Resistance surveillance in Italy: four-year results from the MYSTIC program.

The MYSTIC program is an international, multicenter surveillance study that compares the activity of meropenem, in centers that are prescribers, with that of imipenem, ceftazidime, piperacillin/tazobactam, ciprofloxacin and gentamicin. These Italian data are from 3 centers (neutropenia, cystic fibrosis and intensive care units). A total of 2,072 (238 Gram-positive and 1,834 Gram-negative) aerobic microorganisms were collected during the study. Pseudomonas aeruginosa (33.4%) was the most isolated species followed by Escherichia coli (14.4%). All except one Enterobacteriaceae strain isolated were fully susceptible to meropenem. Moreover, the activity of meropenem against Enterobacteriaceae was about eight-fold greater than that of imipenem and four- to eight-fold more active than that of ceftazidime. Meropenem was highly active against non-fermentative Gram-negative microorganisms, exceeding the activity of most of the other antimicrobial agents tested. Moreover, meropenem showed increasing activity during the 4 years of study (starting from 86.2% in 1997 to 94.0% in 2000). In conclusion, our results indicate that meropenem has excellent potency and spectrum of activity despite being prescribed for the treatment of seriously ill patients, and appears to be a reliable option for the initial empirical treatment of serious nosocomial infections.

[Pulmonary aspergillosis in acute leukemia. Description of a case and review of the literature]. / Aspergillosi polmonare in corso di leucemia acuta. Descrizione di un caso e revisione della letteratura.

A case of pulmonary multiple mycosis, recognized by cultural and radiological investigation, during chemotherapy for poorly outcoming acute leukemia is reported. The factors enhancing disseminated aspergillosis in haematologic malignancies as well as the need of early diagnosis and effective therapy in fungal infections complicating leukemias are also discussed in the light of the last 25 years literature.

[Behavior of Helicobacter pylori in 3d and 4th age-bracket patients]. / Comportamento di Helicobacter pylori in pazienti della III e IV età.

AIMS AND BACKGROUND: Helicobacter pylori is known to be the pathogenic agent of atrophic gastritis and above all ulcer disease. It is also thought to play a role, together with other factors, in the development of stomach cancer and is currently the focus of numerous studies. In industrialised countries, infection is relatively commonplace in children, whereas its incidence rises more steeply in patients aged over 35, reaching a mean prevalence of 50% in over 60 year olds. METHODS: During 1997 the authors carried out an epidemiological study to assay levels of anti-Helicobacter pylori (IgG anti-Hp) in a sample of 91 aged patients hospitalised in the S. Margherita Geriatric Hospital in Pavia. The patients had been admitted to hospital for various pathologies and the study also took into account gastric pathologies which usually, particularly in neoplastic forms, prefers the third and fourth ages. The assay for antibodies was performed using mouse monoclonal antibody, specific for Helicobacter pylori, absorbed on a polyester pad. A total of 5 ml of blood were collected from each patient. The blood samples were all centrifuged and the serum frozen at -20 degrees C until the tests were performed. RESULTS: In this study, 46 of the 91 patients tested were positive for anti-Helicobacter pylori antibodies, 35 were negative and 10 borderline. CONCLUSIONS: The high level of positive results found in these patients is in line with the findings reported by other authors.

Extended-spectrum beta-lactamases from Klebsiella pneumoniae strains isolated at an Italian hospital.

Eighteen strains of Klebsiella pneumoniae recently isolated from hospitalized patients were resistant or moderately resistant to oxyimino-cephalosporins (ceftazidime and/or cefotaxime), aztreonam, cefoxitin and all but one were susceptible to imipenem. Analysis of enzymes produced by these clinical isolates revealed a wide pattern of extended-spectrum beta-lactamases. All isolates produced one or more beta-lactamases that were characterized preliminarily by their isoelectric point. Strains isolated early were from patients in the Intensive Care Unit and produced an ES beta-lactamase with an apparent pI of 7.6, whereas the later isolates were from surgical and medical wards of the same hospital and produced ES beta-lactamases with apparent pI of 8.2 and 8.4, respectively. This suggests the emergence of SHV-5 and MIR-1 beta-lactamases in our hospital. Agarose gel electrophoresis of plasmid DNA revealed the presence of a similar plasmid of approximate size 60 Kb in all isolates.

[Prospective use of immunofluorescence polarization in the study of enzymes modifying aminoglycosides]. / Prospettive di utilizzazione della immunofluorescenza polarizzata per lo studio degli enzimi modificanti gli aminoglicosidi.

A number of assays have been described for aminoglycoside-modifying enzymes; the aim of our investigation was to check the validity of polarized immunofluorescence assay for aminoglycoside enzymes. We have studied three enzymes encoded by R-factors from clinical isolates of Enterobacteriaceae conferring various patterns of aminoglycoside-resistance. The assay resulted valid: this is a simple, rapid and sensitive method.

The role of tissue colonization and bacterial resistance in recurrent tonsillitis.

Unsuccessful medical therapy for treatment of acute tonsillitis frequently results in onset of recurrent or chronic forms rendering surgical treatment necessary. We have studied some of the factors involved in the evolution of these chronic or recurrent forms and, in particular, the distribution of different bacterial strains in tonsillar tissue, their response to treatment with antibiotics and mechanisms of bacterial resistance. The distribution of bacterial flora (saprophytic and pathogenic) present on the surface of the tonsils, in the crypts and in the tonsillar tissue was studied in a control population of 30 children (20 boys and 10 girls) aged between 2-13 years, all affected with chronic tonsillitis and submitted to tonsillectomy. The same study was performed in a group of 80 sex and aged matched children, also presenting with chronic or recurrent tonsillitis and treated with amoxicillin or amoxicillin-clavulanic acid or cefaclor or clarithromycin 72 h before surgery. The 80 subjects were randomly divided into four groups so that each antibiotic was tested on 20 subjects. The distribution of the bacterial population on the surface of tonsillar tissue, in the crypts and in the deeper tonsillar tissue is of particular interest concerning the affinity of bacteria to the different tissue areas. In particular the interaction between crypt and tonsillar core, which could be a factor involved in the process of worsening of bacterial infection in the tonsils, is evidenced. The four antibodies tested showed different abilities to eradicate infection: Haemophilus influenzae was found to be the most resistant germ to antibiotic therapy and was thus the most frequent cause of recurrent infections. The characteristics and the mechanisms of adherence and resistance to beta lactam antibiotics were also analysed.

Comparative activity of piperacillin/tazobactam against clinical isolates of extended-spectrum beta-lactamase-producing Enterobacteriaceae.

beta-Lactam resistance on the part of the Enterobacteriaceae causes serious therapeutic problems in our institutions due to their production of extended-spectrum beta-lactamases (ESbetaLs). We studied the in vitro activity of beta-lactam/beta-lactamase inhibitor combinations and third-generation cephalosporins and monobactams against 71 clinically relevant Enterobacteriaceae which produced TEM- and SHV-derivative ESbetaLs. Of the single drugs and combinations tested, piperacillin/tazobactam proved to be the most effective. Piperacillin/tazobactam was highly active against Proteus mirabilis, with minimum inhibitory concentrations (MICs) ranging from 0.125 to 16 microg/ml; Escherichia coli (MICs from 2 to 16 microg/ml) and Serratia marcescens (MICs from 4 to 8 microg/ml), while its activity against Klebsiella pneumoniae ESbetaL producers turned out to be closely related to the type and the amount of enzyme produced, the MIC ranging from 1 to 128 microg/ml. The antibacterial activity of piperacillin/tazobactam was stronger than that of ticarcillin/clavulanate, ceftriaxone, cefotaxime, ceftazidime and aztreonam, and the combination shared favorable in vitro activity properties against the ESbetaL producers with imipenem which, however, should be kept as reserve product.