Introduction
Emerging organisms are defined as organisms that have newly appeared in the population or have been present for some time but are spreading rapidly in terms of incidence, host range, or geographic distribution. Granulicatella adiacens (G. adiacens) is recorded as one of the emerging organisms.1 These emerging organisms, although less in number, should not be ignored and are necessary to be studied in detail.
Granulicatella adiacens is a Gram positive bacteria and a normal commensal of the oral cavity, genital and gastrointestinal tract, which is also termed as nutritionally variant streptococcus (NVS) because of its requirement of pyridoxal supplements.2
G. adiacens is commonly known to cause infective endocarditis and bacteremia.3, 4, 5 A few cases of musculoskeletal infections such as prosthetic joint infections, osteomyelitis, localized pyogenic infections such as abscess and empyema, and ophthalmological infections such as endopthalmitis with microbial keratitis are also noted.6, 7, 8, 9, 10
Hereby, we are presenting a case of Granulicatella adiacens isolated from the serous fluid of the cellulitis of the right foot.
Case Presentation
History
A 33 year old male, vegetable vendor by occupation, residing at Bhayander in Thane district, non-diabetic and non-hypertensive, presented to the hospital with a complaint of itching, sudden pain and swelling of the right foot and lower limb for 3 days. The patient did not have fever. Patient had scratched his right foot with his nails, which was followed the next day by redness and swelling on the foot. Subsequently, a day later, the swelling and redness spread rapidly to the lower half of his right leg. Patient had no past history of travel, trauma, insect bites, varicose veins, or any other skin disease.
On general examination, the patient was afebrile with mild tachycardia. Rest of the CVS and CNS findings were normal. Local examination revealed erythematous, warm, tender swelling on the entire right foot, extending to the lower half of the right leg. There was no evidence of previous skin infections, blisters, or venous stasis ulcers.
Laboratory investigations
Pathalogical finding
Blood investigations showed neutrophilic leukocytosis (total WBC count = 30,420/µL with 87% neutrophils). The liver function test, renal function, fasting blood glucose were within normal limits. The patient was found to have raised TSH levels of 25.9 mIU/L, diagnosing newly detected hypothyroidism.
Microbiological findings
The serous fluid from the incisions over the erythematous warm leg was collected after cleaning the wound area with sterile normal saline and gauze piece. Thereafter, the nearby area was squeezed, and the serous fluid was collected aseptically in a sterile container. The specimen was sent to the department of Microbiology for bacterial culture. The serous fluid was clear and non-hemorrhagic.
On gram staining, few polymorphonuclear cells with occasional Gram-positive cocci in pairs and chains were seen. The specimen was inoculated on 5% Sheep Blood Agar (SBA) and MacConkey’s agar. After overnight incubation, the colonies on SBA were tiny, pinpoint, translucent, alpha hemolytic with no growth on MacConkey’s agar.The organism was identified by VITEK-2 compact (Biomerieux Clinical Diagnostics, France, headquarters: New Delhi, India) as Granulicatella adiacens with 99% probability. However, VITEK could not provide the susceptibility pattern. Hence, the antimicrobial susceptibility was performed by Kirby Bauer Disc Diffussion (KBDD) method on Mueller Hinton agar with sheep blood and interpreted as per Clinical and Laboratory Standards Institute (CLSI) guidelines-2022 for streptococcus spp. The Granulicatella adiacens isolate was found to be susceptible to ampicillin, amoxicillin- clavulanic acid, ceftriaxone, ciprofloxacin, clindamycin, cotrimoxazole, gentamicin, linezolid, teicoplanin and vancomycin while resistant to azithromycin and erythromycin.
Treatment
At the time of admission, the patient was started on intravenous antibiotic combination of cefoperazone and sulbactam 1.5 gm 12 hourly, intravenous teicoplanin 400 mg 12 hourly, antiemetic, antipyretics, and iron supplementation. Intravenous tramadol and thyronorm tablet were started for the pain in the right foot and hypothyroidism respectively. On the 3rd day of admission, the patient underwent a right foot wound fasciotomy and debridement under popliteal block. The serous fluid was sent for culture and sensitivity testing and based on the antimicrobial susceptibility pattern, the antibiotic was changed on post-op day 3 to intravenous linezolid 600 mg 12 hourly for 2 days along with regular cleaning and dressing of the operative site.
Follow up
Pain and fever subsided over a few days and there was a notable decrease in the total WBC count from 30,420/µL to 11,980/µL. The patient was discharged without any complications post 5 days of surgery on oral ciprofloxacin and oral linezolid for 5 days and his follow-up OPD visits were uneventful.
Discussion
Granulicatella adiacens (G. adiacens), previously known as nutritionally variant streptococcus (NVS), is a rare fastidious bacterium, with new emerging cases being reported since 2000.2 It most commonly causes “culture-negative” infective endocarditis, followed by bacteremia.3, 4, 11, 5, 12 A few cases of prosthetic joint infection (especially knee and hip joint),6 osteomyelitis (vertebral and mandibular)7, abscess,8 empyema9, and endopthalmitis with microbial keratitis,10 have been noted. There have also been isolated reports of G.adiacens causing spondylodiscitis,13 carbuncle,14 urethritis.15 internal jugular vein thrombosis.16 Recent study by Purohit et al identified clinicoepidemiological details of all the cases till date, which showed that bacteremia caused by Granulicatella adiacens has been seen due to the following etiologies: multiple trauma foci, early onset neonatal sepsis, Shone syndrome (coarctation of aorta, mitral stenosis and subvalvular aortic stenosis) and infundibular pulmonary stenosis.9
In this case, the patient came with right foot cellulitis, which presented as erythematous, tender swelling of the right foot. The main differential diagnosis was cellulitis which is mainly caused by group A streptococcus. However, the serous fluid from the wound isolated G.adiacens. In India, there have been a total of 8 studies where G.adiacens bacteria was isolated including 4 cases of infective endocarditis,3, 4, 11, 5 1 case of carbuncle14, 5 cases of bacteraemia and 1 case of ventriculoperitoneal (VP) shunt infection,5 1 case of urethritis,15 2 cases of abscesses8 and a recent fatal case of empyema complicated with sepsis and necrotizing fasciitis.9 In this case, the source of infection could be scratching of foot with contaminated nails since G.adiacens is a normal commensal of oral cavity, gastrointestinal tract or urogenital tract.2
Specimen collection plays an important role, based on which further process depends. Generally, for serous discharge, swab is collected. In our case, the clinicians collected the serous discharge aseptically with syringe and needle, which is much preferred than swab.
Studies recommend the use of pyridoxal supplementation for growth of G adiacens,2 but in our case, there was confluent growth of Granulicatella adiacens on SBA, which was also found by Krishna S.et al.5 Further, it is difficult to identify these rare organisms by conventionally available tests, which could be the reason for underreporting or reporting them as streptococcus spp. Automated systems like VITEK-2 and Matrix-assisted laser desorption ionization–time-of-flight mass spectrometry (MALDI TOF MS) help in identification of such rare organisms.17 The automated system like VITEK also provides a probability percentage about the accuracy of the identified organism, which does increases confidence in the report. Hence, laboratories who do not have automated system facilities should collaborate with those labs for accurate identification. Antimicrobial susceptibility pattern is varied as per different publications.8, 18 Although, G. adiacens is currently sensitive to most of the antibiotics, there is a need to keep a watch on the susceptibility pattern for a longer duration.
Most cases in India have been cured, as seen with our patient; however, one case of empyema was complicated with sepsis and necrotizing fasciitis leading to death of the patient. Hence, we discuss this case, as it is significant for laboratory technicians to prevent its misdiagnosis as well as clinicians to be aware of this rare yet potentially infective bacteria.
Conclusion
Granulicatella adiacens is a rare yet pathogenic bacteria which could be ignored by treating clinicians. Reporting of such rare organisms should be carried out by microbiologist along with communication with clinicians for clinical correlation and insisting of publication of such rare cases for knowledge of scientific community.
