Previous Article | Next Article ![]()
Journal of Clinical Microbiology, August 2008, p. 2817-2819, Vol. 46, No. 8
0095-1137/08/$08.00+0 doi:10.1128/JCM.01018-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.
| CASE REPORT |

Department of Intensive Care Medicine, Chi-Mei Medical Center, Tainan, Taiwan,1 Department of Internal Medicine, Taipei Medical University, Taipei, Taiwan,2 Department of Internal Medicine, Yi-Min Hospital, Taipei, Taiwan,3 Departments of Laboratory Medicine and Internal Medicine, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan4
Received 28 May 2008/ Returned for modification 6 June 2008/ Accepted 16 June 2008
|
|
|---|
|
|
|---|
![]() View larger version (100K): [in a new window] |
FIG. 1. The initial chest X-ray (left) showed no obvious abnormality on admission. A chest X-ray taken on the eighth hospitalization day (right) showed marked cardiomegaly with a flask shape, indicating the presence of pericardial effusion.
|
![]() View larger version (72K): [in a new window] |
FIG. 2. Greenish and turbid pericardial fluid aspirated from the patient with Shewanella algae purulent pericarditis.
|
Microbiology. The organism was initially identified as Shewanella putrefaciens by the Phoenix 100 ID/AST (Becton Dickinson) automated identification system. The subsequent positive growth in 6% NaCl was compatible with identification as Shewanella algae but not S. putrefaciens. S. algae exhibited green to orange colonies on the blood agar plate.
This organism was further confirmed as S. algae by the partial 16S rRNA gene sequence analysis (540 bp). In brief, PCR was performed with primers DG74 (5'-AACTGGAGGAAGGTGGGGAT-3') and RW01 (5'-AGGAGGTGATCCAACCGCA-3'). The amplification products obtained by PCR were sequenced, and the sequences were compared to known 16S rRNA gene sequences in the GenBank database of the National Center for Biotechnology Information by using the BLAST algorithm. The species with the best match was S. algae (accession number EF542799.1).
Discussion. Gram-negative bacilli and gram-positive cocci such as Streptococcus pneumoniae, Staphylococcus aureus, and Streptococcus pyogenes are the most important causative agents of bacterial pericarditis (7). The most common S. algae infections involve ears and soft tissue, but serious infections such as bacteremia, meningitis, and infective endocarditis have also been described (4). This is the first reported case of a purulent pericarditis due to S. algae.
Shewanella species are gram-negative, facultative anaerobic, nonfermentative bacilli and are present ubiquitously in many foods, sewage, freshwater or stagnant water, seas, lakes, rivers, oil emulsions, natural gas, and petroleum brines (8). Although these organisms have been isolated from a variety of clinical specimens, they are rarely reported as pathogens of human infections (4, 8, 10). S. putrefaciens and S. algae (formerly classified as S. putrefaciens biotype II) are the only two species of Shewanella that have been reported to cause human infections (4). These reported infections included biliary tract infection, empyema thoracis, bacteremia, endocarditis, skin and soft tissue infection, dacryocystitis, intracranial abscess, arthritis, peritonitis, ventilator-associated pneumonia, and ear infection (2, 4, 10). To our best knowledge, S. algae has never been reported as a cause of purulent pericarditis in humans.
Most cases of S. algae in humans were acquired from contaminated water through the disintegrated skin. The bacteria resided in devitalized tissues or denuded skin and served as a nidus for opportunistic infection (4). The portal of entry of the organism in our patient was not easily clarified because of the absence of any recent contact with environmental conditions suitable for propagation of the organism. The organism might have gained access into the pericardium by hematogenous spread via a contaminated cutaneous lesion such as her left ankle wound. In addition, our patient had gastric cancer and gallbladder cancer, and her immunocompromised condition may also have contributed to the development of severe S. algae infection with bacteremia and pericardial involvement.
Most of the Shewanella sp. infections reported in the literature have been attributed to S. putrefaciens because S. algae is not included in the databases of automated identification systems. Although available automated identification systems are not able to differentiate between S. algae and S. putrefaciens, S. algae could be easily differentiated from S. putrefaciens by phenotypic characterization (4). In contrast to S. putrefaciens, S. algae is able to produce mucoid colonies with beta-hemolysis on sheep blood agar, to grow at 42°C and in 6% NaCl, to reduce nitrite, and to produce acid from maltose (5). Phenotypic characterization has revealed that more than 80% of human infections were in fact caused by S. algae (9).
S. algae is characteristically susceptible to aminoglycosides, carbapenems, erythromycin, and quinolones but resistant to penicillin (4). In our patient, S. algae was initially susceptible to piperacillin-tazobactam and became resistant to piperacillin-tazobactam 10 days later. Rapid development of drug resistance to imipenem, but not to piperacillin-tazobactam, has been reported (6). The mechanism for the rapid development of drug resistance to piperacillin-tazobactam required further study. Previous reports (3, 5) showed that most Shewanella infections could be effectively treated by a combination of surgical therapy/drainage and appropriate antibiotics. As in this case, prompt drainage of the pericardial fluid might have contributed to a favorable outcome.
Greenish pleural effusion has been reported in a patient with cholecystopleural fistula (1). However, there was no fistula noted between the pericardium and the biliary system in our case. The reason for the greenish color of pericardial fluid is not clear. The ability of S. algae to reduce Fe(III) might have contributed to the green color, but further study is needed (11).
In summary, we report a case of purulent pericarditis with greenish pericardial effusion caused by S. algae in a patient with gastrointestinal malignancy. This case expands the reported spectrum of infection caused by S. algae and raises the possibility that S. algae is a causative pathogen for purulent pericarditis.
Published ahead of print on 25 June 2008. ![]()
|
|
|---|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»