It is believed that several aspects of immunity are altered in patients with diabetes. For example, polymorphonuclear leukocyte function is depressed; leukocyte adherence, chemotaxis and phagocytosis may be affected; and antioxidant systems involved in bactericidal activity may also be impaired. Although these in vitro findings have not yet been fully confirmed in clinical studies, there is evidence that improving glycemic control in patients improves immune function
. Kornum et al. found that an elevated HbA1c predicted increased risk for all-cause community-acquired pneumonia among patients with diabetes
. In diabetic patients with sepsis, one study has demonstrated that HbA1c is an independent prognostic factor for hospital mortality and length of stay
. Regarding the issue of glycemic control and KPLA, only one case series from Taiwan analyzing 6 cases of recurrent KPLA has been reported in the literature. Five of the six patients had diabetes with poor glycemic control, and four had HbA1c >; 9% (range: 9.2–17.5%)
. The current study is, to the best of our knowledge, the first to investigate the effect of glycemic control on characteristics of KPLA in diabetic patients.
In our study, we found that patients with uncontrolled glycemia tended to be younger, and had the trend to have a higher rate of cryptogenic liver abscess, gas-forming liver abscess, and metastatic infection than those with controlled glycemia, although these differences did not reach significance. Young age, newly diagnosed diabetes, cryptogenic liver abscess and metastatic infection were more common in the poor glycemic control group (HbA1c value >; 10%). Cryptogenic invasive KPLA is frequently associated with diabetes
; therefore, we further established that it was highly linked to diabetic patients with high level of HbA1c. The finding that younger patients with KPLA are prone to have uncontrolled glycemia has never been reported, in part due to the small sample sizes of studies reported in the literature
Lin et al. have analyzed the effect of glycemic control of type 2 diabetes on neutrophil phagocytosis of serotype K1/K2 K. pneumoniae isolates. This in vitro study suggests that strict metabolic control may improve the neutrophil phagocytosis of K1/K2 K. pneumoniae in patients with type 2 diabetes
. In the current study focusing on diabetic patients, we not only found that the rate of metastatic infection was more common in patients with poor glycemic control, but also that HbA1c level was an independent risk factor for metastatic infection. It is also notable that there was no mortality, metastatic infection or gas-forming abscess in the group with controlled glycemia. The previous in vitro study by Lin et al. may support our clinical findings, and we suggest that HbA1c level is detrimental in KPLA, and controlled glycemia may prevent the development of serious metastatic complications.
Previous case reports have demonstrated that diagnosis of diabetes may come to light because of KPLA
[32, 33]. It is notable that around 25% of cases were newly recognized diabetes in the current study despite improvement in diagnosis and awareness in recent years, and the existence of a comprehensive national health insurance program in Taiwan that optimizes access to medical care. Due to unrecognized diabetes complicated with infection, extreme hyperglycemia, even hyperglycemic hyperosmolar state or diabetic ketoacidosis, may occur. Physicians should not ignore the underlying diabetes in patients with KPLA in clinical practice. One particularly interesting finding in our study was that liver abscess < 5 cm in diabetic patients was independently associated with metastatic infection, which has not been reported in the literature. It suggested that we should not overlook the risk of complication from small sized liver abscess in diabetic patients.
We acknowledge some limitations in our study that deserve mention. First, the data were collected retrospectively from medical records. Second, participants were recruited from a medical center in Northern Taiwan, and therefore we could not evaluate possible regional variations. Further analyses should be conducted in other regions and countries to confirm our findings. Thirdly, our results were also limited by the incomplete collection of HbA1c data. Finally, the isolates were not collected for further analysis, such as virulence factors or clonal types, in the current study. Despite these limitations, our study is believed to be the first to discuss the characteristics of KPLA due to the different level of glycemic control, which sheds further light on the association between diabetes and KPLA, and our results may partly elucidate the role of host factors in the pathogenesis of KPLA.