Meningitis and renal abscess by Streptococcus chicken group D; 2 case reports

Abstract

Introduction

Enterococcus gallinarum, nicknamed Streptococcus chicken group D, is a motile, Gram-positive facultative anaerobic bacterium that is rarely found in human clinical specimens but frequently encountered in the gastrointestinal tract in poultry. It is an opportunistic pathogen which causes infections in humans rarely. These infections present a significant therapeutic challenge due to their intrinsic resistance to vancomycin and other antibiotics typically used to treat Enterococcus infections. These two case reports aim to contribute to the limited literature on this pathogen in the causation of meningitis and renal abscesses.

 Case report 1

A two-month-old baby boy with a history of mild left ventricular dilatation, possibly secondary to evolving cardiomyopathy combined with a stormy postnatal period, presented with a fever for two days with poor weight gain.

The baby was febrile, tachycardic, and tachypneic but maintained saturation. He was active and alert without nuchal rigidity. Laboratory investigations on admission revealed a neutrophilic leukocytosis, anemia, and CRP of 292mg/dL.  The CSF full report revealed an elevated polymorph count, with significantly low glucose and high protein levels. An ultrasound scan (USS) of the abdomen showed a possibility of a right-sided renal lump.

Further investigations revealed persistently elevated inflammatory markers. Both CSF and Urine cultures remained sterile, while the blood culture grew a motile Enterococcus species, which was confirmed as Enterococcus gallinarum by the Vitek® automated identification system. It was sensitive to linezolid and ampicillin while resistant to vancomycin. Empirical cefotaxime was switched to IV ceftriaxone 340mg daily, and IV Ampicillin 170mg every 6 hours was added following culture results. Repeat USS abdomen revealed right-sided pyelonephritis with abscess formation at the lower pole of the right kidney. The cranial USS was unremarkable. Infective endocarditis was excluded. Aspiration of the renal abscess was not performed, as the response to the current treatment regimen was satisfactory. He was treated for a total of three weeks, and one month review after discharge disclosed no relapses ultrasonically.

 Case report 2

 A 50-year-old man with diabetic ketoacidosis presented with fever, dysuria, and backache for several days. He was septic and in acute kidney injury with rising creatinine of 174 µmol/L, and USS revealed bilateral pyonephrosis and renal abscesses. His white cell count was 7x103 /mm3 with neutrophils at 80%, CRP of 247 mg/L, and urine culture was sterile.

On admission, his blood culture grew Enterococcus gallinarum. Endocarditis was excluded.  He was treated with IV meropenem initially and later combined with linezolid after the sensitivity. Treatment was continued for three weeks until a satisfactory clinical, biochemical, hematological, and radiological response was achieved. Interestingly, it was revealed retrospectively that he is keeping a chicken farm and working there himself with the others.

 Discussion

In addition to enterococcal meningitis, the first patient had pyelonephritis complicated with abscess formation, which is likely due to hematogenous spread. The second patient had renal abscesses. Due to its uncommon etiology, high clinical suspicion, proper and timely bacteriological diagnosis, and targeted antibiotic use with adequate duration of therapy were of paramount importance in treating infections caused by this pathogen. Once blood culture becomes positive, it is necessary to exclude endocarditis and deep-seated abscesses to ensure adequate duration of antibiotics. Avoiding unnecessarily prolonged antibiotic regimens and enhancing immunity are of great value in reducing the incidence of infections in hospital settings.