Multiple organ failure by serotype K1 Klebsiella pneumoniae

Liver abscess syndrome caused by Klebsiella pneumoniae (K. pneumoniae) is a community-acquired infection characterised by primary liver abscess, bacteraemia and metastatic complications (lung, brain and psoas abscesses; osteomyelitis; meningitis; and endophthalmitis) with high mortality (10–40%). It occurs in immunocompetent patients, and the main risk factor is diabetes.¹

Case report

A 67-year-old diabetic patient had a history of ischaemic cardiomyopathy and hypertension. In 2006, he had bilateral pneumonia, calculous cholecystitis and septic shock caused by K. pneumoniae. In 2007, he contracted community-acquired pneumonia (K. pneumoniae in sputum), and in 2008, he underwent laparoscopic cholecystectomy.

He attended the emergency department due to signs and symptoms for 48 h of a sudden decrease in visual acuity, fever (39 °C) and headache. He was diagnosed with posterior uveitis of the right eye, and treatment with corticosteroids was started. One day later, he was in very poor general condition, with severe holocranial headache, phonophobia, photophobia, fever (38 °C) and abdominal pain on palpation.

Complementary studies revealed significant hyperglycaemia, mild hypertransaminaemia, mild impairment of renal function, clear lumbar puncture fluid, pleocytosis and abnormal cerebrospinal fluid protein level. An electrocardiogram, chest X-ray, head CT scan and echocardiogram were normal. An abdominal ultrasound showed a 12-mm abscess on the left lobe of the liver.

Empirical therapy with intravenous ceftriaxone and vancomycin, as well as intravitreal ceftazidime and vancomycin was started. K. pneumoniae susceptible to all antibiotics except ampicillin was isolated in CSF, urine and blood cultures. The isolate was sent to a reference laboratory to confirm the suspected K1 serotype.

Six days after admission, due to the patient's poor clinical course, it was decided to enucleate the right eye. K. pneumoniae was again isolated in the vitreous humour.

The patient had a lower level of consciousness and left-sided hemiparesis. A whole-body CT scan was performed which showed multiple cerebral haemorrhages, pulmonary nodules, 2 abscessified collections in liver segment IV and left-sided perirenal free fluid. Treatment was changed to meropenem, amikacin and linezolid. A planned colonoscopy was performed which showed no abnormalities.

In subsequent ultrasound scans, hepatic fluid collection had reached 40 mm. Radiologically guided percutaneous drainage was unsuccessfully attempted. Treatment with meropenem, ceftriaxone and azithromycin was continued up to 8 weeks. Neurological recovery and resolution of brain, lung and liver lesions were achieved.

Discussion

K. pneumoniae is a Gram-negative enterobacterium that colonises the nasopharynx and gastrointestinal tract. Hypermucoviscosity is a characteristic possessed by only some K. pneumoniae strains that is associated with greater pathogenic power. Serotype K1 strains are positive for the magA gene, associated with hypermucoviscosity, which is part of the capsular operon of serotype K1 and essential for synthesising exopolysaccharides. The mucoid phenotype A (rpmA) regulator plasmid is the transcriptional activator which forms part of the molecular mechanism which in turn amplifies polysaccharide synthesis. Its virulence has also been associated with the aerobactin gene, a siderophore which maintains a constant flow of iron to the bacterium, thereby increasing its lethality.^2–4

These strains cause liver abscesses with metastatic impairment (endogenous endophthalmitis and CNS infections).⁵ This syndrome is an emerging infectious disease, initially reported in Asia but also documented in non-Asian patients and patients whose only risk factor is diabetes (which alters phagocytosis in Kupffer cells). Other authors think that the serotype K1 is the only risk factor for developing septic complications, including in immunocompetent patients.^6,7

Few cases have been reported in Spain.^8,9 This is the first with multi-organ impairment documented at our hospital. The patient was a representative of an airline with journeys to eastern countries and had lived in the United Arab Emirates for 4 years. Therefore, we thought that he may have acquired K. pneumoniae outside of Spain and that it may have found its way into his biliary tract despite the correct antibiotic treatment.

Although K. pneumoniae liver abscess syndrome in our area may be very uncommon, we believe that it should be taken into account, especially in diabetic patients. Diabetes is a risk factor and is associated with a worse visual prognosis in patients with endophthalmitis.² Strict glycaemic control may prevent metastatic complications in patients infected with serotype K1 K. pneumoniae. Even with suitable treatment (third-generation cephalosporins which penetrate the vitreous and CNS well), an early diagnosis would allow prompt percutaneous drainage, which could prevent the development of metastatic foci.¹⁰