Francesco Giuseppe De Rosa

Infections caused by KPC-producing Klebsiella pneumoniae: differences in therapy and mortality in a multicentre study

OBJECTIVES Infections caused by Klebsiella pneumoniae (Kp) carbapenemase (KPC)-producing strains of Kp have become a significant threat in recent years. To assess their outcomes and identify risk factors for 14 day mortality, we conducted a 4 year (2010-13) retrospective cohort study in five large Italian teaching hospitals. METHODS The cohort included 661 adults with bloodstream infections (BSIs; n = 447) or non-bacteraemic infections (lower respiratory tract, intra-abdominal structure, urinary tract or other sites) caused by a KPC-Kp isolate. All had received ≥48 h of therapy (empirical and/or non-empirical) with at least one drug to which the isolate was susceptible. RESULTS Most deaths occurred within 2 weeks of infection onset (14 day mortality: 225/661, 34.1%). Logistic regression analysis identified BSI (OR, 2.09; 95% CI, 1.34-3.29), presentation with septic shock (OR, 2.45; 95% CI, 1.47-4.08), inadequate empirical antimicrobial therapy (OR, 1.48; 95% CI, 1.01-2.18), chronic renal failure (OR, 2.27; 95% CI, 1.44-3.58), high APACHE III score (OR, 1.05; 95% CI, 1.04-1.07) and colistin-resistant isolates (OR, 2.18; 95% CI, 1.37-3.46) as independent predictors of 14 day mortality. Combination therapy with at least two drugs displaying in vitro activity against the isolate was associated with lower mortality (OR, 0.52; 95% CI, 0.35-0.77), in particular in patients with BSIs, lung infections or high APACHE III scores and/or septic shock at infection onset. Combinations that included meropenem were associated with significantly higher survival rates when the KPC-Kp isolate had a meropenem MIC of ≤8 mg/L. CONCLUSIONS KPC-Kp infections are associated with high mortality. Treatment with two or more drugs displaying activity against the isolate improves survival, mainly in patients who are critically ill.

Identifying patients harboring extended-spectrum-beta-lactamase-producing Enterobacteriaceae on hospital admission: derivation and validation of a scoring system.

ABSTRACT Increases in community-acquired infections caused by extended-spectrum-β-lactamase (ESBL)-producing Enterobacteriaceae have important implications for hospital infection control and empirical antibiotic therapy protocols. We developed and validated a tool for identifying patients harboring these organisms at hospital admission. We retrospectively analyzed chart data for 849 adult inpatients. The derivation cohort included 339 patients admitted to a large hospital in Rome during 2008, with (n = 113) or without (n = 226) culture positivity for ESBL-producing Escherichia coli, Klebsiella spp., or Proteus mirabilis within 48 h after admission. Logistic-regression-based prediction scores were calculated based on variables independently associated with the outcome. The model was validated in a second cohort (n = 510) selected with identical criteria in hospitals in Genoa and Turin during 2009. Prediction scores were based on the following six variables (reported with odds ratio for study outcome and the 95% confidence intervals in brackets): recent (≤12 months before admission) hospitalization (5.69 [2.94 to 10.99]), transfer from another health care facility (5.61 [1.65 to 19.08]), Charlson comorbidity score ≥ 4 (3.80 [1.90 to 7.59]), recent (≤3 months before admission) β-lactam and/or fluoroquinolone treatment (3.68 [1.96 to 6.91]), recent urinary catheterization (3.52 [1.96 to 6.91]), and age ≥ 70 years (3.20 [1.79 to 5.70]). The model displayed good calibration and good-to-excellent discrimination in the derivation and validation sets (Hosmer-Lemshow χ2 = 15.28 and 14.07; P = 0.17 and 0.23; areas under the receiver-operating characteristic curve, 0.83 and 0.92). It reliably identified patients likely to be harboring ESBL-producing Enterobacteriaceae at hospital admission who may need special infection control measures. Further study is needed to confirm this models potential as a guide for prescribing empirical antibiotic therapy.

Consensus document on controversial issues for the treatment of infections of the central nervous system: bacterial brain abscesses

BACKGROUND Bacterial brain abscesses remain a serious central nervous system problem despite advances in neurosurgical, neuroimaging, and microbiological techniques and the availability of new antibiotics. The successful treatment of brain abscesses requires surgery, appropriate antibiotic therapy, and eradication of the primary source; nevertheless many controversial issues on the management of this serious infection remain unresolved. CONTROVERSIAL ISSUES The aim of this GISIG (Gruppo Italiano di Studio sulle Infezioni Gravi) working group - a panel of multidisciplinary experts - was to define recommendations for some controversial issues using an evidence-based and analytical approach. The controversial issues were: (1) Which patients with bacterial brain abscesses can be managed safely using medical treatment alone? (1a) What is the efficacy in terms of outcome, tolerability, cost/efficacy, and quality of life of the different antibiotic regimens used to treat bacterial cerebral abscesses? (1b) Which antibiotics have the best pharmacokinetics and/or tissue penetration of brain and/or brain abscess? 2) What is the best surgical approach in terms of outcome in managing bacterial brain abscesses? Results are presented and discussed in detail. METHODS A systematic literature search using the MEDLINE database for the period 1988 to 2008 of randomized controlled trials and/or non-randomized studies was performed. A matrix was created to extract evidence from original studies using the CONSORT method to evaluate randomized clinical trials and the Newcastle-Ottawa Quality Assessment Scale for case-control studies, longitudinal cohorts, and retrospective studies. The GRADE method for grading quality of evidence and strength of recommendation was applied.

Voriconazole in clinical practice

Abstract Invasive fungal diseases are associated with significant morbidity and mortality in immunocompromized patients. Voriconazole is the first line treatment of invasive aspergillosis, and has been successfully used in other invasive fungal infections, such as candidiasis, fusariosis or scedosporidiosis. Voriconazole has non-linear pharmacokinetics and undergoes extensive hepatic metabolism by the cytochrome P450 system that depends on age, genetic factors, and interactions with other drugs. Thus, significant interpatient variability is observed after administration of the same dose. Additionally, the therapeutic window is narrow, with high risk of side effects at serum levels 3–5 times higher than the minimal threshold for efficacy. Therefore, the knowledge of pharmacological properties, metabolism, interactions, dosage indications in various populations and side effects is crucial. Therapeutic drug monitoring can help maximize the efficacy and minimize the risk of toxicity. Pharmacological, mycological and clinical aspects of the treatment with voriconazole are summarized in order to optimize its use in daily clinical practice.

Twelve-Week Treatment of Acute Hepatitis C Virus with Pegylated Interferon-α-2b in Injection Drug Users

Injection drug use is the leading risk factor for infection with hepatitis C virus, and interferon (IFN) treatment in this context is associated with a poor rate of adherence. In this article, we review our experience with injection drug users with acute hepatitis C who are treated with pegylated IFN- alpha -2b for 12 weeks. Acute hepatitis C was diagnosed according to standardized criteria, and patients were treated with a median dosage of IFN- alpha -2b of 1.33 microg/kg per week. A sustained virological response was achieved in 17 (74%) of 23 patients. A sustained virological response was achieved in 14 (87%) of 16 patients treated with a dosage of >or=1.33 microg/kg per week and in 3 (43%) of 7 patients treated with a lower dosage. Sustained virological response was significantly associated only with a pegylated IFN- alpha -2b dosage >or=1.33 microg/kg per week (P=.022). A 12-week regimen of pegylated IFN to treat injection drug users with hepatitis C has a compliance that is much higher than that reported with a 24-week regimen. Adverse effects are minimal if patients are carefully selected.

Predictive Models for Identification of Hospitalized Patients Harboring KPC-Producing Klebsiella pneumoniae

ABSTRACT The production of Klebsiella pneumoniae carbapenemases (KPCs) by Enterobacteriaceae has become a significant problem in recent years. To identify factors that could predict isolation of KPC-producing K. pneumoniae (KPCKP) in clinical samples from hospitalized patients, we conducted a retrospective, matched (1:2) case-control study in five large Italian hospitals. The case cohort consisted of adult inpatients whose hospital stay included at least one documented isolation of a KPCKP strain from a clinical specimen. For each case enrolled, we randomly selected two matched controls with no KPCKP-positive cultures of any type during their hospitalization. Matching involved hospital, ward, and month/year of admission, as well as time at risk for KPCKP isolation. A subgroup analysis was also carried out to identify risk factors specifically associated with true KPCKP infection. During the study period, KPCKP was isolated from clinical samples of 657 patients; 426 of these cases appeared to be true infections. Independent predictors of KPCKP isolation were recent admission to an intensive care unit (ICU), indwelling urinary catheter, central venous catheter (CVC), and/or surgical drain, ≥2 recent hospitalizations, hematological cancer, and recent fluoroquinolone and/or carbapenem therapy. A Charlson index of ≥3, indwelling CVC, recent surgery, neutropenia, ≥2 recent hospitalizations, and recent fluoroquinolone and/or carbapenem therapy were independent risk factors for KPCKP infection. Models developed to predict KPCKP isolation and KPCKP infection displayed good predictive power, with the areas under the receiver-operating characteristic curves of 0.82 (95% confidence interval [CI], 0.80 to 0.84) and 0.82 (95% CI, 0.80 to 0.85), respectively. This study provides novel information which might be useful for the clinical management of patients harboring KPCKP and for controlling the spread of this organism.

Simultaneous quantification of linezolid, rifampicin, levofloxacin, and moxifloxacin in human plasma using high-performance liquid chromatography with UV.

A high-performance liquid chromatography method with UV detection was developed and validated for the simultaneous quantification of linezolid (LZD), rifampicin (RFP), levofloxacin (LEVO), and moxifloxacin (MOXI) in human plasma. The method is based on a simple organic protein precipitation that guarantees rapid sample preparation and a direct injection into the high-performance liquid chromatography system. The use of quinoxaline as internal standard improved accuracy (relative standard deviation, RSD% <14.9%) and precision (RSD% <14.3%). The recovery was 75.9% (RSD% = 5.8). The limits of quantification were 0.234 μg/mL for LEVO, 0.312 μg/mL for LZD, 0.156 μg/mL for MOXI, and 0.622 μg/mL for RFP. This method allows the simultaneous measurement of LEVO, LZD, MOXI, and RFP in human plasma and may be used for both routine clinical applications and pharmacokinetic studies.

Glycopeptide Bone Penetration in Patients with Septic Pseudoarthrosis of the Tibia

Background and objective: In the treatment of bone infections, a major determinant of the clinical response is the active drug concentration at the infected site. Because of the high prevalence of meticillin (methicillin)-resistant staphylococci and enterococci, glycopeptides are widely used for the treatment of bone and joint infections, but data on their penetration into human bone are lacking. The aim of our study was to measure vancomycin and teicoplanin concentrations in infected human bone under steady-state conditions and verify their relationship with inflammatory markers, patient demographic characteristics and pharmacodynamic microbiological markers.Methods and patients: Twenty-seven adult orthopaedic patients undergoing surgical debridement for septic pseudoarthrosis of the tibia and receiving either intravenous vancomycin (Vancocina® 1 g twice daily) or teicoplanin (Targosid® 10 mg/kg/day) were studied from January 2004 to January 2008. Plasma and bone specimens were simultaneously collected during surgery for pharmacokinetic and microbiological assays at a variable interval after antimicrobial administration. Bone samples were dissected into cortical and cancellous bone, cleaned of soft tissues, crushed and eluted into phosphate buffer. Necrotic samples and sequestra were not analysed.Plasma and bone antimicrobial concentrations were measured by a validated method of high-performance liquid chromatography with UV detection, and bone/plasma concentration ratios were calculated. Cortical and cancellous bone area under the concentration-time curve (AUC) over 24 hours (AUC24) values were measured by the linear-log trapezoidal rule, using WinNonlin® software, and were compared with the minimum inhibitory concentrations (MICs) of the infecting agents.Results: For vancomycin, the mean ± SD concentrations were 2.66 ± 1.2 mg/L in cortical bone and 11.53 ± 7.8 mg/L in cancellous bone (corresponding to 20.67% and 89.39% of intraoperative plasma concentrations), and the mean ± SD tissue AUC24 values were 55.15 ± 25.26 h · mg/L for cortical bone and 299.16 ± 299.54 h · mg/L for cancellous bone. For teicoplanin, the mean ± SD concentrations were 2.01 ± 1.7 and 7.51 ± 7.0 mg/L in cortical and cancellous bone, respectively (12.35% and 48.6% of intraoperative plasma concentrations), and the mean ± SD teicoplanin tissue AUC24 values were 34.08 ± 23.6 h · mg/L and 155.17 ± 132.8 h · mg/L for cortical bone and cancellous bone, respectively. The mean vancomycin AUC24/MIC ratios were 215.02 for plasma, 47.14 for cortical bone and 268.95 for cancellous bone. The mean teicoplanin AUC24/MIC ratios were 336.48, 36.27 and 197.21 for plasma, cortical bone and cancellous bone, respectively.Conclusions: Bone penetration of both glycopeptides ranged from poor (<15%) to satisfactory (15–30%) in the cortical compartment, while it was far higher into the highly vascularized cancellous tissue. Vancomycin bone penetration was slightly higher than with teicoplanin, but the difference was not statistically significant. Higher bone concentrations were observed with higher inflammatory markers, possibly as a result of increased vascularization and vascular permeability under inflammatory conditions. Bone concentrations over the MIC and AUC/MIC ratios suggested that both glycopeptides achieve a satisfactory pharmacokinetic exposure in the cancellous bone, as far as Gram-positive pathogens are concerned. On the other hand, cortical bone exposure was suboptimal in most patients. Furthermore, as antimicrobial penetration may be affected by impaired blood supply, the role of radical surgical removal of purulent and necrotic tissues appears to be essential in order to shorten treatment duration and to reduce the risk of treatment failure.

Mortality in patients with early- or late-onset candidaemia

Objectives Although candidaemia is a well-known complication of hospital stay and has a crude mortality of ∼40%, few data are available for episodes diagnosed within 10 days after hospital admission. In this paper, we compared the risk factors for mortality according to the onset of candidaemia. Methods This was a retrospective study of hospitalized patients with early-onset candidaemia (EOC; ≤10 days) or late-onset candidaemia (LOC; >10 days) to identify any distinct clinical characteristics and risk factors for 30 day mortality in two Italian academic centres. Results A total of 779 patients were included in the study: 183 EOC and 596 LOC. Mortality was significantly lower in EOC (71/183, 38.8% versus 283/596, 47.5%, P = 0.03). In EOC, multivariate analysis showed that inadequate initial antifungal therapy (IIAT) (P = 0.005, OR 3.02, 95% CI 1.40–6.51), Candida albicans aetiology (P = 0.02, OR 2.17, 95% CI 1.11–4.26) and older age (P < 0.001, OR 1.05, 95% CI 1.02–1.07) were independent risk factors for mortality. In LOC, liver disease (P = 0.003, OR 2.46, 95% CI 1.36–4.43), IIAT (P = 0.002, OR 2.01, 95% CI 1.28–3.15) and older age (P < 0.001, OR 1.03, 95% CI 1.02–1.04) were independently associated with a fatal outcome, while treatment with caspofungin was associated with survival (P < 0.001, OR 0.42, 95% CI 0.26–0.67). Conclusions EOC has different clinical characteristics and risk factors for mortality compared with LOC. Although EOC mortality is significantly lower, the rate of inappropriate antifungal treatment is higher. Treatment with caspofungin is significantly associated with survival in patients with LOC. Efforts are needed to improve the diagnosis and treatment of EOC.

Development and validation of a new method to simultaneously quantify triazoles in plasma spotted on dry sample spot devices and analysed by HPLC-MS

OBJECTIVES Therapeutic drug monitoring (TDM) of triazoles is widely used in clinical practice to optimize therapy. TDM is limited by technical problems and cost considerations, such as sample storage and dry-ice shipping. We aimed to develop and validate a new method to analyse itraconazole, posaconazole and voriconazole in plasma spotted on dry sample spot devices (DSSDs) and to quantify them by an HPLC system. METHODS Extraction from DSSDs was done using n-hexane/ethyl acetate and ammonia solution. Samples were analysed using HPLC with mass spectrometry (HPLC-MS). Accuracy and precision were assayed by inter- and intra-day validation. The stability of triazoles in plasma spotted on DSSDs was investigated at room temperature for 1 month. The method was compared with a validated standard HPLC method for quantification of triazoles in human plasma. RESULTS Mean inter- and intra-day accuracy and precision were <15% for all compounds. Triazoles were stable for 2 weeks at room temperature. The method was linear (r(2) > 0.999) in the range 0.031-8 mg/L for itraconazole and posaconazole, and 0.058-15 mg/L for voriconazole. High sensitivity was observed; limits of detection were 0.008, 0.004 and 0.007 mg/L for itraconazole, posaconazole and voriconazole, respectively. A high degree of correlation (r(2) > 0.94) was obtained between the DSSD method and the standard method of analysis. CONCLUSIONS The method that we developed and validated to quantify triazoles in human plasma spotted on DSSDs is accurate and precise. It overcomes problems related to plasma sample storage and shipment, allowing TDM to be performed in a cheaper and safer manner.