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- Wild mushroom extracts potentiate the action of standard antibiotics against multiresistant bacteriaPublication . Alves, Maria José; Ferreira, I.C.F.R.; Lourenço, I.; Castro, A.; Pereira, L.; Martins, A.; Pintado, M.Aims: The main objective of this study was to evaluate the capacity of wild mushroom extracts to potentiate the action of standard antibiotics, through synergisms that allow a decrease in their therapeutic doses and ultimately contribute to the reduction of resistances. Methods and Results: Wild mushroom extracts were applied to different multiresistant micro-organisms (Escherichia coli, extended-spectrum betalactamase- producing (ESBL) E. coli and methicillin-resistant Staphylococcus aureus (MRSA), combined with commercial antibiotics (penicillin, ampicillin, amoxicillin/clavulanic acid, cefoxitin, ciprofloxacin, cotrimoxazol, levofloxacin). Microdilution method was used to determine minimum inhibitory concentrations (MICs). The results obtained showed higher synergistic effects against MRSA than against E. coli. Mycena rosea and Fistulina hepatica were the best extracts for synergistic effects against MRSA. The efficiency of Russula delica extract against E. coli 1 (resistant to ampicillin, ciprofloxacin and trimethoprim/sulfasoxazole) and E. coli 2 (resistant to amoxicillin/clavulanic acid and ampicillin) was higher than that of Leucopaxillus giganteus extract; nevertheless, the latter extract exhibited better synergistic effects against ESBL E. coli. Conclusions: This study shows that, similarly to plants, some mushroom extracts can potentiate the action of antibiotics extensively used in clinical practice for Gram-positive or Gram-negative bacteria, with positive action even against multiresistant bacteria. Significance and Impact of the Study: Mushroom extracts could decrease therapeutic doses of standard antibiotics and reduce micro-organism’s resistance to those drugs.
- Virulence and resistance profile of Staphylococcus aureus isolated from foodPublication . Castro, A.; Palhau, C.; Cunha, S.; Camarinha, S.; Silva, J.; Teixeira, PStaphylococcus aureus is considered a global community and health care pathogen responsible for staphylococcal food poisoning. The aim of this study was to characterize several isolates of S. aureus recovered from different food products concerning enterotoxin genes and other virulence factors including antimicrobial resistance. In 2009, a total of 78 coagulase-positive staphylococci from 1454 food samples were identified to species level; 73 were confirmed as S. aureus. Of the S. aureus isolates 5.5% were resistant to oxacillin, 52.0% showed resistance to erythromycin, and 45.2% to tetracycline. Multidrug resistance was observed in 33.3% of the isolates (resistance to three or more antibiotics of different classes). SCCmec types IV and V were detected among methicillin-resistant S. aureus (MRSA). One MRSA isolate was pvl positive. The 52.0% of food isolates were shown to be enterotoxigenic; egc (63.0%), secbov (44.7%) were the main detected SEs. tst gene was also detected in food isolates. The present work demonstrates the presence of virulent S. aureus collected in 2009 in foods.
- Study of Biological Hazards Present on the Surfaces of Selected Fruits and VegetablesPublication . Noronha, Lúcia; Castro, Ana; Ferreira, Vânia; Magalhães, Rui; Almeida, Gonçalo; Mena, Cristina; Silva, Joana; Teixeira, PaulaThis study evaluated the microbial load on the surface of fruits with rough and very pronounced textured peels, namely pineapples and melons (cantaloupe), and investigated the presence of foodborne pathogens in these products since they are usually eaten raw. Similarly, lettuce is one of the most common salad vegetables consumed raw in Portugal, it therefore being important to study the microbial status of lettuce leaves. Enumerations of aerobic mesophilic counts, Enterobacteriaceae, Escherichia coli and coagulase-positive staphylococci, as well as detection of Listeria monocytogenes and Salmonella spp., were performed for all samples. Only in melon samples were E. coli and coagulase-positive staphylococci not detected. Contamination with L. monocytogenes varied from 2.5% and 15% in pineapple/melon and lettuce samples, respectively. Salmonella spp. were not detected. All coagulase-positive staphylococci had similar characteristics and none exhibited multidrug resistance. L. monocytogenes isolates belonged to serogroups II (1/2c or 3c), or to serogroup IV (4b, 4d and 4e). None were found to be resistant to antibiotics commonly used in therapy of listeriosis.
- Chemical composition and antibacterial properties of stem and leaf extracts from Ginja cherry plantPublication . Castro, A.; Silva, N.; Silva, Joana; Teixeira, Paula
- Prevalence of staphylococcus aureus from nares and hands on health care professionals in a portuguese hospitalPublication . Castro, A.; Komora, N.; Ferreira, Vânia; Lira, A.; Mota, M.; Silva, Joana; Teixeira, PaulaAims: The main goal was to estimate the prevalence of methicillin-resistant Staphylococcus aureus on hands and in nose of health care professionals. Methods and Results: Detection of Staph. aureus on hands or in the nose of 169 individuals was performed. Nasal and hand carriage was found in 39 6 and in 8 9% respectively. About 17 2% of the individuals were carriers of methicillin-resistant Staph. aureus (MRSA) in the nose and 4 7% on hands. The majority of nasal MRSA were resistant to b-lactams, erythromycin and ciprofloxacin. All nasal MRSA were SCCmec type IV and Panton-Valentine leukocidin (PVL) negative. One MRSA isolated from hand was SCCmec type V. About 75 6% of MRSA isolates presented the same or closely related restriction patterns. Sixty per cent of Staph. aureus from hands and from noses from the same individual were the same strain. Conclusions: MRSA nasal carriage was high considering healthy health care professionals but in accordance with high level of MRSA infection in Portugal. Isolates recovered in this study seemed to be different from major clones previously isolated in other Portuguese hospitals. Significance and Impact of the Study: These findings may have implications on the knowledge of healthy health care workers as vehicles of MRSA infections among the community. Presence of several virulence factors may contribute to increased pathogenesis in case of infection.
- Prevalence, Antimicrobial Susceptibility and Virulence Factors Profile of Methicillin- resistant Staphylococcus aureus (MRSA) on Food in PortugalPublication . Castro, A.; Palhau, C.; Cunha, S.; Camarinha, J.; Silva, Joana; Teixeira, Paula
- Antimicrobial resistance profile of Staphylococcus aureus isolated from foodPublication . Castro, Ana; Palhau, Carla; Cunha, Sara; Camarinha, Sofia; Silva, Joana; Teixeira, Paula
- Staphylococcus aureus, a food pathogen: virulence factors and antibiotic resistancePublication . Castro, Ana; Silva, Joana; Teixeira, PaulaStaphylococcus aureus is an extraordinarily versatile pathogen responsible for staphylococcal food poisoning, hospital and community infections, as well as toxic shock syndrome. S. aureus is considered the most effective food-borne bacterial pathogen that has ever evolved. The S. aureus metagenome contains 10s of genes encoding staphylococcal enterotoxins, which are responsible for the clinical symptoms associated with staphylococcal food poisoning. S. aureus may be present in food products, being a potential vehicle for transmission. Antibiotics are widely used not only in humans but also in animal husbandry and other agricultural activities. The occurrence of multiresistant strains in food(s) has been increasing; contaminated food is considered an important vehicle for antimicrobial resistance. Methicillin-resistant S. aureus (MRSA) was first recognized in animal infections in 1972 in milk from mastitic cows in Belgium. Animal-associated MRSA infections in humans were first reported during 2003–05 in the Netherlands. Presently, it was reported that livestock-associated MRSA CC398 in pork identifies a potential pathway from farms to the wider population through retail pork. MRSA commonly carry enterotoxin genes but there has been only one report of food intoxication due to MRSA. Antibiotic resistance associated to enterotoxins genes made S. aureus an evolving threat.
- Antibiotic profile of staphylococcus aureus isolated from health care personnel working in health centersPublication . Castro, Ana; Costa, Mariana; Meneses, Tânia; Silva, Joana; Paula Teixeira, Paula
- Phenotypic and genotypic characterization of Staphylococcus aureus isolated from food industry workersPublication . Santos, Carla; Meireles, Helena; Ramos, Bárbara; Castro, Ana; Silva, Joana; Teixeira, Paula