Publications (10)24.44 Total impact
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Article: Rapid identification of bacterial and fungal pathogens from positive blood cultures by MALDI-TOF MS.
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ABSTRACT: Sepsis is a syndrome characterized by a systemic inflammatory response due to severe infection. Early detection of causal agents and appropriate antimicrobial treatment reduce mortality. Conventional microbiological methods often do not provide time critical results for an optimal early management. We used an in-house protocol based on Tween 80 to process 109 positive blood cultures for bacteria and yeast identification by matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS), and results were compared to standard reference or automated methods. MALDI-TOF MS correctly identified 91.7% of the isolates. Correct identification was obtained for 57/62 (91.9%) aerobic/facultative anaerobic Gram-positive isolates, 53 (85.5%) at species level, and 4 (6.4%) at the genus level; 32/32 (100%) aerobic/facultative anaerobic Gram-negative isolates, 31 (96.9%) at species level, and 1 (3.1%) at the genus level; 7/7 (100%) obligate anaerobes, all at the genus level; 3/7 (42.8%) fungi, all at genus level. Overall, the median identification time of MALDI-TOF MS vs reference standard methods was significantly shorter: median (interquartile range) 7.1h (4.7-10.2) vs 48.1h (32.5-50.0), p<0.0001. MALDI-TOF MS is a valuable tool for rapid identification of pathogens in septic patients. An in-house protocol based on Tween 80 can be used to process positive blood cultures.International journal of medical microbiology: IJMM 03/2013; · 2.80 Impact Factor -
Article: Diagnosis of infective endocarditis: comparison of the LightCycler SeptiFast real-time PCR with blood culture.
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ABSTRACT: Infective endocarditis (IE) is a life-threatening condition in which identification of the causative pathogen is pivotal for subsequent effective therapy. Blood culture (BC) is considered the gold standard for microbial diagnosis of IE, but in up to one-third of patients, it can be negative due to a number of possible factors, e.g., prior antimicrobial therapy, fastidious microorganisms, or low bacterial load. The aim of this study was to assess the diagnostic utility of the commercially available PCR based system SeptiFast (SF) for microbial diagnosis of IE from clinical blood specimens. The results indicate that, this test, in combination with BC, could represent a valuable tool for microbial diagnosis of IE. Reduction of SF detection limit set for coagulase-negative staphylococci and streptococci could improve the sensitivity of the test.Journal of Medical Microbiology 03/2012; 61(Pt 6):881-3. · 2.50 Impact Factor -
Article: Diagnostic performance of a multiple real-time PCR assay in patients with suspected sepsis hospitalized in an internal medicine ward.
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ABSTRACT: Early identification of causative pathogen in sepsis patients is pivotal to improve clinical outcome. SeptiFast (SF), a commercially available system for molecular diagnosis of sepsis based on PCR, has been mostly used in patients hospitalized in hematology and intensive care units. We evaluated the diagnostic accuracy and clinical usefulness of SF, compared to blood culture (BC), in 391 patients with suspected sepsis, hospitalized in a department of internal medicine. A causative pathogen was identified in 85 patients (22%). Sixty pathogens were detected by SF and 57 by BC. No significant differences were found between the two methods in the rates of pathogen detection (P = 0.74), even after excluding 9 pathogens which were isolated by BC and were not included in the SF master list (P = 0.096). The combination of SF and BC significantly improved the diagnostic yield in comparison to BC alone (P < 0.001). Compared to BC, SF showed a significantly lower contamination rate (0 versus 19 cases; P < 0.001) with a higher specificity for pathogen identification (1.00, 95% confidence interval [CI] of 0.99 to 1.00, versus 0.94, 95% CI of 0.90 to 0.96; P = 0.005) and a higher positive predictive value (1.00, 95% CI of 1.00 to 0.92%, versus 0.75, 95% CI of 0.63 to 0.83; P = 0.005). In the subgroup of patients (n = 191) who had been receiving antibiotic treatment for ≥24 h, SF identified more pathogens (16 versus 6; P = 0.049) compared to BC. These results suggest that, in patients with suspected sepsis, hospitalized in an internal medicine ward, SF could be a highly valuable adjunct to conventional BC, particularly in patients under antibiotic treatment.Journal of clinical microbiology 02/2012; 50(4):1285-8. · 4.16 Impact Factor -
Article: Procalcitonin predicts real-time PCR results in blood samples from patients with suspected sepsis.
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ABSTRACT: Early diagnosis and rapid bacterial identification are of primary importance for outcome of septic patients. SeptiFast® (SF) real-time PCR assay is of potential utility in the etiological diagnosis of sepsis, but it cannot replace blood culture (BC) for routine use in clinical laboratory. Procalcitonin (PCT) is a marker of sepsis and can predict bacteremia in septic patients. The aim of the present study was to investigate whether PCT serum levels could predict SF results, and could help screening febrile patients in which a SF assay can improve the etiological diagnosis of sepsis. From 1009 febrile patients with suspected sepsis, 1009 samples for BC, SF real-time PCR, and PCT determination were obtained simultaneously, and results were compared and statistically analysed. Receiver operating characteristic (ROC) curves were generated to determine the area under the curve and to identify which cut-off of PCT value produced the best sensitivity to detect SF results. Mean PCT values of sera drawn simultaneously with samples SF positive (35.42±61.03 ng/ml) or BC positive (23.14±51.56 ng/ml) for a pathogen were statistically higher than those drawn simultaneously with SF negative (0.84±1.67 ng/ml) or BC negative (2.79±16.64 ng/ml) samples (p<0.0001). For SF, ROC analysis showed an area under the curve of 0.927 (95% confidence interval: 0.899-0.955, p<0.0001). The PCT cut-off value of 0.37 ng/ml showed a negative predictive value of 99%, reducing the number of SF assays of 53.9%, still identifying the 96.4% of the pathogens. PCT can be used in febrile patients with suspected sepsis to predict SF positive or negative results. A cut-off value of 0.37 ng/ml can be considered for optimal sensitivity, so that, in the routine laboratory activity, SF assay should not be used for diagnosis of sepsis in an unselected patient population with a PCT value <0.37 ng/ml.PLoS ONE 01/2012; 7(12):e53279. · 4.09 Impact Factor -
Article: Comparison of conventional culture with SeptiFast real-time PCR for microbial pathogen detection in clinical specimens other than blood.
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ABSTRACT: Early detection of aetiological agents is pivotal for adequate therapy for bacterial infections. Although culture is still considered the mainstay for laboratory diagnosis, it often lacks sensitivity, especially in patients already treated with antibiotics. The present study investigated the potential clinical utility of the commercial real-time-PCR-based system SeptiFast (SF), originally intended for diagnosis of sepsis from blood specimens, in the aetiological diagnosis of other bacterial infections, in patients undergoing antibiotic therapy. A total of 53 non-blood specimens were analysed for microbial pathogen detection by conventional culture and with SF real-time PCR: 19 (35.8%) synovial fluids, 9 (17.0%) cardiac valve tissues and 25 (47.2%) purulent exudates from various body sites. Overall, the number of specimens positive for a pathogen by SF (26/53; 49.1%) was significantly greater (P=0.001) than that of specimens positive by culture (10/53; 18.9%). In particular, SF was superior to culture for pathogen detection in cardiac valve tissues and synovial fluids. The analysis of concordance showed a fair agreement between the two methods (kappa value=0.314; 95% confidence interval=0.531-0.097). Even with the limitation of the low number of specimens, this study confirmed the great potential of diagnosing bacterial infections by a molecular approach, and indicates that the real-time PCR SF system can be used for specimens other than blood, from patients undergoing antibiotic treatment.Journal of Medical Microbiology 08/2011; 60(Pt 12):1774-8. · 2.50 Impact Factor -
Article: Bactericidal activity of oxacillin and glycopeptides against Staphylococcus aureus in patients with endocarditis: looking for a relationship between tolerance and outcome.
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ABSTRACT: There is no clear relationship between in vitro bactericidal activity tests and clinical outcome. We studied bactericidal activity of oxacillin, vancomycin and teicoplanin against Staphylococcus aureus isolates in patients with endocarditis and then we sought to determine if there was a relationship between in vitro bactericidal activity and clinical outcome. Minimal bacteriostatic and minimal bactericidal concentrations were determined for Staphylococcus aureus strains isolated from patients with endocarditis following standardized methods. Medical records were reviewed retrospectively to collect data on antimicrobial susceptibility at admission, antimicrobial therapy, need for surgery, embolic events and outcome. Sixty-two Staphylococcus aureus strains were studied in 62 patients with endocarditis. Overall, 91.9% definite, 21% methicillin resistant and 72.6% cured. Surgery was performed in 32.3% and embolic events were documented in 64.5%. Tolerance to oxacillin and teicoplanin was more common than vancomycin tolerance among methicillin susceptible Staphylococcus aureus. Among methicillin resistant Staphylococcus aureus teicoplanin was shown to have a higher rate of tolerance than vancomycin. No statistically significant differences on clinical outcome between oxacillin tolerant and oxacillin non tolerant Staphylococcus aureus infections were observed. Tolerance to oxacillin did not adversely affect clinical outcomes of patients with methicillin susceptible Staphylococcus aureus endocarditis treated with a combination of antimicrobials including oxacillin. The cure rate was significantly lower among patients with methicillin resistant Staphylococcus aureus endocarditis. In vitro bactericidal test results were not valid predictors of clinical outcome. Physicians need to use additional parameters when treating patients with staphylococcal endocarditis.Annals of Clinical Microbiology and Antimicrobials 06/2011; 10:26. · 2.64 Impact Factor -
Article: Comparison of the BD Phoenix system with the cefoxitin disk diffusion test for detection of methicillin resistance in Staphylococcus aureus and coagulase-negative staphylococci.
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ABSTRACT: The BD Phoenix system was compared to the cefoxitin disk diffusion test for detection of methicillin (meticillin) resistance in 1,066 Staphylococcus aureus and 1,121 coagulase-negative staphylococcus (CoNS) clinical isolates. The sensitivity for Phoenix was 100%. The specificities were 99.86% for S. aureus and 88.4% for CoNS.Journal of clinical microbiology 06/2009; 47(7):2288-91. · 4.16 Impact Factor -
Article: Drawbacks of antibiotic susceptibility of Streptococcus pneumoniae.
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ABSTRACT: During 10 years penicillin resistance among clinical isolates of S. pneumoniae was more or less stable. The cumulative proportion of penicillin non susceptible S. pneumoniae (PNSP) was 13.0%; 7.2% when isolates with MIC = 2 mg/l were considered. Among PNSP only 2 strains were isolated from sterile body fluids, one having MIC >3.84 mg/l. Lack of susceptibility to cotrimoxazole was 38.4%. All isolates were susceptible to ceftriaxone, levofloxacin, moxifloxacin, and quinupristin-dalfopristin.Le infezioni in medicina: rivista periodica di eziologia, epidemiologia, diagnostica, clinica e terapia delle patologie infettive 01/2004; 11(4):213-5. -
Article: [Clinico-microbiological comments on various cases of candidemia].
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ABSTRACT: During a 3 year period 48 patients with one or more blood cultures positive for Candida spp. were enrolled in the study. One patient presented 3 consecutives episodes of candidemia with infection of the port a cath. Fifty cases of candidemia were diagnosed. Candidemia with infection of the central venous catheter was the most frequent diagnosis (52%); in 20% of cases a tissue localization was also present (disseminated candidiasis). Thirty-four out of 50 episodes occurred in the Surgical Department. Among risk factors the most frequent resulted: prolonged antibiotic treatment (100%), intravascular catheter (86%), parenteral nutrition (74%), abdominal surgery (46%). C. albicans was identified more frequently than others Candida spp., resistance to fluconazole was detected in 20% of strains tested. 34/45 episodes of fungemia were treated with fluconazole, none reported side effects. In 5 cases fluconazole was discontinued for clinical failure. Clinical outcome in patients with Candida infection depends on other factors beside in vitro drug susceptibility tests.Recenti progressi in medicina 07/2002; 93(6):355-60. -
Article: Primary brain abscess with Nocardia farcinica in an immunocompetent patient.
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ABSTRACT: In this paper, we describe a case of an immunocompetent patient with cerebral nocardiosis. The onset was with loss of strength, paresthesia and focal epilepsy of the left arm. MRI showed on T2-weighted sequences a hyperintense central area of pus surrounded by a well-defined hypointense capsule and surrounding edema; on T1-weighted sequences a hypointense necrotic cavity with ring enhancement following administration of intravenous gadolinium. The patient underwent surgical excision of the abscess but culture from the specimen was negative. After 40 days of empirical antimicrobial therapy he developed neurological deterioration with focal epilepsy. A new MRI documented an enlargement of the hypointense lesion in the right frontal-parietal region. A second craniotomy with drainage of the abscess was performed; cultures yielded Nocardia farcinica. Therapy with trimethoprim/sulfamethoxazole, amikacin and meropenem was given for 35 days, and clinical and radiological improvement was observed. Home therapy was done with oral trimethoprim/sulfamethoxazole. Currently, 5 months from the second surgery, the patient can walk with support and no new episodes of epilepsy occurred. Side effects were absent from therapy. The MRI appearance of the brain lesion has improved, with a decrease in size, surrounding edema and ring enhancement.Clinical Neurology and Neurosurgery 06/2002; 104(2):132-5. · 1.58 Impact Factor
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Institutions
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2002–2011
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Università degli Studi di Perugia
- • Department of Clinical and Experimental Medicine
- • Department of Experimental Medicine and Biochemical Sciences
Perugia, Umbria, Italy
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