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Multi-drug resistant Pseudomonas aeruginosa is a gram-negative bacillus responsible for nosocomial infections. Immunoglobulin Y (IgY) is a chicken immunoglobulin used for research, immunodiagnosis, and immunotherapy. IgY presents antimicrobial properties and it is under investigation for use as an adjunct to prophylactic therapies. The current study aimed to assess the synergistic action between anti-P aeruginosa IgY and the beta-lactams ceftazidime, imipenem, and meropenem. IgY antibodies were obtained from laying hens immunized with SPM-1 producing P. aeruginosa (Pa48 spm-1+ ) or VIM-2 producing P. aeruginosa (Pa23 vim-2 + ). The antimicrobial activity of IgY antibodies was evaluated by the growth inhibition test, and the synergistic effect was assessed by determination of the fractional inhibitory concentration index. Anti-Pa48 spm-1+ IgY shows antimicrobial activity at 1.25 mg/ml and anti-Pa23 vim-2+ IgY shows antimicrobial activity at 2.5 mg/ml. The fractional inhibitory concentration indices of anti-Pa48 spm-1+ IgY and ceftazidime, or imipenem, or meropenem at 72 h of experiment were 0.189, 0.209, and 0.440, respectively. For anti-Pa23 vim-2+ IgY, the fractional inhibitory concentration indices were 0.440 with ceftazidime, 0.453 with imipenem, and 0.441 with meropenem at 72 h. We conclude that there is a synergistic action between anti-P. aeruginosa IgY and the antimicrobials tested. Further studies are necessary to investigate the mechanisms associated with this action., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Tityus scorpion stings are an important public health problem in Brazil, where the incidence of such stings exceeds the incidence of the health problems caused by other venomous animals, including snakes. In this study, we have analysed specific enzymatic activities of the venom from the Brazilian scorpions of Tityus genus, i.e., Tityus serrulatus, Tityus bahiensis and Tityus stigmurus. The data presented here revealed that Tityus spp. venoms exhibited significant hyaluronidase activity but no phospholipase activity. All the venom samples exhibited the ability to hydrolyse Abz-FLRRV-EDDnp and dynorphin 1-13 substrates. These activities were inhibited by 1,10-phenanthroline but not by PMSF, indicating the presence of metalloproteinases in the Tityus spp. venoms. The venom peptidase activity on Abz-FLRRV-EDDnp and on dynorphin 1-13 was partially inhibited by therapeutic Brazilian anti-scorpion and anti-arachnidic antivenoms. Dynorphin 1-13 (YGGFLRRIRPKLK) contains two scissile bonds between the residues Leu-Arg and Arg-Arg that are susceptible to cleavage by the Tityus venom metallopeptidase(s). Their cleavage releases leu-enkephalin, an important bioactive peptide. The detection of metalloproteinase(s) with specificity for both dynorphin 1-13 degradation and leu-enkephalin releasing can be important for the mechanistic understanding of hypotension and bradycardia induction in cases of scorpion stings, whereas hyaluronidases might contribute to the diffusion of the toxins present in these venoms. Furthermore, the limited inhibition of the toxic enzymatic activities by commercial antivenoms illustrates the necessity of improvements in current antivenom preparation., (Copyright © 2013 Elsevier Ltd. All rights reserved.)