Accurate assessment of risk factors for nosocomial acquisition of colonization by antibiotic-resistant bacteria (ARB) is often confounded by scarce data on antibiotic use. A 12-month, nested, multicenter cohort study was conducted. Target ARB were methicillin (meticillin)-resistant Staphylococcus aureus (MRSA), vancomycinresistant enterococci (VRE), and ciprofloxacin-resistant Pseudomonas aeruginosa (CR-PA). Nares and rectal swabs were obtained before and after starting antibiotics. Pulsed-field gel electrophoresis was done to define genetic relatedness of the strains. Primary outcomes were (i) the mean time, in days, for acquisition of target ARB colonization in patients previously not colonized; (ii) the rate of acquisition per 1,000 antibiotic-days according to different classes of antibiotics; (iii) the rate of infection caused by the same bacteria as those previously isolated in screening samples; and (iv) the risk factors for ARB acquisition. In total, 6,245 swabs from 864 inpatients were processed. The rate of acquisition was 3%, 2%, and 1% for MRSA, VRE, and CR-PA, respectively. The rate of acquisition of ARB per 1,000 antibiotic-days was 14 for carbapenems, 9 for glycopeptides, and 6 for broad-spectrum cephalosporins and quinolones. The highest rates of acquisition were observed for carbapenems in dialyzed and diabetic patients. Four risk factors were independently associated with acquisition of target ARB: use of carbapenems, age of >70 years, hospitalization for >16 days, and human immunodeficiency virus infection. During the 30-day follow-up, 4 among 42 patients newly colonized by ARB (9%) suffered from an infection due to the same bacteria as those isolated in a previous screening sample. Colonizing and infecting strains from single patients were genotypically identical. Identifying ARB colonization early during antibiotic therapy could target a high-risk hospitalized population that may benefit from intervention to decrease the risk of subsequent nosocomial infections.The control of nosocomial antibiotic-resistant infections is a public health priority worldwide. Meta-analyses have documented that bloodstream infection caused by methicillin (meticillin)-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), extended-spectrum ␤-lactamase-producing Enterobacteriaceae, and multidrug-resistant Acinetobacter baumannii are associated significantly with mortality (7,9,11,24). Numerous papers have demonstrated that prior antimicrobial drug exposure is a strong risk factor for colonization and infection due to a drug-resistant pathogen (2,25,27). However, the association between antibiotic therapy and the acquisition of antibiotic-resistant bacteria (ARB) is still unclear and is often confounded by scarce data on antibiotic usage. In our opinion, two major questions are still unsolved. When does an antibiotic select colonizing ARB in a hospitalized patient? Is there a direct correlation between hospital antibiotic usage, acquisition of ARB colonization, and subsequent bacterial infe...

BackgroundHIV-infected children have a lower seroconversion rate to hepatitis B virus (HBV) immunization than healthy children. Previous studies have produced conflicting results on CD4 cell counts as predictors of vaccine response. No study has evaluated the response rate to HBV vaccination in HIV-infected children receiving highly active antiretroviral therapy (HAART). Our aim was to vaccinate HIV-infected children living in a close community and to investigate the anamnestic response rate after vaccination with its predictors. MethodsEighty-four HIV-positive children aged 1-10 years who were negative for antibodies to the HBV core antigen (anti-HBc) completed immunization with three doses of 5 mg HBVAXPRO (Aventis, Milan, Italy). Quantitative testing for antibodies to the HBV surface antigen (anti-HBs) was performed: a seroprotective titre was defined as anti-HBs410 mUI/mL. ResultsAfter the vaccination, the anti-HBs seroconversion rate was 59.5%. It was higher in individuals in Centers for Disease Control and Prevention (CDC) immune category 1 than in those in CDC categories 2 and 3. Seroconversion was found in 70.8% of HAART-treated and 44.4% of treatmentnaïve children. In multivariable models, HAART use and absolute CD4 cell counts were independently associated with probability of seroconversion and with higher anti-HBs titres. ConclusionsWe found a higher seroconversion rate compared with previous studies in HIV-infected children. In children who are candidates to receive antiretroviral therapy, it may be advisable to defer HBV vaccination until after treatment initiation.

The known greater selective effect of long-acting agents could establish a pressure outcome, resulting in a specific local epidemiology during a relatively short time gap.

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