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The review summarizes the results in the main parasitological topics of our Lab: amoebic infections due to Entamoeba histolytica/Entamoeba dispar complex and to Acanthamoeba spp. respectively, and human infections caused by microsporidia. Different rapid and advanced techniques have been included in the standardized diagnostic protocols for each topic, and a critical comparison among them was made, in order to define the gold standard diagnostic method: a) E. histolytica/E. dispar: in vitro culture, zymodeme typization, biomolecular identification (PCR), immunoenzymatic assay (ELISA) for direct detection in stools of specific surface antigenic lectins; b) Acanthamoeba spp.: in vitro culture, light and ultrastructural characterization, species identification by immunofluorescence method with monoclonal antibodies, in vitro pharmacological studies; c) Microsporidia: ultrastructural (TEM), biomolecular (PCR), biochemical and immunological (SDS-PAGE, Immunoblotting) studies for species identification, use of advanced ultrastructural techniques ("freeze-etching", "deep-etching") in order to deepen the spore wall structure, to study the cytoskeletal function of actin and to define the mode of infection, in vitro pharmacological assays on some inhibitors of chitin-synthases.

Patients and methods: This is a retrospective study performed on HIV-positive patients discharged from our Institution from January 1993 through December 1998 with a diagnosis of bacterial pneumonia. Cases of TB or atypical micobacterial infection were excluded from this analysis. Causative organisms were identified, when possible, by taking into account positive cultures from diverse sources (blood, sputum, pleural fluid and others). Results: In the 6-yr period we considered, 120 patients were identified. Among them, we were able to obtain clinical and imaging data on 98 cases. Focal infiltrates on chest X-ray studies were present in 87.7% of cases, 24.5% had a pleural effusion, 9.2% nodular lesions, 4.1% cavitary images and in 2 patients only hilar lymphadenopaties were noted. Causative agents resulted to be S. aureus (14 cases); P. aeruginosa (11); S. pneumoniae (6); R. equi (4); Enterobacter spp. and K. pneumoniae (3 cases each); E. coli, Peptostreptococcus spp and Enterococcus spp. (1 case each). No causative organism was isolated in 54 patients (55.1%) and the diagnosis was based on clinical and therapeutical grounds. Around half of cases (46.9%) responded well to therapy, while 11 (11.2%) died because of the lung infection. In 3 cases other opportunistic infections were the cause of death and 22 cases of relapse were recorded as well. Five patients resulted lost to follow-up. Conclusions: This retrospective study demonstrated a high prevalence of S. aureus lung infections along with the presence of otherwise rare causative organisms such as R. equi. Radiologic appearance of lung lesions did not differ substantially from the one of HIV negative patients. A relatively good response to antibiotic therapy was also noted.

Diplopia is one of the neuro-ophthalmic manifestations that can be observed during HIV-infection. The etiologic agents of diplopia in HIV-positive patients can be identified with HIV itself or opportunistic pathogens or other related conditions. We reviewed the clinical records of 13 HIV-positive patients with mono or bilateral diplopia, focusing on etiologic agents, clinical evaluation and prognosis. This review encompassed all cases observed from January 1992 to June 1995 at the Infectious Diseases Department, Policlinico S. Matteo, University of Pavia. All patients underwent a complete ophthalmologic examination, including visual acuity, anterior segment evaluation with biomicroscopy, dilated indirect ophthalmoscopy and ocular motility evaluation (with Cover test and Hess-Lancaster test). If requested by clinical findings, radiologic (TC and/or MRI) and cerebrospinal fluid examination were performed in some patients. The most common causes of diplopia-CNS lesions or ocular diseases-, resulted in agreement with those reported in the literature (T. gondii, C. neoformans, non-Hodgkin lymphomas, HIV, JC virus, CMV). We were able to confirm, according to our experience, that diplopia occurrence is often a negative prognostic factor, since it is commonly associated with CNS conditions. In most cases diplopia can herald a near demise (8 patients on 13 died with 60 days from diplopia onset). In those cases where a treatment was available (2 cases of cryptococcosis, 1 case of neurotoxoplasmosis and 1 case of CMV retinitis) a complete resolution of neuro-ophthalmic symptoms was achieved.

The number of subjects with HIV infection or full-blown Acquired Immunodeficiency Syndrome (AIDS) is increasing throughout the world and the range of related opportunistic conditions (infections, neoplasms or degenerative disorders) is also increasing. Consequently, AIDS patients are likely to be prescribed a great number of different drugs. HIV infection is a progressive phenomenon, characterized by inevitable and often irreversible changes which may influence drug disposition, enhancing the risk of toxic adverse effects and drug interactions. One of the stages for the development of new agents and the establishment of an effective therapy is to conduct pharmacokinetic studies. Even though such studies are difficult to realize in AIDS subjects, the knowledge of altered pharmacokinetics of a drug in disease states offers an unique approach for improving and perhaps optimizing the therapeutic management. The purpose of this article is to review our current understanding of how HIV infection influences the various processes of drug disposition (i.e. absorption, distribution, metabolism and excretion).

Rhodococcus equi is a facultative intracellular, obligate aerobe, partially acid fast, gram-positive pathogen that causes cavitary pneumonia in animals and immunocompromised humans. We describe 8 cases of R. equi pneumonia in patients with advanced HIV infection (CD4 counts less than 100/mm3), 7 males and 1 female (mean age 30.8 years), observed between 1991 and 1994. A history of exposure to farm animals was found in 4 patients. The most common presenting symptoms were fever, malaise, dyspnea, cough and hemoptysis, chest pain and weight loss. Chest x-rays showed tipical focal area of consolidation throughout the lung (3 upper, 3 lower and 2 middle fields) associated with cavitation in 4 cases. The definitive diagnosis in our hands was delayed only in the first case in which conflicting data resulted from blood culture (Bacillus sp. isolation) and sputum examen (acid-fast bacterium in the Ziehl-Neelsen stain). Final microbiological diagnosis depended on blood cultures (n=5), bronchoalveolar lavage (n=1), sputum (n=1), lung biopsy (n=1). All the patients were treated with prolonged courses of antibiotic therapy (259 days, range 120-340 in 6 dead patients; more than one year and two months respectively in two patients alive). According to microbial susceptibility TMP/SMX, vancomycin, imipenem, rifampin, aminoglycosides, macrolides and quinolons were more frequently used. Resistant R. equi mutants were selected during therapy with TMP/SMX (n=2), rifampin (n=1) and erythromycin (n=1). Five patient underwent pulmonary lobectomy after exclusion of metastatic bacterial lesions. Only 2 patients are alive, one after 365 days of antibiotic therapy and upper lung lobectomy, one after 60 days of antibiotic therapy. Optimal antimicrobial therapy and the role of surgery remain, in our experience, uncertain.

Infection by Human Immunodeficiency Virus (HIV) is the recognized cause of the Acquired Immunodeficiency Syndrome (AIDS) and related syndromes, all characterized by a devastating and progressive impairment of immunity. What ensues is the onset of opportunistic infections, neoplasms, both central and peripheral nervous system alterations and other conditions as well. Current therapeutic options, either with antiretroviral and anti-infective drugs, are only credited to prolong survival while not assuring definite cure. A significant improvement in the clinical management of these patients could be anticipated only after a better understanding of HIV life-cycle and its pathogenetic mechanisms.

Health-care workers are exposed to risk of HIV infection. Blood and body fluids containing blood are the most important sources of HIV and the major risk for health-care workers occurs by incidental parenteral contact with these fluids. Therefore, the risk can be minimized by taking care to prevent injuries and by using protective barriers for mucous membranes and skin. However, the number of cases reported in literature with occupational HIV infection is extremely low.

Leptospirosis is still endemic in the Po valley. It has an extremely protean clinical picture. In a series of 79 cases diagnosed at Pavia in the period 1970-79 hepatonephritic forms were the most common (29.1%), followed by febrile or pseudo-influenza forms (25.3%), hepatitis (20.2%), nephritis (17.8%), and meningitis (7.6%). Febrile hepatonephritis was always accompanied by the most severe pictures. Timely antibiotic management with penicillin or ampicillin, and above all the early use of peritoneal dialysis (carried in 10 subjects) enable a final cure to be obtained even in these cases. The only death in that series did not appear to be ascribable to the disease itself.