Chapter 121. Intraabdominal Infections and Abscesses (Part 9) Candida spp. can cause renal abscesses. This fungus may spread to the kidney hematogenously or by ascension from the bladder. The hallmark of the latter route of infection is ureteral obstruction with large fungal balls. The presentation of perinephric and renal abscesses is quite nonspecific. Flank pain and abdominal pain are common. At least 50% of patients are febrile. Pain may be referred to the groin or leg, particularly with extension of infection. The diagnosis of perinephric abscess, like that of splenic abscess, is frequently delayed, and the mortality rate in some series is appreciable, although lower than in the past. Perinephric or renal abscess should be most seriously considered when a patient presents with symptoms and signs of pyelonephritis and remains febrile after 4 or 5 days of treatment. Moreover, when a urine culture yields a polymicrobial flora, when a patient is known to have renal stones, or when fever and pyuria coexist with a sterile urine culture, these diagnoses should be entertained. Renal ultrasonography and abdominal CT are the most useful diagnostic modalities. If a renal or perinephric abscess is diagnosed, nephrolithiasis should be excluded, especially when a high urinary pH suggests the presence of a urea- splitting organism. Perinephric and Renal Abscesses: Treatment Treatment for perinephric and renal abscesses, like that for other intraabdominal abscesses, includes drainage of pus and antibiotic therapy directed at the organism(s) recovered. For perinephric abscesses, percutaneous drainage is usually successful. Psoas Abscesses The psoas muscle is another location in which abscesses are encountered. Psoas abscesses may arise from a hematogenous source, by contiguous spread from an intraabdominal or pelvic process, or by contiguous spread from nearby bony structures (e.g., vertebral bodies). Associated osteomyelitis due to spread from bone to muscle or from muscle to bone is common in psoas abscesses. When Pott's disease was common, Mycobacterium tuberculosis was a frequent cause of psoas abscess. Currently, either S. aureus or a mixture of enteric organisms including aerobic and anaerobic gram-negative bacilli is usually isolated from psoas abscesses in the United States. S. aureus is most likely to be isolated when a psoas abscess arises from hematogenous spread or a contiguous focus of osteomyelitis; a mixed enteric flora is the most likely etiology when the abscess has an intraabdominal or pelvic source. Patients with psoas abscesses frequently present with fever, lower abdominal or back pain, or pain referred to the hip or knee. CT is the most useful diagnostic technique. Psoas Abscesses: Treatment Treatment includes surgical drainage and the administration of an antibiotic regimen directed at the inciting organism(s). Pancreatic Abscesses See Chap. 307. Acknowledgment The substantial contributions of Dori F. Zaleznik, MD, to this chapter in previous editions are gratefully acknowledged Further Readings Campillo B et al: Epidemiology of severe hospital- acquired infections in patients with liver cirrhosis: Effect of long- term administration of norfloxacin. Clin Infect Dis 26:1066, 1998 [PMID: 9597225] Gibson FC III et al: Cellular mechanism of intraabdominal absce ss formation by Bacteroides fragilis. J Immunol 160:5000, 1998 [PMID: 9590249] Johanssen EC, Madoff LC: Infections of the liver and biliary system, in Principles and Practice of Infectious Diseases , 6th ed, GL Mandell et al (eds). Philadelphia, Elsevier Churchill Livingstone, 2005, pp 951–959 Levison ME, Bush LM: Peritonitis and intraperitoneal abscesses, in Principles and Practice of Infectious Diseases , 6th ed, GL Mandell et al (eds). Philadelphia, Elsevier Churchill Livingstone, 2005, pp 927-945 Pa ppas PG et al: Guidelines for treatment of candidiasis. Clin Infect Dis 38:161, 2004 [PMID: 14699449] Piraino B et al: Peritoneal dialysis– related infections recommendations: 2005 update. Perit Dial Int 25:107, 2005 [PMID: 15796137] Rahimian J et al: P yogenic liver abscess: Recent trends in etiology and mortality. Clin Infect Dis 39:1654, 2004 [PMID: 15578367] Solomkin JS et al: Guidelines for the selection of anti- infective agents for complicated intra-abdominal infections. Clin Infect Dis 37:997, 20 03 [PMID: 14523762] Tzianabos AO, Kasper DL: Anaerobic infections: General concepts, in Principles and Practice of Infectious Diseases, 6 th ed, GL Mandell et al (eds). Philadelphia, Elsevier Churchill Livingstone, 2005, pp 2810–2816 Tzianabos AO et al: T cells activated by zwitterionic molecules prevent abscesses induced by pathogenic bacteria. J Biol Chem 275:6733, 2000 [PMID: 10702228] van Ruler O et al: Comparison of on- demand vs planned relaparotomy strategy in patients with severe peritonitis: A randomized trial. JAMA 298:865, 2007 Bibliography Altemeier WA et al: Intra- abdominal abscesses. Am J Surg 125:70, 1973 [PMID: 4566907] . Chapter 121. Intraabdominal Infections and Abscesses (Part 9) Candida spp. can cause renal abscesses. This fungus may spread to the kidney. organism. Perinephric and Renal Abscesses: Treatment Treatment for perinephric and renal abscesses, like that for other intraabdominal abscesses, includes drainage of pus and antibiotic therapy. recovered. For perinephric abscesses, percutaneous drainage is usually successful. Psoas Abscesses The psoas muscle is another location in which abscesses are encountered. Psoas abscesses may arise