Propionibacterium acnes is an anaerobic, nonspore-forming, slow growing Gram-positive skin-commensal bacillus. It is often considered as a blood culture contaminant but in some patients it has been identified as the causative agent of life-threatening infections. It can be responsible for serious infections such as brain abscesses, endophtalmitis, subdural empyema, osteomyelitis, native or prosthetic valve endocarditis,1 2 P. acnes endovascular devices have been reported, mostly on aortofemoral prosthesis.3 P. acnes in a 16-year-old boy suffering from congenital heart disease.
CASE REPORT
In March 2006, a 16-year-old boy was admitted to our hospital for management of a suspected pulmonary artery prosthesis infection. He had a history of pulmonary atresia with ventricular septal defect and had had 4 cardiac surgical interventions. In 1991, April 1993 and September 1993, surgery consisted of systemic-pulmonary shunts including successively right, central and left Gore-Tex interposition grafts. In October 2005, a 11-mm prosthetic tube (Shelhig) was inserted between the pulmonary artery and the right ventricle. The pulmonary arteries were enlarged with autologous pericardial patches with no immediate postoperative sequelae. In March 2006, he developed palpitations and weakness. He had no fever. The physical examination was unchanged. He had no acne lesion. A false aneurysm of the prosthesis was suspected on a transthoracic echocardiography. There was no evidence of vegetation seen on the atrioventricular or aortic valves. The presumptive diagnosis was confirmed by a non-ECG-gated cardiac computed tomography that revealed a false aneurysm of the infundibulum patch caused by a disruption between the pericardial patch and the prothesis (Fig. 1 ). A new surgical intervention was performed on March 29: the prosthesis and the false aneurysm (7 cm × 4 cm) were removed and a new Gore-Tex prosthesis was inserted between the right ventricle and the pulmonary artery trunk. He received antibiotics (vancomycin and amikacin) during the surgical intervention.
FIGURE 1.:
Giant false aneurysm of the pulmonary infundibulum (left panel). Note also the disharmonious hypoplasia of the pulmonary artery tree, including thin and irregular pulmonary branches (right panel).
An abscess surrounded the prosthesis. Infected prosthesis and pus were sent to the laboratory. Gram stain of the pus disclosed no bacteria. The culture of pus, prosthesis, and several aerobic and anaerobic blood cultures collected before antibiotic treatment remained sterile.
In the absence of microbial cultures, we performed a universal 16S rRNA PCR amplification from different sites of the pulmonary prosthesis and pleural fluids. Amplification and sequencing of the bacterial 16S rRNA gene revealed the presence of P. acnes on 2 different sites of the pulmonary prosthesis and in the pleural fluid). The diagnosis of vascular device infection with P. acnes was thus confirmed on April 21, 2006. The patient received several antibiotic regimens before precise microbiologic identification: imipenem, vancomycin, amikacin, piperacillin, tazobactam, spiramycin, and ciprofloxacin. After the identification of P. acnes , vancomycin alone was given. The patient was febrile from March 29, 2006 to April 22, 2006. He then became afebrile after the interruption of vancomycin and we concluded that it was an antibiotics related fever.
Because of persistent fever ascribed to vancomycin administration, we decided to introduce a new antibiotic regimen including ceftriaxone 2 g/d and gentamicin 3 mg/kg/d during 15 days. The patient gained weight, was afebrile, and the echocardiography did not reveal a collection around the new prosthesis. He was discharged with ceftriaxone 2 g/d and rifampin 20 mg/kg/d for 1 month, then he received amoxicillin 3 g/d and rifampin for 3 months. The patient resumed normal activity and he remains asymptomatic in March 2007.
DISCUSSION
Propionibacterium acnes is a rare cause of endocarditis that affects mostly intracardiac prosthetic materials such as artificial valves, pacemaker leads,4 5 P. acnes valvular endocarditis have been reported. Only 4 children or adolescents were involved. Endocarditis occurred in 3 patients with congenital heart diseases.6 P. acnes infection of endovascular devices have been reported: 7 on aortofemoral prosthesis and 1 on a ventricular patch.
The diagnosis of P. acnes endocarditis can be difficult. Fever occurs in 72%6 P. acnes : the indolent clinical course of the disease, negative or delayed blood culture results, and the fact that P. acnes may be considered to be a blood-culture contaminant. This might explain why a high proportion of cases of P. acnes endocarditis (70.6%) required surgical intervention because of severe valvular damages or abscesses.7
P. acnes takes a long time to grow (about 3–7 days) and the transportation of infected samples and culture require anaerobic conditions, even if P. acnes cannot be considered as a strict anaerobic bacterium.1 8 2 3
No precise therapeutic guidelines are currently available for the management of P. acnes endocarditis. Antibiotics such as vancomycin, ceftriaxone , cefazolin, amoxicillin, penicillin, clindamycin, pefloxacin, rifampicin, erythromycin, tetracyclin are active in vitro against P. acnes . We chose ceftriaxone because it is active against P. acnes , given once daily and is well tolerated. Caution must be taken because recent data suggest that although P. acnes isolates remain highly susceptible to ceftriaxone , an antagonism has recently been observed between cefotaxime and linezolid, ciprofloxacin, and clindamycin.9 P. acnes can produce biofilm on biomaterials.10
REFERENCES
1. Gunthard H, Hany A, Turina M, Wust J.
Propionibacterium acnes as a cause of aggressive aortic valve endocarditis and importance of tissue grinding: case report and review.
Clin Microbiol . 1994;32:3043–3045.
2. Marques da Silva R, Caugant DA, Eribe ER, et al. Bacterial diversity in aortic aneurysms determined by 16S ribosomal RNA gene analysis.
J Vasc Surg . 2006;44:1055–1060.
3. Le Page L, Podglajen I, Chemla E, Mainardi JL. Molecular diagnosis of a vascular prosthesis infection, due to
Propionibacterium acnes , by amplification and sequencing of 16S rDNA.
Clin Microbiol Infect . 2003;9:1125–1127.
4. Zedtwitz-Liebenstein K, Gabriel H, Graninger W. Pacemaker endocarditis due to
Propionibacterium acnes .
Infection . 2003;31:184–185.
5. Vanagt WY, Daenen WJ, Delhaas T. Propionibacterium acnes endocarditis on an annuloplasty ring in an adolescent boy.
Heart . 2004;90:e56.
6. Delahaye F, Fol S, Celard M, et al. Endocardites infectieuses à
Propionibacterium acnes .
Etude de 11 cas et revue de la littérature. Arch Mal Coeur Vaiss . 2005;98:1212–1218.
7. Clayton JJ, Baig W, Reynolds GW, et al. Endocarditis caused by
Propionibacterium species: a report of three cases and a review of clinical features and diagnostic difficulties.
J Med Microbiol . 2006;55:981–987.
8. Tunney MM, Patrick S, Curran MD, et al. Detection of prosthetic hip infection at revision arthroplasty by immunofluorescence microscopy and PCR amplification of the bacterial 16S rRNA gene.
J Clin Microbiol . 1999;37:3281–3290.
9. Mory F, Fougnot S, Rabaud C, Schuhmacher H, Lozniewski A. In vitro activities of cefotaxime, vancomycin, quinupristin/dalfopristin, linezolid and other antibiotics alone and in combination against
Propionibacterium acnes isolates from central nervous system infections.
J Antimicrob Chemother. 2005;55:265–268.
10. Ramage G, Tunney MM, Patrick S, Gorman SP, Nixon JR. Formation of
Propionibacterium acnes biofilms on orthopaedic biomaterials and their susceptibility to antimicrobials.
Biomaterials . 2003;24:3221–3227.
