Impaired Phagocytosis of Capsular Serotypes K1 or K2Klebsiella pneumoniaein Type 2 Diabetes Mellitus Patients with Poor Glycemic Control

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Abstract
Context: Diabetes mellitus (DM) and capsular serotypes K1 and K2 Klebsiella pneumoniae have been identified as risk factors for liver abscess and complicated endophthalmitis. Objective: The objective of this study was to determine whether poor glycemic control contributes to the development of capsular serotype K1 or K2 K. pneumoniae liver abscess. Design and Setting: Neutrophil phagocytosis in patients with type 2 DM and nondiabetic controls was compared with isolates from liver abscess. Phagocytic rates of 18 K1/K2 and nine non-K1/K2 K. pneumoniae strains were evaluated by flow cytometry and electron microscopy. Patients or Study Participants: Forty patients with type 2 diabetes, 14 with good glycemic control, 26 with poor glycemic control, and 13 age-matched healthy normal subjects, were studied. Main Outcome Measures: Phagocytic rate of K. pneumoniae was measured. Results: Phagocytosis of serotype K1/K2 isolates by neutrophils from diabetics was significantly less than normal controls (P < 0.01). Further analysis revealed that, in type 2 DM patients with poor glycemic control, phagocytosis of K1/K2 was remarkably impaired at 10 min (25.2 ± 1.7 vs. 42.4 ± 1.8%) and persisted until 60 min (51 ± 1.2 vs. 59.4 ± 1.4%; P < 0.01), but in type 2 DM patients with good glycemic control were similar at 10 min (38.2 ± 1.7% vs. 42.4 ± 1.8%) and at 60 min (57 ± 0.3% vs. 59.4 ± 1.4%; P = 0.2). No significant difference in the phagocytosis of non-K1/K2 K. pneumoniae among all subjects was observed. Conclusions: Poor glycemic control plays a role in impairing neutrophil phagocytosis of K1/K2 K. pneumoniae, but does not significantly affect the phagocytosis of non-K1/K2 K. pneumoniae. This study identifies poor glycemic control as a risk factor for susceptibility to serotype K1/K2 K. pneumoniae liver abscess and complicated endophthalmitis.