Are E-test and Vitek2 good choices for tigecycline susceptibility testing when comparing broth microdilution for MDR and XDR Acinetobacter baumannii?

This study reports the results of antimicrobial susceptibility testing of 10 MDR and 74 XDR Acinetobacter bauman- nii clinical isolates from our hospital routine. We used three different methods: two automated systems (Sensititre and VITEK 2) and one standardized manual method (E-test). Since many published papers refer to in vitro tests performed by E-test, the aim of this study was to test if this method is reliable for testing tigecycline. The results obtained show that E-test significantly overestimates the MIC of the broth microdilution (reference test), thus ob- taining a significant number of major errors (resistant instead of sensitive). VITEK 2 also shows the same problem, but it is less critical. We therefore conclude that these methods do not seem to be very reliable in the performance of susceptibility testing of MDR and XDR Acinetobacter baumannii against tigecycline.

Comparison of different methods for determining beta-lactam susceptibility in Pseudomonas aeruginosa.

This study compared the results of antimicrobial susceptibility testing of 77 clinical strains isolated for Pseudomonas aeruginosa to five beta-lactam agents: aztreonam, ceftazidime, imipenem, meropenem and piperacillin+tazobactam. Four different methods were employed: two automated systems (VITEK 2 and Sensititre) and two standardized manual methods (Kirby-Bauer and E-test). The concordances for the susceptibility categories were better for Kirby-Bauer (medium value =89.6%), followed by Sensititre (medium value =87.0%) and VITEK 2 (medium value =82.8%). The disk diffusion method did not present very major errors in comparison to the two automated systems.

[Study on in vitro susceptibility of Candida spp. isolated from blood culture]. / Studio sulla incidenza e sulla sensibilità in vitro di ceppi di Candida spp. isolati da sangue.

In recent years the incidence of bloodstream infections due to Candida species has progressively increased, partly due to the more critical conditions of hospitalized patients. There has been a significant increase in immune-compromised, diabetic and/or elderly patients, also with venous access, with a subsequent increase in Candida species isolated from bloodstream infections. In 2009-2010 in the hospitals of Mestre and Venice we isolated 123 Candida species from bloodstream infections: 59 Candida albicans, 28 Candida parapsilosis, 12 Candida glabrata, 9 Candida tropicalis, and 4 Geotrichum capitatum, while the 11 others belong to 8 different species. We calculated MIC for the following antifungal agents: fluconazole, itraconazole, voriconazole, 5-flucytosine, amphotericin B and caspofungin.

[Study on in-vitro susceptibility of ESBL-positive Escherichia coli isolated from urine specimens]. / Studio sulla sensibilità in vitro di ceppi di Escherichia coli ESBL-produttori isolati da campioni urinari.

Treatment of infections by beta-lactamase-producing microorganisms is very difficult. Our aim was to determine the in vitro susceptibility of 430 ESBL-positive Escherichia coli strains isolated from urinary tract infections. All the microorganisms were isolated in the Microbiology Unit at the Ospedale dell'Angelo in Mestre (Venice) between May 2008 and September 2009 and were confirmed by the double-disk test. All microorganisms were sensitive to imipenem and meropenem, 98.4% to tigecycline, 95.1% to amikacin, 89.3% to nitrofurantoin, 67.5% to gentamycin and 63.2% to piperacillin/tazobactam. Only 22.6% were sensitive to cotrimoxazole, while fluoroquinolone (norfloxacin and levofloxacin) activity was found to be very low (6%).

The Sp1 transcription factor does not directly interact with the HIV-1 Tat protein.

The role of Sp1 in regulating the trans-activating activity of the human immunodeficiency virus type 1 (HIV-1) Tat protein has not yet been clearly defined. In fact, studies on the physical and functional interaction between Sp1 and Tat have yielded contradictory results. Here we investigated whether a physical interaction between Sp1 and Tat indeed occurs, exploiting both biochemical and genetic techniques that allow detection of direct protein-protein interactions. Studies performed with the yeast two-hybrid system indicate that Sp1 does not directly interact with the HIV-1 Tat protein. Control experiments demonstrated that both proteins are functionally expressed in the yeast cells. In vitro binding assays further confirmed that Sp1 does not physically bind Tat. These data suggest that in vivo Tat and Sp1 most likely take part of a multicomponent complex and thus encourage the search of the molecule(s) which mediate Tat-Sp1 interaction.