Nicola Petrosillo

Use of a T cell-based assay for monitoring efficacy of antituberculosis therapy.

Monitoring the efficacy of antituberculosis therapy is crucial both for the individual patient and for better control of the spread of tuberculosis. We studied 18 patients with microbiologically confirmed tuberculosis, both at the time of diagnosis and 3 months after they started therapy, using an in vitro assay that detects T cell-mediated interferon- gamma response to selected peptides of Mycobacterium tuberculosis-specific early secretory antigenic target 6 (ESAT-6) protein. All patients had positive results at diagnosis; however, 3 months later, the response to ESAT-6 peptides was still detectable only in the 5 patients with microbiological isolation and/or absence of clinical improvement after treatment. On the basis of these data, we conclude that our assay is a useful tool in monitoring the efficacy of antituberculosis therapy.

Risk of hepatitis C seroconversion after occupational exposures in health care workers

BACKGROUND To determine the incidence of hepatitis C virus (HCV) seroconversion, health care workers reporting an occupational exposure with blood or other risk-prone body materials from a patient known to be seropositive for HCV antibody were enrolled. METHODS HCV seroconversion within 6 months of a reported exposure was assessed by second-generation enzyme immunoassay and immunoblot assay. RESULTS From January 1992 through December 1993, 331 (51%) hollow-bore needlesticks, 105 (16.5%) suture needle or sharp object injuries, 85 (13%) mucous membrane contaminations, and 125 (19.5%) skin contaminations were reported. Four HCV seroconversions were observed after hollow-bore needlesticks (1.2%; 95% CI 0.3% to 3.0%); no seroconversions occurred after other routes of exposure. Blood-filled needlesticks and source patient coinfection with HIV appeared to be associated with a higher risk of seroconversion. CONCLUSIONS The risk of HCV seroconversion after occupational exposure appears to be low but is not negligible. Aggressive implementation of universal precautions is important for preventing risk-prone exposure, but safer devices are also needed.

Colistin and Rifampicin Compared With Colistin Alone for the Treatment of Serious Infections Due to Extensively Drug-Resistant Acinetobacter baumannii: A Multicenter, Randomized Clinical Trial

BACKGROUND Extensively drug-resistant (XDR) Acinetobacter baumannii may cause serious infections in critically ill patients. Colistin often remains the only therapeutic option. Addition of rifampicin to colistin may be synergistic in vitro. In this study, we assessed whether the combination of colistin and rifampicin reduced the mortality of XDR A. baumannii infections compared to colistin alone. METHODS This multicenter, parallel, randomized, open-label clinical trial enrolled 210 patients with life-threatening infections due to XDR A. baumannii from intensive care units of 5 tertiary care hospitals. Patients were randomly allocated (1:1) to either colistin alone, 2 MU every 8 hours intravenously, or colistin (as above), plus rifampicin 600 mg every 12 hours intravenously. The primary end point was overall 30-day mortality. Secondary end points were infection-related death, microbiologic eradication, and hospitalization length. RESULTS Death within 30 days from randomization occurred in 90 (43%) subjects, without difference between treatment arms (P = .95). This was confirmed by multivariable analysis (odds ratio, 0.88 [95% confidence interval, .46-1.69], P = .71). A significant increase of microbiologic eradication rate was observed in the colistin plus rifampicin arm (P = .034). No difference was observed for infection-related death and length of hospitalization. CONCLUSIONS In serious XDR A. baumannii infections, 30-day mortality is not reduced by addition of rifampicin to colistin. These results indicate that, at present, rifampicin should not be routinely combined with colistin in clinical practice. The increased rate of A. baumannii eradication with combination treatment could still imply a clinical benefit. CLINICAL TRIALS REGISTRATION NCT01577862.

Occupational Human Immunodeficiency Virus Infection in Health Care Workers: Worldwide Cases Through September 1997

The average estimated risk of human immunodeficiency virus (HIV) infection for health care workers following a percutaneous or mucous exposure is <0.5% in incidence studies, although a case-control study suggests it is much higher for highest-risk percutaneous exposure. To characterize exposures resulting in HIV transmission, we reviewed available data on occupational cases reported worldwide, identifying 94 documented and 170 possible cases. The majority of documented infections occurred in nurses, after contact with the blood of a patient with AIDS by means of percutaneous exposure, with a device placed in an artery or vein. High-exposure job categories, e.g., midwives and surgeons, are represented mostly among possible cases. Transmission occurred also through splashes, cuts, and skin contaminations, and in some cases despite postexposure prophylaxis with zidovudine. Health care workers could benefit if these data were incorporated in educational programs designed to prevent occupational bloodborne infections.

Macrolide Efflux Genes mef(A) and mef(E) Are Carried by Different Genetic Elements in Streptococcus pneumoniae

ABSTRACT Susceptibilities to macrolides were evaluated in 267 Streptococcus pneumoniae isolates, of which 182 were from patients with invasive diseases and 85 were from healthy carriers. Of the 98 resistant isolates, 20 strains showed an M phenotype and carried mef. Strains that carried both mef(A) and mef(E) were found: 17 strains carried mef(A) and 3 carried mef(E). The characteristics of the strains carrying the mef genes and the properties of the mef-containing elements were studied. Strains carrying mef(A) belonged to serotype 14, were susceptible to all the antibiotics tested except erythromycin, and appeared to be clonally related by pulsed-field gel electrophoresis (PFGE). The three mef(E) strains belonged to different serotypes, showed different susceptibility profiles, and did not appear to be related by PFGE. The sequences of a fragment of the mef-containing element, which encompassed mef and the msr(A) homolog, were identical among the three mef(E)-positive strains and among the three mef(A)-positive strains, although there were differences between the sequences for the two variants at 168 positions. In all mef(A)-positive strains, the mef element was inserted in celB, which led to impairment of the competence of the strains. In line with insertion of the mef(E) element at a different site, the competence of the mef(E)-positive strains was maintained. Transfer of erythromycin resistance by conjugation was obtained from two of three mef(A) strains but from none of three mef(E) strains. Due to the important different characteristics of the strains carrying mef(A) or mef(E), we suggest that the distinction between the two genes be maintained.

Prevalence of Infected Patients and Understaffing Have a Role in Hepatitis C Virus Transmission in Dialysis

To assess hepatitis C virus (HCV) incidence rates and identify determinants of infection among hemodialysis patients, a multicenter study was conducted in 58 units in ITALY: An initial seroprevalence survey was conducted among 3,492 patients already on hemodialysis therapy as of January 1997 and among an additional 434 patients who began dialysis up to January 1998. HCV antibodies were assessed by third-generation enzyme immunoassays. Patients testing seronegative at baseline were enrolled into a 1-year incidence study with serological follow-up at 6 and 12 months. For patients who seroconverted, an HCV RNA assay was performed on stored baseline samples to confirm new infection. A nested case-control study was subsequently performed to investigate potential risk factors. For each incident case, three controls negative for both HCV antibodies and HCV RNA were randomly selected. At enrollment, HCV seroprevalence was 30.0%. During follow-up, 23 new HCV cases were documented, with a cumulative incidence of 9.5 cases/1,000 patient-years. By logistic regression analysis, an increased risk for HCV infection emerged for patients attending the dialysis units with a high prevalence of HCV-infected patients at baseline (odds ratio [OR], 4.6) and for those attending units with a low personnel-patient ratio (OR, 5.4). Among extradialysis factors, a history of surgical intervention in the previous 6 months (OR, 16.7) significantly increased HCV risk. These findings suggest that the combination of understaffing and a high level of infected patients in the dialysis setting increases the risk for HCV nosocomial transmission. This is likely related to an increased likelihood for breaks in infection control measures.

Continuous versus intermittent infusion of vancomycin for the treatment of Gram-positive infections: systematic review and meta-analysis

OBJECTIVES To summarize available evidence on the effect of continuous infusion (CoI) of vancomycin compared with intermittent infusion (InI) in adult patients with Gram-positive infections. METHODS MEDLINE, EMBASE and Cochrane databases were searched. Randomized clinical trials (RCTs) and observational studies that comparatively assessed CoI and InI of vancomycin in terms of mortality, clinical cure, toxicity rates and serum drug exposure [trough concentration (C(min)) for InI and steady-state concentration (C(ss)) for CoI; area under the curve at 24 h (AUC(24)) for both] were included. Meta-analysis was conducted combining and analysing the relative risk (RR) and computing a summary RR of the effects with 95% confidence interval (CI). The standardized mean difference was calculated for continuous outcomes. The I(2) test was calculated to assess heterogeneity across studies. RESULTS One RCT and five observational studies were included in the analysis. Compared with InI, CoI of vancomycin was associated with a significantly lower risk of nephrotoxicity (RR 0.6, 95% CI 0.4-0.9, P = 0.02; I(2)= 0). Overall mortality was not different between the two groups (RR 1.03, 95% CI 0.7-1.6, P = 0.9; I(2)= 0). CONCLUSIONS Our meta-analysis suggests that administration of vancomycin for the treatment of Gram-positive infections by CoI is associated with a significantly lower risk of nephrotoxicity when compared with InI of the drug. RCTs are needed to define the impact on mortality rate and on the pharmacodynamic activity in terms of AUC/MIC ratio.

Primary Pulmonary Hypertension in HIV Patients: A Systematic Review

The relationship between grade of pulmonary hypertension and factors associated with human immunodeficiency virus among patients with HIV infection is poorly documented. This report documents the most extensive attempt made thus far to determine whether a relationship exists between degree of pulmonary hypertension and the following conditions: HIV risk factor, degree of immunosuppression, presence or absence of AIDS, and presence or absence of liver cirrhosis. A retrospective study involving a search of the published literature on primary pulmonary hypertension among HIV cases from 1987 to 1998, using the Medline and Aidsline databases was conducted. Patients for whom secondary causes of pulmonary hypertension could be excluded were selected, and the following information for each was recorded: age, gender, risk factors for HIV infection, HIV disease stage according to the Centers for Disease Control, previous oppor tunistic and neoplastic diseases, CD4+ cell count (cells/L), presence or absence of liver cirrhosis, pulmonary systolic artery pressure level, and lung pathology specimens. Information about the patients survival time was also recorded. Seventy-six patients were judged to have primary pulmonary hypertension and were included in the study. While no correlation was found between pulmonary systolic artery pressure level and CD4+ cell counts, a statistically significant difference was found between HIV-positive patients with and without AIDS as determined by the Centers for Disease Control criteria with regard to the degree of pulmonary hypertension, expressed as pulmonary systolic artery pressure level (85.4 ± 17 mm Hg vs 71.8 ± 15 mm Hg, p < 0.013). Although a higher PAPS was present in HIV cirrhotic patients, a statistically significant difference was not found between degree of pulmonary hyper tension and evidence of hepatic cirrhosis (85 ±21 mm Hg vs 73.1 ± 15 mm Hg, p < 0.062). Patients with AIDS and primary pulmonary hypertension present a higher degree of pulmonary hypertension than non-AIDS patients. Pulmonary hypertension associated with HIV seems to be related to a cytokine-related stimulation and proliferation of endothelium. High levels of cytokines present in AIDS patients can favor pulmonary hypertension, but the role of a host response to HIV—determined by one or more HLA subtypes—is suspected to enhance high cytokine production levels.

Accuracy of Immunodiagnostic Tests for Active Tuberculosis Using Single and Combined Results: A Multicenter TBNET-Study

Background The clinical application of IFN-γ release assays (IGRAs) has recently improved the diagnosis of latent tuberculosis infection. In a multicenter study of the Tuberculosis Network European Trialsgroup (TBNET) we aimed to ascertain in routine clinical practice the accuracy of a novel assay using selected peptides encoded in the mycobacterial genomic region of difference (RD) 1 for the diagnosis of active tuberculosis in comparison with tuberculin skin test (TST), QuantiFERON-TB GOLD In-Tube (Cellestis Ltd., Carnegie, Australia) and T-SPOT.TB (Oxfordimmunotec, Abingdon, UK). Principal Findings 425 individuals from 6 different European centres were prospectively enrolled. We found that sensitivity of the novel test, TST, QuantiFERON-TB GOLD In-Tube and T-SPOT.TB was respectively 73.1%, 85.3%, 78.1%, and 85.2%; specificity was respectively 70.6%, 48.0%, 61.9% and 44.3%; positive likelihood ratios were respectively 2.48, 1.64, 2.05, and 1.53; negative likelihood ratios were respectively 0.38, 0.31, 0.35, 0.33. Sensitivity of TST combined with the novel test, QuantiFERON-TB GOLD In-Tube and T-SPOT.TB increased up to 92.4%, 97.7% and 97.1%, respectively. The likelihood ratios of combined negative results of TST with, respectively, the novel test, QuantiFERON-TB GOLD In-Tube and T-SPOT.TB were 0.19, 0.07 and 0.10. Conclusions The assay based on RD1 selected peptides has similar accuracy for active tuberculosis compared with TST and commercial IGRAs. Then, independently of the spectrum of antigens used in the assays to elicit mycobacterial specific immune responses, the novel test, IGRAs, and the TST do not allow an accurate identification of active tuberculosis in clinical practice. However, the combined use of the novel assay or commercial IGRAs with TST may allow exclusion of tuberculosis.

In vitro activity of tigecycline in combination with various antimicrobials against multidrug resistant Acinetobacter baumannii

BackgroundInfections sustained by multidrug-resistant (MDR) and pan-resistant Acinetobacter baumannii have become a challenging problem in Intensive Care Units. Tigecycline provided new hope for the treatment of MDR A. baumannii infections, but isolates showing reduced susceptibility have emerged in many countries, further limiting the therapeutic options. Empirical combination therapy has become a common practice to treat patients infected with MDR A. baumannii, in spite of the limited microbiological and clinical evidence supporting its efficacy. Here, the in vitro interaction of tigecycline with seven commonly used anti-Acinetobacter drugs has been assessed.MethodsTwenty-two MDR A. baumannii isolates from Intensive Care Unit (ICU) patients and two reference strains for the European clonal lineages I and II (including 3, 15 and 6 isolates that were resistant, intermediate and susceptible to tigecycline, respectively) were tested. Antimicrobial agents were: tigecycline, levofloxacin, piperacillin-tazobactam, amikacin, imipenem, rifampicin, ampicillin-sulbactam, and colistin. MICs were determined by the broth microdilution method. Antibiotic interactions were determined by chequerboard and time-kill assays. Only antibiotic combinations showing synergism or antagonism in both chequerboard and time-kill assays were accepted as authentic synergistic or antagonistic interactions, respectively.ResultsConsidering all antimicrobials in combination with tigecycline, chequerboard analysis showed 5.9% synergy, 85.7% indifference, and 8.3% antagonism. Tigecycline showed synergism with levofloxacin (4 strains; 16.6%), amikacin (2 strains; 8.3%), imipenem (2 strains; 8.3%) and colistin (2 strains; 8.3%). Antagonism was observed for the tigecycline/piperacillin-tazobactam combination (8 strains; 33.3%). Synergism was detected only among tigecycline non-susceptible strains. Time-kill assays confirmed the synergistic interaction between tigecycline and levofloxacin, amikacin, imipenem and colistin for 5 of 7 selected isolates. No antagonism was confirmed by time-kill assays.ConclusionThis study demonstrates the in vitro synergistic activity of tigecycline in combination with colistin, levofloxacin, amikacin and imipenem against five tigecycline non-susceptible A. baumannii strains, opening the way to a more rationale clinical assessment of novel combination therapies to combat infections caused by MDR and pan-resistant A. baumannii.