結果、ABPC/SBT 3g 1日4回となりました。
A psoas (or iliopsoas) abscess is a collection of pus in the iliopsoas muscle compartment. It may arise via contiguous spread from adjacent structures (secondary abscess) or by the hematogenous route from a distant site (primary abscess).
Primary psoas abscesses are most frequently due to infection with a single organism. In regions where Mycobacterium tuberculosis is endemic, this is a frequent cause of psoas abscess. The most common bacterial cause is Staphylococcus aureus, including methicillin-resistant S. aureus (MRSA). Secondary psoas abscess may be monomicrobial or polymicrobial and frequently consist of enteric organisms (both aerobic and anaerobic bacteria).
Symptoms and signs of psoas abscess include back or flank pain, fever, inguinal mass, limp, anorexia, and weight loss. Pain may localize to the back, flank, or lower abdomen, with or without radiation to the hip and/or the posterior aspect of the thigh. Limitation of hip movement is common and patients frequently prefer to be in a position of less discomfort that includes hip flexion and lumbar lordosis. Pain is exacerbated when performing movements in which the psoas muscle is stretched or extended; the "psoas sign" is pain brought on by extension of the hip.
The diagnosis of a psoas abscess may be suspected on clinical grounds and confirmed on imaging studies. Computed tomography (CT) is the optimal radiographic modality to evaluate for psoas abscess. Blood samples and abscess material should be sent to the microbiology lab for Gram stain and bacterial culture. Acid-fast bacilli smear and mycobacterial culture should also be performed in the setting of risk for tuberculosis.
Management of psoas abscess consists of drainage and prompt initiation of appropriate antibiotic therapy. We suggest initial management with percutaneous drainage (by ultrasound or CT guidance) (Grade 2C). Following needle aspiration, a pigtail catheter may be placed in situ to allow further drainage.
Empiric antibiotic therapy should include activity against S. aureus (including activity against MRSA in regions where prevalence is substantial) and enteric organisms (both aerobic and anaerobic enteric flora). Antimicrobial therapy should be tailored to culture and susceptibility results.
In general, directed antimicrobial therapy (based on the results of cultures and smears) is preferable to empiric therapy. It is preferable to attempt to make definitive diagnosis before initiating antibiotic therapy. For circumstances in which prompt microbial diagnosis is not feasible, empiric antibiotic therapy should include activity against S. aureus (including activity against methicillin-resistant S. aureus in regions where prevalence is substantial) and enteric organisms (both aerobic and anaerobic enteric flora) .
Antimicrobial therapy should be tailored to culture and susceptibility results. Evidence of mycobacterial infection should prompt management as described in detail separately.
Parenteral antibiotics should be administered in conjunction with psoas abscess drainage. Antibiotics alone are unlikely to be curative, although some success with antibiotic therapy alone has been reported in a small number of patients with abscesses <3 cm.
The optimal duration of antibiotics is uncertain; three to six weeks of therapy following adequate drainage is likely appropriate; the decision on duration of therapy may be impacted by the presence of osteomyelitis, for example. Follow-up imaging should be performed near the end of the planned course of antimicrobial therapy to ensure satisfactory response to therapy. Most, if not all, cases of tuberculous psoas abscesses have associated vertebral osteomyelitis.
Both blood cultures and abscess material should be obtained in all cases and sent to the microbiology laboratory for Gram stain and bacterial culture. Acid-fast bacilli (AFB) smear and mycobacterial culture should also be performed when tuberculosis is suspected or when routine Gram staining is negative. These specimens should be obtained when a diagnosis of psoas abscess is confirmed and before initiation of antimicrobial therapy, if feasible, to optimize the culture yield.
Blood cultures are positive in 41 to 68 percent of cases; the most frequent blood culture isolate is S. aureus. Psoas abscess with or without vertebral osteomyelitis can be a presentation of endocarditis. Therefore, if there is any supportive evidence for this diagnosis, then echocardiography should be considered.