Prosthetic valve endocarditis caused by Bordetella holmesii, an Acinetobacter lookalike

Abstract

We report a case of fulminant endocarditis on a prosthetic homograft aortic valve caused by Bordetella holmesii, which was successfully managed by surgical valve replacement and antibiotic treatment. B. holmesii, a strictly aerobic, small, Gram-negative coccobacillus, has been implicated as an infrequent cause of a pertussis-like syndrome and other respiratory illnesses. However, B. holmesii is also a rare cause of septicaemia and infective endocarditis, mostly in immunocompromised patients. To our knowledge, this is the first report of B. holmesii endocarditis on a prosthetic aortic valve. Routine laboratory testing initially misidentified the strain as Acinetobacter sp. Correct identification was achieved by 16S rRNA gene and outer-membrane protein A (ompA) gene sequencing. Interestingly, matrix-assisted laser desorption/ionization timeof-flight mass spectrometry also produced an accurate species-level identification. Subsequent susceptibility testing and review of the literature revealed ceftazidime, cefepime, carbapenems, aminoglycosides, fluoroquinolones, piperacillin/tazobactam, tigecycline and colistin as possible candidates to treat infections caused by B. holmesii. Case reportA 36-year-old man, known as a heavy smoker and an excessive alcohol consumer, was admitted to the emergency department with a septicaemia-like clinical presentation, dyspnoea and oedema of the lower limbs. On arrival, he suffered from an acute lung oedema due to septic shock. He complained of general malaise for the previous 2 weeks and of a chilling fever for the previous 3 days. His ). The cardiac markers troponin T and the MB isoenzyme of creatinine kinase were both increased to 0.11 mg l 21 (reference range ,0.03 mg l 21 ) and 11.3 mg l 21 (reference range ,6.7 mg l 21 ), respectively. He had a medical history of infectious endocarditis on a post-rheumatic aortic and mitral valve caused by Streptococcus bovis 7 years before. This had been managed by antibiotic treatment, replacement of the aortic valve by a homograft, and replacement of the mitral valve by a mechanical valve using a Bentall procedure.Transoesophageal echocardiography revealed leaflet vegetations of 1 cm on the aortic homograft with massive aortic regurgitation due to the destruction of one leaflet. There were no signs of prosthetic valve endocarditis of the mitral valve. Empirical antibiotic treatment consisting of vancomycin, gentamicin and flucloxacillin was initiated. Three days after admission, the damaged aortic homograft was replaced by a mechanical composite graft (St Jude Regent, 23 mm) during a redo Bentall procedure. The patient Abbreviation: MALDI-TOF, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.The GenBank/EMBL/DDBJ accession numbers for the 16S rRNA gene and the ompA gene sequences of Bordetella holmesii strain M10-4183 are JN664969 and JQ650246, respectively.

<i>Bordetella holmesii</i>: Comparison of Two Isolates from Blood and a Respiratory Sample

“…Bho1 and FR4020 present a bhoE sequence identical to that in GenBank (DQ402419). OmpA, encoding a porin-like protein, is sometimes preferred for identification purposes, because it displays a higher degree of mutational variation than 16S rRNA [12]. The sequences of ompA in Bho1 and FR4020 were 100% identical to that in GenBank for other B. holmesii isolates (Accession no.…”

“…This poses a potential problem, because the diagnosis of B. pertussis infection is based on the PCR detection of IS481 sequences. The development of specific PCR diagnosis for B. holmesii infection, targeting the recA gene [7][8][9], or the transposase IS1001bho [10], the amplification of specific target as bhoE [11] or the sequencing of 16sRNA or OmpA [12] has made it possible for a number of retrospective studies to demonstrate an increase in the number of reported cases of respiratory infections due to B. holmesii over the last few years [10,11,[13][14][15][16][17][18][19][20][21]. We wondered whether this increase in detection reflected a real increase in the number of infections or was simply a consequence of the increasing use of RT-PCR targeting IS481 for the diagnosis of B. pertussis since 2005.…”

Bordetella holmesii, an Emerging Cause of Septic Arthritis

“…A recent report described four adolescents lacking normal splenic function who presented with mild febrile illness and had B. holmesii bacteremia (4); there has also been a description of septic arthritis caused by B. holmesii in an adolescent with chronic hemolytic anemia who was asplenic and had no concom-itant bacteremia (11). A number of other very recent reports document pericardial and endocardial infection with B. holmesii in immunocompromised adults (5,12,13).…”

“…Cellular fatty acid profiles and 16S rRNA gene sequencing are useful for making a definitive identification (3). Matrix-assisted laser desorption ionization-time of flight mass spectrometry has also been shown to have a role in the identification of many bacteria; this technology has been used to successfully identify B. holmesii (5,6).…”

First Case of Pseudoclavibacter bifida Bacteremia in an Immunocompromised Host with Chronic Obstructive Pulmonary Disease (COPD)

“…DNA was extracted from fresh colonies grown on blood agar (homemade Columbia agar supplemented with 5% horse blood) using the QIAamp DNA minikit (Qiagen, Hilden, Germany) in accordance with the manufacturer's instructions. The bacterial 16S rRNA gene was amplified using the following primers: 5=-AGA GTT TGA TCC TGG CTC AG-3= (forward; Escherichia coli positions 8 to 27) and 5=-TAC CTT GTT ACG ACT TCG TCC CA-3= (reverse; E. coli positions 1504 to 1485) (1,2). Amplification products of approximately 1,350 nucleotides (nt) were checked by agarose gel electrophoresis (2%) and visualized through ethidium bromide staining.…”