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

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.

In Vitro Antimicrobial Susceptibility Profiles of Gram-Positive Anaerobic Cocci Responsible for Human Invasive Infections

“…In our study, susceptibility to moxifloxacin greatly varied depending on the species (9–43%), which is concordant with observations reported in the literature (0–48%) [ 20 , 23 , 25 , 26 , 30 , 31 , 32 , 37 ]. In agreement with these studies, we also observed that F. magna was more resistant than other species.…”

“…As observed here, clindamycin resistance rates among GPAC vary widely and this resistance is rising, especially in F. magna (3–51%) and Peptoniphilus spp. (1–36%) for which MIC 90 range from 2 to >256 mg/L [ 11 , 16 , 17 , 19 , 20 , 22 , 23 , 25 , 26 , 37 ]. In a recent global program (T.E.S.T.…”

“…(1-36%) for which MIC 90 range from 2 to >256 mg/L [11,16,17,19,20,22,23,25,26,37]. In a recent global program (T.E.S.T.…”

Antimicrobial Susceptibility Patterns and Wild-Type MIC Distributions of Anaerobic Bacteria at a German University Hospital: A Five-Year Retrospective Study (2015–2019)

“…Blood cultures accounted for almost 16% of all tested isolates. In this group, 22% were Gram-negative with the distribution of isolates comparable with previous reports [ 43 ]. Although it can be difficult to authenticate the relevance of the presence of bacteria that are part of the normal skin microbiota such as Cutibacterium , the presence of certain Gram-positive and most Gram-negative anaerobes in blood cultures almost always represents true bacteremia [ 44 ].…”

Pathogenic Spectrum and Resistance Pattern of Bloodstream Infections Isolated from Postpartum Women: A Multicenter Retrospective Study

“… 20 A different retrospective study revealed that 43.9% of anaerobic bacteria belong to the genus Bacteroides , 7% to the genus Fusobacterium , and 2.1% to the genus Prevotella . 21 Currently, studies on the analysis of anaerobic bacteria in postpartum infections with BSI are scarce, additional attention should be paid to BSI caused by anaerobes among postpartum women, and more efforts should be spent identifying the potential sources of anaerobe infections and guiding clinicians in rational drug use according to population characteristics in the future.…”