Browsing by Author "Carvalheira, Ana Isabel Teixeira"
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- Acinetobacter and public health : risks posed by strains isolated from foodsPublication . Carvalheira, Ana Isabel Teixeira; Teixeira, Paula Cristina Maia; Silva, Joana Gabriela Laranjeira daAcinetobacter spp. has emerged as a pathogen of a major public health concern due to their increased resistance to antibiotics and their association with a wide range of nosocomial infections. The aim of this work was to gain insight into the food-related ecology and epidemiology of Acinetobacter spp. and to compare food and clinical strains regarding biofilm production, resistance to desiccation and disinfectant susceptibility. As there is no standard procedure to recover Acinetobacter spp. from food, two selective enrichment media were evaluated for the recovery of low levels of these organisms. Enrichment in Dijkshoorn enrichment medium followed by plating on CHROMagarTM Acinetobacter medium was shown to be a reliable method. Using this procedure, Acinetobacter spp. were isolated from 77.9% of fruit (35/50) and vegetables (39/45) samples and from all the meat analysed (50). A high genetic diversity established by pulsed-field gel electrophoresis (PFGE) was observed among the isolates and based on the analysis of the partial sequence of rpoB,181 strains ecovered from fruits and vegetables and 156 strains recovered from meat samples were identified as members of eighteen and thirteen distinct species, respectively. Acinetobacter calcoaceticus and Acinetobacter johnsonii were the most common species (both with the frequency of 26.5%) recovered from fruit and vegetables, while Acinetobacter guillouiae (34.9%), A. johnsonii (15%) and A. bereziniae (12%) were the most common species recovered from meats. Acinetobacter spp. belonging to the A. baumannii group (11.0% from fuit and vegetables, 18.7% from meats), which is most frequently associated with nosocomial infections worldwide, were also recovered. Most of these strains were resistant to some of the antimicrobials recommended to treat Acinetobacter infections such as piperacillin¬tazobactam, ceftadidime, ciprofloxacin, as well as to colistin and polymyxin B, the last-resort drugs to treat infections caused by multidrug-resistant Acinetobacter. Overall, 29.8% of the isolates from fruit and lettuces, and 51.2% of the isolates from meats were classified as multidrug¬resistant (MDR), and 4.4% and 9.6% as extensively drug-resistant (XDR), respectively. The taxonomic status of six strains of Acinetobacter obtained from meats, was investigated, using a polyphasic analysis, since their partial rpoB sequence similarities to other Acinetobacter species with validly published names were lower than 95%. The species status of two groups was confirmed by comparative multilocus sequence analysis, including also the gyrB, recA and 16S rRNA genes, low (below 95%) whole-genome sequence (WGS) average nucleotide identity (ANI) values and low (below 70%) digital DNA¬DNA hybridization (dDDH) similarities between the WGS of the proposed type strains of each novel species and the representatives of the known Acinetobacter species. Phylogenomic treeing from core genome analysis supported these results as well as, the coherence of each new species¬lineage was supported by matrix-assisted laser desorption/ionization time¬of-flight mass spectrometry, differentiation of the species at the protein level by cellular fatty acids profiles and by unique and differential combinations of metabolic and physiological properties shared by each novel species. These strains represented two coherent lineages that were distinct from each other and from all known species, and the names Acinetobacter portensis sp. nov. (four strains: AC 877T = CCUG 68672T = CCM 8789T as type strain), and Acinetobacter guerrae sp. nov. (two strains: AC 1271T = CCUG 68674T = CCM 8791T as type strain) were proposed for these novel species. Control the dissemination of A. baumannii is challenging mainly due to its high adaptability to adverse environmental conditions. The biofilm formation ability in silicon and stainless steel, the resistance to desiccation on a stainless steel surface and the susceptibility to eleven commercial antimicrobial products was compared between food (10) and clinical strains (10). The clinical strains were selected based on their presumptive persistent and non-persistent status among 104 isolates recovered from patients in Hospital de São Marcos, Braga. Predominant clones of MDR A. baumannii repeatedly isolated in different years (2004 to 2007) or in different months (isolates recovered in 2014) were defined as persistent and strains recovered sporadically (with a PFGE pattern observed only once among all isolates) were defined as non-persistent. There were no significant differences between clinical and food strains since all the strains were able to form biofilm on silicon and stainless steel surfaces, exhibited desiccation resistance capacity ranging from 14 to 77 days and were susceptible to disinfectants at the recommended use concentrations. However, the biofiom-forming capacity of persistent strains was significantly higher than the non-persistant strains on both surfaces. The resistance to desiccation of persistent strains (mean survival time: 65.8 days) was also significantly longer than that of the non-persistent strains (mean survival time: 35.8 days). Therefore, these factors may contribute to their maintenance in the hospital setting. A high intra¬species variability in susceptibility to disinfectants was observed for A. baumannii and there was no correlation between the efficiency of disinfectants and the origin of the isolates. Moreover, no correlation between antibiotic resistance and biofilm production, resistance to desiccation and disinfectant susceptibility was found. Therefore, food products may be a potential vehicle of spread in the community and clinical environments of Acinetobacter strains resistant to several antibiotics, able to produce biofilm and to survive to desiccation, which may led to nosocomial and community¬acquired infections in susceptible individuals.
- Occurrence of acinetobacter SPP. In vegetablesPublication . Carvalheira, Ana Isabel Teixeira; Ferreira, Vânia; Silva, Joana; Teixeira, Paula