Mortality in KPC-producing Klebsiella pneumoniae bloodstream infections: a changing landscape.

OBJECTIVES: To assess the impact of carbapenem resistance on mortality in Klebsiella pneumoniae bloodstream infection (BSI) in the era of novel ß-lactam/ß-lactamase inhibitor combinations. MATERIAL AND METHODS: Retrospective study of patients with K. pneumoniae BSI between January and August 2020 in 16 centres (CARBANEW study within the MULTI-SITA project). RESULTS: Overall, 426 patients were included: 107/426 (25%) had carbapenem-resistant K. pneumoniae (CR-Kp) BSI and 319/426 (75%) had carbapenem-susceptible K. pneumoniae (CS-Kp) BSI. Crude cumulative 30 day mortality was 33.8% and 20.7% in patients with, respectively, CR-Kp BSI and CS-Kp BSI (P = 0.027). Carbapenemase production or carbapenemase-encoding genes were detected in 84/98 tested CR-Kp isolates (85.7%), mainly KPC (78/84; 92.9%). Ceftazidime/avibactam was the most frequently used appropriate therapy for CR-Kp BSI (80/107; 74.7%). In multivariable analyses, variables showing an unfavourable association with mortality after correction for multiple testing were age-adjusted Charlson comorbidity index (HR 1.20; 95% CI 1.10-1.31, P < 0.001) and Pitt score (HR 1.33; 95% CI 1.15-1.55, P < 0.001), but not carbapenem resistance (HR 1.28, 95% CI 0.74-2.22, P = 0.410). In a propensity score-matched analysis, there was no difference in mortality between patients appropriately treated with ceftazidime/avibactam for CR-Kp BSI and patients appropriately treated with other agents (mainly meropenem monotherapy or piperacillin/tazobactam monotherapy) for CS-Kp BSI (HR 1.07; 95% CI 0.50-2.29, P = 0.866). CONCLUSIONS: Our results suggest that the increased mortality in CR-Kp BSI compared with CS-Kp BSI is not (or no longer) dependent on the type of therapy in areas where ceftazidime/avibactam-susceptible KPC-producing isolates are the most prevalent type of CR-Kp.

Ceftazidime-Avibactam Use for Klebsiella pneumoniae Carbapenemase-Producing K. pneumoniae Infections: A Retrospective Observational Multicenter Study.

BACKGROUND: A growing body of observational evidence supports the value of ceftazidime-avibactam (CAZ-AVI) in managing infections caused by carbapenem-resistant Enterobacteriaceae. METHODS: We retrospectively analyzed observational data on use and outcomes of CAZ-AVI therapy for infections caused by Klebsiella pneumoniae carbapenemase-producing K. pneumoniae (KPC-Kp) strains. Multivariate regression analysis was used to identify variables independently associated with 30-day mortality. Results were adjusted for propensity score for receipt of CAZ-AVI combination regimens versus CAZ-AVI monotherapy. RESULTS: The cohort comprised 577 adults with bloodstream infections (n = 391) or nonbacteremic infections involving mainly the urinary tract, lower respiratory tract, and intra-abdominal structures. All received treatment with CAZ-AVI alone (n = 165) or with ≥1 other active antimicrobials (n = 412). The all-cause mortality rate 30 days after infection onset was 25% (146/577). There was no significant difference in mortality between patients managed with CAZ-AVI alone and those treated with combination regimens (26.1% vs 25.0%, P = .79). In multivariate analysis, mortality was positively associated with presence at infection onset of septic shock (P = .002), neutropenia (P < .001), or an INCREMENT score ≥8 (P = .01); with lower respiratory tract infection (LRTI) (P = .04); and with CAZ-AVI dose adjustment for renal function (P = .01). Mortality was negatively associated with CAZ-AVI administration by prolonged infusion (P = .006). All associations remained significant after propensity score adjustment. CONCLUSIONS: CAZ-AVI is an important option for treating serious KPC-Kp infections, even when used alone. Further study is needed to explore the drug's seemingly more limited efficacy in LRTIs and potential survival benefits of prolonging CAZ-AVI infusions to ≥3 hours.

Efficacy of Ceftazidime-Avibactam Salvage Therapy in Patients With Infections Caused by Klebsiella pneumoniae Carbapenemase-producing K. pneumoniae.

Background: Ceftazidime-avibactam (CAZ-AVI) has been approved in Europe for the treatment of complicated intra-abdominal and urinary tract infections, as well as hospital-acquired pneumonia, and for gram-negative infections with limited treatment options. CAZ-AVI displays in vitro activity against Klebsiella pneumoniae carbapenemase (KPC) enzyme producers, but clinical trial data on its efficacy in this setting are lacking. Methods: We retrospectively reviewed 138 cases of infections caused by KPC-producing K. pneumoniae (KPC-Kp) in adults who received CAZ-AVI in compassionate-use programs in Italy. Case features and outcomes were analyzed, and survival was then specifically explored in the large subcohort whose infections were bacteremic. Results: The 138 patients started CAZ-AVI salvage therapy after a first-line treatment (median, 7 days) with other antimicrobials. CAZ-AVI was administered with at least 1 other active antibiotic in 109 (78.9%) cases. Thirty days after infection onset, 47 (34.1%) of the 138 patients had died. Thirty-day mortality among the 104 patients with bacteremic KPC-Kp infections was significantly lower than that of a matched cohort whose KPC-Kp bacteremia had been treated with drugs other than CAZ-AVI (36.5% vs 55.8%, P = .005). Multivariate analysis of the 208 cases of KPC-Kp bacteremia identified septic shock, neutropenia, Charlson comorbidity index ≥3, and recent mechanical ventilation as independent predictors of mortality, whereas receipt of CAZ-AVI was the sole independent predictor of survival. Conclusions: CAZ-AVI appears to be a promising drug for treatment of severe KPC-Kp infections, especially those involving bacteremia.

The role of carbapenem-resistant pathogens in cSSTI and how to manage them.

PURPOSE OF REVIEW: Skin and soft tissue infections (SSTIs) with a wide spectrum of disease severity ranging from uncomplicated to potentially lethal are still a leading cause of morbidity and mortality. The burden of carbapenem-resistant gram-negative bacteria (CR-GNB) in SSTIs is increasing. Luckily, the armamentarium of drugs available is recently expanding as well. The present review looks at data on the role CR-GNB in SSTIs and on the old and new drugs available for the treatment of carbapenem-resistant Enterobacteriaceae (CRE), Pseudomonas, and Acinetobacter. RECENT FINDINGS: The most recent information concern the availability of new antibiotics that, even if no specific clinical trials on complicated SSTIs (cSSTIs) have been performed, may play a role in clinical practice also for the treatment of cSSTIs caused by CR-GNB. Ceftolozane-tazobactam has been found to be a good option for CR Pseudomonas infections including SSTIs. Ceftazidime-avibactam is approved for several indications, including aerobic GNB infections with limited treatment options. Meropenem-vaborbactam therapy has been associated with decreased mortality in infections caused by CRE. Eravacycline has the potential to become useful for the treatment of CR Acinetobacter for which the treatment options are limited. SUMMARY: In the carbapenem resistance era, the physicians goal should be to stratify patients according to risk factors for CR-GNB causing SSTIs in order to minimize inappropriate initial therapies. Some recently approved drugs seem destined to become the backbone of target therapy in patients with severe infections caused by susceptible CR-GNB strains. Prompt diagnosis of cSSTIs is crucial and, when feasible, surgical debridement as source control is essential as well.

Desirability of outcome ranking (DOOR) for comparing diagnostic tools and early therapeutic choices in patients with suspected candidemia.

Desirability of outcome ranking (DOOR) has been developed for assessing desirability of outcome in interventional studies. However, its possible use in observational studies of the diagnosis and early treatment of infectious diseases has not been explored so far, and it might introduce interesting features in specific scenarios. This was a post hoc analysis of a prospective observational study in intensive care unit patients with sepsis and at risk of candidemia. The probabilities that a randomly selected patient would have a more, less, and equally cost-effective early therapeutic choice following a BDG-based diagnostic strategy rather than the empirical administration of antifungals to all patients were calculated using DOOR methods. The probability of a more cost-effective therapeutic choice following the BDG-based rather than the empirical strategy was 67.81% (95% CI 67.32-68.30), whereas the probabilities of a less and equally cost-effective early therapeutic choice were 19.68% (95% CI 19.27-20.10) and 12.50% (95% CI 12.16-12.85), respectively. The application of DOOR methods to observational studies focused on diagnosis and early treatment is a novel field that could merit further investigation.

Optimizing therapy in carbapenem-resistant Enterobacteriaceae infections.

PURPOSE OF REVIEW: In the absence of randomized clinical trial data, questions remain regarding the optimal treatment of carbapenem-resistant Enterobacteriaceae (CRE) infections. CRE have historically been susceptible to polymyxins, tigecycline or aminoglycosides (mostly gentamicin), and these antibiotics have long been considered the drugs of choice for CRE infections, although varying rates of resistance to all have been reported. This review looks at data from clinical studies assessing the outcomes of CRE infections treated with different antibiotic regimens. RECENT FINDINGS: The recently approved fixed-dose combination agent, ceftazidime-avibactam (CAZ-AVI), is active against KPC and OXA-48-producing Enterobacteriaceae. The limited clinical data available on CAZ-AVI indicate that it is associated with survival benefits relative to other commonly used regimens, although development of resistance is a concern. New drugs active against CRE isolates (including the recently approved meropenem-vaborbactam) are in different stages of development. SUMMARY: CAZ-AVI and meropenem-vaborbactam seem destined to become the backbone of target therapy for high-risk patients with severe infections caused by susceptible CRE strains. However, empirical therapy should be based on risk factors to be defined in the near future, whereas the necessity of combinations with CAZ-AVI requires further studies. Polymyxins are still important options for low-risk patients with susceptible CRE infections, but also for high-risk patients in regions where metallo-ß-lactamase-producing CRE predominate because CAZ-AVI and meropenem-vaborbactam are both ineffective against these strains.

Combined use of serum (1,3)-ß-D-glucan and procalcitonin for the early differential diagnosis between candidaemia and bacteraemia in intensive care units.

BACKGROUND: This study aimed to assess the combined performance of serum (1,3)-ß-D-glucan (BDG) and procalcitonin (PCT) for the differential diagnosis between candidaemia and bacteraemia in three intensive care units (ICUs) in two large teaching hospitals in Italy. METHODS: From June 2014 to December 2015, all adult patients admitted to the ICU who had a culture-proven candidaemia or bacteraemia, as well as BDG and PCT measured closely to the time of the index culture, were included in the study. The diagnostic performance of BDG and PCT, used either separately or in combination, was assessed by calculating the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and positive and negative likelihood ratios (LR+ and LR-). Changes from pre-test probabilities to post-test probabilities of candidaemia and bacteraemia were inferred from Fagan's nomograms. RESULTS: One hundred and sixty-six patients were included, 73 with candidaemia (44%) and 93 with bacteraemia (56%). When both markers indicated candidaemia (BDG ≥80 pg/ml and PCT <2 ng/ml) they showed higher PPV (96%) compared to 79% and 66% for BDG or PCT alone, respectively. When both markers indicated bacteraemia (BDG <80 pg/ml and PCT ≥2 ng/ml), their NPV for candidaemia was similar to that of BDG used alone (95% vs. 93%). Discordant BDG and PCT results (i.e. one indicating candidaemia and the other bacteraemia) only slightly altered the pre-test probabilities of the two diseases. CONCLUSIONS: The combined use of PCT and BDG could be helpful in the diagnostic workflow for critically ill patients with suspected candidaemia.

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.

Predictive models for identification of hospitalized patients harboring KPC-producing Klebsiella pneumoniae.

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.

Use of Cefiderocol in Adult Patients: Descriptive Analysis from a Prospective, Multicenter, Cohort Study.

INTRODUCTION: Cefiderocol is a siderophore cephalosporin showing activity against various carbapenem-resistant Gram-negative bacteria (CR-GNB). No data currently exist about real-world use of cefiderocol in terms of types of therapy (e.g., empirical or targeted, monotherapy or combined regimens), indications, and patient characteristics. METHODS: In this multicenter, prospective study, we aimed at describing the use of cefiderocol in terms of types of therapy, indications, and patient characteristics. RESULTS: Cefiderocol was administered as empirical and targeted therapy in 27.5% (55/200) and 72.5% (145/200) of cases, respectively. Overall, it was administered as monotherapy in 101/200 cases (50.5%) and as part of a combined regimen for CR-GNB infections in the remaining 99/200 cases (49.5%). In multivariable analysis, previous isolation of carbapenem-resistant Acinetobacter baumannii odds ratio (OR) 2.56, with 95% confidence interval (95% CI) 1.01-6.46, p = 0.047] and previous hematopoietic stem cell transplantation (OR 8.73, 95% CI 1.05-72.54, p = 0.045) were associated with administration of cefiderocol as part of a combined regimen, whereas chronic kidney disease was associated with cefiderocol monotherapy (OR 0.38 for combined regimen, 95% CI 0.16-0.91, p = 0.029). Cumulative 30-day mortality was 19.8%, 45.0%, 20.7%, and 22.7% in patients receiving targeted cefiderocol for infections by Enterobacterales, A. baumannii, Pseudomonas aeruginosa, and any metallo-ß-lactamase producers, respectively. CONCLUSIONS: Cefiderocol is mainly used for targeted treatment, although empirical therapies account for more than 25% of prescriptions, thus requiring dedicated standardization and guidance. The almost equal distribution of cefiderocol monotherapy and cefiderocol-based combination therapies underlines the need for further study to ascertain possible differences in efficacy between the two approaches.

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.

Predictors of mortality in bloodstream infections caused by Klebsiella pneumoniae carbapenemase-producing K. pneumoniae: importance of combination therapy.

BACKGROUND: The spread of Klebsiella pneumoniae (Kp) strains that produce K. pneumoniae carbapenemases (KPCs) has become a significant problem, and treatment of infections caused by these pathogens is a major challenge for clinicians. METHODS: In this multicenter retrospective cohort study, conducted in 3 large Italian teaching hospitals, we examined 125 patients with bloodstream infections (BSIs) caused by KPC-producing Kp isolates (KPC-Kp) diagnosed between 1 January 2010 and 30 June 2011. The outcome measured was death within 30 days of the first positive blood culture. Survivor and nonsurvivor subgroups were compared to identify predictors of mortality. RESULTS: The overall 30-day mortality rate was 41.6%. A significantly higher rate was observed among patients treated with monotherapy (54.3% vs 34.1% in those who received combined drug therapy; P = .02). In logistic regression analysis, 30-day mortality was independently associated with septic shock at BSI onset (odds ratio [OR]: 7.17; 95% confidence interval [CI]: 1.65-31.03; P = .008); inadequate initial antimicrobial therapy (OR: 4.17; 95% CI: 1.61-10.76; P = .003); and high APACHE III scores (OR: 1.04; 95% CI: 1.02-1.07; P < .001). Postantibiogram therapy with a combination of tigecycline, colistin, and meropenem was associated with lower mortality (OR: 0.11; 95% CI: .02-.69; P = .01). CONCLUSIONS: KPC-Kp BSIs are associated with high mortality. To improve survival, combined treatment with 2 or more drugs with in vitro activity against the isolate, especially those also including a carbapenem, may be more effective than active monotherapy.

Multidrug-resistant Proteus mirabilis bloodstream infections: risk factors and outcomes.

Our aims were to identify (i) risk factors associated with the acquisition of multidrug-resistant (MDR, to 3 or more classes of antimicrobials) Proteus mirabilis isolates responsible for bloodstream infections (BSIs) and (ii) the impact on mortality of such infections. Risk factors for acquiring MDR P. mirabilis BSIs were investigated in a case-case-control study; those associated with mortality were assessed by comparing survivors and nonsurvivors in a cohort study. The population consisted of 99 adult inpatients with P. mirabilis BSIs identified by our laboratory over an 11-year period (1999 to 2009), 36 (33.3%) of which were caused by MDR strains, and the overall 21-day mortality rate was 30.3%. Acquisition of an MDR strain was independently associated with admission from a long-term care facility (odds ratio [OR], 9.78; 95% confidence interval [CI], 1.94 to 49.16), previous therapy with fluoroquinolones (OR, 5.52; 95% CI, 1.30 to 23.43) or oxyimino-cephalosporins (OR, 4.72; 95% CI, 1.31 to 16.99), urinary catheterization (OR, 3.89; 95% CI, 1.50 to 10.09), and previous hospitalization (OR, 2.68; 95% CI, 10.4 to 6.89). Patients with MDR P. mirabilis BSIs received inadequate initial antimicrobial therapy (IIAT, i.e., treatment with drugs to which the isolate displayed in vitro resistance) more frequently than those with non-MDR infections; they also had increased mortality and (for survivors) longer post-BSI-onset hospital stays. In multivariate regression analysis, 21-day mortality was associated with septic shock at BSI onset (OR, 12.97; 95% CI, 32.2 to 52.23), P. mirabilis isolates that were MDR (OR, 6.62; 95% CI, 16.4 to 26.68), and IIAT (OR, 9.85; 95% CI, 26.7 to 36.25), the only modifiable risk factor of the 3. These findings can potentially improve clinicians' ability to identify P. mirabilis BSIs likely to be MDR, thereby reducing the risk of IIAT--a major risk factor for mortality in these cases--and facilitating the prompt implementation of appropriate infection control measures.

New Drugs for the Treatment of Pseudomonas aeruginosa Infections with Limited Treatment Options: A Narrative Review.

P. aeruginosa is still one of the most threatening pathogens responsible for serious hospital-acquired infections. It is intrinsically resistant to many antimicrobial agents and additional acquired resistance further complicates the management of such infections. High rates of combined antimicrobial resistance persist in many countries, especially in the eastern and south-eastern parts of Europe. The aim of this narrative review is to provide a comprehensive assessment of the epidemiology, latest data, and clinical evidence on the current and new available drugs active against P. aeruginosa isolates with limited treatment options. The latest evidence and recommendations supporting the use of ceftolozane-tazobactam and ceftazidime-avibactam, characterized by targeted clinical activity against a significant proportion of P. aeruginosa strains with limited treatment options, are described based on a review of the latest microbiological and clinical studies. Cefiderocol, with excellent in vitro activity against P. aeruginosa isolates, good stability to all ß-lactamases and against porin and efflux pumps mutations, is also examined. New carbapenem combinations are explored, reviewing the latest experimental and initial clinical evidence. One section is devoted to a review of new anti-pseudomonal antibiotics in the pipeline, such as cefepime-taniborbactam and cefepime-zidebactam. Finally, other "old" antimicrobials, mainly fosfomycin, that can be used as combination strategies, are described.

XDR-Pseudomonas aeruginosa Outside the ICU: Is There Still Place for Colistin?

BACKGROUND: Pseudomonas aeruginosa represents, among the nosocomial pathogens, one of the most serious threats, both for the severity of its clinical manifestations and its ability to develop complex profiles of resistance; Methods: we retrospectively collected the data of 21 patients admitted to a tertiary-care University Hospital of Rome with infections due to XDR-P. aeruginosa isolates during the second half of 2020; Results: in our institution, the percentage of XDR-P. aeruginosa isolates is 3.1%. None of the patients was admitted to the intensive care unit at the moment of the infection's onset. Susceptibility to colistin was preserved in all the tested isolates. Rates of resistance to ceftolozane/tazobactam and ceftazidime/avibactam in these XDR strains were consistent; Conclusions: XDR-P. aeruginosa can be a threatening problem even outside the ICUs, especially in frail patients in wards with features of long-term acute care hospitals. In such a setting, ceftolozane/tazobactam and ceftazidime/avibactam should be administered with caution taking into account the microbiological susceptibility results. Colistin, even with its known safety and efficacy limits, could represent the only available therapeutic option due to its highly preserved susceptibility against XDR isolates of P. aeruginosa.

Compassionate use of meropenem/vaborbactam for infections caused by KPC-producing Klebsiella pneumoniae: a multicentre study.

Objectives: To explore the real-life performance of meropenem/vaborbactam for treating serious KPC-producing Klebsiella pneumoniae infections, including those resistant to ceftazidime/avibactam. Methods: A retrospective observational cohort study was conducted in 12 Italian hospitals. Enrolled patients had K. pneumoniae carbapenemase (KPC)-producing K. pneumoniae (KPC-Kp) infections (59.5% of which were ceftazidime/avibactam resistant). Patients who received ≥72 h of meropenem/vaborbactam therapy (with or without other antimicrobials) in a compassionate-use setting were included. Results: The 37 infections (all hospital-acquired) were mainly bacteraemic (BSIs, n = 23) or lower respiratory tract infections (LRTIs, n = 10). Clinical cure was achieved in 28 (75.6%) cases and microbiologically confirmed in all 25 with follow-up cultures. Three (10.7%) of the 28 clinical cures (all BSIs, 2/3 microbiologically confirmed) were followed by in-hospital recurrences after meropenem/vaborbactam was discontinued (median interval: 18 days). All three recurrences were susceptible to meropenem/vaborbactam and successfully managed with meropenem/vaborbactam combined with colistin or fosfomycin. Nine patients (24.3%) (all with BSIs or LRTIs) died in hospital with persistent signs of infection. Most were aged over 60 years, with high comorbidity burdens and INCREMENT scores ≥8. Only one had received meropenem/vaborbactam monotherapy. Six began meropenem/vaborbactam therapy >48 h after infection onset. Outcomes were unrelated to the isolate's ceftazidime/avibactam susceptibility status. The single adverse event observed consisted of severe leukopenia with thrombocytopenia. Conclusions: With the well-known limitations of real-life retrospective studies, our results support previous findings indicating that meropenem/vaborbactam therapy will be a safe, effective tool for managing serious KPC-Kp infections, including the increasing proportion displaying resistance to ceftazidime/avibactam.

Epidemiology, aetiology and treatment of skin and soft tissue infections: final report of a prospective multicentre national registry.

Skin and soft tissue infections (SSTIs) represent a heterogenous group of pathological conditions involving the skin or the underlying subcutaneous tissues, fascia and muscle, characterised by a considerable variety of clinical presentations, severity and possible aetiological pathogens. Although previous analyses on restricted types of SSTIs and population have already been published, we conducted a large nationwide surveillance program on behalf of the Italian Society of Infectious and Tropical Diseases to assess the clinical and microbiological characteristics of the whole SSTI spectrum, from mild to severe life-threatening infections, in both inpatients and outpatients and their management. Twenty-nine Infectious Diseases (ID) Centres throughout Italy collected prospectively data concerning both the clinical and microbiological diagnosis of patients affected by SSTIs via an electronic case report form. We included in our database all cases managed by ID specialists participating to the study, independently from their severity or the setting of consultation. Here, we integrated previous preliminary results analysing and reporting data referring to a 3-year period (October 2016-October 2019). During this period, the study population included 478 adult patients with diagnosis of SSTI. The type of infection diagnosed, the aetiological agent involved and some notes on antimicrobial susceptibilities were collected and reported herein. We also analysed the most common co-morbidities, the type and duration of therapy executed, before and after ID intervention and the length of stay. The results of our study provide information to better understand the national epidemiologic data and the current clinical management of SSTIs in Italy.

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

Increases in community-acquired infections caused by extended-spectrum-ß-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) ß-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 χ(2) = 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 model's potential as a guide for prescribing empirical antibiotic therapy.

Factors Associated with Inadequate Intravenous Colistin Dosages: Post Hoc Analysis of a Multicenter, Cross-Sectional Study.

Colistin is a last-resort agent for the treatment of infections due to Gram-negative bacteria with difficult-to-treat resistance. The primary objective of this post hoc analysis of a cross-sectional study conducted in 22 Italian hospitals was to assess factors associated with inadequate intravenous colistin dosage. Overall, 187 patients receiving intravenous colistin were included in the analyses. Inadequate colistin dosages were administered in 27% of cases (50/187). In multivariable analysis, AKI (dummy variable with KDIGO stage 0 as a reference, odds ratio (OR) 3.98 with 95% confidence interval (CI) 1.48-10.74 for stage 1, OR 4.44 with 95% CI 1.17-16.93 for stage 2, OR 9.41 with 95% CI 1.59-55.70 for stage 3; overall p = 0.001) retained an independent association with inadequate colistin dosage, whereas the presence of a central venous catheter was associated with adequate colistin dosage (OR: 0.34 for inadequate dosage, 95% CI: 0.16-0.72, p = 0.004). These results were confirmed in an additional multivariable model with the center as a random effect. The association between AKI and inadequate dosage may reflect the perception of an increased risk of nephrotoxicity in patients with impaired renal function, which nonetheless should not be accompanied by dosage reductions beyond those recommended and could represent the target of dedicated antimicrobial stewardship efforts.

Characterisation and risk factor profiling of Pseudomonas aeruginosa urinary tract infections: pinpointing those likely to be caused by multidrug-resistant strains.

This study aimed to characterise UTIs caused by Pseudomonas aeruginosa in hospitalised adults and to identify risk factors for infections caused by multidrug-resistant (MDR) strains. A retrospective case-case-control study was conducted in two Italian teaching hospitals. Totally, 242 monomicrobial P. aeruginosa UTIs were analysed; 65 (26.9%) were caused by MDR strains. Clinical treatment failure at 72 h in 215 patients receiving empirical therapy was more frequent in MDR versus non-MDR cases [35/59 (59.3%) vs. 55/156 (35.3%); P = 0.001], particularly when a ß-lactam/ß-lactamase inhibitor or fluoroquinolone was initially prescribed. By Day 7 (when all regimens were consistent with antimicrobial susceptibility results), treatment failure rates were similar [MDR 15/65 (23.1%) vs. non-MDR 25/177 (14.1%); P = 0.09]. In-hospital mortality rates remained low in both groups [6/65 (9.2%) vs. 22/177 (12.4%); P = 0.49], but median hospital stay for MDR cases was longer (48 vs. 22 days; P ≤ 0.001). Models for predicting MDR and non-MDR P. aeruginosa UTIs displayed good discriminatory power. Presence of ≥3 risk factors for MDR P. aeruginosa UTI was associated with an OR for this outcome of 7.44 (95% CI 3.24-17.57; P < 0.001; specificity 91%, accuracy 75%). The model for predicting non-MDR P. aeruginosa UTI displayed similar accuracy (74%) with a risk factor burden threshold of ≥2 (OR = 7.02, 95% CI 4.61-10.70; P < 0.001). Risk factor assessment can identify UTIs in hospitalised patients likely to be caused by MDR P. aeruginosa, thereby facilitating targeted infection control and timelier effective treatment.