Indian Pediatrics 1999;36: 1264-1266
Bacteremia due to Gemella morbillorum
|Purva Mathur, Benu Dhawan, Lalit Kumar+,
L.S. Arya*, Rama Chaudhry
From the Departments of
Microbiology and *Pediatrics and +I.R.C.H., All India Institute of Medical
Sciences, New Delhi 110 029, India.
Gemella morbillorum, previously known as Streptococcus morbillorum was reclassified into the genus Gemella in 1988 on the basis of DNA hybridization(1). Human infections caused by G. morbillorum are rare. The cases reported are predominantly endovascular infections(2) but acute invasive infections due to this bacterium, such as septic arthritis(3) and meningitis(4) have only recently been recognized. Reported cases of G. morbillorum infection have rarely affected children. We report a case of bacteremia caused by G. morbillorum in a child with neuro-blastoma. This is believed to be the first reported case of infection with this organism in a child from the Indian sub-continent.
A 9-year-old boy was admitted to the hospital with a three and a half month history of fever, loss of appetite, progressive weight loss and chest pain. Approximately 15 days prior to admission, he developed weakness of the lower extremities and retention of urine. He had received antituberculous treatment from a private practitioner, which was later dis-continued because of the development of jaundice. On admission, the patient was pale and lethargic, with a temperature of 102° F. Physical examination revealed a large mass in the left hypochondrium extending to the epigastric region. The mass was hard in consistency, tender and had an ill-defined margin. Evidence of cord compression at T-10 level was present. Laboratory studies disclosed the following significant findings: leukocyte count 8000/mm3 (87% neutrophils); hemoglobin 8.6 g/dl; and platelet count 300,000/mm3. Cultures of blood, obtained simultaneously from two different sites at the time of admission, were reported as sterile. Computed tomography of the chest and spine showed a large well defined left intrathoracic extra parenchymal lesion with left pleural effusion and intraspinal extension. The child was started on intravenous ciprofloxacin and gentamicin for presumed sepsis.
Fine needle aspiration cytology of the abdominal mass showed features of round cell tumor suggestive of neuroblastoma. A diagnosis of neuroblastoma of the left adrenal with intrathoracic extension, and paraplegia with bilateral hydronephrosis was made. Chemo-therapy for the neuroblastoma was started. The patient continued to remain febrile.
Three weeks after admission, blood cultures were once again taken. Two complete sets (one aerobic and one anaerobic culture bottle each) of blood for cultures were collected at an interval of 30 minutes from 2 different sites for aerobic and anaerobic bacterial isolation. The organism isolated from both samples of blood was preliminarily identified as an alpha haemolytic Streptococci.
The isolate was distinguished from viridans Streptococci and identified as G. morbillorum by a positive L-pyrrolidonyl-b naphthylamide hydrolysis test, a positive leucine amino-peptidase test, susceptibility to a 30 mg disc of vancomycin, absence of production of gas from glucose, inability to hydrolyse Esculin, inability to grow in 6.5% sodium chloride and at a temperature of both 10°C and 45°C(5). Identification of the isolate was confirmed as G. morbillorum by the API 20 Strep System (bio Merieux, Inc., Hazelwood, Mo.).
In a standard Kirby-Bauer sensitivity test, the organism was sensitive to penicillin, amoxy-cillin, cloxacillin, cefotaxime, cefuroxime, ticarcillin/clavulanic acid, cefuroxime and resistant to both ciprofloxacin and amikacin. Thereafter, intravenous antimicrobial therapy with cloxacillin was started and ciprofloxacin was stopped. Amikacin was also added to the antibiotic regimen despite the organism being resistant to it, to give a prophylactic broad spectrum coverage against nosocomial infec-tions. The patient improved gradually; became afebrile and follow up blood cultures taken later were negative. The tumor regressed in size. The patient was discharged with advice to come for follow-up in the Pediatric Oncology Clinic.
G. morbillorum was originally isolated in 1917 by Tunnicliff(6). Because of its anaerobic nature, especially during initial isolation, the organism was transferred to the genus Peptostreptococcus and later to the genus Streptococcus on the basis of the fact that lactic acid is its major metabolic product. Recently, DNA-DNA filter hybridization, guanine and cytosine content analysis, and 16S rRNA, oligonucleotide cataloguing revealed its close resemblance to Gemella haemolysans, thereby resulting in another change of nomenclature(1). Gemellae are anaerobic to aerotolerant Gram positive cocci that may be found as part of the normal oropharyngeal microflora in humans. They may exhibit alpha hemolysis on blood agar, thus resulting in initial presumptive identification as a viridans Streptococcus.
Human infections caused by G. morbillorum are unusual. G. morbillorum and the only other member of the genus, G. haemolysans, appear to cause a spectrum of infection similar to that seen with viridans Streptococci. Cases of endocarditis, other endovascular infections, meningitis, and septic arthritis due to G. morbillorum have been reported(2-4). In addition, reports on septicemia due to viridans Streptococci in patients with cancer, included six patients with infection due to this organism, identified therein as S. morbillorum(7).
Reviewing the literature, there appear to have been only two reported pediatric cases of bacteremia due to G. morbillorum(8). In both cases an association of G. morbillorum with septic shock syndrome, which was fatal in one case was demonstrated. The organism was presumably seeded into the bloodstream from the oral flora following intubation in the first case. Whereas in the other case bacteremia probably appeared as a complication of maxillary sinusitis.
In our case, the patient had malignancy and probably acquired the systemic infection from an infected central venous catheter as a catheter was in place at the time blood was obtained for culture. This child remained febrile when em-pirical treatment with intravenous ciprofloxacin and gentamicin was given before results of culture were obtained. It was only after identi-fication of this organism was made and antibiotic susceptibility ascertained that the treatment was modified to cloxacillin to which, the child responded immediately.
The fact that infection occurred in a child who was receiving chemotherapy and hence immunocompromised, suggests the possibility that G. morbillorum may be encountered as an opportunistic pathogen in immunocompromised patients.
As far as we are aware, our's is the only reported case of infection due to this organism in a child, from the Indian sub-continent. Despite its rarity, the pathogenicity of G. morbillorum should not be underestimated, especially in immunocompromised patients.
1. Kilpper-Balz R, Schleifer KH. Transfer of Streptococcus morbillorum to the Gemella genus, Gemella morbillorum comb. Nov. Int J Syst Bacteriol 1988; 38: 442-443.
2. Calopa M, Rubio F, Aguilar M, Peres J. Giant basilar aneurysm in the course of subacute bacterial endocarditis. Stroke 1990; 21: 1625-1627.
3. Omran Q, Wood CA. Endovascular infection and septic arthritis caused by Gemella morbillorum. Diagn Microbiol Infect Dis 1993; 16: 131-134.
4. Debast SB, Koot R, Mas JF. Infections caused by Gemella morbillorum. Lancet 1993; 342: 560.
5. Facklam RR, Washington II JA. Streptococcus and related catalase-negative Gram-positive cocci. In: Manual of Clinical Microbiology. Eds. Balows A, Hauslers Jr WJ, Herrman KL, Isenberg HD, Shadomy HJ. Washington, DC, American Society for Microbiology, 1991; pp 238-257.
6. Tunnicliff R. The cultivation of a micrococcus from blood in pre and eruptive stages of measles. JAMA 1917; 68: 1028-1030.
7. Elting LS, Bodey GP, Keefe BH. Septicemia and shock syndrome due to viridans Streptococci: A case control study of predisposing factors. Clin Infect Dis. 1992; 14: 1201-1207.
8. Vasishtha S, Isenberg HD, Sood SK. Gemella morbillorum as a cause of septic shock. Clin Infect Dis. 1996; 22: 1084-1086.