Inhibitory action of antibiotics on Kluyveromyces marxianus

A bioassay containing Kluyveromyces marxianus in microtiter plates was used to determine the inhibitory action of 28 antibiotics (aminoglycosides, beta-lactams, macrolides, quinolones, tetracyclines and sulfonamides) against this yeast in whey. For this purpose, the dose-response curve for each antibiotic was constructed using 16 replicates of 12 different concentrations of the antibiotic. The plates were incubated at 40°C until the negative samples exhibited their indicator (5-7h). Subsequently, the absorbances of the yeast cells in each plate were measured by the turbidimetric method (λ=600nm) and the logistic regression model was applied. The concentrations causing 10% (IC10) and 50% (IC50) of growth inhibition of the yeast were calculated. The results allowed to conclude that whey contaminated with cephalosporins, quinolones and tetracyclines at levels close to the Maximum Residue Limits inhibits the growth of K. marxianus. Therefore, previous inactivation treatments should be implemented in order to re-use this contaminated whey by fermentation with K. marxianus.

Anaphylactic reaction in patient allergic to mango

Background

An allergy to mango is extremely rare. The antigenic composition of the fruit is not fully known. Profilin from mango has a structure similar to birch tree profiling: it is responsible for cross-reactions between mango and pear, apple, and peach. A panallergen with a structure similar to mugwort defensin (Art v 1) which cross-reacts with celery, carrot, peanuts, pepper, aniseed, and caraway has been previously described.

Case study

A female patient, 30 years old, was admitted in February 2017 because of recurrent allergic reactions following consumption of various foods. The most severe allergic reaction in the patient’s life occurred after eating a mango fruit. Within several minutes the patient developed a generalised urticaria, followed by facial oedema, strong stomach pain and watery diarrhoea. The diagnostics involved skin tests with a set of inhalatory and food allergens, including native skin tests. The patient also experienced symptoms of recurrent, generalized urticaria in connection with consumption of various types of food, especially complex dishes containing many different ingredients. Additionally, an interview revealed that the patient was experiencing symptoms of the oral allergy syndrome after ingesting various fruit and vegetables, especially during late summer and fall. Diagnostics was extended by determining the levels of IgE specific for allergen components, using the ImmunoCap ISAC method. In order to confirm the occurence of a cross-reaction between mugwort and mango allergens, we performed the inhibition test of IgE specific for mugwort using a mango allergen extract and ImmunoCap matrix.

Results

Skin prick tests (SPT) were positive for allergens of grass 7 mm; weeds 8 mm; cat’s fur 5 mm; mugwort 6 mm. SPT were also positive for mango. The level of specific IgE was increased for allergens of mugwort, grass, celery, pepper, carrot, mango, banana, peach, and apple. The ImmunoCap ISAC test demonstrated a high level of specific IgE rPhl p 1 (timothy grass) and Art v 1 (mugwort). We also performed the IgE inhibition test using both mango extract and ImmunoCap matrix and confirmed a cross-reaction with Art v 1 in the pathogenesis of symptoms observed in the patient.

Conclusions

An anaphylactic reaction to consumed mango, resulting from cross-allergy with mugwort Art v 1 was diagnosed in the patient. Acute urticarial in this case is a manifestation of IgE-mediated food allergy. During in vitro diagnostic procedures we found an elevated concentration of IgE specific to several food allergens (including celery, peppers, carrot, banana, peach, apple, shrimp). The elimination diet removing allergens the patient was allergic to was recommended. Considering the anaphylactic reaction the patient was instructed to carry a rescue set composed of an adrenaline autosyringe, steroids, and antihistamines.

IgE cross-reactivity of peanut with walnut and soybean in children with food allergy

BACKGROUND

Peanut allergies are common and can be life-threating for sensitised individuals. Peanut allergens share significant amino acid homology with those of other legumes and tree nuts, but their cross-reactivity still remains unclear.

OBJECTIVE

We sought to determine the clinical significance of the cross-reactivity of peanut allergens with those of walnut and soybean.

METHODS

Pooled sera from eight subjects with both peanut and walnut specific IgE were investigated in an inhibition test. After the sera were incubated with either peanut or walnut protein extracts, the quantity of IgE antibodies against the peanut and walnut was measured using an immunoCAP test. Likewise, pooled sera from 18 subjects with both peanut and soybean specific IgE antibodies were incubated with either peanut or soybean protein extracts and evaluated with a peanut and soybean immunoCAP test. SDS-PAGE and immunoblotting were also performed with peanut, walnut and soybean protein extracts and relevant sera.

RESULTS

Peanut specific IgE was inhibited up to 20% and 26% by walnut and soybean protein extracts, respectively. In reverse, walnut and soybean specific IgE were inhibited up to 21% and 23% by peanut protein extracts, respectively. In the immunoblot analysis, pooled serum from the subjects with peanut specific IgE antibodies reacted with walnut protein extracts significantly.

CONCLUSION

Although the clinical significance of the cross-reactivity of peanut specific IgE with walnut and soybean protein extracts has not been established, we believe that individuals who are allergic to peanuts need to be cautious about consuming walnuts and soybeans.