Orthopaedic Knowledge Update®: Musculoskeletal Infection 2 Print + Ebook (AAOS - American Academy of Orthopaedic Surgeons)

Section 6: Bone, Joint, and Soft-Tissue Infections

to clindamycin should be addressed by consulting an infectious diseases specialist. 47 Antimicrobial agents should be tailored to results of Gram stain, culture, and sensitivity testing once avail able, and consultation from infectious disease specialists should be obtained 31 ( Table 3 ). A retrospective study published in 2022 reported that the ideal duration of antimicrobial treatment is not well defined and could be shortened in select patients. 48 Continuation of antimicro bial agents is essential until the patient is hemodynam ically stable and no further débridement is required. 43 Additional Interventions Guidelines published in 2021 emphasized that optimiza tion of patient’s physiologic state is crucial before surgery; aggressive supportive care with fluids and vasopressors may be required in hemodynamically unstable patients. 49 Intravenous immunoglobulin can be administered in patients with NSTI in the setting of streptococcal toxic shock syndrome. 50 Combining clindamycin with intra venous immunoglobulin is likely efficient by decreased circulating toxins produced by group A Streptococcus and by other mechanisms. 46,51 Although the role of Directed Antibiotic Therapy Based on Microbiologic Findings in Necrotizing Soft-Tissue Infection Pathogens Choice of Antibiotics Polymicrobial a Piperacillin-tazobactam b Group A Streptococcus; Clostridium spp. Penicillin G plus clindamycin Aeromonas hydrophila A fluoroquinolone plus ceftriaxone Vibrio vulnificus Doxycycline plus either cefo taxime or ceftriaxone MRSA Vancomycin or daptomycin plus linezolid or clindamycin ESBL-producing Meropenem Table 3 ESBL = extended-spectrum beta-lactamase, MRSA = methicillin resistant Staphylococcus aureus , NSTI = necrotizing soft-tissue infection a The treatment of aerobic gram-negative bacteria infection may vary depending on the prevalence of multidrug-resistant organisms with various mechanisms of resistance. a In addition to piperacillin-tazobactam, antibiotic coverage for MRSA, Group A Streptococcus , and other beta-hemolytic streptococci should be added if culture results are positive. For MRSA, include the addi tion of vancomycin or daptomycin plus clindamycin or linezolid. For beta-hemolytic streptococci, this include clindamycin or linezolid. Enterobacterales ( Escherichia coli , Klebsiella pneumoniae ) a

hyperbaric oxygen therapy in wound healing has been debated because of the lack of strong research evidence, it could be considered if readily available. However, it should not delay standard care. 52 Patients with trau matic wounds should be vaccinated against tetanus if they have not been immunized in the past 5 years. In addition to standard precautions, patients with NSTIs due to group A Streptococcus require droplet and contact precautions, which may be stopped after 24 hours of initiating antimicrobial therapy. 53 A randomized dou ble-blind placebo-controlled trial from 2020 showed that administering reltecimod (a molecule able to mod ulate the host immune response) within 6 hours of NSTI diagnosis lead to improvement of organ dysfunction and hospital discharge status. 54 However, further studies are warranted to establish recommendations in surgical and Infectious Diseases Society of America’s guidelines. 31,43 A patient who sustains close contact with an NSTI due to group A Streptococcus should imperatively be warned to promptly seek medical attention if signs and symptoms of NSTIs present within 30 days of diagnosing the index case. It was also suggested in 2019 that close contacts receive postexposure prophylaxis with penicillin, especially in highly susceptible individuals (recent surgery or immu nocompromised), although the efficacy of this practice is undefined currently due to lack of clinical trial data. 55 NONNECROTIZING COMPLICATED SSTIs Pyomyositis is an acute skeletal muscle infection arising from hematogenous spread that can result in abscess for mation. A review from 2021 reported that pyomyositis can also arise from direct injection in people who inject drugs. 56 A 2020 study determined that pyomyositis is most commonly caused by S aureus ; Streptococcus spp. and other pathogens can also cause pyomyositis. 57 Risk fac tors associated with pyomyositis include trauma, vigorous exercise, injection drug use, concurrent infection with Toxocara spp, and malnutrition. A 2021 meta-analysis reported that immunocompromising conditions, including HIV infection, diabetes mellitus, malignancy, cirrhosis, chronic renal disease, organ transplant, rheumatologic conditions, and administration of immunosuppressive agents, can predispose to the development of pyomyositis. 58 A retrospective study from 2021 reported that large muscles of the lower limbs (such as the quadriceps femo ris and gluteal muscles) and the trunk muscles are most frequently involved. 59 The course of pyomyositis can vary and has been classified into three stages with most patients presenting at stage 2. Stage 1 is characterized by low grade fever, swelling, induration, and crampy soreness of affected muscle. A frank fluctuating abscess may not be present and percutaneous aspiration of the muscle may

Section 6: Bone, Joint, and Soft-Tissue Infections

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Orthopaedic Knowledge Update ® : Musculoskeletal Infection 2