Jeremy Van, DO, Justin Mitchell, DO, MS; Rush University Medical Center, Chicago, IL
Introduction: Hypermucoviscous (HMV) Klebsiella pneumoniae (KP) is a hypervirulent strain of KP containing regulator of mucoid phenotype A1/A2 and mucoviscosity-associated gene. This increases capsule production and confers a HMV state. With (w/) this genotype and phenotype, there is a high risk of disseminated infection. This case describes a patient (pt) w/ HMV KP bacteremia complicated by pyogenic liver abscess (PLA).
Methods: A 42-year-old Hispanic male w/ past medical history (PMHx) of type II diabetes mellitus (DMII) presented w/ 3 weeks of generalized abdominal pain. No PMHx of liver/biliary disease. AST 34, ALT 29, Alk Phos 120, Hgb A1c 14. CT Abdomen and Pelvis (CTAP) w/ IV contrast (IVC) showed a 4.9 x 6.7 cm multiloculated cystic lesion in the posterior right hepatic lobe; re-demonstrated on MRI. Blood cultures (cx) were positive (+) for pan sensitive (PS) KP w/ + string test (ST). Purulent fluid was aspirated from the lesion and aerobic cx grew PS KP w/ + ST. Acid fast bacilli cx, anaerobic cx, and fungal cx were negative. Cysticercosis IgG and stool Ova and Parasites were negative as well. He was treated w/ IV Rocephin for 4 weeks. Discussion: HMV KP PLA tend to be found in Asian pts w/ an increasing number of cases in North America. DMII is believed to be a risk factor because of impaired neutrophil phagocytosis of K1/K2 hypercapsular serotypes in HMV KP. Data is limited on how HMV KP is acquired but it develops in those without biliary disease, a common risk factor for other PLA’s. It also tends to seed the liver hematogenously from an intestinal route of entry. A unique feature, uncommon in other enteric gram-negative bacilli, is the ability to metastatically spread, causing endophthalmitis for example. The “string” test, using an inoculation loop on a cx and generating a viscous string >5mm, helps to identify HMV phenotype. CTAP w/ IVC is the recommended imaging tool and the abscess needs to be drained for cx data. There is high drug sensitivity and a 4 to 6 week course of a cephalosporin is the mainstay of therapy. Longer courses are warranted for persistent radiographic evidence of abscess. Colorectal cancer increases the risk for PLA via portal venous bacterial invasion from colonic mucosal defects. It is important for pts w/ HMV KP PLA to get a screening colonoscopy. Jun JB. Klebsiella pneumoniae Liver Abscess. 2018 Sept 28. 210–218.
Shon AS, Bajwa RP, Russo TA. Hypervirulent (Hypermucoviscous) Klebsiella pneumoniae: A New and Dangerous Breed. 2013 Feb 15. 107–118.
Axial View: 4.9x6.7cm multiloculated posterior right hepatic lobe lesion with thick walled mildly enhancing septations and cystic spaces with mild diffusion restriction
Coronal view of the lesion
Disclosures: Jeremy Van indicated no relevant financial relationships. Justin Mitchell indicated no relevant financial relationships.