Corynebacterium striatum bacteremia associated with cellulitis in a patient with cirrhosis

Abstract

Corynebacteria are a bacteria usually associated as a contaminant due to their presence in normal human skin and mucosal membranes. However, they are increasingly becoming recognized as an opportunistic pathogen. Corynebacteria can be pathogens in immunocompromised patients or those with malignancies or prosthetic devices. We present a rare case of bacteremia due to multidrug resistant Corynebacterium striatum in a 52-year-old male with cirrhosis. The patient had lower extremity cellulitis which likely served as a port of entry.

Introduction

Corynebacterium is a gram positive, aerobic rod. It is a bacterium which is usually thought to be a contaminant when cultured from blood because it is a normal inhabitant of skin and mucous membranes [1]. There have been numerous reports of Corynebacterium emerging as an opportunistic pathogen in patients who are immunocompromised, have a malignancy or are critically ill [1]. There are few case reports of nosocomial infections of Corynebacterium striatum associated with wound infections [2], as well as its recent emergence as a multidrug resistant nosocomial pathogen [3]. It was only until recently that Corynebacterium striatum was recognized as a pathogen and not merely a contaminant in both immunocompromised or immunocompetent hosts. We present a case of an immunocompetent patient with a bloodstream infection with Corynebacterium striatum associated with cellulitis.

Case report

A 52-year-old man presented to the Emergency Department due to altered mental status and lethargy. The patient had a past medical history of prior intravenous (IV) heroin abuse and was enrolled in a methadone program, chronic hepatitis C with concomitant liver cirrhosis and pancytopenia (Model for End-Stage Liver Disease score 18), hypothyroidism, peripheral vascular disease with chronic venous stasis in the lower extremities and essential hypertension. On presentation, his temperature was 103.3 °F, pulse rate 106 beats/minute and respiratory rate 22 breaths/minute. The patient was lethargic and minimally responsive to verbal stimuli, and responsive to painful stimuli. There was a holosystolic murmur at the cardiac apex not previously described. There was bilateral lower extremity chronic venous stasis with superimposed erythema bilaterally which was warm to touch. On the right anterior shin, there were two ecchymotic cutaneous wounds with serous exudates. On the left anterior shin, there were 3 ulcers of red granulating tissue without exudate.

Laboratory evaluation showed a hemoglobin of 9.2 g/dL, a platelet count of 26,000/μL with a leukocyte count of 5,700/μL. Liver function tests were within normal limits. The ammonia level was 105 μmol/L and lactic acid was 2.7 mmol/L. Urine toxicology was positive for methadone, and the blood alcohol level was negative. The chest radiograph was unremarkable for any acute pathology. Computed tomography (CT) scan of the brain was unremarkable. CT of the abdomen and pelvis without IV contrast was consistent with hepatic cirrhosis and portal hypertension.

The patient was admitted for sepsis secondary to lower extremity cellulitis and for suspected hepatic encephalopathy. He was treated with ceftriaxone 1 g once as well as lactulose 20 g every 6 h and rifaximin 550 mg every 12 h in the emergency room. After admission, vancomycin 1500 mg every 8 h and clindamycin IV 600 mg every 8 h were given. On hospital day two, a single set of admission blood cultures grew gram positive rods at 10 h in two bottles. Due to concern for bacteremia with listeriosis, the patient’s antimicrobial coverage was changed to vancomycin 1500 mg every 8 h along with ampicillin 2000 mg every 4 h and clindamycin was discontinued. The organism was identified as Corynebacterium striatum. Repeat blood cultures yielded the same pathogen at 28 h in yet another two bottles. Blood cultures were sent to a laboratory for speciation and susceptibility testing for the blood culture isolate. The patient’s ammonia levels normalized, however, the patient continued to appear lethargic. A transthoracic echocardiogram and eventually a transesophageal echocardiogram were unremarkable for any valvular vegetations. Blood cultures were sent to a laboratory for speciation and susceptibility testing for the blood culture isolate however this data was not available during the patient’s hospital stay. Treatment was switched to daptomycin 500 mg daily on the fifth day of his admission as he was not clinically improving. Within two days of this change, the patient’s clinical status improved significantly with return to his baseline mental status. The patient completed a total of 18 days of antimicrobial therapy.

Discussion

Corynebacterium striatum is a nondiphtherial Corynebacterium, which is gram positive, catalase positive, nonspore- forming, nonmotile, and rod-shaped [4]. It is generally considered to be a skin and mucosal colonizer. In rare cases, this microorganism has been found to be a pathogen. Case reports have shown Corynebacterium striatum to be associated with increased pathogenicity [4].

Our patient presented with C. striatum bacteremia. The persistent bacteremia suggested that the organism is a pathogen in this case. The role of this bacterium in clinical disease is now more clearly established. Corynebacterium striatum is recognized as a true pathogen when isolated in several samples from sterile body sites or from indwelling medical devices [4,5]. It has been associated with bacteremia, endocarditis with valvular damage, meningitis, urinary tract infections, respiratory tract infections and skin wounds [6,7].

While data has shown that there are high rates of resistance to many antimicrobial agents, vancomycin, linezolid, and daptomycin have been found to be effective in treating C. striatum [3]. There have been high rates of resistance found to penicillin, clindamycin, cefotaxime, erythromycin, and ciprofloxacin [3]. Since our patient failed to improve on vancomycin and susceptibility testing was unavailable, the antimicrobial therapy was changed to daptomycin. The patient was successfully treated with daptomycin, with subsequent blood cultures being negative. The cause of the patient’s altered mental status on presentation appeared to be multifactorial. The patient did not improve significantly with lactulose and rifaximin with normalization of serum ammonia. Clinical improvement occurred only with the initiation of appropriate antimicrobial therapy.

Pathogenicity of Corynebacterium has been significantly associated with immune compromise or indwelling catheters [8]. We wished to discuss the association of this organism in a patient with Cirrhosis. The role cirrhosis in bacteremia with a multi- drug resistant organism has been studied and reported. Cirrhotic patients have a 10-fold increase in susceptibility to blood stream infections as compared to the general population as well as a significantly higher rate of mortality [9]. Furthermore, bacteremia caused by a multi drug resistant organism accounts for nearly one-third of blood stream infections (BSI) in cirrhotic patients [9]. Risk factors for BSI were further stratified based on the stages of liver disease. Patients with cirrhosis have a greater risk of developing Gram-positive BSI as compared to patients with chronic hepatitis [10]. Our case shows the importance of understanding Corynebacterium as an emergent pathogenic microbe, risk factors for infection should be considered and appropriate treatment initiated promptly. It is important to understand when an isolate represents an infection, a colonization or a contamination. This can only be done with clinical assessment. Clinicians should also consider the possibility of multidrug resistant strains of Corynebacterium.

Author statement

N.E., A.U. and K.T. all wrote the presented article. E.C. reviewed and edited the article and supervised the findings of this work. All authors discussed the results and contributed to the final manuscript. All authors provided critical feedback and helped shape the analysis and manuscript