Infection of the peritoneal fluid (ascites) with gram-negative bacteria is the most common cause of SBP.[5] The most frequently isolated gram negative bacterial species in ascitic fluid from those with SBP are E. coli and Klebsiella.[5] Gram-positive cocci species, such as streptococci and staphylococci, have historically been responsible for less than 25% of SBP cases though the incidence of such cases has been increasing.[5] Anaerobic and fungal infections of the ascitic fluid are rare but have been reported with organisms such as Aeromonas, Bordetella bronchiseptica, Candida species, Salmonella paratyphi A, and Pasteurella multocida.[5]