Clinical Findings and Antimicrobial Susceptibility of Anaerobic Bacteria Isolated in Bloodstream Infections.

Fernando Cobo,Carla Foronda,Isabel Casanovas,José María Navarro-Marí,Elizabeth Calatrava,Jaime Borrego,Esther Gómez

doi:10.3390/antibiotics9060345

Fernando Cobo, Carla Foronda + Show 5 more

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https://doi.org/10.3390/antibiotics9060345

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Journal: Antibiotics	Publication Date: Jun 19, 2020
Citations: 10	License type: CC BY 4.0

Affiliation: Instituto de Investigación Biosanitaria

Abstract

The objectives of this study were to report on the antimicrobial susceptibility of 141 clinically significant anaerobic bacteria isolated from bloodstream infections between January 2016 and April 2020 in a tertiary-care hospital in Granada (Spain) and to describe the main clinical features of the patients. Species identification was performed by MALDI-TOF MS (Bruker Daltonics, Billerica, MA, USA). Antimicrobial susceptibility tests were performed against penicillin, amoxicillin-clavulanic acid, imipenem, moxifloxacin, clindamycin, metronidazole, and piperacillin-tazobactam using the gradient diffusion technique and EUCAST breakpoints, except for moxifloxacin (CLSI breakpoints). The most frequent anaerobes were Bacteroides (43.9%, n = 62), Clostridium (24.1%, n = 34) and Gram-positive anaerobic cocci (GPACs) (15.6%, n = 22). Almost all tested anaerobes were susceptible to imipenem and amoxicillin-clavulanic acid, except for Bacteroides. High overall resistance rates to clindamycin were observed, especially for Gram-positive anaerobic cocci (GPACs) (54.5%) and for Bacteroides spp. (45.1%). Overall, low resistance rates to almost all antibiotics were observed for Clostridium. High resistance rates to penicillin were also observed for Gram-positive anaerobic bacilli (GPABs) (44.4%), as well as to metronidazole (22.2%), although only nine isolates were included. Antimicrobial susceptibility testing for anaerobes should always be performed in severe infections, such as those localized in the bloodstream. The information obtained contributes to selecting empirical treatments according with local data on resistance.

Highlights

Anaerobic bacteria are common pathogens in humans
Regarding other Gram-positive anaerobic bacilli (GPABs), 44.4% were resistant to benzylpenicillin, and 22.2% were resistant to both metronidazole and moxifloxacin
This study summarizes the findings of resistance to some antimicrobials in 141 strains of anaerobic bacteria isolated from bloodstream infections

Summary

Introduction

Anaerobic bacteria are common pathogens in humans. The majority of anaerobes are involved in mild mixed infections, but, in some circumstances, they may cause severe diseases, like when present in blood or in other sterile body sites. The presence of anaerobic microorganisms in the bloodstream continues to have a high associated mortality rate requiring a rapid diagnostic and an appropriate treatment [1,2]. The detection rate of anaerobes in blood cultures is around 0.5–11% of all bacteraemic episodes, depending on patient age and condition and on geographic location [3]. Antimicrobial susceptibility testing of anaerobic isolates is currently needed for severe infections (such as bloodstream infections) or for epidemiological studies [7,8], but the observation of higher levels in the resistance of anaerobes to Antibiotics 2020, 9, 345; doi:10.3390/antibiotics9060345 www.mdpi.com/journal/antibiotics

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