| Grant number: | 16/07995-6 |
| Support Opportunities: | Regular Research Grants |
| Duration: | September 01, 2016 - August 31, 2018 |
| Field of knowledge: | Biological Sciences - Microbiology - Applied Microbiology |
| Principal Investigator: | Jorge Luiz Mello Sampaio |
| Grantee: | Jorge Luiz Mello Sampaio |
| Host Institution: | Faculdade de Ciências Farmacêuticas (FCF). Universidade de São Paulo (USP). São Paulo , SP, Brazil |
| Associated researchers: | Darlan Augusto da Costa Rocha ; David Santos Marco Antonio ; Juliana Coutinho Campos ; Mayne de Oliveira Pereira |
Abstract
Acinetobacter spp. and Pseudomonas aeruginosa are important agents of health care-associated infections worldwide. The empirical treatment of serious infections caused by these agents usually includes the carbapenems. When this therapy is inadequate, there is a significant increase in mortality. The use of rapid methods for early detection of carbapenem resistance can potentially help to reduce this mortality. The carbapenem resistance can occur by target alteration, low permeability or carbapenemase production, the latter being the most efficient mechanism. In a recent study of prevalence of carbapenemases, our group showed that among 119 P. aeruginosa isolates, 42 (35.3%) were able to degrade imipenem in a spectrophotometric hydrolysis assay, but only 17 (14.3%) were positive for known carbapenemase genes, most of them blaSPM-1. These findings suggest the presence of new carbapenemases in 25 of these isolates. Furthermore, when evaluated by ERIC-PCR, these isolates showed different profiles.The same study from our group showed that among 113 isolates of Acinetobacter, 91 (80.5%) were able to degrade imipenem in a spectrophotometric hydrolysis assay. In 66 of the isolates the blaOXA-51 gene was detected, but the change in absorbance during analysis of imipenem hydrolysis activity using the same experimental conditions for all isolates showed a great variability: from 0.123 to 0.825. In an A. baumannii isolate, which houses the blaOXA-51 and blaOXA-143 genes, the absorbance variation was 0.275. Using this threshold, we considered the possibility that isolates with values equal to or larger than this and which were positive only for blaOXA-51, possibly can harbor new carbapenemase genes. Of this group, 16 isolates have different profiles when evaluated by ERIC-PCR.An emerging group of carbapenemases in Acinetobacter are the NDMs. During the period from January 2014 to March 2016, we identified five autochthonous cases of colonization with NDM-1-producing Acinetobacter in the same 11 hospitals in São Paulo, where the carbapenemase frequency study in P. aeruginosa and Acinetobacter was held by our group: A. radioresistens, A. ursingii, A. johnsonii, junii and A. pittii . They were detected in rectal swab cultures of hospitalized patients. To date there are no reports from Brazil on the detection of NDM-1 in these first four species and oddly enough, the first two isolates were detected before there was the detection of Enterobacteriaceae producing this carbapenemase in patients from the city of São Paulo.The characterization of new carbapenemases gene is essential for its detection can be performed using rapid molecular tests, such as the real-time PCR, allowing early therapeutic setting. In the case of emerging resistance mechanism, the characterization of the genetic background of NDM-1 is of great importance for the understanding of its potential to spread in São Paulo.This project aims to characterize the genetic context of new or emerging carbapenemases in P. aeruginosa and Acinetobacter using next-generation sequencing, cloning, hybridization and evaluation of the hydrolysis profile. (AU)
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