Experimental models and limited clinical data support a potential role for telavancin, a bactericidal lipoglycopeptide antibiotic, for treatment of Staphylococcus aureus bacteremia (SAB). Additional clinical experience is needed to fully assess use of telavancin for SAB.
Staphylococcus aureus bacteremia (SAB) is one of the most common serious bacterial infections and the most frequent invasive infection due to methicillin-resistant S. aureus (MRSA). Treatment is challenging, particularly for MRSA, because of limited treatment options.
Telavancin is a bactericidal lipoglycopeptide antibiotic that is active against a range of clinically relevant gram-positive pathogens including MRSA. In experimental animal models of sepsis telavancin was shown to be more effective than vancomycin.
In clinically evaluable patients enrolled in a pilot study of uncomplicated SAB, cure rates were 88% for telavancin and 89% for standard therapy. Among patients with infection due to only gram-positive pathogens enrolled in the 2 phase 3 studies of telavancin for treatment of hospital-acquired pneumonia, cure rates for those with bacteremic S. aureus pneumonia were 41% (9/22, telavancin) and 40% (10/25, vancomycin) with identical mortality rates. These data support further evaluation of telavancin in larger, prospective studies of SAB.
Staphylococcus aureus; MRSA; bacteremia; telavancin; experimental
Tedizolid, a novel oxazolidinone, is approved for treatment of acute bacterial skin and skin structure infections (ABSSSIs). Tedizolid offers several potential advantages over current ABSSSI treatment options. First, tedizolid has a prolonged half-life, which allows for once-daily dosing. Second, tedizolid has broad spectrum activity against Gram-positive organisms including methicillin-resistant Staphylococcus aureus, coagulase-negative staphylococci, and enterococci. Third, tedizolid, available in both intravenous and oral formulations, has high oral bioavailability, allowing for easy oral step-down therapy. Fourth, in patients who have been prescribed selective serotonin reuptake inhibitors or monoamine oxidase inhibitors, tedizolid may have fewer drug interactions than linezolid. Finally, tedizolid may have fewer or comparatively delayed onset side effects than linezolid, including thrombocytopenia and nausea. This review covers the microbiology, pharmacology, mode of action, and pharmacokinetics of tedizolid as well as patient-focused perspectives such as quality of life, patient satisfaction/acceptability, adherence, and uptake and provides expert opinion on the current use of tedizolid for ABSSSIs and potential future therapeutic applications.
cellulitis; new antibiotics; oxazolidinones; infectious diseases; MRSA
Sepsis, a leading cause of morbidity and mortality, is not a homogeneous disease but rather a syndrome encompassing many heterogeneous pathophysiologies. Patient factors including genetics predispose to poor outcomes, though current clinical characterizations fail to identify those at greatest risk of progression and mortality.
The Community Acquired Pneumonia and Sepsis Outcome Diagnostic study enrolled 1,152 subjects with suspected sepsis. We sequenced peripheral blood RNA of 129 representative subjects with systemic inflammatory response syndrome (SIRS) or sepsis (SIRS due to infection), including 78 sepsis survivors and 28 sepsis non-survivors who had previously undergone plasma proteomic and metabolomic profiling. Gene expression differences were identified between sepsis survivors, sepsis non-survivors, and SIRS followed by gene enrichment pathway analysis. Expressed sequence variants were identified followed by testing for association with sepsis outcomes.
The expression of 338 genes differed between subjects with SIRS and those with sepsis, primarily reflecting immune activation in sepsis. Expression of 1,238 genes differed with sepsis outcome: non-survivors had lower expression of many immune function-related genes. Functional genetic variants associated with sepsis mortality were sought based on a common disease-rare variant hypothesis. VPS9D1, whose expression was increased in sepsis survivors, had a higher burden of missense variants in sepsis survivors. The presence of variants was associated with altered expression of 3,799 genes, primarily reflecting Golgi and endosome biology.
The activation of immune response-related genes seen in sepsis survivors was muted in sepsis non-survivors. The association of sepsis survival with a robust immune response and the presence of missense variants in VPS9D1 warrants replication and further functional studies.
ClinicalTrials.gov NCT00258869. Registered on 23 November 2005.
Electronic supplementary material
The online version of this article (doi:10.1186/s13073-014-0111-5) contains supplementary material, which is available to authorized users.
Tedizolid, a novel oxazolidinone with activity against a wide range of Gram-positive pathogens, was evaluated in two noninferiority phase 3 acute bacterial skin and skin structure infection trials. The data from individual trials showed its noninferior efficacy compared to that of linezolid and a favorable tolerability profile. To evaluate potential differences, the pooled data were analyzed. The patients received 200 mg of tedizolid once daily for 6 days or 600 mg of linezolid twice daily for 10 days. Efficacy was evaluated at 48 to 72 h (primary endpoint), on days 11 to 13 (end of therapy [EOT]), and 7 to 14 days after the EOT (posttherapy evaluation). Treatment-emergent adverse events and hematologic and clinical laboratory parameters were collected. The baseline characteristics were comparable between the treatment groups: 852/1,333 (64%) patients were from North America, and the majority of infections were caused by Staphylococcus aureus. Tedizolid was noninferior to linezolid (early clinical responses, 81.6% versus 79.4%, respectively). The early responses remained relatively consistent across various host/disease factors and severity measures. Nausea was the most frequently reported adverse event (tedizolid, 8.2%; linezolid, 12.2%; P = 0.02), with onset occurring primarily during the first 6 days. Fewer tedizolid than linezolid patients had platelet counts of <150,000 cells/mm3 at the EOT (tedizolid, 4.9%; linezolid, 10.8%; P = 0.0003) and during the postbaseline period through the last day of active drug visit (tedizolid, 6.4%; linezolid, 12.6%; P = 0.0016). Efficacy was achieved with a 6-day once-daily course of therapy with the option of an intravenous/oral regimen, and fewer low platelet counts and gastrointestinal side effects were reported with tedizolid than with linezolid, all of which aligns well with antimicrobial stewardship principles. (These studies have been registered at ClinicalTrials.gov under registration no. NCT01170221 and NCT01421511.)
Staphylococcus aureus bacteremia is a common infection associated with significant morbidity and mortality. Telavancin is a bactericidal lipoglycopeptide active against Gram-positive pathogens, including methicillin-resistant S. aureus (MRSA). We conducted a randomized, double-blind, Phase 2 trial in patients with uncomplicated S. aureus bacteremia.
Patients were randomized to either telavancin or standard therapy (vancomycin or anti-staphylococcal penicillin) for 14 days. Continuation criteria were set to avoid complicated S. aureus bacteremia. The primary end point was clinical cure at 84 days.
In total, 60 patients were randomized and 58 received ≥1 study medication dose (all-treated), 31 patients fulfilled inclusion/exclusion and continuation criteria (all-treated target [ATT]) (telavancin 15, standard therapy 16), and 17 patients were clinically evaluable (CE) (telavancin 8, standard therapy 9). Mean age (ATT) was 60 years. Intravenous catheters were the most common source of S. aureus bacteremia and ~50% of patients had MRSA. A similar proportion of CE patients were cured in the telavancin (88%) and standard therapy (89%) groups. All patients with MRSA bacteremia were cured and one patient with MSSA bacteremia failed study treatment in each group. Although adverse events (AEs) were more common in the telavancin ATT group (90% vs. 72%), AEs leading to drug discontinuation were similar (7%) in both treatment arms. Potentially clinically significant increases in serum creatinine (≥1.5 mg/dl and at least 50% greater than baseline) were more common in the telavancin group (20% vs. 7%).
This study suggests that telavancin may have utility for treatment of uncomplicated S. aureus bacteremia; additional studies are warranted. (Telavancin for Treatment of Uncomplicated Staphylococcus Aureus Bacteremia (ASSURE); NCT00062647).
Bacteremia; Staphylococcus aureus; Telavancin; Vancomycin
Existing data are not consistently supportive of improved clinical outcome when vancomycin dosing regimens aimed at achieving target trough levels are used. A retrospective, post hoc, subgroup analysis of prospectively collected data from the Phase 3 ATTAIN trials of telavancin versus vancomycin for treatment of nosocomial pneumonia was conducted to further investigate the relationship between vancomycin serum trough levels and patient outcome.
Study patients were enrolled in 274 study sites across 38 countries. A total of 98 patients had Staphylococcus aureus nosocomial pneumonia and vancomycin serum trough levels available. These patients were grouped according to their median vancomycin trough level; < 10 μg/mL, 10 μg/mL to < 15 μg/mL, and ≥ 15 μg/mL.
Clinical cure rates in the < 10 μg/mL, 10 μg/mL to < 15 μg/mL, and ≥ 15 μg/mL vancomycin trough level groups were 70% (21/30), 55% (18/33), and 49% (17/35), respectively (p = 0.09), and the frequencies of patient death were 10% (3/30), 15% (5/33), and 20% (7/35), respectively (p = 0.31). Renal adverse events were more frequent in the ≥ 15 μg/mL (17% [6/35]) than the < 10 μg/mL (0%) and 10 μg/mL to < 15 μg/mL (3% [1/33]) trough level groups (p < 0.01). When patients with acute renal failure or vancomycin exposure within 7 days prior to study medication were excluded, clinical cure rates in the < 10 μg/mL, 10 μg/mL to < 15 μg/mL, and ≥ 15 μg/mL vancomycin trough level groups (71% [12/17], 60% [9/15], and 27% [3/11], respectively; p = 0.04) and the number of deaths (12% [2/17], 20% [3/15], and 45% [5/11], respectively; p = 0.07) demonstrated a trend towards worse outcomes in the higher vancomycin trough level groups.
The findings of our study suggest that higher vancomycin trough levels do not result in improved clinical response but likely increase the incidence of nephrotoxicity.
NCT00107952 and NCT00124020
Vancomycin; Trough levels; Nosocomial pneumonia; Staphylococcus aureus
U.S. Food and Drug Administration draft guidance for future antibiotic clinical trials of bacterial nosocomial pneumonia recommends the use of diagnostic criteria according to American Thoracic Society/Infectious Diseases Society of America (ATS/IDSA) guidelines and the use of a primary endpoint of 28-day all-cause mortality. The effect of applying these guidelines on outcomes of phase III nosocomial pneumonia studies of telavancin was evaluated in a post hoc analysis. ATS/IDSA criteria were applied in a blind fashion to the original all-treated (AT) group. Clinical cure rates at final follow-up were determined in the refined AT and clinically evaluable (CE) groups (ATS/IDSA-AT and ATS/IDSA-CE, respectively). The exploratory endpoint of 28-day survival was evaluated for the ATS/IDSA-AT group. Noninferiority of telavancin versus vancomycin was demonstrated, with similar cure rates in the ATS/IDSA-AT (59% versus 59%) and ATS/IDSA-CE (83% versus 80%) groups. Cure rates favored telavancin in ATS/IDSA-CE patients where Staphylococcus aureus was the sole pathogen (86% versus 75%). Overall, 28-day survival rates were similar in the telavancin (76%) and vancomycin (77%) groups but lower in telavancin-treated patients with preexisting moderate-to-severe renal impairment (creatinine clearance [CLCR] of <50 ml/min). Telavancin should be administered to patients with moderate-to-severe renal impairment only if treatment benefit outweighs the risk or if no suitable alternatives are available.
Sepsis is a common cause of death, but outcomes in individual patients are difficult to predict. Elucidating the molecular processes that differ between sepsis patients who survive and those who die may permit more appropriate treatments to be deployed. We examined the clinical features, and the plasma metabolome and proteome of patients with and without community-acquired sepsis, upon their arrival at hospital emergency departments and 24 hours later. The metabolomes and proteomes of patients at hospital admittance who would die differed markedly from those who would survive. The different profiles of proteins and metabolites clustered into fatty acid transport and β-oxidation, gluconeogenesis and the citric acid cycle. They differed consistently among several sets of patients, and diverged more as death approached. In contrast, the metabolomes and proteomes of surviving patients with mild sepsis did not differ from survivors with severe sepsis or septic shock. An algorithm derived from clinical features together with measurements of seven metabolites predicted patient survival. This algorithm may help to guide the treatment of individual patients with sepsis.
Major postoperative infections (MPIs) are poorly understood complications of cardiac surgery. We examined the epidemiology, microbiology, and outcome of MPIs occurring after cardiac surgery.
The study cohort was drawn from the Society of Thoracic Surgeon National Cardiac Database and comprised adults who underwent cardiac surgery at 5 tertiary hospitals between 2000 and 2004. We studied the incidence, microbiology, and risk factors of MPI (bloodstream or chest wound infections within 30 days after surgery), as well as 30-day mortality. We used multivariate regression analyses to evaluate the risk of MPI and mortality.
MPI was identified in 341 of 10,522 patients (3.2%). Staphylococci were found in 52.5% of these patients, gram-negative bacilli (GNB) in 24.3%, and other pathogens in 23.2%. High body mass index, previous coronary bypass surgery, emergency surgery, renal impairment, immunosuppression, cardiac failure, and peripheral/cerebrovascular disease were associated with the development of MPI. Median postoperative duration of hospitalization (15 days vs 6 days) and mortality (8.5% vs 2.2%) were higher in patients with MPIs. Compared with uninfected individuals, odds of mortality were higher in patients with S aureus MPIs (adjusted odds ratio, 3.7) and GNB MPIs (adjusted odds ratio, 3.0).
Staphylococci accounted for the majority of MPIs after cardiac surgery. Mortality was higher in patients with Staphylococcus aureus- and GNB-related MPIs than in patients with MPIs caused by other pathogens and uninfected patients. Preventive strategies should target likely pathogens and high-risk patients undergoing cardiac surgery.
Wound infection; Sepsis; Cardiac surgical procedures; Morbidity; Mortality
The HACEK organisms (Haemophilus species, Aggregatibacter species, Cardiobacterium hominis, Eikenella corrodens, and Kingella species) are rare causes of infective endocarditis (IE). The objective of this study is to describe the clinical characteristics and outcomes of patients with HACEK endocarditis (HE) in a large multi-national cohort. Patients hospitalized with definite or possible infective endocarditis by the International Collaboration on Endocarditis Prospective Cohort Study in 64 hospitals from 28 countries were included and characteristics of HE patients compared with IE due to other pathogens. Of 5591 patients enrolled, 77 (1.4%) had HE. HE was associated with a younger age (47 vs. 61 years; p<0.001), a higher prevalence of immunologic/vascular manifestations (32% vs. 20%; p<0.008) and stroke (25% vs. 17% p = 0.05) but a lower prevalence of congestive heart failure (15% vs. 30%; p = 0.004), death in-hospital (4% vs. 18%; p = 0.001) or after 1 year follow-up (6% vs. 20%; p = 0.01) than IE due to other pathogens (n = 5514). On multivariable analysis, stroke was associated with mitral valve vegetations (OR 3.60; CI 1.34–9.65; p<0.01) and younger age (OR 0.62; CI 0.49–0.90; p<0.01). The overall outcome of HE was excellent with the in-hospital mortality (4%) significantly better than for non-HE (18%; p<0.001). Prosthetic valve endocarditis was more common in HE (35%) than non-HE (24%). The outcome of prosthetic valve and native valve HE was excellent whether treated medically or with surgery. Current treatment is very successful for the management of both native valve prosthetic valve HE but further studies are needed to determine why HE has a predilection for younger people and to cause stroke. The small number of patients and observational design limit inferences on treatment strategies. Self selection of study sites limits epidemiological inferences.
TD-1792 is a first-in-class glycopeptide-cephalosporin heterodimer that exhibits bactericidal activity against Gram-positive pathogens. We conducted a randomized, double-blind, active-control, phase II trial in patients with complicated skin and skin structure infections caused by suspected or confirmed Gram-positive organisms. Patients 18 to 65 years old were randomized to receive 7 to 14 days of either TD-1792 (2 mg/kg of body weight intravenously [i.v.] every 24 h [q24h]) or vancomycin (1 g i.v. q12h, with dosage regimens adjusted per site-specific procedures). A total of 197 patients were randomized and received at least one dose of study medication. Rates of clinical success at the test-of-cure evaluation were similar in all analysis populations. Among 170 clinically evaluable patients, cure rates were 91.7% and 90.7% in the TD-1792 and vancomycin groups, respectively (95% confidence interval [CI] of −7.9 to 9.7 for the difference). In microbiologically evaluable patients with methicillin-resistant Staphylococcus aureus at baseline (n = 75), cure rates were 94.7% in the TD-1792 group and 91.9% in the vancomycin group. Microbiological eradication of Gram-positive pathogens (n = 126) was achieved in 93.7% and 92.1% of patients in the TD-1792 and vancomycin groups, respectively. Seven patients were discontinued from study medication due to an adverse event (AE): 2 and 5 in the TD-1792 and vancomycin groups, respectively. AEs were of similar types and severities between the two groups, other than pruritus, which was more common in patients who received vancomycin. No patients in the TD-1792 group experienced a serious AE. This study supports further clinical development of TD-1792 in patients with Gram-positive infection.
The aim of this study was to provide a contemporary picture of the presentation, etiology and outcome of infective endocarditis (IE) in a large patient cohort from multiple locations worldwide.
Prospective cohort study of 2781 adults with definite IE admitted to 58 hospitals in 25 countries between June 2000 and September 2005.
The median age of the cohort was 57.9 (IQR 43.2–71.8) years and 72% had native valve IE. Most (77%) patients presented early in the disease (<30 days) with few of the classic clinical hallmarks of IE. Recent health-care exposure was found in one quarter of patients. Staphylococcus aureus was the most common pathogen (31%). Mitral (41%) and aortic (38%) valves were infected most commonly. Complications were common: stroke (17%); embolization other than stroke (23%); heart failure (32%) and intracardiac abscess (14%). Surgical therapy was common (48%) and in-hospital mortality remained high (18%). Prosthetic valve involvement (OR 1.47, 95%CI 1.13–1.90), increasing age (OR 1.30, 95%CI 1.17–1.46 per 10-year interval), pulmonary edema (OR 1.79, 95%CI 1.39–2.30), S. aureus infection (OR 1.54, 95%CI 1.14–2.08), coagulase-negative staphylococcal infection (OR 1.50, 95%CI 1.07–2.10), mitral valve vegetation (OR 1.34, 95%CI 1.06–1.68), and paravalvular complications (OR 2.25, 95%CI 1.64–3.09) were associated with increased risk of in-hospital death, while viridans streptococcal infection (OR 0.52, 95%CI 0.33–0.81) and surgery (OR 0.61, 95%CI 0.44–0.83) were associated with decreased risk.
In the early 21st century, IE is more often an acute disease, characterized by a high rate of S. aureus infection. Mortality remains relatively high.
The significance of heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA) is unknown. Using a multinational collection of isolates from methicillin-resistant S. aureus (MRSA) infective endocarditis (IE), we characterized IE patients with and without hVISA, and genotyped the infecting strains.
MRSA bloodstream isolates from 65 patients with definite IE from 8 countries underwent PCR for 31 virulence genes, pulsed-field gel electrophoresis, and multilocus sequence typing. hVISA was defined using population analysis profiling (PAP).
Nineteen (29.2%) of 65 MRSA IE isolates exhibited hVISA by PAP. Isolates from Oceania and Europe were more likely to exhibit hVISA than isolates from the United States (77.8% vs. 35.0% vs. 13.9%; P < .001). The prevalence of hVISA was higher among isolates with a vancomycin minimum inhibitory concentration of 2 mg/L (P = .026). hVISA-infected patients were more likely to have persistent bacteremia (68.4% vs. 37.0%; P = .029) and heart failure (47.4% vs. 19.6%; P = .033). Mortality of hVISA- and non-hVISA-infected patients did not differ (42.1% vs. 34.8%, P = .586). hVISA and non-hVISA isolates were genotypically similar.
In these analyses, hVISA occurred in over one-quarter of MRSA IE isolates, was associated with certain IE complications, and varied in frequency by geographic region.
hVISA; Methicillin-resistant Staphylococcus aureus; endocarditis; genotype
The impact of early surgery on mortality in patients with native valve endocarditis (NVE) is unresolved. This study seeks to evaluate valve surgery compared to medical therapy for NVE, and to identify characteristics of patients who are most likely to benefit from early surgery.
Methods and Results
Using a prospective, multinational cohort of patients with definite NVE, the effect of early surgery on in-hospital mortality was assessed using propensity-based matching adjusting for survivor bias, and instrumental variable analysis. Patients were stratified by propensity quintile, paravalvular complications, valve perforation, systemic embolization, stroke, Staphylococcus aureus infection and congestive heart failure.
Of the 1552 patients with NVE, 720 (46%) underwent early surgery and 832 (54%) were treated with medical therapy. Compared to medical therapy, early surgery was associated with a significant reduction in mortality in the overall cohort (12.1% [87/720] vs. 20.7% [172/832]) and after propensity-based matching and adjustment for survivor bias (absolute risk reduction (ARR) = -5.9 %; p<0.001). Using a combined instrument, the instrumental variable adjusted ARR in mortality associated with early surgery was -11.2% (p<0.001). In sub-group analysis, surgery was found to confer a survival benefit compared to medical therapy among patients with a higher propensity for surgery (ARR= -10.9% for quintiles 4 and 5; p=0.002); those with paravalvular complications (ARR= -17.3 %; p<0.001), systemic embolization (ARR= -12.9%; p=0.002), S aureus NVE (ARR= -20.1%; p<0.001) and stroke (ARR= -13%; p=0.02) but not with valve perforation or congestive heart failure.
Early surgery for NVE is associated with an in-hospital mortality benefit compared to medical therapy alone.
early surgery; infective endocarditis; medical therapy; in hospital mortality
Background. Using multinational collections of methicillin-susceptible Staphylococcus aureus (MSSA) isolates from infective endocarditis (IE) and soft tissue infections (STIs), we sought to (1) validate the finding that S. aureus in clonal complex (CC) 30 is associated with hematogenous complications and (2) test the hypothesis that specific genetic characteristics in S. aureus are associated with infection severity.
Methods. IE and STI isolates from 2 cohorts were frequency matched by geographic origin. Isolates underwent spa typing to infer CC and multiplex polymerase chain reaction for presence of virulence genes.
Results. 114 isolate pairs were genotyped. IE isolates were more likely to be CC30 (19.5% vs 6.2%; P = .005) and to contain 3 adhesins (clfB, cna, map/eap; P < .0001 for all) and 5 enterotoxins (tst, sea, sed, see, and sei; P ≤ .005 for all). CC30 isolates were more likely to contain cna, tst, sea, see, seg, and chp (P < .05 for all).
Conclusions. MSSA IE isolates were significantly more likely to be CC30 and to possess a distinct repertoire of virulence genes than MSSA STI isolates from the same region. The genetic basis of this association requires further study.
Non-communicable diseases are rapidly overtaking infectious, perinatal, nutritional and maternal diseases as the major causes of worldwide death and disability. It is estimated that within the next 10-15 years, the increasing burden of chronic diseases and the ageing of the population will expose the world to an unprecedented burden of chronic diseases. Preventing the potential ramifications of a worldwide epidemic of chronic non-communicable diseases in a sustainable manner requires coordinated, collaborative efforts. Herein we present our collaboration's strategic plan to understand, treat and prevent chronic cardiovascular and pulmonary disease in Western Kenya which builds on a two decade partnership between academic universities in North America and Kenya; the Academic Model Providing Access to Healthcare (AMPATH). We emphasize the importance of training Kenyan clinician-investigators who will ultimately lead efforts in cardiovascular and pulmonary disease care, education and research. This penultimate aim will be achieved by our five main goals. Our goals include creating an administrative core capable of managing operations, develop clinical and clinical research training curricula, enhancing existing technology infrastructure and implementing relevant research programs. Leveraging a strong international academic partnership with respective expertise in cardiovascular medicine, pulmonary medicine and medical informatics we have undertaken to understand and counter cardiovascular and pulmonary disease in Kenya by addressing patient care, teaching and clinical research.
Objective To quantify the change in prescribing of antibiotic prophylaxis before invasive dental procedures for patients at risk of infective endocarditis, and any concurrent change in the incidence of infective endocarditis, following introduction of a clinical guideline from the National Institute for Health and Clinical Excellence (NICE) in March 2008 recommending the cessation of antibiotic prophylaxis in the United Kingdom.
Design Before and after study.
Population All patients admitted to hospital in England with a primary or secondary discharge diagnosis of acute or subacute infective endocarditis.
Main outcome measures Monthly number of prescriptions for antibiotic prophylaxis consisting of a single 3 g oral dose of amoxicillin or a single 600 mg oral dose of clindamycin, and monthly number of cases of infective endocarditis, infective endocarditis related deaths in hospital, or cases of infective endocarditis with a possible oral origin for streptococci.
Results After the introduction of the NICE guideline there was a highly significant 78.6% reduction (P<0.001) in prescribing of antibiotic prophylaxis, from a mean 10 277 (SD 1068) prescriptions per month to 2292 (SD 176). Evidence that the general upward trend in cases of infective endocarditis before the guideline was significantly altered after the guideline was lacking (P=0.61). Using a non-inferiority test, an increase in the number of cases of 9.3% or more could be excluded after the introduction of the guideline. Similarly an increase in infective endocarditis related deaths in hospital of 12.3% or more could also be excluded.
Conclusion Despite a 78.6% reduction in prescribing of antibiotic prophylaxis after the introduction of the NICE guideline, this study excluded any large increase in the incidence of cases of or deaths from infective endocarditis in the two years after the guideline. Although this lends support to the guideline, ongoing data monitoring is needed to confirm this, and further clinical trials should determine if antibiotic prophylaxis still has a role in protecting some patients at particularly high risk.
The results from two methodologically identical double-blind studies indicate that telavancin is noninferior to vancomycin based on clinical response in the treatment of hospital-acquired pneumonia due to Gram-positive pathogens.
Background. Telavancin is a lipoglycopeptide bactericidal against gram-positive pathogens.
Methods. Two methodologically identical, double-blind studies (0015 and 0019) were conducted involving patients with hospital-acquired pneumonia (HAP) due to gram-positive pathogens, particularly methicillin-resistant Staphylococcus aureus (MRSA). Patients were randomized 1:1 to telavancin (10 mg/kg every 24 h) or vancomycin (1 g every 12 h) for 7–21 days. The primary end point was clinical response at follow-up/test-of-cure visit.
Results. A total of 1503 patients were randomized and received study medication (the all-treated population). In the pooled all-treated population, cure rates with telavancin versus vancomycin were 58.9% versus 59.5% (95% confidence interval [CI] for the difference, –5.6% to 4.3%). In the pooled clinically evaluable population (n = 654), cure rates were 82.4% with telavancin and 80.7% with vancomycin (95% CI for the difference, –4.3% to 7.7%). Treatment with telavancin achieved higher cure rates in patients with monomicrobial S. aureus infection and comparable cure rates in patients with MRSA infection; in patients with mixed gram-positive/gram-negative infections, cure rates were higher in the vancomycin group. Incidence and types of adverse events were comparable between the treatment groups. Mortality rates for telavancin-treated versus vancomycin-treated patients were 21.5% versus 16.6% (95% CI for the difference, –0.7% to 10.6%) for study 0015 and 18.5% versus 20.6% (95% CI for the difference, –7.8% to 3.5%) for study 0019. Increases in serum creatinine level were more common in the telavancin group (16% vs 10%).
Conclusions. The primary end point of the studies was met, indicating that telavancin is noninferior to vancomycin on the basis of clinical response in the treatment of HAP due to gram-positive pathogens.
Using 98 clinical methicillin-susceptible Staphylococcus aureus isolates of known β-lactamase (Bla) type, we found a pronounced inoculum effect for cephalexin (mostly Bla type A and C strains), a mild inoculum effect for cephalothin (especially types B and C), and no inoculum effects for ceftriaxone and cefuroxime. Ceftobiprole showed the lowest MICs at a high inoculum but with a slight increase for Bla-positive versus Bla-negative strains. Since a potential therapeutic effect associated with a cephalosporin inoculum effect has been described, further studies are warranted.
The role of Panton-Valentine leukocidin (PVL) in determining the severity and outcome of complicated skin and skin structure infections (cSSSI) caused by methicillin (meticillin)-resistant Staphylococcus aureus (MRSA) is controversial. We evaluated potential associations between clinical outcome and PVL status by using MRSA isolates from patients enrolled in two large, multinational phase three clinical trials assessing telavancin for the treatment of cSSSI (the ATLAS program). MRSA isolates from microbiologically evaluable patients were genotyped by pulsed-field gel electrophoresis (PFGE) and PCR for pvl and 31 other putative virulence determinants. A single baseline pathogen of MRSA was isolated from 522 microbiologically evaluable patients (25.1%) among 2,079 randomized patients. Of these MRSA isolates, 83.2% (432/519) exhibited the USA300 PFGE genotype and 89.1% (465/522) were pvl positive. Patients with pvl-positive MRSA were more likely than those with pvl-negative MRSA to be young, to be North American, and to present with major abscesses (P < 0.001 for each). Patients were significantly more likely to be cured if they were infected with pvl-positive MRSA than if they were infected with pvl-negative MRSA (91.6% versus 80.7%; P = 0.015). This observation remained statistically significant after adjustment for presence of abscess, fever, or leukocytosis; infection size; diabetes; patient age; and study medication received. The fnbA, cna, sdrC, map-eap, sed, seg, sei, sej, SCCmec type IV, and agr group II genes were also associated with clinical response (P < 0.05). This contemporary, international study demonstrates that pvl was not the primary determinant of outcome in patients with MRSA cSSSI.
Methicillin (meticillin)-susceptible Staphylococcus aureus (MSSA) strains producing large amounts of type A β-lactamase (Bla) have been associated with cefazolin failures, but the frequency and impact of these strains have not been well studied. Here we examined 98 MSSA clinical isolates and found that 26% produced type A Bla, 15% type B, 46% type C, and none type D and that 13% lacked blaZ. The cefazolin MIC90 was 2 μg/ml for a standard inoculum and 32 μg/ml for a high inoculum, with 19% of isolates displaying a pronounced inoculum effect (MICs of ≥16 μg/ml with 107 CFU/ml) (9 type A and 10 type C Bla producers). At the high inoculum, type A producers displayed higher cefazolin MICs than type B or C producers, while type B and C producers displayed higher cefamandole MICs. Among isolates from hemodialysis patients with MSSA bacteremia, three from the six patients who experienced cefazolin failure showed a cefazolin inoculum effect, while none from the six patients successfully treated with cefazolin showed an inoculum effect, suggesting an association between these strains and cefazolin failure (P = 0.09 by Fisher's exact test). In summary, 19% of MSSA clinical isolates showed a pronounced inoculum effect with cefazolin, a phenomenon that could explain the cases of cefazolin failure previously reported for hemodialysis patients with MSSA bacteremia. These results suggest that for serious MSSA infections, the presence of a significant inoculum effect with cefazolin could be associated with clinical failure in patients treated with this cephalosporin, particularly when it is used at low doses.
We investigated associations between the genotypic and phenotypic features of Staphylococcus aureus bloodstream isolates and the clinical characteristics of bacteremic patients enrolled in a phase III trial of S. aureus bacteremia and endocarditis. Isolates underwent pulsed-field gel electrophoresis, PCR for 33 putative virulence genes, and screening for heteroresistant glycopeptide intermediate S. aureus (hGISA). A total of 230 isolates (141 methicillin-susceptible S. aureus and 89 methicillin-resistant S. aureus [MRSA]) were analyzed. North American and European S. aureus isolates differed in their genotypic characteristics. Overall, 26% of the MRSA bloodstream isolates were USA 300 strains. Patients with USA 300 MRSA bacteremia were more likely to be injection drug users (61% versus 15%; P < 0.001), to have right-sided endocarditis (39% versus 9%; P = 0.002), and to be cured of right-sided endocarditis (100% versus 33%; P = 0.01) than patients with non-USA 300 MRSA bacteremia. Patients with persistent bacteremia were less likely to be infected with Panton-Valentine leukocidin gene (pvl)-constitutive MRSA (19% versus 56%; P = 0.005). Although 7 of 89 MRSA isolates (8%) exhibited the hGISA phenotype, no association with persistent bacteremia, daptomycin resistance, or bacterial genotype was observed. This study suggests that the virulence gene profiles of S. aureus bloodstream isolates from North America and Europe differ significantly. In this study of bloodstream isolates collected as part of a multinational randomized clinical trial, USA 300 and pvl-constitutive MRSA strains were associated with better clinical outcomes.
In a prospective, randomized trial, daptomycin was non-inferior to standard therapy for Staphylococcus aureus bacteraemia and right-sided endocarditis. Since rates of infection due to methicillin-resistant S. aureus (MRSA) infection are increasing and treatment outcomes for bacteraemia caused by MRSA are generally worse than those observed with methicillin-susceptible S. aureus bacteraemia, clinical characteristics and treatment results in the trial’s pre-specified subset of patients with MRSA were analysed.
Clinical characteristics and outcomes of patients receiving daptomycin were compared with those receiving vancomycin plus low-dose gentamicin. Success was defined as clinical improvement with clearance of bacteraemia among patients who completed adequate therapy, received no potentially effective non-study antibiotics and had negative blood cultures 6 weeks after end of therapy.
Twenty of the 45 (44.4%) daptomycin patients and 14 of the 43 (32.6%) vancomycin/gentamicin patients were successfully treated (difference 11.9%; confidence interval −8.3 to 32.1). Success rates for daptomycin versus vancomycin/gentamicin were 45% versus 27% in complicated bacteraemia, 60% versus 45% in uncomplicated bacteraemia and 50% versus 50% in right-sided MRSA endocarditis. Cure rates in patients with septic emboli and in patients who received pre-enrolment vancomycin were similar between treatment groups. However, in both treatment groups, success rates were lower in the elderly (≥75 years). Persisting or relapsing bacteraemia occurred in 27% of daptomycin and 21% of vancomycin/gentamicin patients; among these patients, MICs of ≥2 mg/L occurred in five daptomycin and four vancomycin/gentamicin patients. The clinical course of several patients may have been influenced by lack of surgical intervention.
Daptomycin was an effective alternative to vancomycin/gentamicin for MRSA bacteraemia or right-sided endocarditis.
MRSA; endovascular infections; bloodstream infections; combination therapy; clinical trial