Complications of Ascites Ascitic Fluid Infection

Categories and Diagnosis of Ascitic Fluid Infection

Ascitic fluid infection can be classified into three categories based on ascitic fluid PMN count, culture, and the presence or absence of a surgical source. These include spontaneous ascitic fluid infection, secondary bacterial peritonitis, and polymicrobial bacterascites. The spontaneous ascitic fluid infection is further divided into three subcategories, including (1) SBP, (2) monomicrobial non-neutrocytic bacterascites (MNB), and (3) culture-negative neutrocytic ascites (CNNA).

Table 113-2 summarizes the ascitic fluid analysis for different types of ascetic fluid infection. SBP constitutes two-thirds of all culture-positive spontaneous ascitic fluid infections. sBP is always monomicrobial. MNB contributes to the remaining one-third of all culture-positive spontaneous ascitic fluid infection. it can be regarded as an early-stage or even a common variant of ascitic fluid infection that progresses to SBP in 40% of cases and resolves without antibiotic coverage in the remaining 60%. Most episodes of CNNA are diagnosed because suboptimal cul

TABLE 113-2. Categories of Ascitic Fluid Infection

Category

PMN

AF Culture

Other Characteristics

SBP

a 250/mm3

Single organism

A low ascitic fluid total protein increases risk for SBP

CNNA

a 250/mm3

Negative culture

Should rule out other causes of elevated PMN

MNB

< 250/mm3

Single organism

An early stage of SBP, 40% will progress to SBP

Polymicrobial bacterascites

< 250/mm3

Multiple organisms

Indicative of needle perforation by paracentesis

Secondary bacterial peritonitis

a 250/mm3

Multiple organisms

Presence of intra-abdominal infection

Adapted with modification from Anadon and Arroyo, 2003.

AF = ascitic fluid; CNNA = culture-negative neutrocytic ascites; MNB = monomicrobial non-neutrocytic bacterascites; PMN = polymorphonuclear leukocyte; SBP = spontaneous bacterial peritonitis.

Adapted with modification from Anadon and Arroyo, 2003.

AF = ascitic fluid; CNNA = culture-negative neutrocytic ascites; MNB = monomicrobial non-neutrocytic bacterascites; PMN = polymorphonuclear leukocyte; SBP = spontaneous bacterial peritonitis.

ture techniques are used. In the setting of optimal culture methodology, CNNA may represent spontaneously recovering SBP and resolving ascitic fluid PMN count.

The source of secondary bacterial peritonitis can be divided into the following two subsets: (1) free perforation of a viscus (eg, duodenal ulcer) and (2) loculated abscess without perforation. Polymicrobial bacterascites is indicative of gut perforation due to the paracentesis needle. It occurs in less than 1 of 150 paracenteses, and peritonitis affects less than 1 of 1,500 paracenteses.

Treatment of Ascitic Fluid Infection

Patients with a clinical presentation suggestive of ascitic fluid infection should receive empirical antibiotics. Indications for treatment include ascitic fluid PMN a 250 cells/mm3, and/or convincing signs and symptoms of infection. For symptomatic patients without an elevated ascitic fluid PMN count, empirical antibiotics should be initiated but can be then discontinued after 2 days if cultures demonstrate no growth.

Escherichia coli, streptococci (mostly pneumococci), and Klebsiella pneumoniae cause most episodes of spontaneous ascitic fluid infection, with only 1% contribution from anaerobes. Cefotaxime or a similar third-generation cephalosporin is the antibiotic of choice, and is superior to ampicillin plus tobramycin. Aminoglycosides should be avoided because of their nephrotoxicity. Cefotaxime covers 98% of the flora and does not lead to superinfection or nephrotoxicity. Intravenous (IV) dosing of 2 g every 8 hours achieves excellent levels in ascitic fluid. Five days of treatment is as efficacious as 10 days and is significantly less expensive. A follow-up paracentesis is indicated if secondary bacterial peritonitis is suspected or the typical response to cefotaxime does not occur.

The decision to treat patients with MNB depends on the presence or absence of convincing signs and symptoms of infection, regardless of the ascitic fluid PMN count. Cefotaxime 2 g every 8 hours should be empirically initiated for symptomatic patients, with follow-up paracentesis performed at 48 hours. On the other hand, asymptomatic patients do not need treatment immediately but require repeat paracentesis promptly for cell count and culture.

For secondary bacterial peritonitis, IV cefotaxime and metronidazole should be initiated immediately to cover both aerobic and anaerobic flora. Imaging is needed to confirm and localize the site of perforation. Emergent surgical laparotomy is mandatory for both perforation and nonperforation peritonitis. Without surgical intervention, mortality is 100%. Despite a low mortality associated with the polymicrobial bacterascites, most physicians would initiate antibiotics. A combination of cefotaxime and metronidazole should be used if decision is made to treat the patient. Repeat paracentesis is helpful to follow the ascitic fluid PMN count and culture, whether the patient has been placed on empiric antibiotic coverage.

IV Volume Expanders in Patients with SBP

SBP is associated with a reduction in effective arterial blood volume and impaired renal function. The latter is the most important predictor of in-hospital mortality in these patients. IV albumin 1.5 g/kg at the time of diagnosing SBP and 1.0 g/kg on day 3 of antibiotic treatment significantly decreased the risk for renal insufficiency and SBP-related mortality in a randomized trial. It is reasonable to administer intravenous albumin in this setting.

Prophylaxis against SBP

SBP occurs most often in cirrhotic patients with (1) a prior episode of SBP, (2) AFTP < 1.0 g/dL, and (3) acute episode of GI hemorrhage. Oral norfloxacin 400 mg daily prevents SBP in inpatients with prior SBP or a low AFTP. When given twice daily for 7 days after emergent gastroscopy in patients with GI hemorrhage, norfloxacin reduces the incidence of inpatient SBP by over 80%. Trimethoprim-sulfamethoxazole one double-strength tablet daily orally has also been shown effective in prophylaxis of SBP.

Antibiotic prophylaxis does not improve survival, but may select resistant gut flora. Prolonged antibiotic use before OLT places patients at risk for fungal infection post-transplant. Thus, prophylaxis is recommend for short term inpatient use in patients with AFTP < 1 g/dL or variceal hemorrhage, and long term outpatient use for patients who survive an SBP episode.

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  • Ilmari
    What causes negative neutrocytic ascites?
    8 years ago

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