Introduction
Pyogenic liver abscesses (PLA) are the most common type of visceral abscesses. Microbiology of PLAs is diverse and microorganisms involved differ mostly due to factors related to the patient, pathogenesis and geographic differences. Treatment includes percutaneous abscess drainage and empiric broad-spectrum antibiotic that covers streptococci, gram-negative bacilli, and anaerobes.
Aims & Methods
We present a retrospective study of 115 patients with pyogenic liver abscesses (PLA) diagnosed and treated in a peripheral portuguese hospital, in Lisbon district, from January 2012 to December 2022. The aim of this study is to analyze microbiology of PLAs and antibiotic treatment in an European Centre. Amebic liver abscesses were excluded.
Results
Of the 115 patients included, the majority were men born in Portugal. The most common risk factors identified were biliary calculi (32%, N=36) and diabetes mellitus (27%, N=31). At the time of PLA diagnosis, 41% of the patients had bile duct obstruction and 32% had undergone biliary tract manipulation in the prior 30 days. Around 10% of the PLAs were attributed to hematogenous seeding from the systemic circulation. Blood cultures were obtained in 73% of the patients (N=84), and only 33% were positive (N=38). The most frequent isolated microorganisms in blood samples were Escherichia coli (34%, N=23) and Klebsiella Pneumoniae (17%, N=11). Only one extended-spectrum beta-lactamase bacteria (ESBL) was identified in the systemic circulation and no Klebsiella Pneumoniae Carbapenemase (KPC) was identified. 49% underwent CT or ultrasound-guided liver abscess drainage and culture of the collected fluid (N=57). All abscesses larger than 5cm were drained. Drainage cultures were positive in 70% of patients (N=40). Around 60% of these patients had one microorganism isolated and the others had 2 to 4 microorganisms isolated. The most common isolated microorganisms in the drainage liquid were also Escherichia coli (22%, N=11) and Klebsiella Pneumoniae (16%, N=8). Three ESBL were detected in drained liquid cultures and no KPC was found. Piperacillin-Tazobactam (54%,N=63) was the most used empiric antibiotic followed by Meropenem (14%,N=16) and Ceftriaxone (12%, N=14). Piperacillin-Tazobactam was effective in 84% of patients, Meropenem was effective in 100% and Ceftriaxone was effective in 90%. Metronidazol was added to the previous antibiotics in 21% of cases (N=24); it was mostly added to Ceftriaxone and Piperacillin-Tazobactam, 64% and 17% of cases, respectively. The most frequent anaerobes identified were Fusobacterium Nucleatum and Bacterioides Fragilis. All patients that had Fusobacterium Nucleatum identified had previous history of dental procedure (N=4). A total of 28 different microorganisms were isolated in blood and abscess drainage culture. The average antibiotic duration and was 24±9 days, which is similar to the average hospital length of stay: 24±15 days. 30-day mortality was 9% (N=10).
Conclusion
The diversity of pathogens associated to PLAs in a single centre reflects the different cause of each PLA. Escherichia coli and K. pneumoniae were the most commonly identified pathogens. Bacteremia was documented in 33% of cases and drainage culture was positive in 70% of cases. More than one microorganism was identified in 40% of drainage cultures. PLA are associated to significant use of broad-spectrum antibiotics, frequently unnecessarily.
References
Meddings L, Myers RP, Hubbard J, et al. A population-based study of pyogenic abscesses in the United States: incidente, mortality and temporal trends. Am J Gastroenterol 2010;
Mohsen AH, Green ST, Read RC, McKendrick MW. Liver abscess in adults: ten years experience in a UK centr. QJM 2002.