Epidemiological characteristics and antimicrobial susceptibility among carbapenem-resistant non-fermenting bacteria in Brazil

Introduction: Non-fermenting Gram-negative bacteria such as Pseudomonas aeruginosa and Acinetobacter baumannii are widespread in the
environment and are increasingly associated with nosocomial infections. Extensive and indiscriminate use of antibiotics in hospitals has
contributed to an increased number of infections caused by these microorganisms, that are resistant to a wide variety of antimicrobials, including
β-lactams. This study aimed to isolate and identify carbapenem-resistant Acinetobacter spp. and P. aeruginosa from hospitalized patients, to
determine their antimicrobial susceptibility patterns and to screen for blaOXA-23, blaOXA-24, blaOXA-51, blaOXA-58, and blaOXA-143 genes among the isolated bacteria.

 

Methodology: Antimicrobial resistance patterns were performed using the disk-diffusion method. Genetic markers related to carbapenem
resistance were screened by polymerase chain reaction.

 

Results: Carbapenem-resistant Acinetobacter spp. (n = 44) and P. aeruginosa (n = 28) samples were isolated from patients admitted to a tertiary
hospital. Polymyxin B was the only effective drug for all isolates. Considering the oxacillinase gene screening, genetic markers were observed
only in Acinetobacter isolates. The most frequent genotype observed was blaOXA-23+/blaOXA-51+(45.5%), followed by blaOXA-51+/blaOXA-143+(41%). The oxacillinase genes blaOXA-24 and blaOXA-58 were not detected. High mortality rates (> 70%) were observed.

 

Conclusions: The data suggest the need for rational use of antimicrobials associated with early diagnosis of multidrug-resistant bacteria,
especially considering non-fermenting Gram-negative rods, which are widespread in hospitals. The findings of blaoxa-51-strains suggest the
occurrence and spread of non-A. baumannii species throughout our hospitals. Effective implementation of surveillance programs in hospitals
is needed to reduce infectious and resistant intra- and inter-species bacteria.

 

Key words: Pseudomonas; Acinetobacter; carbapenem-resistant bacteria.

 

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