The dark side of SARS-CoV-2 rapid antigen testing: screening asymptomatic patients

Several reports showed SARS-CoV-2 rapid antigen tests (RATs) performances among COVID-19 symptomatic subjects in outpatient settings during periods of highest incidence of infections and high rates of hospital admissions, but few data are present for asymptomatic patients. We investigated the role of RATs in an emergency department, as a novel screening tool before admission for COVID-19 asymptomatic patients. A total of 116 patients were screened on admission in a 250-bed community hospital in Morges, Switzerland. RAT detected 2/7 RT-PCR-positive patients and delivered two false-positive results. These data suggest the non-fiability of RATs screening in this clinical scenario.

Assessment of the Role of 1,3-β-d-Glucan Testing for the Diagnosis of Invasive Fungal Infections in Adults

Detection of 1,3-β-d-glucan (BDG) in serum has been evaluated for its inclusion as a mycological criterion of invasive fungal infections (IFI) according to EORTC and Mycoses Study Group (MSG) definitions. BDG testing may be useful for the diagnosis of both invasive aspergillosis and invasive candidiasis, when interpreted in conjunction with other clinical/radiological signs and microbiological markers of IFI. However, its performance and utility vary according to patient population (hematologic cancer patients, solid-organ transplant recipients, intensive care unit patients) and pretest likelihood of IFI. The objectives of this article are to provide a systematic review of the performance of BDG testing and to assess recommendations for its use and interpretation in different clinical settings.

Nosocomial influenza in south-western Swiss hospitals during two seasonal epidemics: an observational study

BACKGROUND

In Switzerland each year, influenza leads to between 112,000 and 275,000 medical consultations. Data on nosocomial influenza infection are limited.

AIM

To describe nosocomial cases of seasonal influenza in south-western Switzerland.

METHODS

This study was conducted during two seasonal influenza epidemics from 2016 to 2018 in 27 acute care public hospitals in south-western Switzerland. During these two time-periods, every patient hospitalized for >72 h who was positively screened by reverse transcription-polymerase chain reaction or antigen detection for influenza was included in the survey. Characteristics of patients included age, sex, and comorbidities. Included patients were followed up until discharge or death. Complications and administration of antineuraminidases and/or antibiotics were registered.

FINDINGS

The median influenza vaccine coverage of healthcare workers was 40%. In all, 836 patients were included (98% with type A influenza virus in 2016-2017; 77% with type B virus in 2017-2018). Most patients (81%) had an unknown vaccine status. Overall, the incidence of nosocomial influenza was 0.5 per 100 admissions (0.35 per 1000 patient-days). The most frequent comorbidities were diabetes (20%), chronic respiratory diseases (19%), and malnutrition (17%). Fever (77%) and cough (66%) were the most frequent symptoms. Seventy-one percent of patients received antineuraminidases, 28% received antibiotics. Infectious complications such as pneumonia were reported in 9%. Overall, the all-cause mortality was 6%.

CONCLUSION

The occurrence of nosocomial influenza underlines the importance of vaccinating patients and healthcare workers, rapidly recognizing community- or hospital-acquired cases, and applying adequate additional measures to prevent dissemination, including the timely administration of antineuraminidases to avoid antibiotic use (and misuse).

Accuracy of Sensititre YeastOne echinocandins epidemiological cut-off values for identification of FKS mutant Candida albicans and Candida glabrata: a ten year national survey of the Fungal Infection Network of Switzerland (FUNGINOS)

OBJECTIVES

Echinocandins represent the first-line treatment of candidaemia. Acquired echinocandin resistance is mainly observed among Candida albicans and Candida glabrata and is associated with FKS hotspot mutations. The commercial Sensititre YeastOne™ (SYO) kit is widely used for antifungal susceptibility testing, but interpretive clinical breakpoints are not well defined. We determined echinocandins epidemiological cut-off values (ECV) for C. albicans/glabrata tested by SYO and assessed their ability to identify FKS mutants in a national survey of candidaemia.

METHODS

Bloodstream isolates of C. albicans and C. glabrata were collected in 25 Swiss hospitals from 2004 to 2013 and tested by SYO. FKS hotspot sequencing was performed for isolates with an MIC≥ECV for any echinocandin.

RESULTS

In all, 1277 C. albicans and 347 C. glabrata were included. ECV 97.5% of caspofungin, anidulafungin and micafungin were 0.12, 0.06 and 0.03 μg/mL for C. albicans, and 0.25, 0.12 and 0.03 μg/mL for C. glabrata, respectively. FKS hotspot sequencing was performed for 70 isolates. No mutation was found in the 52 'limit wild-type' isolates (MIC=ECV for at least one echinocandin). Among the 18 'non-wild-type' isolates (MIC>ECV for at least one echinocandin), FKS mutations were recovered in the only two isolates with MIC>ECV for all three echinocandins, but not in those exhibiting a 'non-wild-type' phenotype for only one or two echinocandins.

CONCLUSION

This 10-year nationwide survey showed that the rate of echinocandin resistance among C. albicans and C. glabrata remains low in Switzerland despite increased echinocandin use. SYO-ECV could discriminate FKS mutants from wild-type isolates tested by SYO in this population.

Diagnosis and management of Aspergillus diseases: executive summary of the 2017 ESCMID-ECMM-ERS guideline

The European Society for Clinical Microbiology and Infectious Diseases, the European Confederation of Medical Mycology and the European Respiratory Society Joint Clinical Guidelines focus on diagnosis and management of aspergillosis. Of the numerous recommendations, a few are summarized here. Chest computed tomography as well as bronchoscopy with bronchoalveolar lavage (BAL) in patients with suspicion of pulmonary invasive aspergillosis (IA) are strongly recommended. For diagnosis, direct microscopy, preferably using optical brighteners, histopathology and culture are strongly recommended. Serum and BAL galactomannan measures are recommended as markers for the diagnosis of IA. PCR should be considered in conjunction with other diagnostic tests. Pathogen identification to species complex level is strongly recommended for all clinically relevant Aspergillus isolates; antifungal susceptibility testing should be performed in patients with invasive disease in regions with resistance found in contemporary surveillance programmes. Isavuconazole and voriconazole are the preferred agents for first-line treatment of pulmonary IA, whereas liposomal amphotericin B is moderately supported. Combinations of antifungals as primary treatment options are not recommended. Therapeutic drug monitoring is strongly recommended for patients receiving posaconazole suspension or any form of voriconazole for IA treatment, and in refractory disease, where a personalized approach considering reversal of predisposing factors, switching drug class and surgical intervention is also strongly recommended. Primary prophylaxis with posaconazole is strongly recommended in patients with acute myelogenous leukaemia or myelodysplastic syndrome receiving induction chemotherapy. Secondary prophylaxis is strongly recommended in high-risk patients. We strongly recommend treatment duration based on clinical improvement, degree of immunosuppression and response on imaging.

Hemostatic Activation under Anticoagulant Treatment: A Comparison of Unfractionated Heparin vs. Nadroparin in the Treatment of Proximal Deep Vein Thrombosis

Background: Multiple clinical trials have been performed to compare standard heparin with low molecular weight heparin in the therapy of deep vein thrombosis, but little is known about the time course of the markers of hemostatic system during the treatment with these two heparin regimens.

Methods: Twenty patients with proximal deep vein thrombosis confirmed by duplex ultrasound and phlebography were randomly assigned to either unfractionated heparin (UH) given as an intravenous bolus of 80 U/kg followed by a constant infusion of 18 U/kg/h, or nadroparin 185 AXa IU/kg once daily subcutaneously. Oral anticoagulants were started at day 4. Markers of hemostatic activation (F1+2, FPA, TAT, D-dimer) were measured daily for 4 days. Primary end-points were the time course of these markers; secondary endpoints consisted in the evaluation of thromboembolic and hemorrhagic complications by clinical outcome and Marder score.

Results: Treatment with UH resulted in a rapid achievement of therapeutic heparin levels. UH reduced markers of fibrin formation and fibrinolysis more rapidly than nadroparin (p < 0.05). Within the nadroparin group activation of prothrombotic markers four hours after the subcutanous injection (peak level) was significantly lower when compared with the time prior to injection (trough level). Secondary endpoints showed no significant difference between the two groups.

Conclusion: Continuous intravenous perfusion of UH administered on a basis of a weight-adjusted nomogram controlled markers of the hemostatic system more rapidly than once-daily subcutaneously administered weight-adjusted nadroparin.

CSF lactate for accurate diagnosis of community-acquired bacterial meningitis

CSF lactate measurement is recommended when nosocomial meningitis is suspected, but its value in community-acquired bacterial meningitis is controversial. We evaluated the diagnostic performance of lactate and other CSF parameters in a prospective cohort of adult patients with acute meningitis. Diagnostic accuracy of lactate and other CSF parameters in patients with microbiologically documented episodes was assessed by receiver operating characteristic (ROC) curves. The cut-offs with the best diagnostic performance were determined. Forty-five of 61 patients (74%) had a documented bacterial (n = 18; S. pneumoniae, 11; N. meningitidis, 5; other, 2) or viral (n = 27 enterovirus, 21; VZV, 3; other, 3) etiology. CSF parameters were significantly different in bacterial vs. viral meningitis, respectively (p < 0.001 for all comparisons): white cell count (median 1333 vs. 143/mm(3)), proteins (median 4115 vs. 829 mg/l), CSF/blood glucose ratio (median 0.1 vs. 0.52), lactate (median 13 vs. 2.3 mmol/l). ROC curve analysis showed that CSF lactate had the highest accuracy for discriminating bacterial from viral meningitis, with a cutoff set at 3.5 mmol/l providing 100% sensitivity, specificity, PPV, NPV, and efficiency. CSF lactate had the best accuracy for discriminating bacterial from viral meningitis and should be included in the initial diagnostic workup of this condition.

Candida species distribution and antifungal susceptibility testing according to European Committee on Antimicrobial Susceptibility Testing and new vs. old Clinical and Laboratory Standards Institute clinical breakpoints: a 6-year prospective candidaemia survey from the fungal infection network of Switzerland

We analyzed the species distribution of Candida blood isolates (CBIs), prospectively collected between 2004 and 2009 within FUNGINOS, and compared their antifungal susceptibility according to clinical breakpoints defined by the European Committee on Antimicrobial Susceptibility Testing (EUCAST) in 2013, and the Clinical and Laboratory Standards Institute (CLSI) in 2008 (old CLSI breakpoints) and 2012 (new CLSI breakpoints). CBIs were tested for susceptiblity to fluconazole, voriconazole and caspofungin by microtitre broth dilution (Sensititre® YeastOne™ test panel). Of 1090 CBIs, 675 (61.9%) were C. albicans, 191 (17.5%) C. glabrata, 64 (5.9%) C. tropicalis, 59 (5.4%) C. parapsilosis, 33 (3%) C. dubliniensis, 22 (2%) C. krusei and 46 (4.2%) rare Candida species. Independently of the breakpoints applied, C. albicans was almost uniformly (>98%) susceptible to all three antifungal agents. In contrast, the proportions of fluconazole- and voriconazole-susceptible C. tropicalis and F-susceptible C. parapsilosis were lower according to EUCAST/new CLSI breakpoints than to the old CLSI breakpoints. For caspofungin, non-susceptibility occurred mainly in C. krusei (63.3%) and C. glabrata (9.4%). Nine isolates (five C. tropicalis, three C. albicans and one C. parapsilosis) were cross-resistant to azoles according to EUCAST breakpoints, compared with three isolates (two C. albicans and one C. tropicalis) according to new and two (2 C. albicans) according to old CLSI breakpoints. Four species (C. albicans, C. glabrata, C. tropicalis and C. parapsilosis) represented >90% of all CBIs. In vitro resistance to fluconazole, voriconazole and caspofungin was rare among C. albicans, but an increase of non-susceptibile isolates was observed among C. tropicalis/C. parapsilosis for the azoles and C. glabrata/C. krusei for caspofungin according to EUCAST and new CLSI breakpoints compared with old CLSI breakpoints.

[Antimicrobial agents and renal elimination: towards individual dosage adjustment?]

The efficacy and safety of anti-infective treatments are associated with the drug blood concentration profile, which is directly correlated with a dosing adjustment to the individual patient's condition. Dosing adjustments to the renal function recommended in reference books are often imprecise and infrequently applied in clinical practice. The recent generalisation of the KDOQI (Kidney Disease Outcome Quality Initiative) staging of chronically impaired renal function represents an opportunity to review and refine the dosing recommendations in patients with renal insufficiency. The literature has been reviewed and compared to a predictive model of the fraction of drug cleared by the kidney based on the Dettli's principle. Revised drug dosing recommendations integrating these predictive parameters are proposed.

[Empirical antibiotic therapy for febrile neutropenia]

Immediate broad-spectrum empirical antibacterial therapy is the key of management in febrile neutropenic patients. These patients can be stratified according to the risk of complications with the clinical MASCC score. Patients at low risk of complications can be efficaciously treated with oral antibiotics (e.g. fluoroquinolone and beta-lactam), provided that compliance and drug absorption are adequate. Early discharge is possible if clinical, logistic, and social criteria are fulfilled. Intravenous antibiotic therapy with broad-spectrum beta-lactam antibiotics in the hospital remains the standard in high-risk patients. The empirical addition of an aminoglycoside and/or a glycopeptide is recommended if the local incidence of infections due to beta-lactam resistant pathogens is high or in critically ill septic patients.

Low Mannose-Binding Lectin Concentration Is Associated with Severe Infection in Patients with Hematological Cancer Who Are Undergoing Chemotherapy

BACKGROUND

Mannose-binding lectin (MBL) is a serum lectin involved in innate immune response. Low serum MBL concentration may constitute a risk factor for infection in patients receiving myelosuppressive chemotherapy.

METHODS

We conducted a prospective, observational study that assessed MBL concentration as a risk factor for infection in patients with hematological malignancy who were hospitalized to undergo at least 1 chemotherapy cycle. MBL deficiency was defined using an algorithm that considered the serum MBL concentration and the MBL genotype. The primary end point was the ratio of duration of febrile neutropenia to the duration of neutropenia. Secondary end points included the incidence of severe infection (e.g., sepsis, pneumonia, bacteremia, and invasive fungal infection). Logistic regression analysis was conducted, and Fisher's exact test was used to analyze binary outcomes, and Kaplan-Meier estimates and log rank tests were used for time-to-event variables.

RESULTS

We analyzed 255 patients who received 569 cycles of chemotherapy. The median duration of neutropenia per cycle was 7 days (interquartile range, 0-13 days). Sixty-two patients (24%) were found to have MBL deficiency. Febrile neutropenia occurred at least once in 200 patients. No difference in the primary outcome was seen. The incidence of severe infection was higher among MBL-deficient patients than among non-MBL-deficient patients (1.96 vs. 1.34 cases per 100 days for analysis of all patients [P=.008] and 1.85 vs. 0.94 cases per 100 days excluding patients with acute leukemia [P<.001]).

CONCLUSIONS

MBL deficiency does not predispose adults with hematological cancer to more-frequent or more-prolonged febrile episodes during myelosuppressive chemotherapy, but MBL-deficient patients have a greater number of severe infections and experience their first severe infection earlier, compared with nondeficient patients.

Nécrose du segment antérieur sur kératomycose à Fusarium polyrésistant

Keratomycosis is a rare sight-threatening infection of the cornea, with greater morbidity than bacterial keratitis. Predisposing factors in its pathogenesis are corneal trauma, mostly of plant origin, and overuse of topical corticosteroids, associated or not with antibiotics. We report a case of a 71-year-old man who developed Fusarium (lichenicola or solani) keratitis, 15 days after beginning topical therapy with a corticosteroid and antibiotic. Despite aggressive antifungal therapy with fluconazole, he required a penetrating keratoplasty for impending corneal perforation, and finally, even after systemic use of itraconazole and topical use of amphotericin B, the infection progressed and an evisceration was required. In the evisceration material, a multidrug-resistant Fusarium lichenicola or solani, was found, partially sensitive to voriconazole only.

[Utility of procalcitonin for the diagnosis and the follow-up of infections in febrile neutropenic patients]

Procalcitonin is a marker of severe bacterial infections in non-neutropenic patients. The goal of this review is to assess its utility in the management of neutropenic patients. A delayed treatment of infection in this setting results in severe morbidity and high mortality. As traditional diagnostic tools often fail to exclude infection when fever occurs, all these patients receive empirical antimicrobial therapies during long periods of time. Present knowledge suggests that procalcitonin may contribute to identify patients in whom 1) antibiotics could be stopped in the absence of bacterial infection, 2) investigations and adjustments of the antimicrobial therapy for persistent fever are needed. The use of procalcitonin for the management of febrile neutropenic patients should be studied prospectively.

Disposition of voriconazole during continuous veno-venous haemodiafiltration (CVVHDF) in a single patient

OBJECTIVES

To determine whether voriconazole dosage adjustment is required during continuous veno-venous haemodiafiltration (CVVHDF).

METHODS

Voriconazole pharmacokinetics were studied in a critically ill patient under CVVHDF. The analysis was carried out for 12 h following a 6 mg/kg dose. Voriconazole concentrations were measured by HPLC in blood inlet and outlet lines and in dialysate.

RESULTS

The total body clearance of voriconazole was 20.3 L/h, with a terminal half-life of 13.7 h and a distribution volume of 399 L. The estimated sieving coefficient was 0.53 and the filtration-dialysis clearance 1.2 L/h.

CONCLUSIONS

CVVHDF does not significantly affect voriconazole disposition and requires no dosage adjustment.

Vancomycin versus placebo for treating persistent fever in patients with neutropenic cancer receiving piperacillin-tazobactam monotherapy

This prospective, double-blind trial assessed whether the addition of a glycopeptide would be able to reduce the time to defervescence in neutropenic patients with cancer who had persistent fever 48-60 h after the initiation of empirical piperacillin-tazobactam monotherapy. Of 763 eligible patients, 165 with persistent fever were randomized to receive piperacillin-tazobactam therapy plus either vancomycin therapy or placebo. Defervescence was observed in 82 (95%) of 86 patients in the vancomycin group and in 73 (92%) of 79 patients in the placebo group (P=.52). The distributions of the time to defervescence were not statistically significant between the 2 groups (estimated hazard ratio, 1.03; 95% confidence interval, 0.75-1.43; P=.75). The number of additional episodes of gram-positive bacteremia and the percentage of patients for whom amphotericin B was empirically added to their therapy regimen were also similar in both groups. This study failed to demonstrate that the empirical addition of vancomycin therapy to the treatment regimen is of benefit to persistently febrile neutropenic patients with cancer.

Sensitive bioassay for determination of fluconazole concentrations in plasma using a Candida albicans mutant hypersusceptible to azoles

The antifungal agent fluconazole (FLC) is widely used in clinical practice. Monitoring FLC levels is useful in complicated clinical settings and in experimental infection models. A bioassay using Candida pseudotropicalis, a simple and cost-effective method, is validated only for FLC levels ranging from 5 to 40 mg/liter. An extension of the analytical range is needed to cover most yeast MICs. A new bioassay in RPMI agar containing methylene blue was developed using C. albicans DSY1024, a mutant rendered hypersusceptible to FLC constructed by the deletion of the multidrug efflux transporter genes CDR1, CDR2, CaMDR1, and FLU1. Reproducible standard curves were obtained with FLC concentrations in plasma ranging from 1 to 100 mg/liter (quadratic regression coefficient > 0.997). The absolute sensitivity was 0.026 microg of FLC. The method was internally validated according to current guidelines for analytical method validation. Both accuracy and precision lied in the required +/-15% range. FLC levels measured by bioassay and by high-performance liquid chromatography (HPLC) performed with 62 plasma samples from humans and rats showed a strong correlation (coefficients, 0.979 and 0.995, respectively; percent deviations of bioassay from HPLC values, 0.44% +/- 15.31% and 2.66% +/- 7.54%, respectively). In summary, this newly developed bioassay is sensitive, simple, rapid, and inexpensive. It allows nonspecialized laboratories to determine FLC levels in plasma to within the clinically relevant concentration range and represents a useful tool for experimental treatment models.

Fluconazole plus cyclosporine: a fungicidal combination effective against experimental endocarditis due to Candida albicans

Recent observations demonstrated that fluconazole plus cyclosporine (Cy) synergistically killed Candida albicans in vitro. This combination was tested in rats with C. albicans experimental endocarditis. The MICs of fluconazole and Cy for the test organism were 0.25 and >10 mg/liter, respectively. Rats were treated for 5 days with either Cy, amphotericin B, fluconazole, or fluconazole-Cy. Although used at high doses, the peak concentrations of fluconazole in the serum of rats (up to 4.5 mg/liter) were compatible with high-dose fluconazole therapy in humans. On the other hand, Cy concentrations in serum (up to 4.5 mg/liter) were greater than recommended therapeutic levels. Untreated rats demonstrated massive pseudohyphal growth in both the vegetations and the kidneys. However, only the kidneys displayed concomitant polymorphonuclear infiltration. The therapeutic results reflected this dissociation. In the vegetations, only the fungicidal fluconazole-Cy combination significantly decreased fungal densities compared to all groups, including amphotericin B (P < 0.0001). In the kidneys, all regimens except the Cy regimen were effective, but fluconazole-Cy remained superior to amphotericin B and fluconazole alone in sterilizing the organs (P < 0.0001). While the mechanism responsible for the fluconazole-Cy interaction is hypothetical, this observation opens new perspectives for fungicidal combinations between azoles and other drugs.

Potent synergism of the combination of fluconazole and cyclosporine in Candida albicans

Several types of drugs currently used in clinical practice were screened in vitro for their potentiation of the antifungal effect of the fungistatic agent fluconazole (FLC) on Candida albicans. These drugs included inhibitors of multidrug efflux transporters, antimicrobial agents, antifungal agents, and membrane-active compounds with no antimicrobial activity, such as antiarrhythmic agents, proton pump inhibitors, and platelet aggregation inhibitors. Among the drugs tested in an agar disk diffusion assay, cyclosporine (Cy), which had no intrinsic antifungal activity, showed a potent antifungal effect in combination with FLC. In a checkerboard microtiter plate format, however, it was observed that the MIC of FLC, as classically defined by the NCCLS recommendations, was unchanged when FLC and Cy were combined. Nevertheless, if a different reading endpoint corresponding to the minimal fungicidal concentration needed to decrease viable counts by at least 3 logs in comparison to the growth control was chosen, the combination was synergistic (fractional inhibitory concentration index of <1). This endpoint fitted to the definition of MIC-0 (optically clear wells) and reflected the absence of the trailing effect, which is the result of a residual growth at FLC concentrations greater than the MIC. The MIC-0 values of FLC and Cy tested alone in C. albicans were >32 and >10 microg/ml, respectively, and decreased to 0.5 and 0.625 microg/ml when the two drugs were combined. The combination of 0.625 microg of Cy per ml with supra-MICs of FLC resulted in a potent antifungal effect in time-kill curve experiments. This effect was fungicidal or fungistatic, depending on the C. albicans strain used. Since the Cy concentration effective in vitro is achievable in vivo, the combination of this agent with FLC represents an attractive perspective for the development of new management strategies for candidiasis.

Hemostatic activation under anticoagulant treatment: a comparison of unfractionated heparin vs. nadroparin in the treatment of proximal deep vein thrombosis

BACKGROUND

Multiple clinical trials have been performed to compare standard heparin with low molecular weight heparin in the therapy of deep vein thrombosis, but little is known about the time course of the markers of hemostatic system during the treatment with these two heparin regimens.

METHODS

Twenty patients with proximal deep vein thrombosis confirmed by duplex ultrasound and phlebography were randomly assigned to either unfractionated heparin (UH) given as an intravenous bolus of 80 U/kg followed by a constant infusion of 18 U/kg/h, or nadroparin 185 AXa IU/kg once daily subcutaneously. Oral anticoagulants were started at day 4. Markers of hemostatic activation (F1+2, FPA, TAT, D-dimer) were measured daily for 4 days. Primary endpoints were the time course of these markers; secondary endpoints consisted in the evaluation of thromboembolic and hemorrhagic complications by clinical outcome and Marder score.

RESULTS

Treatment with UH resulted in a rapid achievement of therapeutic heparin levels. UH reduced markers of fibrin formation and fibrinolysis more rapidly than nadroparin (p < 0.05). Within the nadroparin group activation of prothrombotic markers four hours after the subcutaneous injection (peak level) was significantly lower when compared with the time prior to injection (trough level). Secondary endpoints showed no significant difference between the two groups.

CONCLUSION

Continuous intravenous perfusion of UH administered on a basis of a weight-adjusted nomogram controlled markers of the hemostatic system more rapidly than once-daily subcutaneously administered weight-adjusted nadroparin.

Effect of intravenous heparin infusion on thrombin-antithrombin complex and fibrinopeptide A in unstable angina

BACKGROUND

In unstable angina, the clinical efficacy of heparin is limited in time, and recurrence of adverse events has been reported after discontinuation of the anticoagulant.

METHODS

In 21 episodes of unstable angina, we used the plasma level of fibrinopeptide A (FPA) and of thrombin-antithrombin complex (TAT) to evaluate the pattern of thrombin inhibition by heparin and the effect of stopping heparin and initiating aspirin.

RESULTS

At admission, the plasma level of FPA was increased: median value 3.7 ng/mL compared with 5.5 ng/mL in a control group of 20 patients with early myocardial infarction (not significant). The following findings were observed during a 4-day course of intravenous heparin infusion: (1) FPA decreased significantly 6 hours after the start of therapy; (2) FPA was lower when activated partial thromboplastic time (aPTT) was >1.5 times baseline; (3) there was a significant negative correlation between aPTT and FPA. Twenty-four hours after heparin was discontinued and aspirin initiated, a significant increase in TAT and FPA in plasma was observed.

CONCLUSIONS

The results confirm ongoing fibrin formation in the active phase of unstable angina, indicate incomplete and variable inhibition of thrombin by heparin during continuous infusion, and suggest a risk of re-emergence of thrombosis (in spite of initiating aspirin) 24 hours after withdrawal of heparin. Data demonstrate a better control of thrombin activity when heparin is infused at rates that maintain aPTT at >1.5 times baseline, as currently recommended in unstable angina.

Y-688, a new quinolone active against quinolone-resistant Staphylococcus aureus: lack of in vivo efficacy in experimental endocarditis

Y-688 is a new fluoroquinolone with increased activity against ciprofloxacin-resistant staphylococci. The MICs of Y-688 and other quinolones were determined for 58 isolates of ciprofloxacin-resistant and methicillin-resistant Staphylococcus aureus (MRSA). The MICs at which 50% and 90% of bacteria were inhibited were >/=128 and >/=128 mg/liter, respectively, for ciprofloxacin, 16 and 32 mg/liter, respectively, for sparfloxacin, and 0.25 and 1 mg/liter, respectively, for Y-688. This new quinolone was further tested in rats with experimental endocarditis due to either of two isolates of ciprofloxacin-resistant MRSA (namely, P8/128 and CR1). Infected animals were treated for 3 days with ciprofloxacin, vancomycin, or Y-688. Antibiotics were administered through a computerized pump to simulate human-like pharmacokinetics in the serum of rats. The anticipated peak and trough levels of Y-688 were 4 and 1 mg/liter at 0.5 and 12 h, respectively. Treatment with ciprofloxacin was ineffective. Vancomycin significantly decreased vegetation bacterial counts for both organisms (P less, similar 0.05). In contrast, Y-688 only marginally decreased vegetation bacterial counts (P greater, similar 0.05). Moreover, several vegetation that failed Y-688 treatment grew staphylococci for which the MICs of the test antibiotic were increased two to eight times. Y-688 also selected for resistance in vitro, and isolates for which the MICs were increased eight times emerged at a frequency of ca. 10(-8). Thus, in spite of its low MIC for ciprofloxacin-resistant MRSA, Y-688 failed in vivo and its use carried the risk of resistance selection. The fact that ciprofloxacin-resistant staphylococci became rapidly resistant to this potent new drug suggests that the treatment of ciprofloxacin-resistant MRSA with new quinolones might be more problematic than expected.