A scalable method for O-antigen purification applied to various Salmonella serovars.

The surface lipopolysaccharide of gram-negative bacteria is both a virulence factor and a B cell antigen. Antibodies against O-antigen of lipopolysaccharide may confer protection against infection, and O-antigen conjugates have been designed against multiple pathogens. Here, we describe a simplified methodology for extraction and purification of the O-antigen core portion of Salmonella lipopolysaccharide, suitable for large-scale production. Lipopolysaccharide extraction and delipidation are performed by acetic acid hydrolysis of whole bacterial culture and can take place directly in a bioreactor, without previous isolation and inactivation of bacteria. Further O-antigen core purification consists of rapid filtration and precipitation steps, without using enzymes or hazardous chemicals. The process was successfully applied to various Salmonella enterica serovars (Paratyphi A, Typhimurium, and Enteritidis), obtaining good yields of high-quality material, suitable for conjugate vaccine preparations.

Serological response to hepatitis B virus vaccine in HIV-infected children in Tanzania.

BACKGROUND: HIV-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. METHODS: Eighty-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 microg HBVAXPRO (Aventis, Milan, Italy). Quantitative testing for antibodies to the HBV surface antigen (anti-HBs) was performed: a seroprotective titre was defined as anti-HBs>10 mUI/mL. RESULTS: After 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 treatment-naïve children. In multivariable models, HAART use and absolute CD4 cell counts were independently associated with probability of seroconversion and with higher anti-HBs titres. CONCLUSIONS: We 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.

Determination of free polysaccharide in Vi glycoconjugate vaccine against typhoid fever.

Glycoconjugate vaccines based on the Vi capsular polysaccharide directed against Salmonella enterica serovar Typhi are licensed or in development against typhoid fever, an important cause of morbidity and mortality in developing countries. Quantification of free polysaccharide in conjugate vaccines is an important quality control for release, to monitor vaccine stability and to ensure appropriate immune response. However, we found that existing separation methods based on size are not appropriate as free Vi non-specifically binds to unconjugated and conjugated protein. We developed a method based on free Vi separation by Capto Adhere resin and quantification by HPAEC-PAD. The method has been tested for conjugates of Vi derived from Citrobacter freundii with different carrier proteins such as CRM197, Tetanus Toxoid and Diphtheria Toxoid.

[Bacterial meningitis in adults: a retrospective multicentric study in Tuscany (Italy)]. / Le meningiti batteriche dell'adulto: studio retrospettivo multicentrico della Toscana.

The Infectious Diseases Unit of Lucca Hospital conducted a multicentric retrospective study to evaluate the epidemiological and clinical features of adult patients affected by bacterial meningitis attending all the Infectious Diseases Units of Tuscany (Italy) from July 1999 to June 2004. A specific questionnaire was sent to all the units to collect information about each case of bacterial meningitis occurring in patients older than sixteen. Patients with meningitis by Mycobacterium tuberculosis were excluded from the analysis. Nine out of 12 Infectious Diseases Units of Tuscany took part in the study and 197 cases were identified. Most cases of meningitis occurred during 2002 with a slight reduction in cases in subsequent years. Streptococcus pneumoniae and Neisseria meningitidis were the most frequently isolated pathogens with an increase in diagnosis from 1999 to 2004; in 23.8% of patients no pathogens were isolated, with a reduction in meningitis from unknown aetiology from 1999 to 2004. Most patients were treated with a combination of two antibiotics, and corticosteroid drugs were added to the therapy; in the group of patients treated with corticosteroid drugs invalidating complications occurred in 23% of cases and 5% of patients died. In all, 27 out of 197 subjects (13.7%) developed invalidating complications and 20 out of 197 patients (10.2%) died.

[Retrospective study of tuberculosis in the Province of Siena]. / Studio retrospettivo sui ricoveri per tubercolosi nella Provincia di Siena.

We report here the results of a retrospective study carried out on 200 tuberculosis cases admitted to the Hospital of Siena during the period 1994-2003. For each case, epidemiological, clinical and microbiological data were collected in order to analyze the trend of tuberculosis over the years and to compare our experience with similar studies. Indigenous patients were significantly older than immigrants (60.1 vs 34.2 yrs) more frequently affected by underlying chronic diseases. Overcrowding and HIV infection were predisposing conditions in 30 subjects (15% of cases) recently arrived from high endemicity countries. Pulmonary tuberculosis (TB) was diagnosed in 71% of cases, irrespective of origin. The death rate was 5%. Microbiological investigation was positive in 74.4% of examined subjects; 9.8% of isolates were resistant to one or more antituberculous drugs. The number of cases admitted to the Hospital seems to have slowly decreased in the last few years; factors that may influence this trend are discussed. Our results confirm a distinct epidemiological pattern of the disease between indigenous patients and immigrants, which is typical of low-endemicity countries. The delay in the diagnosis and management of the disease observed in this case-series report underlines the need to improve information on TB and skill in treatment, and to maintain specialized centres.