الفهرس 
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Abstract
Bacterial infection is a serious and often fatal complication of patients with liver disease and can prove fatal either directly or by precipitation of gastrointestinal bleeding, renal failure, or hepatic encephalopathy.
Often recognition of infection is made more difficult by the absence of the normal clinical feature of infection that is fever, rigors, hypotension and leucocytosis in which case the only clues may be deterioration of hepatic coma or renal function.
Thus, the development of diagnostic tools that are accurate and easily available is highly desirable. Lipocalin 2 may represent a prominent step in this direction since serum concentrations of lipocalin 2 allowed an accurate diagnosis of bacterial infection with negative and positive predictive values superior to results obtained using white blood cell counts and CRP.
Lipocalin 2, also known as Neutrophil gelatinase-associated lipocalin (NGAL), is a 25-kDA protein belonging to the lipocalin superfamily
Lipocalin 2 is an essential component of the antimicrobial innate immune system it is present in neutrophils and multiple other tissues. Elevated levels of lipocalin 2 have been detected in the blood of patients with bacterial urinary tract infection, community-acquired pneumonia, sepsis, as well as in the cerebrospinal fluid and peritoneal fluid of patients with bacterial meningitis and peritonitis.
Lipocalin 2 exerts bacteriostatic effects, which are explained by its ability to capture and deplete siderophores, small iron-binding molecules that are synthesized by certain bacteria as a means of iron acquisition. Consistently, lipocalin 2 deficiency in genetically modified mice leads to an increased growth of bacteria.
The objective of this study was to evaluate the role of lipocalin-2 as a diagnostic marker for bacterial infection in hepatic patients.
The study was carried out during the period from November 2014 to september 2015. The subjects of this study included 60 patients were admitted to medical, surgical and pediatric wards or attending the outpatient clinics at National Liver Institute, Menoufia University. The study also included 20 apparently healthy persons with matched age and sex as a control group.
The patients were classified into 2 groups. The first group included 40 patients of chronic liver disease with different types of infections. The second group included 20 patients of chronic liver disease without bacterial infection. It also included 20 apparently healthy persons with matched age and sex as a control group.
All patients and control were subjected to full history taking, complete clinical examination blood samples were collected for CBC, liver function tests, CRP and level of lipocalin 2 by ELISA. Microbiological examination (blood, urine, sputum and ascetic fluid cultures) were done for patients.
The current study showed that:
•According to types of infection of infected group, bacteremia was the most common infection (70%) followed by urinary tract infection (32.5%), followed by chest infection (22.5%) while spontaneous bacterial peritonitis was the least type of infection (20%).
•Regarding types of isolated oraganisms of different samples in infected patients the most commonly isolated organism was staph aureus from blood culture (35%), Staph aureus, klebsilla and E-coli from urine culture (10%), Klebsiela from sputum culture (15%) and E-coli from ascetic culture (17.5%).
•As regard level of infection markers in the studied groups:
WBCs was significantly higher in hepatic patients with bacterial infection (group 1) compared to other groups.
CRP level was significantly higher in hepatic patients with bacterial infection than hepatic patients without bacterial infection and control also CRP were significantly higher in hepatic patients without bacterial infection than control.
Serum level of lipocalin -2 was significantly higher in hepatic patients with bacterial infection than hepatic patients without bacterial infection and control. Serum lipocalin 2 positively correlated with CRP and WBCs count. •According to ROC curve analysis for lipocalin 2 levels, the current study showed that lipocalin-2 level at a cut-off of > 60 ng/ml had the sensitivity of 90%, the specificity of 72%, PPV of 77%, NPV of 88% accuracy of 81% in diagnosis of infection.
•According to ROC curve analysis for CRP levels, the present study showed that CRP level at a cut-off of > 5.5 mg/l had the sensitivity of 82%, the specificity of 70%, PPV of 73%, NPV of 80% Accuracy of 76% in diagnosis of infection.