<i>Acinetobacter</i> Infections in Patients with Human Immunodeficiency Virus Infection: Microbiological and Clinical Epidemiology

<i>Background:</i> We evaluated the role of complications caused by <i>Acinetobacter </i>spp. in the setting of HIV infection. <i>Methods:</i> Clinical records of 1,923 consecutive HIV-infected patients hospitalized in a 9-year period were retrospectively reviewed, in order to identify all cases of <i>Acinetobacter</i> spp. complications, and to assess their occurrence and outcome according to several epidemiological, clinical and laboratory parameters. <i>Results:</i> Ten patients out of 1,923 (0.52%) developed <i>Acinetobacter</i> spp. infections: sepsis in four cases, urinary tract infection in three, pneumonia in two and septicaemic pneumonia in the remaining patient. All patients were severely immunocompromised, as shown by a mean CD4+ lymphocyte count of 122 cells/µl and a frequent prior diagnosis of AIDS. As opposed to other infections, septicaemia was associated with a significantly lower CD4+ cell count and a more frequent occurrence of neutropenia. Hospital-acquired <i>Acinetobacter</i> spp. infections were significantly more frequent than community-acquired ones, and prevailingly involved patients with AIDS and leucopenia, being responsible for frequent blood dissemination. Antimicrobial, corticosteroid and cotrimoxazole treatment were frequently carried out during the month preceding disease onset. Antibiotic susceptibility studies proved the complete resistance of microbial isolates to ampicillin and cephalothin and poor sensitivity to second-generation cephalosporins and gentamicin, while greater susceptibility was shown to ceftazidime, netilmicin and amikacin, followed by piperacillin, cotrimoxazole and quinolones. Appropriate antimicrobial treatment led to clinical and microbiological cure in all cases, with no related mortality or relapses. <i>Conclusions:</i> Since only 23 episodes of HIV-associated <i>Acinetobacter</i> spp. infections have been described to date in 11 different reports (nine cases of bacteraemia, eight of pneumonia, two of urinary tract involvement, one of intravenous access device infection, one of meningitis and two with unspecified localization), our series represents the largest one dealing with HIV-associated <i>Acinetobacter</i> spp. infections. According to our experience, <i>Acinetobacter</i> spp. may be responsible for appreciable morbidity among patients with HIV infection, above all when a low CD4+ cell count, neutropenia and hospitalization are present. Clinicians and microbiologists who work in the field of HIV infection should consider the potential pathogenic role of <i>Acinetobacter</i> spp. organisms even in the absence of some presumed risk factors, because of the relationship between these infections and immunodeficiency, hospitalization, other infectious complications, prior antibiotic and steroid treatment and extended antimicrobial resistance patterns.