The correct identification of Candida species is of great importance, as it presents prognostic and therapeutical significance, allowing an early and appropriate antifungical therapy. The purpose of this study was to identify isolates of Candida spp. from oral mucosa of 38 patients with oral candidosis evaluated in 2004 by phenotypic methods and PCR, discriminating C. albicans from the other Candida species. The tests used for phenotypic analysis were germ-tube and chlamydoconidia production, culture in CHROMAgar™ Candida, carbohydrate assimilation test, growth at 45ºC and culture in Tween 80 agar. Genotypic confirmation was performed by PCR. Phenotypic tests showed that 63.2% strains formed germ-tubes, 73.7% produced chlamydoconidia, and 63.2% showed green colonies in chromogenic medium, presumptively indicating C. albicans or C. dubliniensis. The carbohydrate assimilation test confirmed these results. A total of 21% strains were identified as C. krusei and 13.2% were indicative of C. tropicalis. Of these later strains, three produced chlamydoconidia. The association of other phenotypic tests with culture in Tween 80 agar identified 95.8% of strains as C. albicans and 4.2% as C. dubliniensis. All 24 strains indicative of C. albicans and C. dubliniensis were confirmed by PCR as C. albicans.

Bacterial persistence is a feature that allows susceptible bacteria to survive extreme concentrations of antibiotics and it has been verified in a number of species, such as Escherichia coli, Pseudomonas aeruginosa, Staphylococcus spp., Mycobacterium spp. However, even though Acinetobacter baumannii is an important nosocomial pathogen, data regarding its persistence phenotype are still lacking. Therefore, the aim of this study was to evaluate the persistence phenotype in A. baumannii strains, as well as its variation among strains after treatment with polymyxin B and tobramycin. Stationary cultures of 37 polymyxin B-susceptible clinical strains of A. baumannii were analyzed for surviving cells after exposure to 15 µg/mL of polymyxin B for 6 h, by serial dilutions and colony counting. Among these, the 30 tobramycin-susceptible isolates also underwent tobramycin treatment at a concentration of 160 µg/mL and persister cells occurrence was evaluated equally. A high heterogeneity of persister cells formation patterns among isolates was observed. Polymyxin B-treated cultures presented persister cells corresponding from 0.0007% to 10.1% of the initial population and two isolates failed to produce detectable persister cells under this condition. A high variability could also be observed when cells were treated with tobramycin: the persister fraction corresponded to 0.0003%–11.84% of the pre-treatment population. Moreover, no correlation was found between persister subpopulations comparing both antibiotics among isolates, indicating that different mechanisms underlie the internal control of this phenotype. This is the first report of persister cells occurrence in A. baumannii. Our data suggest that distinct factors regulate the tolerance for unrelated antibiotics in this species, contrasting the multi-drug tolerance observed in other species (eg. dormancy-mediated tolerance). Supporting this observation, polymyxin B – an antibiotic that is believed to act on non-dividing cells as well – failed to eradicate persister cells in the majority of the isolates, possibly reflecting a disconnection between persistence and dormancy.

Introduction: Acinetobacter baumannii is a major pathogen causing infections in intensive care units (ICUs). In this study, we aimed to evaluate the presence of A. baumannii in an ICU environment and gloves from ICU workers and to characterize the antimicrobial resistance of the isolates in comparison with those isolated from ICU patients at the same hospital. Methods: ICU samples were collected from March to November 2010. Isolates biochemically characterized as Acinetobacter calcoaceticusAcinetobacter baumannii complex were evaluated by PCR targeting the 16S rDNA and bla OXA-51 genes. Antimicrobial susceptibility was determined using the disk diffusion method, and carbapenem-resistant isolates were also evaluated for the minimum inhibitory concentration of imipenem using broth microdilution. The presence of the bla OXA-23 gene was evaluated in isolates with reduced susceptibility to carbapenems. Results: A. baumannii was detected in 9.5% (84) of the 886 samples collected from the ICU environment, including from furniture, medical devices, and gloves, with bed rails being the most contaminated location (23.8%; 20/84). Multidrug-resistant (MDR) A. baumannii was found in 98.8% (83/84) of non-clinical and 97.8% (45/46) of clinical isolates. Reduced susceptibility to carbapenems was detected in 83.3% (70/84) of non-clinical and 80.4% (37/46) of clinical isolates. All isolates resistant to carbapenems harbored bla . Conclusions: We found a strong similarity between the antimicrobial susceptibility profiles of non-clinical and clinical A. baumannii isolates. Such data highlight the ICU environment as a potential origin for the persistence of MDR A. baumannii, and hence the ICU may be a source of hospital-acquired infections caused by this microorganism.

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