Granulicatella adiacens as a Cause of Bacteremia in Immunocompromised Patients: A Case Report

-  Granulicatella species (spp) is an opportunistic infection in immunocompromised patients especially neutropenic, particularly if they required long hospitalization and intensive care unit admission.

-  Infection rate of Granulicatella spp may be underestimated since the organism necessitates automated identification.

-  Resistance among Granulicatella spp to penicillin, macrolide and cephalosporins has been described and should be taken into account when considering empirical therapy.

DISCUSSION

Nutritionally variant streptococci (NVS) show better growth on media supplemented with thiol or pyridoxal. With the increased use of automated blood culture bottles that contain pyridoxal and L‑cystein, their isolation rate has increased.  G. adiacens is an uncommon cause of infection, usually related to endocarditis or indwelling device related infection or surgery with the organism being isolated from brain abscess, CSF, joint space. However, literature has reported cases of bacteremia with Granulicatella spp without endocarditis [8].

Nutritionally variant streptococci should be suspected upon detection of Gram positive cocci through stained films together with negative culture results, due to required fastidious culture conditions, therefore, appropriate supplemented media and a reliable detection system is required for identification [9]. Commercial blood culture media contain pyridoxal, thus, support growth of NVS, also, Satellitism around Staphylococcus aureus colonies can enhance growth. Using the API Strep or the advanced laboratory systems as Matrix-assisted laser desorption ionization time-of-flight mass spectrometry or the VITEK 2 system, NVS can be identified to the species level with good sensitivity and specificity [2].

Granulicatella isolates were mainly isolated from immunocompromised patients, perhaps due to the weakened immune mechanism and the disrupted mucosal barrier immune function, which enhance the patient own normal flora to cross these barriers reaching different body sites as blood, endocardium, bones or body fluids as ascitic or pleural fluid where, they can exert a virulent pathogenic effect [10].

Kawai and Shiojiri [11] reported a case of a 58 years old adult Japanese male with Bipolar disorder, treated with Lithium and presented to the emergency department with fever and loss of consciousness, pan- CT (Computed Tomography) scan with contrast was done to identify the infected focus, revealing left cervical vein thrombosis, intramuscular abscesses around the left femur and pulmonary embolism, the patient was diagnosed with Jugular vein thrombophlebitis, lithium intoxication and uremia, for which he underwent hemodialysis, also blood culture was withdrawn which showed positive signal within 20 hours of incubation, G. adiacens was found to be the implicated organism. Ampicillin (AMP) was started and subsequent blood cultures were negative. On day 16, AMP was changed to cefotaxime (CTX) as drug fever was suspected to be caused by AMP.  CT scan was done on day 40, pulmonary embolism disappeared, but, the left cervical vein thrombus did not get smaller in size, and the femur abscesses got larger, which necessitated drainage. After drainage, edoxaban was added. Repeated CT scan on day 56, showed complete resolution of the left cervical vein thrombus and gluteal abscesses, however, femur abscesses did not disappear completely. Intravenous (IV) CTX was changed to oral amoxicillin. On day 98, He was transferred to a healthcare facility that provide psychiatric care with oral amoxicillin for another two weeks and long-term edoxaban administration. In this patient, poor dental hygiene with periodontitis, was incriminated as the risk factor for left cervical vein thrombus, since, G. adiacens is a part of the normal oral flora and can cause endodontic infections with subsequent spread to surrounding tissues.

Also, Cho et al. [12] reported a case of a 45-year-old male presented to the outpatient clinic after accidental discovery of a left sided abdominal mass. Endoscopic ultrasound-guided fine needle aspiration or biopsy (EUS-FNA or FNB) was done as a part of the patient investigations which was complicated after ten days by septic shock and splenic abscess. Piperacillin/tazobactam (TZP) was started with the onset of septic shock, and blood culture was withdrawn, which showed positive growth of G. adiacens, TZP was changed to ampicillin/sulbactam (SAM). The patient condition improved and was discharged. Pathological examination of the resected splenic mass revealed diffuse large B-cell lymphoma. After recovery from septic shock, he got vaccination against encapsulated organisms and splenectomy was performed four weeks after vaccination. Then, the patient received chemotherapy and underwent complete remission. This case highlighted that EUS-FNA or FNB in rare cases may precipitate infection with subsequent septicemia.

CONCLUSION

Granulicatella species are nutritionally deficient fastidious organisms, part of the human normal flora, which usually affect immunocompromised patients.  Granulicatella should be suspected in patients where slowly-growing mucoid alpha-haemolytic gram positive cocci are isolated.  In case of absent or poor growth on culture plates, we recommend to perform satellitism to enhance recovery of the organism together with further incubation of the culture plates.‎

Funding: None

Ethical consideration: All the information gathered from the patients was handled confidentially, and it was used only for research purpose.

Conflict of interest: There is no conflict of interest.