KPLA is a critical infectious disease, which could cause sepsis and/or other severe complications. However, few studies on the complications of KPLA have been published. In this study, KPLA was diagnosed in 135 of the 360 (37.5%) patients, and the incidence of sepsis in KPLA was 27.4% (37 of 135 patients). Our study found the sepsis group was more likely to have the metastatic infections with lung and eye.
A large proportion of the patients in our study were males, with the average age of 60.9±12.7 years old, compared with previous studies[2, 15]. Zhang J et al. reported that elderly patients with age over of 65 years were more likely to develop pyogenic liver abscess. The previous studies reported that the mean age was 59.6 years, and the age group with the greatest number of patients was 51 to 60 years. In present study, the results showed that men were more likely to develop sepsis than women. Hormonally active women are better protected from sepsis than men. Sex hormones play an important role in inflammatory responses. It was notable that fever was present in 91.1% of patients, which was consistent with other studies. In our study, 50.0% of KPLA patients were diabetic. As reported previously, diabetes mellitus were the most common underlying disease in KPLA patients. The functional abnormality in neutrophil chemotaxis and phagocytosis may contribute to a relatively high incidence of KPLA in diabetes mellitus. In this investigation, we found that sepsis patients had a higher incidence of frailty, diarrhea, which were non-specific and may lead to a delayed diagnosis of PLA. Furthermore, patients with sepsis had a significantly higher prevalence of underlying diseases with fatty liver, chronic renal insufficiency, hepatic dysfunction, which indicates that PLA patients with sepsis had a greater incidence of metabolic disorders.
The laboratory features are also non-specific for the diagnosis of KPLA. Most patients had increased levels of white blood cell counts (WBC), neutrophil percentage (NE%), C-reactive protein (CRP), procalcitonin (PCT), fibrinogen, which were considered to be the markers for infection. Furthermore, blood urea nitrogen and creatinine levels of the sepsis group were higher, which suggests that renal insufficiency in KPLA patients with sepsis was more evident. In addition, these laboratory examinations may reduce the misdiagnosis of PLA.
Extrahepatic metastatic infection is one of the fatal complications for KPLA patients. Recently, K. pneumoniae liver abscess with septic metastatic lesions has been often reported[22, 23]. KPLAs were associated with metastatic infection especially including eye or central nervous system (CNS), which is consistent with several studies that metastatic infections are more common in KPLAs than non-KPLAs and the prevalence rate of metastatic infections has increased[9, 24]. In this investigation, the incidence of extrahepatic metastatic infection in KPLA was 8.8%, which was consistent with previous reports[1, 25]. We observed that KPLA patients with sepsis may be more likely to have some complications, including acute kidney injury, acute respiratory distress syndrome, and spontaneous bacterial peritonitis. The sepsis group also revealed a high incidence of metastatic infection. Our results corresponded to the previous investigations, this may be due to the failure of liquefaction owing to the high prevalence of a phagocytosis-resistant, capsular serotype Klebsiella pneumoniae associated with liver abscess. In our study, 12 patients with KPLA had severe metastatic infectious conditions at admission. The mortality was 1.5% overall, and 2 of them died of overwhelming sepsis and multiple organ failure. Our data showed that three patients had endophthalmitis. Despite aggressive intravenous and intravitreal antibiotic therapy, 2 of them were eventually eviscerated or enucleated. Other associated septic metastatic infections included pulmonary infection in 11 cases, pleural effusion in 4 cases, brain abscess or meningitis in 1 case, and peritonitis in 1 case.
In the present study, we found that most of the K. pneumoniae strains isolated were susceptible to most of the antibiotics, but with resistance only to ampicillin. Previous studies also reported that the emergence of carbapenem-resistant K. pneumoniae in some strains may lead to final treatment failure. Therefore, the antibiotics are most widely used in current clinical practice. However, the rising trend in resistance have been reported elsewhere in the world. As known the capsule of K. pneumoniae may play an important role in the resistance of uptake and killing by host phagocytes, it is prudent to ensure sensitivity-directed antibiotics therapy during KPLA treatment to prevent further development of antibiotic resistance.
In general, strategy of therapeutic methods was dependent on the size and number of abscesses, degree of abscess liquefaction, and with/without other possible complications. In our study, the first treatment was antibiotics and percutaneous pigtail catheter drainage of KPLA, followed by antibiotic alone. Intravenous antibiotics were given to all these patients and 90.4% underwent percutaneous drainage, 4.4% underwent surgical drainage. There were no significant differences between these two groups of patients in treatment of PLA. For antibiotic treatment, the most commonly used antibiotics were carbapenems and third generation cephalosporin combined with or without metronidazole. Except for complicated cases, we recognize that appropriate antibiotic coverage and early adequate percutaneous drainage should be considered as the cornerstones of therapy for KPLA patients. As for KPLA patients with severe infectious symptoms at admission, adequate coverage with empirical antibiotics may be reasonable until culture data are available.
We acknowledge the limitations in our study. Firstly, this was a retrospective, single-center study, and may not be generalizable, as the majority of our patients were Chinese. Secondly, we excluded the patients with liver abscesses demonstrated no growth on either blood or pus cultures, which was probably related to the use of empirical antibiotics treatment prior to blood or pus collection. In this study, it was excluded because it was hard to specify the pathogen. Finally, whether there is any epidemiologic evidence of the relationship between K. pneumoniae capsular serotyping or plasmid-associated virulent factor and the clinical manifestations remains to be investigated. However, we believe that these results may be generalized to routine clinical practice in Chinese patients with pyogenic liver abscess.
In conclusion, PLA is a relatively common infectious disease, and the incidence rate of sepsis in KPLA is quite high. KPLA patients with and without sepsis had many distinct clinical features. Metabolic disorders, including fatty liver, chronic renal insufficiency and hepatic dysfunction are common underlying conditions in patients with sepsis. Furthermore, KPLA patients with sepsis had a significantly higher risk of severe metastatic complications, including lung and eye infections. Based on our data, it is necessary to further elucidate the clinical and microbiological features of KPLA, with a focus on septic metastatic infection.