Daniele Roberto Giacobbe

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.

Risk factors and mortality of healthcare-associated and community-acquired Staphylococcus aureus bacteraemia

Staphylococcus aureus bacteraemia (SAB) is a leading cause of mortality and morbidity in both nosocomial and community settings. The objective of the study is to explore epidemiological characteristics and predisposing risk factors associated with healthcare-associated (HCA) and community-acquired (CA) SAB, and to evaluate any differences in mortality and efficacy of initial antimicrobial therapy on treatment outcome. We conducted a two-part analysis. First, a triple case-control study in which groups of HCA SAB with onset ≥ 48 h after hospital admission (HCA ≥ 48 h), HCA SAB with onset <48 h of hospital admission (HCA <48 h), and CA SAB were compared with controls. Second, a cohort study including all patients with SAB was performed to identify factors associated with in-hospital mortality. SAB was diagnosed in 165 patients over the study period (January 2007 to December 2007). Five variables were independently associated with HCA ≥ 48 h SAB: presence of central venous catheter, solid tumour, chronic renal failure, previous hospitalization and previous antibiotic therapy. Significant risk factors for HCA <48 h SAB were: Charlson Comorbidity Index ≥ 3, previous hospitalization, living in long-term care facilities and corticosteroid therapy. Factors independently associated with CA SAB were: diabetes mellitus, HIV infection and chronic live disease. Patients with HCA <48 h SAB were significantly more likely to receive initial inadequate antimicrobial treatment than patients with CA or HCA ≥ 48 h SAB (44.8% versus 33.3% and 31.5%, respectively). Logistic-regression analysis identified three variables as independent predictors of mortality: presentation with septic shock, infection with methicillin-resistant S. aureus, and initial inadequate antimicrobial treatment. More than half of patients with SAB have MRSA strains and presentation with septic shock, and inappropriate empirical therapy was associated with increased mortality.

Management of ventilator-associated pneumonia: epidemiology, diagnosis and antimicrobial therapy

Ventilator-associated pneumonia (VAP) is the most frequent infection among patients hospitalized in intensive care units, maintaining a high morbidity and mortality. The global incidence of VAP ranges from 8 to 28%. Early-onset VAP is mainly caused by community pathogens with a favorable pattern of antibiotic sensitivity, whereas late-onset VAP is often caused by multidrug-resistant pathogens, mainly methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa and Acinetobacter spp. and enteric Gram-negative bacilli. The diagnosis of VAP remains difficult to confirm, lacking both microbiological analysis and radiological signs of high specificity. The Clinical Infection Pulmonary Score has been proposed to overcome the difficulties related to the diagnosis, but is not applicable to all patient categories. A continuous evaluation of the antimicrobial therapeutic options, along with their pharmacodynamic and pharmacokinetic profiles, is mandatory to create therapeutic protocols and reduce VAP-related mortality.

Will new antimicrobials overcome resistance among Gram-negatives?

The spread of resistance among Gram-positive and Gram-negative bacteria represents a growing challenge for the development of new antimicrobials. The pace of antibiotic drug development has slowed during the last decade and, especially for Gram-negatives, clinicians are facing a dramatic shortage in the availability of therapeutic options to face the emergency of the resistance problem throughout the world. In this alarming scenario, although there is a shortage of compounds reaching the market in the near future, antibiotic discovery remains one of the keys to successfully stem and maybe overcome the tide of resistance. Analogs of already known compounds and new agents belonging to completely new classes of antimicrobials are in early stages of development. Novel and promising anti-Gram-negative antimicrobials belong both to old (cephalosporins, carbapenems, β-lactamase inhibitors, monobactams, aminoglycosides, polymyxin analogues and tetracycline) and completely new antibacterial classes (boron-containing antibacterial protein synthesis inhibitors, bis-indoles, outer membrane synthesis inhibitors, antibiotics targeting novel sites of the 50S ribosomal subunit and antimicrobial peptides). However, all of these compounds are still far from being introduced into clinical practice. Therefore, infection control policies and optimization in the use of already existing molecules are still the most effective approaches to reduce the spread of resistance and preserve the activity of antimicrobials.

Meropenem for treating KPC-producing Klebsiella pneumoniae bloodstream infections: Should we get to the PK/PD root of the paradox?

ABSTRACT The objective of this study was to assess the achievement of pharmacokinetic/pharmacodynamic (PK/PD) targets of meropenem (MEM) in critically-ill patients with bloodstream infections (BSI) due to Klebsiella pneumoniae-carbapenemase-producing Klebsiella pneumoniae (KPC-Kp) with MEM minimum inhibitory concentrations (MICs) ≥16 mg/L. Nineteen critically-ill patients with KPC-Kp BSI were given combination therapy including MEM, tigecycline, plus colistin or gentamicin (according to susceptibility testing). MEM was administered as an extended 3-hour infusion of 2 g every 8 hours, or adjusted according to renal function. MEM plasma concentrations were determined by high-performance liquid chromatography. PK/PD targets for MEM were defined as T > 40% 1×MIC and T > 40% 4×MIC. Possible synergisms between MEM and coadministered agents were assessed by time-kill assays based on plasma levels for MEM and on fixed plasma concentrations for the other agents. In none of 19 patients MEM reached any PK/PD target. The actual MEM MICs were 256, 512, and 1024 mg/L in 1, 3, and 15 isolates, respectively. However, theoretically, the PK/PD target of T > 40% 1×MIC could have been achieved in 95%, 68%, 32% and 0% of the isolates for MIC equal to 8, 16, 32, and 64 mg/L, respectively. No synergisms were observed between MEM and coadministered agents. In conclusion, high-dose MEM failed to reach PK/PD targets in 19 patients with BSI due to KPC-Kp with very high MEM MICs. On a theoretical basis, our results suggest a possible usefulness of MEM against resistant blood isolates with MICs up to 32 mg/L.

Effectiveness of a project to prevent HIV vertical transmission in the Republic of Congo

OBJECTIVES To evaluate the effectiveness of a prevention programme against the vertical transmission of HIV in a resource-limited setting and to investigate variables associated with compliance. PATIENTS AND METHODS The Kento-Mwana project (2005-2008) provided counselling, serological and biomolecular testing and prophylaxis/therapy to HIV-positive pregnant women and their children attending four antenatal clinics in Pointe Noire, Republic of Congo. Expected and actual rates of vertical transmission of HIV were compared. Univariate and multivariate analyses were performed in order to identify variables associated with non-compliance. RESULTS The observed transmission rate in the group who completed follow-up was 5/290 (1.7%, 95% CI 0.6%-4.1%). The overall estimated transmission rate in the target population, computed taking into account the expected vertical transmission of HIV among drop-outs, was 67-115/638 (10.5%-18.0%). A comparison between this rate and the expected transmission rate in the absence of intervention (25%-40%) showed that the programme was able to prevent approximately 50% of vertical transmissions. Older age (OR 0.33, 95% CI 0.16-0.66, P = 0.002), telephone availability (OR 0.42, 95% CI 0.24-0.72, P = 0.002) and occupation (OR 0.57, 95% CI 0.29-1.10, P = 0.092) were associated with better compliance. CONCLUSIONS Despite the vast majority of women accepting counselling and testing, many of them refused prophylaxis or dropped out, thus reducing the effectiveness of the intervention from an ideal 2% to a still important but less impressive median transmission rate of 15% (range 10.5%-18%). Promoting participation and compliance, rather than increasing the potency of antiretroviral regimens, is crucial for preventing the vertical transmission of HIV in Africa.

Initial serum (1,3)-β-d-glucan as a predictor of mortality in proven candidaemia: findings from a retrospective study in two teaching hospitals in Italy and Brazil

A retrospective study was conducted to assess the role of initial serum (1,3)-β-d-glucan (BDG) values in predicting mortality in proven candidaemia. The study was conducted in two large teaching hospitals in Italy and Brazil. From January 2009 to June 2014, all patients with proven candidaemia who underwent a BDG test within 96 hours before or after the first positive blood culture were included in the study. The primary end point was 28-day mortality, with the role of initial BDG being assessed by univariate and multivariate analyses. A total of 104 patients met the inclusion criteria. Overall, the crude 28-day mortality was 30% (31/104). In the final multivariate model, an initial BDG of >287 pg/mL (odds ratio (OR) 4.40, 95% confidence interval (CI) 1.56-12.39, p 0.005), haemodialysis (OR 4.33, 95% CI 1.24-15.17, p 0.022) and a Pitt score of ≥ 2 (OR 4.10, 95% CI 1.24-13.54, p 0.021) were significant predictors of 28-day mortality. The >287 pg/mL cutoff predicted 28-day mortality with 65% sensitivity and 70% specificity. Centre of enrolment (p for interaction 0.012), haemodialysis (p for interaction 0.062) and timing of BDG test of more than 24 hours before or after the positive culture (p for interaction 0.143) appeared to interact with BDGs ability to predict mortality. Although not statistically significant, the last two of these interactions might partially explain why BDGs ability to predict mortality was present only in the Italian cohort.

Impact of a mixed educational and semi-restrictive antimicrobial stewardship project in a large teaching hospital in Northern Italy

AbstractBackgroundThe overuse of antimicrobials favors the dissemination of antimicrobial resistance, as well as invasive fungal diseases and Clostridium difficile infections (CDI). In this study, we assessed the impact of a mixed educational and semi-restrictive antimicrobial stewardship (AMS) project in a large teaching hospital in Italy.MethodsThe AMS project was conducted from May 2014 to April 2016. It consisted of two initiatives in two consecutive periods: (1) educational activities; (2) semi-restrictive control of antimicrobial prescribing through a computerized software. The primary endpoint was consumption of antibacterials and antifungals. Secondary endpoints were incidence of CDI, methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infections (BSI), carbapenem-resistant Klebsiella pneumoniae (CRKP) BSI, and Candida BSI.ResultsDuring the study period, a statistically significant reduction in consumption was observed for antibacterials (−1.45 defined daily doses (DDD)/1000 patient-days monthly, 95% confidence intervals [CI] −2.38 to −0.52, p 0.004), mainly driven by reductions in the use of fluoroquinolones, third/fourth generation cephalosporins, and carbapenems. No decrease in consumption of antifungals was observed (−0.04 DDD/1000 patient-days monthly, 95% CI −0.34 to +0.25, p 0.750). A statistically significant trend towards reduction was observed for incidence of CRKP BSI (incidence rate ratio 0.96, 95% CI 0.92–0.99, p 0.013). No statistically significant variations in trends were observed for CDI, MRSA BSI, and Candida BSI.ConclusionsThe mixed AMS project was effective in reducing the use of major antibacterials and the incidence of CRKP BSI. Further research is needed to assess the extent of long-term benefits of semi-restrictive approaches.

Bordetella holmesii endocarditis in a patient with systemic lupus erythematous treated with immunosuppressive agents

Sir, Bordetella holmesii, formerly designated as CDC non-oxidizer group 2, was recently classified as a member of the genus Bordetella. This pathogen has been reported as a rare cause of bactaeremia, respiratory tract infection, and endocarditis, particularly in younger patients. Anatomic or functional asplenia, renal transplantation, HIV infection, long-term steroid therapy, Hodgkin’s lymphoma, and chronic obstructive pulmonary disease are all predisposing conditions for invasive disease. Bordetella spp. represents one of the non-HACEK (Haemophilus species, Actinobacillus actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, and Kingella species) Gram-negative rods that can cause endocarditis. Infective endocarditis (IE) caused by non-HACEK Gram-negative bacilli is a rare and poorly understood disease; only few cases have been described so far and all present a high mortality rate (24%). From 1972 to 2011, only two cases of Bordetella holmesii endocarditis have been found in a review of the English literature. The diagnosis of B. holmesii IE was confirmed by the presence of a valvular vegetation in only one of these two cases, and was documented through the use of the echocardiography; in the other case, the diagnosis was only clinically suspected. Here we report a case of IE caused by Bordetella holmesii in a patient affected by systemic lupus erythematous (SLE) and receiving an immunosuppressive treatment with azathioprine and prednisone. On March 2011, a 48-year-old male patient was admitted to the Infectious Diseases Department of the San Martino University Hospital of Genoa, Italy, due to a long history of fever and fatigue. His medical history included an autoimmune thyroiditis and a recent diagnosis of SLE, which had been based on physical examination and laboratory test results (positivity of antinuclear antibody test). Before this hospitalization, no organ involvement of SLE had been described and no new sign was diagnosed on this matter at the Infectious Diseases Department. In his medical history, the patient had received remittent courses of prednisone therapy (25 mg/die) for his rheumatic conditions. On 1 February 2011, due to a persistent febrile state, azathioprine was introduced to his therapeutic scheme. During this period, a positron emission tomography/computed tomography scan was performed and it documented no evidence of metabolically active disease. However, due to the presence of a diastolic murmur on auscultation, a transthoracic echocardiography (TTE) was performed, which documented the presence of mobile vegetation on a bicuspid aortic valve, with moderate–severe aortic regurgitation and left ventricle overload. No lesions compatible with Libman–Sacks endocarditis existed prior to this episode. The immunosuppressive therapy was then discontinued and the patient was hospitalized at the Infectious Diseases Department with the diagnosis of suspected IE. His temperature was 36.3uC, heart rate was 90 bpm, and blood pressure was 125/65 mmHg. Physical examination revealed normal S1 and S2 sounds, but a 2/6 diastolic murmur on the aortic auscultation site was detected. Laboratory test results showed elevated C-reactive protein (90.9 mg/l, normal range: 0–5 mg/l) and no leukocytosis. Serial sets of blood cultures were performed and colonies of Gramnegative rods grew from five of them. The isolated pathogen grew on blood and chocolate agar plates after 2 days of incubation, but showed a very limited growth on MacConkey agar. The strain produced a diffusible brown pigment on blood agar plate and was catalase negative. Initially, it was not possible to identify the isolate neither through routine laboratory procedure by using VITEK 2 AES (BioMérieux, Durham, NC, USA) nor by the API NE and NH strips (BioMérieux). The strain was subsequently identified as Bordetella holmesii by sequence analysis of the hypervariable regions V3 and V6 of the 16S rRNA gene; by insertion elements (IS1001, IS1002, and IS481) analysis; by using previously described primers and conditions, and by differential biochemical tests (oxidase, nitrate reduction, and urease production) used to differentiate Bordetella

Bloodstream infections in internal medicine

ABSTRACT Bloodstream infections (BSI) carry a heavy burden of morbidity and mortality in modern internal medicine wards (IMW). These wards are often filled with elderly subjects with several risk factors for BSI, such as multiple comorbidities, polypharmacy, immunosuppression, and indwelling devices. Diagnosing BSI in such a setting might require a high degree of suspicion, since the clinical presentation could be affected by underlying conditions and concomitant medications, which might delay the administration of an appropriate antimicrobial therapy, an event strongly and unfavorably influencing survival. Furthermore, selecting the appropriate antimicrobial therapy to treat these patients is becoming an increasingly complex task in which all possible benefits and costs should be carefully analyzed from patient and public health perspectives. Only a specialized, continuous, and interdisciplinary approach could really improve the management of IMW patients in an era of increasing antimicrobial resistance and complexity of care.