRSA-strains (first isolates) by macrorestriction analysis of chromosomal DNA revealed nine different genotypes. More than 60% of all isolates belonged to one type that was confirmed to be closely related to the "South Germany" epidemic strain. A strong correlation between severity of underlying disease and length of hospitalisation on the one hand and detection of MRSA on the other could be demonstrated. Detection of MRSA was significantly more common in patients with adult respiratory distress syndrome (ARDS), sepsis, kidney failure, prolong respiratory treatment and in patients with prolonged phases of haemodynamic instability. It appeared that the mortality rate of MRSA-infected patients was higher (28.6%) than the mortality rate of all patients (6.5%). CONCLUSION: Following of a strict hygiene regime is important to prevent clonal spread of MRSA and especially to protect immunocompromised patients from complicating infections.