Clinical microbiology

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A 61-year-old man with chronic hepatitis B and dyslipidemia visited the emergency department with a

epartment with aith chronic hepa-iral load and lipidrosuvastatin. Twone extraction of amplications iden-mination. No pro-

ck stiffness and as showed a whiteneutrophils, a he-of 162,000/mL, an

(CRP) level of 12.15 mg/dL. Under suspicion of meningitis, two pairsof aerobic and anaerobic blood cultures were collected and alumbar puncture was performed. CSF revealed a glucose level of13mg/dL with a serum glucose level of 124mg/dL, a protein level of205.8 mg/dL, a red blood cell (RBC) count of 160/mL, and a WBCcount of 3430/mL with 50% neutrophils. Gram staining of the CSFexhibited no organisms. CSF samples for bacterial culture wereinoculated in the blood agar plates, MacConkey agar plates,

* Corresponding author. Division of Infectious Diseases, Department of Medicine,Samsung Medical Center, Sungkyunkwan University School of Medicine, 81, Irwon-ro, Gangnam-gu, Seoul 135-710, Republic of Korea.

E-mail addresses: collacin@gmail.com, cikang@skku.edu (C.-I. Kang).1

Contents lists availab

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Anaerobe 34 (2015) 161e163These authors contributed equally to this article.erythrocyte sediment rate of 57 mm/h, and a C-reactive proteinParvimonas micra is part of the normal ora of the oral cavity,and it has been recognized to cause gingival infection [1,2]. Cases ofmeningitis due to P. micra have been reported in the setting ofvertebral osteomyelitis and epidural abscesses and there has beenno report of primary bacterial meningitis caused by this organism[3e5]. We experienced a case of meningitis with bacteremia causedby P. micra after tooth extraction. Since anaerobic culture is notroutinely performed with Cerebrospinal uid (CSF) specimen, thepathogen was isolated only from blood cultures. Our case suggeststhat this organism is capable of being a bacterial meningitis path-ogen and meningitis caused by oral anaerobes could beunderdiagnosed.

A 61-year-old man visited the emergency dfever and severe headache. He was diagnosed wtitis B and dyslipidemia 10 years ago and his vprole were well-controlled with entecavir andweeks before symptom onset, he had undergomolar due to dental caries, but there were no cotied after extraction on follow-up dental exaphylactic antibiotics were prescribed.

On examination, he had a fever (38 C), nepositive Brudzinski sign. Initial laboratory testblood cell (WBC) count of 6570/mL with 81.5%moglobin level of 15.6 g/dL, a platelet count1. Introduction 2. Case reportReceived in revised form25 April 2015Accepted 4 May 2015Available online 12 May 2015

Keywords:Parvimonas micraMeningitishttp://dx.doi.org/10.1016/j.anaerobe.2015.05.0041075-9964/ 2015 Elsevier Ltd. All rights reserved.fever and severe headache. He was diagnosed with bacterial meningitis after a lumbar puncture, andblood culture revealed Parvimonas micra bacteremia. Although he had a history of extraction of a molartwo weeks before symptom onset, there was no evidence of abscess formation on physical examinationor imaging studies. He was successfully treated with oral metronidazole for 12 days after 9 days oftreatment with IV ceftriaxone and vancomcycin. This is the rst report of primary bacterial meningitiscaused by this organism, which indicates that this organism is capable of being a bacterial meningitispathogen.

2015 Elsevier Ltd. All rights reserved.Article history:Received 4 March 2015a r t i c l e i n f o a b s t r a c tBacteremic meningitis caused by Parvimimmunocompetent host

Jae-Hoon Ko a, 1, Jin Yang Baek b, 1, Cheol-In Kang a,

Sun Young Cho a, Young Eun Ha a, So Hyun Kim b,Nam Yong Lee c, Jae-Hoon Song a

a Division of Infectious Diseases, Samsung Medical Center, Sungkyunkwan University ScRepublic of Koreab Asia Pacic Foundation for Infectious Diseases (APFID), Seoul, Republic of Koreac Department of Laboratory Medicine, Samsung Medical Center, Sungkyunkwan Univernas micra in an

oo Joo Lee a, Ji Yong Lee a,o Ryeon Chung a, Kyong Ran Peck a,

l of Medicine, 81 Irwon-ro, Gangnam-gu, Seoul 135-710,

School of Medicine, Seoul, Republic of Korea

le at ScienceDirect

obe

vier .com/locate/anaerobe

major role in treating the meningitis in the present case, the isolatewas susceptible to all antibiotics used. Given these antimicrobialsusceptibility data, we think ceftriaxone and vancomycin can besafely used as an empiric antimicrobial regimen for bacterialmeningitis, even in cases of GPAC infection.

We treated the patient with oral metronidazole for 12 days after9 days of treatment with IV antibiotics. The optimal duration ofantimicrobial therapy for bacterial meningitis depends on thecausative pathogens and clinical course [20]. Since there are noclinical practice guidelines for the management of anaerobicmeningitis and the patient's headache slowly improved, we treatedhim for 21 days. Although IV antibiotics are recommended forbacterial meningitis to ensure an adequate CSF concentration, weprescribed oral metronidazole as it has high oral bioavailabilityapproaching 100% [21]. There was no recurrence of the infection or

robechocolate agar plates, and thioglycollate broth.With a diagnosis of bacterial meningitis, he received intrave-

nous (IV) ceftriaxone, vancomycin, and ampicillin empirically withdexamethasone. After 24 h, the growth of gram positive cocci inchains was reported in the anaerobic blood culture bottles, andampicillin was discontinued. On hospital day 3, his fever subsidedand the initial CSF culture showed no growth of microorganisms.Two pairs of aerobic and anaerobic blood cultures were performedon the same day to conrm bacteremia clear-up, and they reportednegative after 5 days of incubation. The patient underwent a repeatlumbar puncture on hospital day 6 as his headache worseneddespite the decrease in peripheral leukocytes and CRP. The follow-up CSF results were much improved e a glucose level of 29 mg/dLwith a serum glucose level of 115 mg/dL, a protein level of 79.8 mg/dL, a RBC count of 5/mL, and a WBC count of 270/mL with 79%neutrophils. On hospital day 8, the initial blood culture isolate wasidentied as P. micra.

To explore possible co-existing infection foci such as a peri-odontal, epidural, or brain abscess, brain MRI and dental exami-nation were performed, which showed leptomeningealenhancement along the cerebellar folia and chronic periodontitis.There was no evidence of abscess formation on physical examina-tion or imaging studies. On hospital day 10, his antibiotics werechanged to oral metronidazole 500mg qid. Hewas discharged fromthe hospital and continued antimicrobial therapy for a total of 21days.

The blood isolate was initially identied as P. micra by VITEK 2(bioMerieux Inc., Durham, NC, USA). Since P. micra is not a typicalbacterial meningitis pathogen, we also performed 16S rDNAsequencing analysis to conrm the test results. 16S rDNA PCRamplication and sequencing were performed as previouslydescribed [6]. The universal eubacterial primers fD1 (50-AGAGTTTGATCCTGGCTCAG-30) and rP2 (ACGGCTACCTTGTTAC-GACTT-30) were used. The 16S rRNA gene sequence (1420 bp) wascompared using BLAST searches in the GenBank and EzTaxon publicdatabases. The sequence was 99.72% identical (four nucleotidesdifference) to that of P. micra (GenBank accession numberABEE02000013).

Minimum inhibitory concentrations (MICs) of penicillin, ampi-cillin, ceftriaxone, cefoxitin, clindamycin, metronidazole, and van-comycinwere determined by the agar dilutionmethod according toClinical and Laboratory Standards Institute (CLSI) guidelines [7].In vitro antimicrobial susceptibility testing was performed usingBrucella agar plates supplemented with 5 mg of hemin, 1 mg ofvitamin K per milliliter, and 5% laked sheep blood. The plates wereincubated for 48 h at 37 C in anaerobic jars (GasPak AnaerobicSystem; BBL, Cockeysville, MD, USA) [8]. The reference strains wereBacteroides thetaiotaomicron ATCC 29741 and Clostridium difcileATCC70057. Interpretive criteria for susceptibility were thoseindicated in a CLSI document [7]. The strain was found to be sus-ceptible to all antibiotics tested (Table 1). Although CLSI guidelinesdo not suggest a susceptibility breakpoint for vancomycin, thepresent strain was susceptible to vancomycin based on recom-mendations by the European Committee on Antimicrobial Sus-ceptibility Testing (EUCAST) (http://www.srga.org/eucastwt/mictab/index.html).

3. Discussion

P. micra, previously known as Peptostreptococcus micros, is partof the normal ora of the gingival crevices and gastrointestinal tract[1]. It is being increasingly recognized as important oral pathogen[1,2], and sporadic cases of extra-oral cavity infections such as anempyema, endocarditis, pericarditis, septic pulmonary embolism,

J.-H. Ko et al. / Anae162septic knee, prosthetic joint infection, and vertebral osteomyelitishave been reported [3e5,9e14]. Cases of meningitis due to P. micrahave been reported in the setting of vertebral osteomyelitis andepidural abscesses [3e5]. There has been no report of primarybacterial meningitis caused by this organism, thus the patient un-derwent dental examination and brain MRI to determine thepossible source of infection, and these studies revealed only chronicperiodontitis. Considering the history of tooth extraction twoweeks before admission, the pathogenesis of bacterial meningitis inthis patient is thought to be hematogenous seeding of transientP. micra bacteremia during the dental procedure. To our knowledge,this is the rst report of primary bacterial meningitis caused byP. micra.

Since common bacterial meningitis pathogens are considered tobe aerobic bacteria [15,16], anaerobic culture of CSF is not recom-mended [17]. This could explain why P. micra was discovered inblood cultures, but not in CSF cultures in this case. Such phenom-enonwas also observed in a previous report of bacterial meningitiscaused by fusobacterium necrophorum [18]. Although 16S rDNA PCRmight help detection of the pathogen from CSF, no CSF sample wasremained when we noticed that blood culture isolate was P. micra.Given this point, bacterial meningitis caused by oral anaerobescould be underdiagnosed. Our case suggests that CSF cultures foranaerobes should be considered in cases with a high risk ofanaerobic infection due to oral ora such as patients with a historyof dental procedures.

P. micra has been reported to be highly susceptible to antibioticsincluding penicillin, amoxicillin, cefoxitin, imipenem, clindamycin,metronidazole, and vancomycin [1,8,19]. Susceptibility data forceftriaxone was not readily available, probably because it isconsidered a drug for aerobic infections. Since the patient in thepresent case report improved with ceftriaxone and vancomycin, wealso determined the MIC of ceftriaxone in addition to other anti-biotics considered to be active against Gram-positive anaerobiccocci (GPAC). Although we do not know which antibiotic played a

Table 1In vitro activity of antimicrobial agents against the Parvimonas micra isolate.

Antimicrobial agent MIC (mg/L) Susceptibility

Ampicillina 0.12 SPenicillina

4. Conclusion

This is the rst report of primary bacterial meningitis caused byP.micra after tooth extraction and suggests that this organism can bea bacterialmeningitis pathogen, even in an immunocompetent host.

Potential conicts of interest

On behalf of all authors, the corresponding author states thatthere is no conict of interest.

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Bacteremic meningitis caused by Parvimonas micra in an immunocompetent host1. Introduction2. Case report3. Discussion4. ConclusionPotential conflicts of interestReferences