Elderly patients have more severe biliary infections: influence of complement-killing and induction of TNFalpha production.

Background: Biliary bacteria are more common in elderly patients and cause more serious illnesses. The reasons for this are unclear. We noted previously that bacterial serum-sensitivity and induction of TNFalpha production in sera (iTNFsera) were associated with severe biliary infections. We examined the influence of age and these factors on illness severity.
Methods: Three-hundred and forty patients were studied. Gallstones and bile were cultured. Illness was staged as none (no clinical infection or inflammation), SIRS (fever, leukocytosis), severe (cholangitis, abscess, empyema), or MODS (bacteremia, hypotension, organ dysfunction/failure). Bacterial serum-sensitivity and TNFalpha induction were measured. Younger (< 70 years) and elderly (> or = 70 years) patients were compared.
Results: Biliary bacteria were more common in elderly (64% vs 41%, P < .0001). Among patients with biliary bacteria, the elderly had more serious illnesses: none: 44% younger, 19% elderly; SIRS: 16% younger, 22% elderly; severe: 22% younger, 21% elderly; MODS 18% younger, 38% elderly (P = .003). Bacteria from elderly patients induced more TNFalpha (580 vs 310 pg/ml, P = .023). In both groups, serum-sensitive bacteria caused infectious manifestations and induced abundant TNFalpha; however, serum-resistant bacteria from elderly usually (69%) caused infectious manifestations and abundant TNFalpha, while serum-resistant bacteria from younger patients rarely (8%) caused infectious manifestations and minimal TNFalpha. Elderly patients with high iTNFsera bacteria had more severe illnesses.
Conclusions: Biliary bacteria were more common in elderly patients and produced more serious illnesses. Many younger patients with biliary bacteria displayed no infectious manifestations. Elderly patients harbored more virulent bacteria, and had a heightened response to high iTNFsera bacteria, as well as bacteria largely tolerated by younger patients.