Firstdescription...

Case report
First description of Anaerococcus octavius as cause of bacteremia
Fernando Cobo*,Jos e María Navarro-Marí
Department of Microbiology and Instituto Biosanitario,University Hospital Virgen de Las Nieves,Department of Medicine,University of Granada,Granada, Spain
a r t i c l e i n f o
Article history:
Received13September2019 Received in revised form
20November2019
Accepted21November2019 Available online22November2019
Handling Editor:Boyanova Lyudmila
Keywords:
A.octavius
bacteremia
Cancer
Anaerobe
Antimicrobials a b s t r a c t
Anaerococcus spp.are Gram-positive anaerobic cocci involved in human skin and soft-tissue infections, among other diseases.We report thefirst known case of bacteremia due to A.octavius,detected in an elderly patient.A71-year-old woman with a history of breast cancer presented with fever and cognitive impairment for more than three days.A.octavius was isolated in blood cultures,and only resistance to clindamycin was reported.Her general condition improved after treatment with metronidazole and she was discharged.
©2019Elsevier Ltd.All rights reserved.
1.Introduction
Anaerococcus octavius(formerly Peptostreptococcus octavius)are obligate anaerobic non-spore-forming cocci that have not previ-ously been associated with human infections.This microorganism wasfirst described by Murdoch et al.,in1997[1]and reassigned to the Anaerococcus genus by Ezaki et al.,in2001[2].It has frequently been isolated in skin,vagina,and nasal cavity[2],but no human infections in pure culture have been reported in the literature.We recently diagnosed thefirst case of bacteremia caused by A.octavius,detected in an elderly patient.This pathogen was encountered as a pure culture in this infection.
2.Case report
An immunocompetent71-year-old woman was admitted to the Neurology Department due to fever and cognitive impairment for more than three days.Family history included liver cancer of her father and lung cancer of her mother.The patient was referred from the Emergency Department due to a worsening of her general condition.In the neurological examination,only a motor dysfunc-tion was documented.She had been diagnosed with breast cancer three years earlier,treated with tumorectomy and local radio-therapy,and had a history of mitral and aortic insufficiency.She had never received chemotherapy,and there was no evidence of tumor recurrence at her admission.Physical examination revealed the presence of fever(38.5 C),pulse of95bpm,and mitral and aortic heart murmurs,and blood analysis showed elevated C-reactive protein(13mg/L).Remaining parameters,including liver and renal function,were normal.Chest X-ray showed no remarkablefindings, and brain CT scan did not reveal intracranial expansive processes or acute hemorrhagic lesions.After taking two sets of blood cultures, treatment was started with intravenous(i.v.)cefotaxime(1g/8h/3 days);on day2of incubation,both anaerobic bottles were found to be positive(BD BACTEC FX40,Becton Dickinson).The sample was subcultured in aerobic or anaerobic blood agar(BD Columbia Agar with5%Sheep Blood,Becton Dickinson,Franklin Lakes,NY).All media were incubated at37 C.The anaerobic system used was the AnaeroGen Compact(Oxoid Ltd,Wide Road,Basingstoke,England).
Gram staining of the blood cultures exhibited abundant Gram-positive cocci;on the second day of incubation,abundant col-onies of these microorganisms were observed in pure culture,in anaerobic blood agar alone.MALDI-TOF MS version8(7854msp) (Bruker Biotyper,Billerica,MA)was employed to identify the strain as Clostridium beijerinckii(score1.18)and it was sent to the National
*Corresponding author.Department of Microbiology and Instituto Biosanitario, Hospital Virgen de las Nieves Avda Fuerzas Armadas,218014Granada,Spain.
E-mail addresses:**************************************,microhaya@gmail. com(F.
Cobo).
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https:///10.1016/j.anaerobe.2019.102130
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Anaerobe61(2020)102130
Centre for Microbiology(Majadahonda,Madrid,Spain)forfinal
identification.The isolate was identified by means of16S rDNA
sequence analysis using a previously reported method[3].A frag-
ment of1101bp was obtained,giving99.2%similarity with
A.octavius(Gene Bank sequence:NR_026360).Antimicrobial sus-
ceptibility testing was performed by using the E-test.According the
2019EUCAST criteria[4],the strain was susceptible to all antimi-
crobials tested except clindamycin.The following MIC values were
obtained for this strain:penicillin(<0.016m g/mL),amoxicillin-clavulanate(<0.016m g/mL),piperacillin-tazobactam(0.032m g/ mL),clindamycin(>256m g/mL),meropenem(<0.002m g/mL), imipenem(<0.002m g/mL),vancomycin(0.25m g/mL),and metro-nidazole(0.38m g/mL).
Antimicrobial treatment was changed to i.v.metronidazole(1.5
g/day/5days)and the condition of the patient improved,allowing
her discharge from the hospital.At5months of follow-up,the
general condition of the patient remains good.
3.Discussion
We report thefirst case of bacteremia due to A.octavius,
detected in a71-year-old woman with a breast cancer.Only resis-
tance to clindamycin was documented,and treatment with
metronidazole was established,observing an improvement in her
general condition.
Anaerococcus genus encompasses13species,with A.prevotii
being the most frequent.Members of the genus are typically iso-
lated from the human vagina and purulent secretions[2].A.prevotii
is often recovered from vaginal discharges and from different types
of abscess[5],ctolyticus and A.vaginalis have been isolated
from diabetic foot and pressure ulcers[6],and strains of A.octavius
have been recovered from nasalflora,skin,and vagina[7,8].
A.vaginalis and A.prevotii have been identified in blood cultures by
mass spectrometry and16S rRNA gene sequencing[9];however,to
our best knowledge,no bloodstream infections due to A.octavius
have previously been reported.In the present case,the source of
infection was unknown,although the most likely route would be
colonization of the upper respiratory tract.
The definitive diagnosis of anaerobes is based on phenotypic
tests and/or molecular methods.The availability of proteomic
techniques such as MALDI-TOF MS in routine clinical laboratory
analysis facilitates thefinal identification of these bacteria and the
recognition of new species of anaerobes.However,as in the present
report,molecular techniques are needed for thefinal identification,
especially when the MALDI-TOF MS score is low[10].In the present
case,the microorganism was included in the version of the data-
base used but with only two inputs,which may explain the low
score.
Anaerococcus species are considered susceptible to penicillins
overall,but resistance to tetracycline,erythromycin,and clinda-
mycin has been reported by some authors[11].Resistance of
A.prevotii to clindamycin,levofloxacin and ceftazidime has been
described[12,13],and A.murdochii has shown resistance to kana-
mycin and clindamycin and intermediate resistance to penicillin
[14].However,another study found that four isolates of Anaero-
coccus species were susceptible to clindamycin,among other anti-
microbials[15].In the present case,resistance to clindamycin(MIC >256m g/mL)was observed,as in some recent studies,therefore,the antibiotic is not appropriate as empirical treatment.
In conclusion,this study shows that Anaerococcus species can
cause infections in pure culture,and presents thefirst known report of A.octavius as a cause of bloodstream infection.These findings and recent studies on the antimicrobial resistance of Anaerococcus spp.strongly support the need for caution in the antimicrobial treatment of these infections,especially in the se-lection of empirical therapy,and for the routine susceptibility testing of Gram-positive anaerobes.
Funding
None.
Declaration of competing interest
The authors declare no conflict of interest. Acknowledgements
The authors thank Dr.Juan Antonio S a ez from the National Centre for Microbiology(Majadahonda,Madrid,Spain)for the definitive identification of the strain.
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