Attainment of Target Antibiotic Levels by Oral Treatment of Left-Sided Infective Endocarditis: A POET Substudy.

BACKGROUND: In the POET (Partial Oral Endocarditis Treatment) trial, oral step-down therapy was noninferior to full-length intravenous antibiotic administration. The aim of the present study was to perform pharmacokinetic/pharmacodynamic analyses for oral treatments of infective endocarditis to assess the probabilities of target attainment (PTAs). METHODS: Plasma concentrations of oral antibiotics were measured at day 1 and 5. Minimal inhibitory concentrations (MICs) were determined for the bacteria causing infective endocarditis (streptococci, staphylococci, or enterococci). Pharmacokinetic/pharmacodynamic targets were predefined according to literature using time above MIC or the ratio of area under the curve to MIC. Population pharmacokinetic modeling and pharmacokinetic/pharmacodynamic analyses were done for amoxicillin, dicloxacillin, linezolid, moxifloxacin, and rifampicin, and PTAs were calculated. RESULTS: A total of 236 patients participated in this POET substudy. For amoxicillin and linezolid, the PTAs were 88%-100%. For moxifloxacin and rifampicin, the PTAs were 71%-100%. Using a clinical breakpoint for staphylococci, the PTAs for dicloxacillin were 9%-17%.Seventy-four patients at day 1 and 65 patients at day 5 had available pharmacokinetic and MIC data for 2 oral antibiotics. Of those, 13 patients at day 1 and 14 patients at day 5 did only reach the target for 1 antibiotic. One patient did not reach target for any of the 2 antibiotics. CONCLUSIONS: For the individual orally administered antibiotic, the majority reached the target level. Patients with sub-target levels were compensated by the administration of 2 different antibiotics. The findings support the efficacy of oral step-down antibiotic treatment in patients with infective endocarditis.

MIC Discrepancies between Parenteral and Oral Anti-Staphylococcal Beta-Lactams among MSSA.

INTRODUCTION: Recent evidence has shown that oral antibiotic therapy is not inferior to IV antibiotic therapy in the treatment of complicated Staphylococcus aureus infections. Therefore, oral antibiotic therapy is now frequently prescribed in clinical practice due to cost benefit, ease of administration, decreased complication rate, and lack of need for IV access. In vitro susceptibility testing for ß-lactam oral antibiotics is not routinely performed as the guidelines provided by the Clinical and Laboratory Standards Institute (CLSI) recommend using oxacillin and cefoxitin as surrogate markers. Hence, oral antibiotic susceptibilities for cephalexin and dicloxacillin are not reported and implied based on oxacillin and cefoxitin. The objective of the current study was to determine whether susceptibilities among S. aureus isolates are predictable when comparing commonly used IV and oral beta-lactams. METHODS: Cefazolin, cephalexin, dicloxacillin, and oxacillin broth microdilution minimum inhibitory concentrations (MICs) were determined for 100 clinical isolates of methicillin-sensitive S. aureus by broth microdilution following CLSI guidelines. RESULTS: Among these isolates, median MICs for cephalexin were eight-fold higher than cefazolin MICs and median MICs for dicloxacillin were four-fold less than oxacillin MICs. Ten percent of more strains studied had a major or very major error in its susceptibility reporting when cephalexin was compared to its surrogate marker oxacillin. DISCUSSIONS/CONCLUSIONS: The variations in MICs observed compounded with the dosing and pharmacokinetic differences of oral versus IV ß-lactam suggests that establishing breakpoints for oral ß-lactam antibiotics is necessary to ensure adequate therapy is selected for the treatment of complex S. aureus infections.

The road to biologics in patients with hidradenitis suppurativa: a nationwide drug utilization study.

BACKGROUND: Prolonged systemic antibiotic treatment is often a part of management of hidradenitis suppurativa (HS). Although biologic therapies are now available, the patient's treatment journey leading to biologic therapy is unclear. OBJECTIVES: To examine treatment patterns and duration of systemic treatment use in patients with HS preceding biologic therapy. METHODS: We identified all patients with HS receiving treatment with biologics in the Danish National Patient Registry from 2010 to 2018 and extracted their entire prescription history of specific systemic treatments from the Danish National Prescription Registry since its inception in 1995. The patients' treatment journeys are graphically displayed through Sankey diagrams and box plots generated to show temporal distributions. Descriptive patient characteristics were presented as frequencies with percentages for categorical variables and as means with SDs or medians with interquartile ranges (IQRs) for continuous variables. RESULTS: A total of 225 patients with HS were included. Patients had most frequently been treated with penicillin (n = 214; 95·1%), dicloxacillin (n = 194; 86·2%), tetracycline (n = 145; 64·4%) and rifampicin/clindamycin (n = 111; 49·3%), as well as the retinoids isotretinoin and acitretin, and dapsone. Prior to biologic therapy, patients received a mean of 4·0 (SD 1·3) different systemic therapies, across a mean of 16·9 (SD 11·3) different treatment series. The mean time from first systemic therapy until biologic therapy was initiated was 15·3 (SD 5·1) years [8·2 (SD 5·9) years when excluding penicillin and dicloxacillin]. CONCLUSIONS: Patients with HS who receive biologic therapy have long preceding treatment histories with multiple drug classes and treatment series, many of which are supported by relatively weak evidence in HS. Delay in the initiation of biologic therapy may represent a missed opportunity to prevent disease progression. What is already known about this topic? The treatment journey leading to biologic therapy in patients with HS has not previously been investigated. What does this study add? Our data from 225 patients with HS illustrate that patients who receive biologic therapy have long preceding treatment histories with multiple drug classes and treatment series, many of which are supported by relatively weak evidence in HS.

Transfer of Dicloxacillin into Human Milk.

Background: Dicloxacillin is a beta-lactam antibiotic that is commonly used in the treatment of lactational mastitis in breastfeeding women. Although penicillins have long been considered safe for breastfeeding mothers and their infants, there is almost no data on the transfer of dicloxacillin into human breast milk despite the fact that it is commonly used for mastitis. Case Report: This study determined the drug concentration-time profile of dicloxacillin in milk samples collected from three lactating mothers consuming 500 mg dicloxacillin taken every 6 hours for treatment of mastitis. Milk levels were measured using liquid chromatography mass spectrometry. The maximum concentration of dicloxacillin in milk was 67.6 ng/mL. The relative infant dose (RID) was calculated to be 0.03%. This value is well below the theoretical level of concern of 10%. Discussion: The limited transfer of dicloxacillin into human milk is probably explained by the high plasma protein binding of dicloxacillin and its subsequent poor penetration into human milk. Conclusion: In this case series, the level of dicloxacillin in milk was found to be very low, and the RID to be only 0.03% of the maternal dose. Although the levels detected were low, dicloxacillin does transfer into breast milk. Caution should be exercised in infants with hypersensitivity to penicillins.

Systemic thioridazine in combination with dicloxacillin against early aortic graft infections caused by Staphylococcus aureus in a porcine model: In vivo results do not reproduce the in vitro synergistic activity.

INTRODUCTION: Conservative treatment solutions against aortic prosthetic vascular graft infection (APVGI) for inoperable patients are limited. The combination of antibiotics with antibacterial helper compounds, such as the neuroleptic drug thioridazine (TDZ), should be explored. AIM: To investigate the efficacy of conservative systemic treatment with dicloxacillin (DCX) in combination with TDZ (DCX+TDZ), compared to DCX alone, against early APVGI caused by methicillin-sensitive Staphylococcus aureus (MSSA) in a porcine model. METHODS: The synergism of DCX+TDZ against MSSA was initially assessed in vitro by viability assay. Thereafter, thirty-two pigs had polyester grafts implanted in the infrarenal aorta, followed by inoculation with 106 CFU of MSSA, and were randomly administered oral systemic treatment with either 1) DCX or 2) DCX+TDZ. Treatment was initiated one week postoperatively and continued for a further 21 days. Weight, temperature, and blood samples were collected at predefined intervals. By termination, bacterial quantities from the graft surface, graft material, and perigraft tissue were obtained. RESULTS: Despite in vitro synergism, the porcine experiment revealed no statistical differences for bacteriological endpoints between the two treatment groups, and none of the treatments eradicated the APVGI. Accordingly, the mixed model analyses of weight, temperature, and blood samples revealed no statistical differences. CONCLUSION: Conservative systemic treatment with DCX+TDZ did not reproduce in vitro results against APVGI caused by MSSA in this porcine model. However, unexpected severe adverse effects related to the planned dose of TDZ required a considerable reduction to the administered dose of TDZ, which may have compromised the results.

Combination of thioridazine and dicloxacillin as a possible treatment strategy of staphylococci.

We have previously shown that the phenothiazine, thioridazine, acts in synergy with the beta-lactam antibiotic, dicloxacillin, to kill methicillin-resistant Staphylococcus aureus. In this study, we investigated whether synergy by combining these two drugs could also be observed in vancomycin intermediate susceptible S. aureus (VISA) and methicillin-resistant Staphylococcus epidermidis (MRSE). Synergy was observed in three of four tested VISA strains, suggesting that the thickening of cell wall does not interfere with the effects of thioridazine. In S. epidermidis, no synergy was observed in all tested strains, suggesting that synergy by combining thioridazine and dicloxacillin is isolated to S. aureus species.

TarO-specific inhibitors of wall teichoic acid biosynthesis restore ß-lactam efficacy against methicillin-resistant staphylococci.

The widespread emergence of methicillin-resistant Staphylococcus aureus (MRSA) has dramatically eroded the efficacy of current ß-lactam antibiotics and created an urgent need for new treatment options. We report an S. aureus phenotypic screening strategy involving chemical suppression of the growth inhibitory consequences of depleting late-stage wall teichoic acid biosynthesis. This enabled us to identify early-stage pathway-specific inhibitors of wall teichoic acid biosynthesis predicted to be chemically synergistic with ß-lactams. We demonstrated by genetic and biochemical means that each of the new chemical series discovered, herein named tarocin A and tarocin B, inhibited the first step in wall teichoic acid biosynthesis (TarO). Tarocins do not have intrinsic bioactivity but rather demonstrated potent bactericidal synergy in combination with broad-spectrum ß-lactam antibiotics against diverse clinical isolates of methicillin-resistant staphylococci as well as robust efficacy in a murine infection model of MRSA. Tarocins and other inhibitors of wall teichoic acid biosynthesis may provide a rational strategy to develop Gram-positive bactericidal ß-lactam combination agents active against methicillin-resistant staphylococci.

Obesity and risk of infection: results from the Danish Blood Donor Study.

BACKGROUND: It is well known that obesity complicates the course of several diseases. However, it is unknown whether obesity affects the risk of infection among healthy individuals. METHODS: We included 37,808 healthy participants from the Danish Blood Donor Study, who completed a questionnaire on health-related items. Obesity was defined as a body mass index ≥ 30 kg/m(2). Infections among participants were identified by relevant ICD-10 codes in the Danish National Patient Register and Anatomical Therapeutic Chemical (ATC) codes in the Danish Prescription Register. Multivariable Cox proportional hazards analysis with age as the underlying timescale was used as the statistical model. RESULTS: During 113,717 person-years of observation, 1,233 participants were treated for infection at a hospital. Similarly, during 58,411 person-years of observation, 15,856 participants filled at least one prescription of antimicrobials. Obesity was associated with risk of hospital-based treatment for infection (women: hazard ratio [HR] = 1.5, 95% confidence interval [CI] = 1.1, 1.9; men: HR = 1.5, 95% CI = 1.2, 1.9). For specific infections, obesity was associated with increased risk of abscesses (both sexes), infections of the skin and subcutaneous tissue (men), and respiratory tract infections and cystitis (women). Similarly, obesity was associated with filled prescriptions of antimicrobials overall (women: HR = 1.22, 95% CI = 1.14, 1.30; men: HR = 1.23, 95% CI: 1.15, 1.33) and particularly with phenoxymethylpenicillin, macrolides, dicloxacillin and flucloxacillin, and broad-spectrum penicillins. CONCLUSIONS: In a large cohort of healthy individuals, obesity was associated with risk of infection. This result warrants further studies of metabolism and the immune response.

Primary diffuse large B-cell lymphoma associated with chronic osteomyelitis of the knee.

Diffuse large B-cell lymphoma (DLBCL) associated with chronic inflammation is a recently adopted category of DLBCL, which describes an aggressive B-cell lymphoma raised in the setting of non-immune chronic inflammation. Primary presentation of this subtype of DLBCL in bone is extremely rare. Here, we present the case of a 27 year old woman with DLBCL of the right distal femur, identified after a three-year history of chronic osteomyelitis. In this report, we describe the clinical and histopathologic features of this unusual presentation of DLBCL and discuss aspects relevant to diagnosis and treatment of this entity.

Validación del método para control de calidad de dicloxacilina sódica en dicloxen cápsulas / Validation of the quality control method for sodium dicloxacillin in Dicloxen capsules

Introducción: la dicloxacilina sódica es un derivado semisintético perteneciente al grupo de las isoxasocil penicilinas que se presenta en suspensión oral y cápsulas. Para el análisis de la materia prima y de estas formas terminadas se recomienda el uso de cromatografía líquida de alta resolución (CLAR), método que no se encuentra disponible en el laboratorio productor de dicloxen cápsulas para el análisis de rutina de este medicamento. Objetivo: desarrollar y validar un método por espectrofotomería UV útil para el control de calidad de dicloxacilina sódica en dicloxen cápsulas. Métodos: se desarrolló un método por espectrofotometría UV directa basado en la determinación de una solución acuosa del analito a 274 nm; el cual fue una modificación del método de identificación establecido en la Farmacopea japonesa, 2011, para la materia prima. Por tratarse de un método modificado se realizó su validación a través de los parámetros linealidad, precisión, exactitud y especificidad frente a los componentes de la formulación dicloxen cápsulas. Resultados: la concentración prefijada en el procedimiento propuesto como 100 por ciento fue de 0,3 mg/mL de analito, lo cual está en correspondencia con la adecuada respuesta medida. En el espectro UV del dicloxacina sódica se observaron dos máximos de absorción, a la lmáxima= 274 nm y a 283 nm. Se seleccionó el valor de l= 274 nm para la cuantificación. Se estableció una metodología analítica muy sencilla que permitiera obtener una solución transparente a partir de la forma terminada, de igual concentración a la solución de referencia. El cumplimiento satisfactorio de todos los criterios de aceptación establecidos para los parámetros especificidad, linealidad, exactitud y precisión permitió demostrar la validez del método en estudio para el control de calidad de dicloxacina sódica en dicloxen cápsulas en el rango de 80 a 120 por ciento. Conclusiones : el método por espectrofotometría UV resulta específico, lineal, exacto y preciso para su aplicación al control de calidad de dicloxacilina sódica en dicloxen cápsulas(AU)

Introduction: sodium dicloxacillin is a semi synthetic derivative of the isoxasocyl penicillin group that may appear in oral suspension form and in caplets. For the analysis of the raw materials and the finished products, it is recommended to use high performance liquid chromatograpy that is an unavailable method at the dicloxen capsule manufacturing lab for the routine analysis of the drug. Objective: to develop and to validate a useful ultraviolet spectrophotometry method for the quality control of sodium dicloxacillin in Dicloxen capsules. Methods: a direct ultraviolet spectrophotometry was developed on the basis of determination of aqueous solution of the analyte at 274 nm distance; the latter was a change from the original detection method set by the Japanese pharmacopeia, 2011 for the raw materials. Since this was a modified method, it had to be validated through parameters such as linearity, precision, accuracy and specificity versus the components of Dicloxen capsule formulation. Results: the preset 100 percent concentration in the suggested procedure was 0.3 mg/mL of analyte, which is in line with the adequate response measured in this test. The ultraviolet spectrum of sodium dicloxacillin showed two maximum absorption values, lmaximun= 274 nm and 283 nm. The choice was l= 274 nm for quantitation. The set analytical methodology was very simple and allowed obtaining a transparent solution from the finished form, which had a concentration value similar to that of the reference solution. The compliance with all the set acceptance criteria for specificity, linearity, accuracy and precision allowed demonstrating the validity of the method under study for the quality control of sodium dicloxacillin in Dicloxen capsules in the 80-120 percent range Conclusions: the ultraviolet spectrophotometry method proved to be specific, linear, accurate and precise for the quality control of sodium dicloxacillin in Dicloxen capsules(AU)

Relative efficacy of cefuroxime versus dicloxacillin as definitive antimicrobial therapy in methicillin-susceptible Staphylococcus aureus bacteraemia: a propensity-score adjusted retrospective cohort study.

OBJECTIVES: The objective of the present study was to compare the efficacy of cefuroxime with that of dicloxacillin as definitive antimicrobial therapy in methicillin-susceptible Staphylococcus aureus bacteraemia (MS-SAB) using a Danish bacteraemia database, information on the indication for antimicrobial therapy, multivariate adjustment and propensity score (PS) matching. METHODS: This was a retrospective cohort study. MS-SAB cases from 1 January 2006 to 31 December 2008 were included from a total of seven hospitals in the greater Copenhagen area and seven hospitals in the North Denmark Region. Information including demographics, antimicrobial therapy and clinical condition was obtained. The physician's note detailing the indication for starting empirical antimicrobial therapy was given special attention. Hazard ratios (HRs) and 95% CIs for 30 day and 90 day mortality were calculated using PS-adjusted Cox proportional hazards regression analyses. In addition, PS matching was performed. RESULTS: A total of 691 patients with MS-SAB received either dicloxacillin (n = 368) or cefuroxime (n = 323) as definitive antimicrobial therapy. Twenty-eight different indications for empirical antimicrobial therapy were identified and grouped into eight categories. There was no statistically significant difference in 30 day mortality between the two groups (HR 1.02, 95% CI 0.68-1.52). Definitive antimicrobial therapy with cefuroxime was associated with increased 90 day mortality in a PS-adjusted multivariate analysis (HR 1.43, 95% CI 1.03-1.98) and in the PS matching (OR 1.65, 95% CI 1.06-2.56). Antimicrobial therapy for an indication of 'severe infection' was independently associated with 90 day mortality (HR 1.97, 95% CI 1.19-3.28). CONCLUSIONS: Definitive antimicrobial therapy with cefuroxime was associated with significantly higher 90 day mortality than was dicloxacillin therapy in patients with MS-SAB.

Ultrasound-guided drainage of subcutaneous abscesses on the trunk is feasible.

INTRODUCTION: Subcutaneous trunk abscesses are frequent, and current treatment options generally involve incision. By contrast, the standard care for breast abscesses is ultrasound-guided drainage. The aim of this study was to evaluate the feasibility of ultrasound-guided drainage combined with antibiotics in the treatment of subcutaneous abscesses on the trunk. MATERIAL AND METHODS: In this prospective study, 27 patients were treated with ultrasound-guided needle aspiration and oral antibiotics. Follow-up was performed at a 3-6-day interval, and the procedure was repeated if the abscess was not obliterated. RESULTS: Treatment was initially successful in 25 of the 27 participants (93%); two patients went on to surgery. The median time from first treatment to the final control visit was nine days. The 25 patients with initial successful treatment were contacted after a median of 84 days, and six (24%) of these reported recurrence of an abscess at the puncture site. 88% of the patients reported that they were satisfied or very satisfied with ultrasound-guided drainage. CONCLUSION: Our results indicate that ultrasound-guided drainage combined with antibiotics is feasible in the treatment of small subcutaneous abscesses on the trunk. Ultrasound-guided drainage was well-tolerated, had a high degree of success and short healing times. Additional randomised studies are needed to verify our findings. FUNDING: not relevant. TRIAL REGISTRATION: not relevant.

Effectiveness of penicillin, dicloxacillin and cefuroxime for penicillin-susceptible Staphylococcus aureus bacteraemia: a retrospective, propensity-score-adjusted case-control and cohort analysis.

OBJECTIVES: Penicillin-susceptible Staphylococcus aureus isolates account for a fifth of cases of S. aureus bacteraemia (SAB) in Denmark, but little is known about treatment outcomes with penicillins or other antimicrobials. Here we compare penicillin, dicloxacillin and cefuroxime as definitive treatments in relation to 30 day mortality. METHODS: A retrospective chart review of 588 penicillin-susceptible S. aureus cases at five centres from January 1995 to December 2010. Data on demographics, antimicrobial treatment, clinical signs and symptoms, and mortality at day 30 were collected. Hazard ratios (HRs) with 95% CIs associated with mortality were modelled using propensity-score-adjusted Cox proportional hazards regression analysis. Propensity-score-matched case-control studies were carried out. RESULTS: Definitive therapy with cefuroxime was associated with an increased risk of 30 day mortality compared with penicillin (adjusted HR 2.54, 95% CI 1.49-4.32). Other variables that were statistically significantly associated with 30 day mortality included increasing age, disease severity and a primary respiratory focus. Osteomyelitis/arthritis was associated with a lower risk of death than were other secondary manifestations. Propensity-score-matched case-control studies confirmed an increased risk of 30 day mortality: cefuroxime treatment (39%) versus penicillin treatment (20%), P = 0.037; and cefuroxime treatment (38%) versus dicloxacillin treatment (10%), P = 0.004. CONCLUSIONS: Definitive therapy for penicillin-susceptible SAB with cefuroxime was associated with a significantly higher mortality than was seen with therapy with penicillin or dicloxacillin.

Delayed cerebritis after bilateral stereotactic implantation of globus pallidus interna electrodes for treatment of dystonia.

Deep brain stimulation (DBS) is being used to treat an increasing number of movement and psychiatric disorders. However, the risk of infection remains as a problem that can hinder the usefulness of this technology. We report a case of a patient with dystonia who underwent bilateral globus pallidus interna electrode and impulse generator (IPG) placement, developed an infection of his IPG, and later cerebritis. The patient was initially treated with antibiotics and partial hardware removal. Follow-up cranial imaging showed an area concerning for cerebritis around one of the intracranial electrodes. The patient was then treated with complete hardware removal followed by a course of intravenous antibiotics. Four-month follow-up imaging showed resolution of the infection. This case demonstrates the importance of following cranial imaging in DBS patients with delayed infection, continued vigilance for infection in implanted patients and that partial hardware removal may not be successful in the setting of methicillin-sensitive Staphylococcus aureus infections.

On the demand for prescription drugs: heterogeneity in price responses.

This paper estimates the price elasticity of demand for prescription drugs using an exogenous shift in consumer co-payment caused by a reform in the Danish subsidy scheme for the general public. Using purchasing records for the entire Danish population, I show that the average price response for the most commonly used drug yields demand elasticities in the range of -0.36 to -0.5. The reform is shown to affect women, the elderly, and immigrants the most. Furthermore, this paper shows significant heterogeneity in the price response over different types of antibiotics, suggesting that the price elasticity of demand varies considerably even across relatively similar drugs.

Activity of oxacillin versus that of vancomycin against oxacillin-susceptible mecA-positive Staphylococcus aureus clinical isolates evaluated by population analyses, time-kill assays, and a murine thigh infection model.

We compared the activity of dicloxacillin with that of vancomycin against 15 oxacillin-susceptible, methicillin-resistant Staphylococcus aureus (OS-MRSA) clinical isolates. By population analyses, we found that 6 OS-MRSA isolates were able to grow in the presence of up to 8 µg/ml dicloxacillin and 9 isolates were able to grow in 12 to >32 µg/ml dicloxacillin; all isolates grew in up to 2 µg/ml vancomycin. Both drugs exhibited similar bactericidal activities. In experimental infections, the therapeutic efficacy of dicloxacillin was significant (P < 0.05 versus untreated controls) in 10 OS-MRSA isolates and vancomycin was effective (P < 0.05) against 12 isolates; dicloxacillin had an efficacy that was comparable to that of vancomycin (P > 0.05) in 8 isolates. The favorable response to dicloxacillin treatment might suggest that antistaphylococcal penicillins could be used against OS-MRSA infections.