Maria Bruna Pasticci

A multicentre evaluation of the accuracy and performance of IP-10 for the diagnosis of infection with M. tuberculosis

IP-10 has potential as a diagnostic marker for infection with Mycobacterium tuberculosis, with comparable accuracy to QuantiFERON-TB Gold In-Tube test (QFT-IT). The aims were to assess the sensitivity and specificity of IP-10, and to evaluate the impact of co-morbidity on IP-10 and QFT-IT. 168 cases with active TB, 101 healthy controls and 175 non-TB patients were included. IP-10 and IFN-γ were measured in plasma of QFT-IT stimulated whole blood and analyzed using previously determined algorithms. A subgroup of 48 patients and 70 healthy controls was tested in parallel with T-SPOT.TB IP-10 and QFT-IT had comparable accuracy. Sensitivity was 81% and 84% with a specificity of 97% and 100%, respectively. Combining IP-10 and QFT-IT improved sensitivity to 87% (p < 0.0005), with a specificity of 97%. T-SPOT.TB was more sensitive than QFT-IT, but not IP-10. Among non-TB patients IP-10 had a higher rate of positive responders (35% vs 27%, p < 0.02) and for both tests a positive response was associated with relevant risk factors. IFN-γ but not IP-10 responses to mitogen stimulation were reduced in patients with TB and non-TB infection. This study confirms and validates previous findings and adds substance to IP-10 as a novel diagnostic marker for infection with M. tuberculosis. IP-10 appeared less influenced by infections other than TB; further studies are needed to test the clinical impact of these findings.

Cross-resistance between methicillin and cephalosporins for staphylococci: a general assumption not true for cefamandole.

The antibacterial activity of cefamandole was evaluated against 120 methicillin-susceptible and methicillin-resistant Staphylococcus aureus and coagulase-negative staphylococcal strains, using both large (10(8) CFU per ml) and small (10(4) CFU per ml) inocula. Cefamandole appeared superior to cephalothin against methicillin-resistant strains, displaying at 10 micrograms/ml a bacteriostatic and for some strains a bactericidal action against a large inoculum of bacteria.

Outbreak of infusion-related septicemia by Ralstonia pickettii in the Oncology Department.

Hospital acquired blood stream infection by Ralstonia pickettii in 9 cancer patients related to the heparin solution contamination used to flush the central venous catheter.

In vitro activity effects of twelve antibiotics alone and in association against twenty-seven Enterococcus faecalis strains isolated from Italian patients with infective endocarditis: high in vitro synergistic effect of the association ceftriaxone-fosfomycin.

Background: In 2004–2008, the epidemiological and clinical Infective Endocarditis Study Group (SEI) evaluated 852 cases of infective endocarditis. Staphylococcus aureus was the main involved pathogen (24.5%) and Enterococcus faecalis etiology was described in 11% of the cases. The aim of this study was to evaluate the in vitro activity of 12 antibiotics alone and in association against 27 strains of E. faecalis isolated from blood cultures of patients with infective endocarditis. Results: The results showed high in vitro activity of tigecycline, daptomycin and linezolid. A high synergistic effect was obtained with the association ceftriaxone-fosfomycin [fractional inhibitory concentration (FIC)50 = 0.34, FIC90 = 0.78]. Furthermore, ceftriaxone plus ampicillin presented additive results (FIC50 = 0.66, FIC90 = 1.00), and ceftriaxone plus fosfomycin and ceftriaxone plus ampicillin were significantly more active in vitro than each drug alone. The efficacy of ceftriaxone plus fosfomycin was confirmed by the association testing using the broth dilution technique. Conclusion: Fosfomycin seems particularly significant and its association with ceftriaxone could be considered as a useful therapeutic option in medical treatment of E. faecalis infective endocarditis.

Diagnosis of infective endocarditis: comparison of the LightCycler SeptiFast real-time PCR with blood culture

Infective endocarditis (IE) is a lifethreatening condition, in which identification of the causative pathogen is pivotal for subsequent effective therapy. Blood culture (BC) is considered the gold standard for microbiological diagnosis of IE (Watkin et al., 2003) but in up to one third of patients with suspected IE, BC can be negative due to a number of possible factors, such as prior antimicrobial therapy, the presence of fastidious microorganisms, or a low bacterial load (Lamas & Eykyn, 2003; Naber & Erbel, 2007). Identification of pathogens from heart valve tissue by real-time PCR has been shown to be a reliable technique (Lang et al., 2004; Mencacci et al., 2011). Several studies have demonstrated the diagnostic value of PCR in IE patients (Kühn et al., 2011; Zaloudı́ková et al., 2011), but few studies (Casalta et al., 2009) have evaluated the diagnostic utility of the commercially available PCR-based system SeptiFast (SF, Roche Diagnostics) for testing blood specimens. The SF system is able to detect and differentiate between a wide range of Gram-negative and Gram-positive bacteria, as well as some fungi, commonly involved in systemic infections (Lehmann et al., 2008). The aim of this study was to assess the diagnostic performance of the SF system, compared with BC, using blood specimens from patients with IE.

Malignant syphilis with ocular involvement in an HIV–infected patient

Malignant syphilis is now considered a rare disease, more commonly affecting individuals with poor health, malnutrition or HIV infection. We present a 34-year-old man with HIV infection who developed multiple atypical cutaneous ulcerations, leonine facies, a scleral nodule and keratitis with visual loss. The diagnosis of malignant syphilis was delayed due to the insidious presentation, but was confirmed via immunohistochemical (IHC) staining with anti-Treponema antibodies of a skin biopsy. Significant clinical improvement was observed following a 15-day course of penicillin and tigecycline therapy. In advanced HIV disease, cutaneous manifestations are often difficult to identify and present a challenge for the clinician. Clinical manifestations of secondary syphilis vary greatly, earning the epigram of ‘the great imitator’. It is important to recognize atypical presentations of syphilis, especially among HIV-infected individuals. Unlike historical cases of malignant syphilis, Treponema pallidum was found in the tissue section using IHC staining methods. We emphasize the importance of lues maligna in the differential diagnosis of HIV-infected patients with diffuse ulceronodular lesions as well as the usefulness of histological investigations and IHC studies.

Bactericidal activity of oxacillin and glycopeptides against Staphylococcus aureus in patients with endocarditis: Looking for a relationship between tolerance and outcome

BackgroundThere 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.MethodsMinimal 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.Results and DiscussionSixty-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.ConclusionsIn vitro bactericidal test results were not valid predictors of clinical outcome. Physicians need to use additional parameters when treating patients with staphylococcal endocarditis.

Ceftriaxone versus Imipenem/Cilastatin as Empirical Monotherapy for Infections in Cancer Patients

We conducted a prospective randomized clinical trial to compare the efficacy and tolerability of monotherapy with ceftriaxone (active ingredient of Rocephin) (CRO) versus imipenem/cilastatin (I/C) in febrile cancer patients with or without neutropenia. 120 febrile episodes were randomized and 89 (75%) were evaluable for efficacy analysis. The overall response rates to both regimens were good (86 and 79% improved in response to CRO and I/C, respectively). Overall mortality was low and similar in the two groups. Both regimens were well tolerated. Our preliminary data corroborate the efficacy of CRO or I/C as empirical monotherapy for febrile episodes in cancer patients. It will be up to future investigations to show whether one of these regimens is superior to the other.

In vitro Antimicrobial Activity of Ampicillin-Ceftriaxone and Ampicillin-Ertapenem Combinations Against Clinical Isolates of Enterococcus faecalis with High Levels of Aminoglycoside Resistance

This paper reports on the in vitro antimicrobial activity of ampicillin-ceftriaxone and ampicillin-ertapenem combinations against five strains of E. faecalis with high-level aminoglycoside resistance recovered from blood of septicemic patients. Double disk diffusion test and time killing curves were used. A bacteriostatic synergistic effect between ampicillin and ceftriaxone was detected using the disk diffusion assay for three of the five enterococcal strains studied. With the same three isolates enhanced bactericidal activity was also observed using time killing experiments. Overall, for these three strains, after 24 hr of contact, a decrease ≥ 2 log10 from the initial bacterial inoculum was registered with most ampicillin-ceftriaxone combinations, reaching with some of them a colony reduction ≥ 3 log10. This bactericidal interaction was negatively influenced increasing the bacterial inoculum. In all five isolates neither a bacteriostatic nor a bactericidal cooperation was observed for ampicillin combined with 2 mg/l of ertapenem. This investigation broadened the evidence of antimicrobial synergism in vitro between ampicillin and ceftriaxone in selected strains of Enterococcus faecalis with high-level aminoglycoside resistance.

A commercially available multiplex real-time PCR for detection of pathogens in cardiac valves from patients with infective endocarditis

Infective endocarditis (IE) is a life-threatening condition, burdened by high mortality. Current guidelines recommend that, in case of negative culture result, tissues from excised heart valves or vegetations from patients with suspected IE should be referred for broad-range bacterial PCR and sequencing. In this proof-of-concept study, the diagnostic utility of the commercially available multiplex real-time PCR system SeptiFast (SF), performed on cardiac valves, was evaluated in a selected population of 20 patients with definite IE of known origin, in comparison with culture. A significant difference was found between SF and culture in the rate of pathogen detection (19 versus 3 respectively; chi-square 14.06; P=0.0002). SF sensitivity was 95%; specificity, 100%; positive predictive value (PPV), 100%; and negative predictive value (NPV), 83.3%. Culture sensitivity was 15%; specificity, 100%; PPV, 100%; and NPV, 22.7%. SF assay, performed on culture-negative excised heart valves, can be useful for the etiological diagnosis of IE.