In vitro antimicrobial activity of piperacillin/tazobactam in comparison with other broad-spectrum beta-lactams.

Combining tazobactam, a beta-lactamase inhibitor, with the ureidopenicillin, piperacillin, successfully restores the activity of piperacillin against beta-lactamase producing bacteria. Thus, piperacillin/tazobactam is highly active against most clinically important species of Gram-negative and Gram-positive bacteria, including anaerobes. We evaluated the in vitro activity of piperacillin/tazobactam against clinical isolates from a tertiary university hospital located in Sao Paulo, Brazil. Its activity was compared to that of ticarcillin/clavulanic acid, ampicillin/sulbactam, ceftazidime, ceftriaxone, cefotaxime, cefoxitin, aztreonam, and imipenem against 820 isolates (608 Gram-negative and 212 Gram-positive) collected from hospitalized patients in 1999. The most frequent species tested were Pseudomonas aeruginosa (168/20%), Escherichia coli (139/17%), Acinetobacter spp. (131/16%), and Staphylococcus aureus (76/9%). Of the isolates studied, 30% were from the bloodstream, 16% from the lower respiratory tract, and 11% from surgical wounds or soft tissue. The isolates were susceptibility tested by the broth microdilution method according to NCCLS procedures. The isolates tested were highly resistant to most antimicrobial agents evaluated. Imipenem resistance was not verified among Enterobacteriaceae, and piperacillin/tazobactam was the second most active beta-lactams against this group of bacteria (80.0% susceptibility). Extended-spectrum beta-lactamase production was very high among E. coli (approximately 20%) and Klebsiella pneumoniae (approximately 40%). Imipenem was uniformly active against these species (100% susceptibility) and piperacillin/tazobactam was the second most active compound inhibiting 84.4% of isolates. Pseudomonas aeruginosa was highly resistant to all beta-lactams evaluated and piperacillin/tazobactam was the most active compound against this species. Our results demonstrate an extremely high level of antimicrobial resistance in the hospital evaluated, especially among non-enteric Gram-negative bacilli. Due to this high level of resistance, piperacillin/tazobactam represents an important contribution to the treatment of nosocomial infections.

Cytomegalovirus antigenemia in acquired immunodeficiency syndrome patients with untreated cytomegalovirus retinitis.

PURPOSE: To determine the frequency of cytomegalovirus (CMV) viremia in patients with acquired immunodeficiency syndrome (AIDS) and untreated CMV retinitis using conventional cell culture isolation and the sensitive CMV antigenemia assay. METHODS: We examined 24 AIDS patients with ophthalmologic diagnosis of untreated CMV retinitis and 24 AIDS patients without present or past retinitis (control patients) from three medical centers between September 1992 and March 1994. Cytomegalovirus antigenemia was detected by an indirect peroxidase staining in 300,000 cytocentrifuged neutrophils, using a mixture of murine monoclonal antibodies directed against the pp65 lower matrix protein of CMV. RESULTS: Positive antigenemia was demonstrated in eight (33.3%) of the 24 retinitis patients and in none of the 24 control patients (P < .001). Only two of the eight antigenemia-positive patients had a concurrent positive CMV isolation from blood leukocytes by conventional cell culture assay. CONCLUSIONS: These results emphasize the risk of extraocular disease in AIDS patients with CMV retinitis because the virus is often present in peripheral blood leukocytes. The CMV antigenemia assay may be a simple and rapid means of identifying those patients with unilateral retinitis at highest risk of developing CMV retinitis of the fellow eye or of visceral CMV disease if intravitreal injections or implants are used as sole treatment for CMV retinitis.