Portal de Periódicos da CAPES

Aerococcus viridans Endocarditis

1984; Elsevier BV; Volume: 59; Issue: 1 Linguagem: Inglês

10.1016/s0025-6196(12)60342-5

1942-5546

Francis D. Pien, Walter R. Wilson, K Kunz, John A. Washington,

Streptococcal Infections and Treatments

Aerococcus viridans organisms are gram-positive cocci with a strong tendency to form tetrads. These bacteria have infrequently been encountered as a human pathogen, particularly in bacterial endocarditis. A review of the literature suggests that treatment of A. viridans endocarditis should be similar to that for endocarditis caused by penicillin-susceptible streptococci. Aerococcus viridans organisms are gram-positive cocci with a strong tendency to form tetrads. These bacteria have infrequently been encountered as a human pathogen, particularly in bacterial endocarditis. A review of the literature suggests that treatment of A. viridans endocarditis should be similar to that for endocarditis caused by penicillin-susceptible streptococci. In 1953, Williams and associates1Williams REO Hirch A Cowan ST Aerococcus, a new bacterial genus.J Gen Microbiol. 1953; 8: 475-480Crossref PubMed Scopus (94) Google Scholar proposed the name Aerococcus viridans to describe a group of aerobic a-hemolytic, gram-positive cocci that have a strong tendency to form tetrads rather than clusters or chains. We report a case of A. viridans endocarditis. The patient was hospitalized and treated in Hawaii; the microorganism was identified and susceptibility tests were performed in Mayo Clinic laboratories. A 28-vear-old man presented with a 6-month history of various rheumatic complaints, including pain in the shoulders, back, and left knee. He had a history of fever for 1 month, anemia, and microscopic hematuria. On admission to Straub Clinic Hospital, he was afebrile and had systolic and diastolic murmurs of aortic insufficiency which were loudest at the cardiac apex. The spleen was not palpable, and he had no physical signs of peripheral emboli or hypersensitivity phenomena. No clinical signs of cardiac failure were noted. The patient denied recent exposure to needles or dental work; he was employed as a hotel kitchen helper and a commercial fisherman. Six blood culture sets were positive for a slow-growing gram-positive coccus, which was identified as A. viridans by the Mayo Clinic Microbiology Laboratory on the basis of the following test results: gram-positive cocci in tetrads on Gram's stain, a negative catalase test, and a weakly positive bile-esculin reaction. The microorganism was subcultured, and repeat Gram's stain demonstrated characteristic grampositive cocci in tetrads. Results of antibiotic sensitivity tests done by agar- or broth-dilution methods were as follows: minimal inhibitory concentrations of 0.13 ug/ml for penicillin, 0.13 ug/ml for cephapirin, 1.0 ug/ml for vancomycin, and 1.0 ug/ml for gentamicin. The minimal bactericidal concentration was 0.13 ug/ml for cephapirin. The patient was initially treated with several antibiotics elsewhere. Antimicrobial therapy at Straub Clinic was aqueous penicillin G (20 million U daily) and gentamicin (60 mg every 8 hours) administered intravenously for 2 weeks. An echocardiogram revealed a flail aortic leaflet with vegetations, aortic insufficiency, and left ventricular enlargement. On the eighth day of antimicrobial therapy, the patient underwent aortic valve replacement. Gram's stain of the large vegetations showed focal aggregates of grampositive cocci; cultures of the aortic valve were negative for bacterial growth. Postoperatively, the patient received intravenous penicillin and gentamicin therapy for an additional week and then was dismissed with a 2-week oral regimen of phenoxymethyl penicillin (1 g three times daily). The patient was well during 6 months of outpatient follow-up. Aerococci differ from streptococci because they are weakly catalase-positive organisms and tend to form tetrads rather than chains in broth media. These slowgrowing bacteria ferment maltose and mannitol and tolerate 40% bile, 10% salt, 0.25% crystal violet, and 0.01% potassium tellurite.2Buchanan RE Gibbons NE Bergey's Manual of Determinative Bacteriology. Eighth edition. Williams & Wilkins Company, Baltimore1974: 515-516Google Scholar, 3Whittenbury R A study of some pediococci and their relationship to Aerococcus viridans and the enterococci.J Gen Microbiol. 1965; 40: 97-106Crossref Google Scholar, 4Evans JB Kerbaugh MA Recognition of Aerococcus viridans by the clinical microbiologist.Health Lab Sci. 1970; 7: 76-77PubMed Google Scholar Unlike enterococci, aerococci are highly susceptible to many antibiotics and do not contain the group D streptococcal antigen.4Evans JB Kerbaugh MA Recognition of Aerococcus viridans by the clinical microbiologist.Health Lab Sci. 1970; 7: 76-77PubMed Google Scholar, 5Untereker WJ Hanna BA Endocarditis and osteomyelitis caused by Aerococcus viridans.Mt Sinai J Med NY. 1976; 43: 248-252PubMed Google Scholar Previously, A. viridans had been termed Pediococcus homari or Gaffkya homari by some authors, but it is now considered to be a separate genus and species.2Buchanan RE Gibbons NE Bergey's Manual of Determinative Bacteriology. Eighth edition. Williams & Wilkins Company, Baltimore1974: 515-516Google Scholar A. viridans is ubiquitous in nature and may be isolated from dust, vegetables, and crustaceans.4Evans JB Kerbaugh MA Recognition of Aerococcus viridans by the clinical microbiologist.Health Lab Sci. 1970; 7: 76-77PubMed Google Scholar, 5Untereker WJ Hanna BA Endocarditis and osteomyelitis caused by Aerococcus viridans.Mt Sinai J Med NY. 1976; 43: 248-252PubMed Google Scholar, 6Deibel RH Niven Jr, CF Comparative study of Gaffkya homari, Aerococcus viridans, tetrad-forming cocci from meat curing brines, and the genus Pediococcus.J Bacteriol. 1960; 79: 175-180PubMed Google Scholar In an environmental study of a hospital in North Carolina, this organism was frequently found on objects in the operating room, recovery room, nursery, intensive care unit, patient wards, and delivery suite.7Kerbaugh MA Evans JB Aerococcus viridans in the hospital environment.Appl Microbiol. 1968; 16: 519-523PubMed Google Scholar Our patient may have been exposed to this microorganism during his work as a commercial fisherman. Human infections caused by A. viridans have been described. Nathavitharana and associates8Nathavitharana KA Arseculeratne SN Aponso HA Vijeratnam R Jayasena L Navaratnam C Acute meningitis in early childhood caused by Aerococcus viridans.Br Med J. 1983; 286: 1248Crossref PubMed Scopus (39) Google Scholar recently reported three cases of acute childhood Aerococcus meningitis from Sri Lanka. Colman9Colman G Aerococcus-like organisms isolated from human infections.J Clin Pathol. 1967; 20: 294-297Crossref PubMed Scopus (45) Google Scholar reported 10 clinical isolates from several European sources. These cases included three urinary tract infections, one case each of empyema, an infected wound, and a mouth isolate, and four cases of endocarditis. No clinical data were reported on the patients with endocarditis except that the isolates were reportedly susceptible to penicillin, streptomycin, erythromycin, and tetracycline. The minimal inhibitory concentrations of these isolates to benzyl penicillin were 1.6 U or less (1.0 ug/ml). Parker and Ball10Parker MT Ball LC Streptococci and aerococci associated with systemic infection in man.J Med Microbiol. 1976; 9: 275-302Crossref PubMed Scopus (255) Google Scholar reported four cases of endocarditis and three cases of bacteremia caused by A. viridans but provided no clinical information about their patients. These cases represented 1% of the clinically important “streptococcal” isolates received by the Central Public Health Laboratory, Colindale, London, for the period 1972 through 1974. Table 1 includes our case and the only other two case reports5Untereker WJ Hanna BA Endocarditis and osteomyelitis caused by Aerococcus viridans.Mt Sinai J Med NY. 1976; 43: 248-252PubMed Google Scholar, 11Janosek J Eckert J Hudáç A Aerococcus viridans as a causative agent of infectious endocarditis.J Hyg Epidemiol Microbiol Immunol (Praha). 1980; 24: 92-96PubMed Google Scholar of bacterial endocarditis caused by A. viridans for which we could find clinical data. Obviously, this environmental organism may cause serious medical consequences, including infective endocarditis. The few clinical reports available suggest that patients with A. viridans endocarditis may be treated successfully with penicillin G or a cephalosporin in dosages similar to those for patients with endocarditis caused by penicillinsusceptible viridans streptococci.Table 1Bacterial Endocarditis Caused by Aerococcus viridansAntibiotic sensitivities (μg/ml)CaseReference no.Age (yr) and sexPredisposing heart diseaseInfected valvePenicillinCephalothen or cephapirinVancomycinAntimicrobial therapy and outcome1554 MMitral valve prolapseMitral0.067.505.0Aqueous penicillin G, 18 × 106 U/day for 5 wk, then orally administered penicillin for 2 wk. Had osteomyelitis of lumbar spine21150 MRheumatic mitral insufficiencyAortic0.04……Parenterally administered penicillin G plus streptomycin. Died of congestive heart failure. Postmortem cultures of cardiac vegetations sterile3Current report28 MNo history of heart diseaseAortic0.130.131.0Parenterally administered penicillin plus gentamicin. Aortic valve replacement because of flail leaflet. Cure. (See text for details) Open table in a new tab