Perfil fenotípico e genotípico de resistência e virulência de Vibrio parahaemolyticus isolados de água e ostras / Phenotypic and genotypic profile of resistance and virulence of Vibrio parahaemolyticus isolated from water and oysters

Este estudo teve como objetivo identificar cepas de Vibrio parahaemolyticus isoladas de amostras de ostras e água e determinar seu perfil fenotípico (lipase, gelatinase, caseinase, fosfolipase, urease, amílases, DNase e beta-hemólise), genes de virulência (tdh, trh e ure) e de resistência antimicrobiana (blaSHV, blaTEM-1 e blaCTX-M). O potencial de virulência fenotípica de V. parahaemolyticus foi obtido, principalmente, para amilase (93,3%), gelatinase (83,3%) e fosfolipase (80%), com a presença do gene ure (23,3%) e ausência dos genes tdh e trh. V. parahaemolyticus foi resistente (96,7%) a pelo menos um antimicrobiano, com multirresistência mediada por plasmídeos em 53,3% das cepas. Apesar da ausência de enzimas β-lactamases, a presença dos genes nas cepas de V. parahaemolyticus isoladas da água [blaTEM (66,6%), blaCTX-M (91,6%)] foi maior do que nas amostras de ostras [blaTEM (33,3%), blaCTX-M (55,5%)]. Conclui-se que os dados fenotípicos e genotípicos para V. parahaemolyticus nem sempre são compatíveis, aumentando o risco de armazenamento e transmissão de genes de resistência propagados pelo consumo de frutos do mar contaminados.

The Phenotypic/Genotypic Profile of OXA-10-like harboring, Carbapenem-Resistant Pseudomonas aeruginosa : Using Validated Pharmacokinetic/Pharmacodynamic in vivo Models to Further Evaluate Enzyme Functionality and Clinical Implications

In vitro MICs and in vivo pharmacodynamics of ceftazidime and cefepime human-simulated regimens (HSR) against mCIM-positive P. aeruginosa harboring different OXA-10-like subtypes were described. The murine thigh model assessed ceftazidime (2g q8h HSR) and cefepime (2g and 1g q8h HSR). Phenotypes were similar despite possessing OXA-10-like subtypes with differing spectra. Ceftazidime produced ≥1-log 10 kill in all isolates. Cefepime activity was dose-dependent and MIC driven. This approach may be useful in assessing implications of β-lactamase variants.

Analysis of MC1R, MITF, TYR, TYRP1, and MLPH Genes Polymorphism in Four Rabbit Breeds with Different Coat Colors

Pigmentation genes such as MC1R, MITF, TYR, TYRP1, and MLPH play a major role in rabbit coat color. To understand the genotypic profile underlying coat color in indigenous Chinese rabbit breeds, portions of the above-mentioned genes were amplified and variations in them were analyzed by DNA sequencing. Based on the analysis of 24 Tianfu black rabbits, 24 Sichuan white rabbits, 24 Sichuan gray rabbits, and 24 Fujian yellow rabbits, two indels in MC1R, three SNPs in MITF, five SNPs (single nucleotide polymorphisms) in TYR, one SNP in TYRP1, and three SNPs in MLPH were discovered. These variations have low-to-moderate polymorphism, and there are significant differences in their distribution among the different breeds (p < 0.05). These results provide more information regarding the genetic background of these native rabbit breeds and reveal their high-quality genetic resources.

Efficacy of human-simulated exposures of meropenem/vaborbactam and meropenem against OXA-48 β-lactamase-producing Enterobacterales in the neutropenic murine thigh infection model

Objectives Despite vaborbactam lacking inhibitory activity against OXA-48, approximately a third of OXA-48-harbouring Enterobacterales test susceptible to meropenem/vaborbactam due to its higher breakpoint than meropenem alone. The present study evaluated the efficacy of human-simulated exposures of meropenem/vaborbactam against OXA-48-harbouring Enterobacterales in the neutropenic murine thigh model. Methods Twenty-six isolates [OXA-48 (n = 24) and KPC (n = 2)] were evaluated. MICs were conducted in triplicate per CLSI. Mice received human-simulated regimens of meropenem/vaborbactam, meropenem or vehicle for 24 h. Mice were inoculated with ∼1 × 107 cfu/mL in each thigh 2 h prior to dosing and both thighs were harvested at 24 h. Efficacy was assessed using mean log10 cfu/thigh at 24 h and the achievement of 1 log10 reduction relative to 0 h control as an established surrogate marker predictive of success for serious infections. Results Meropenem/vaborbactam MICs ranged from 1 to 64 mg/L. The mean inoculum at 0 h was 5.77 ± 0.26 compared with 8.26 ± 1.53 for controls at 24 h. As anticipated for KPCs, meropenem/vaborbactam resulted in enhanced mean ± SD change in bacterial density (−1.10 ± 0.26), compared with meropenem (1.45 ± 0.88). Vaborbactam did not enhance mean ± SD change against OXA-48 isolates compared with meropenem (−0.44 ± 1.29 and −0.43 ± 1.36, respectively). For OXA-48-harbouring isolates with meropenem/vaborbactam MICs ≥16 (n = 5), 8 (n = 5), 4 (n = 9) and ≤2 (n = 5) mg/L, 0%, 0%, 44% and 60% of isolates achieved the target reduction ≥1 log10 with either agent, respectively. Conclusions These data highlight that meropenem/vaborbactam and meropenem humanized exposures in vivo resulted in similar, albeit poor, activity against OXA-48-producing Enterobacterales despite susceptible MICs per EUCAST and CLSI interpretation. As a result, caution is warranted when treating meropenem/vaborbactam-susceptible Enterobacterales without a genotypic profile.

Evaluation of the EDTA-Modified Carbapenem Inactivation Method for Detecting Metallo-β-Lactamase-Producing Pseudomonas aeruginosa

ABSTRACT The prevalence of carbapenem-resistant Pseudomonas aeruginosa is increasing. Identification of carbapenemase-producing P. aeruginosa will have therapeutic, epidemiological, and infection control implications. This study evaluated the performance of the EDTA-modified carbapenem inactivation method (eCIM) in tandem with the modified carbapenem inactivation method (mCIM) against a large collection of clinical P. aeruginosa isolates (n = 103) to provide clinicians a phenotypic test that not only identifies carbapenemase production but also distinguishes between metallo-β-lactamase and serine-carbapenemase production in P. aeruginosa. The mCIM test was performed according to Clinical and Laboratory Standards Institute guidelines, while the eCIM was conducted as previously described for Enterobacteriaceae. Test performance was compared to the genotypic profile as the reference. mCIM testing successfully categorized 91% (112/123) of P. aeruginosa isolates as carbapenemases or non-carbapenemase producers, with discordant isolates being primarily Guiana extended-spectrum (GES)-type producers. To increase the sensitivity of the mCIM for GES-harboring isolates, a double inoculum, prolonged incubation, or both was evaluated, with each modification improving sensitivity to 100% (12/12). Upon eCIM testing, all Verona integrin-encoded metallo-β-lactamases (VIM; n = 27) and New Delhi metallo-β-lactamases (NDM; n = 13) tested had 100% concordance to their genotypic profiles, whereas all Klebsiella pneumoniae carbapenemase (KPC; n = 8) and GES (n = 12) isolates tested negative, as expected, in the presence of EDTA. The eCIM failed to identify all imipenemase (IMP)-producing (n = 22) and Sao Paulo metallo-β-lactamase (SPM)-producing (n = 14) isolates. KPC-, VIM-, and NDM-producing P. aeruginosa were well defined by the conventional mCIM and eCIM testing methods; additional modifications appear required to differentiate GES-, IMP-, and SPM-producing isolates.

Pathogenic potential of Brucella ovis field isolates with different genotypic profile and protection provided by the vaccine strain B. ovis ΔabcBA against B. ovis field isolates in mice

ABSTRACT: Brucella ovis causes economic and reproductive losses in sheep herds. The goal of this study was to characterize infection with B. ovis field isolates in a murine model, and to evaluate protection induced by the candidate vaccine strain B. ovis ΔabcBA in mice challenged with these field isolates. B. ovis field strains were able to colonize and cause lesions in the liver and spleen of infected mice. After an initial screening, two strains were selected for further characterization (B. ovis 94 AV and B. ovis 266 L). Both strains had in vitro growth kinetics that was similar to that of the reference strain B. ovis ATCC 25840. Vaccination with B. ovis ΔabcBA encapsulated with 1% alginate was protective against the challenge with field strains, with the following protection indexes: 0.751, 1.736, and 2.746, for mice challenged with B. ovis ATCC25840, B. ovis 94 AV, and B. ovis 266 L, respectively. In conclusion, these results demonstrated that B. ovis field strains were capable of infecting and inducing lesions in experimentally infected mice. The attenuated vaccine strain B. ovis ΔabcBA induced protection in mice challenged with different B. ovis field isolates, resulting in higher protection indexes against more pathogenic strains.