Why would an infection produce gas bubbles, also known as crepitus or subcutaneous emphysema?

From the Guidelines

Gas bubbles in an infection are typically caused by gas-producing bacteria, particularly those that cause a condition called gas gangrene or clostridial myonecrosis, as seen in type I NSTIs which involve aerobic and anaerobic organisms, including Clostridium species 1. The most common bacteria responsible are Clostridium species, especially Clostridium perfringens, which thrive in low-oxygen environments and produce gases as they multiply and release toxins. These bacteria often enter the body through deep wounds, surgical sites, or injuries where oxygen supply is limited. The gas bubbles form within tissues as these anaerobic bacteria metabolize carbohydrates and proteins, producing hydrogen, nitrogen, and other gases as byproducts. This process causes tissue destruction and the characteristic crepitus (crackling sensation) that can be felt when pressing on affected areas. Other gas-forming infections include necrotizing fasciitis and certain types of cellulitis caused by bacteria like E. coli, Klebsiella, or Streptococcus. Some key points to consider in the management of these infections include:

• Prompt surgical consultation is recommended for patients with aggressive infections associated with signs of systemic toxicity or suspicion of necrotizing fasciitis or gas gangrene 1
• Empiric antibiotic treatment should be broad, covering Gram-positive, Gram-negative, and anaerobic organisms, until culture-specific results and sensitivities are available 1
• The use of antimicrobial therapy is an adjuvant treatment and must be combined with early surgical debridement 1 Gas-producing infections are medical emergencies requiring immediate treatment with broad-spectrum antibiotics, surgical debridement of dead tissue, and sometimes hyperbaric oxygen therapy to kill the anaerobic bacteria and stop the infection from spreading. Key considerations for antibiotic therapy include:
• Coverage of MRSA and invasive GAS virulence proteins 1
• Use of piperacillin-tazobactam or carbapenems for Gram-negative bacteria, depending on local prevalence of ESBL-producing Enterobacteriaceae 1
• Monitoring of procalcitonin levels to guide antimicrobial discontinuation 1

From the Research

Infection with Gas Bubbles

• Infections with gas bubbles are often associated with anaerobic bacteria, such as Clostridium perfringens, which produce gas as a byproduct of their metabolism 2, 3.
• The production of gas bubbles is a result of the bacterial fermentation process, which occurs in the absence of oxygen 3.
• Clostridium perfringens is a Gram-positive, spore-forming anaerobic bacterium that is widely distributed in the environment and can cause gas gangrene, a potentially fatal infection 3.

Causes of Gas Bubbles in Infections

• The presence of gas bubbles in infections is often a sign of anaerobic bacterial growth, which can occur in devitalized tissue or in areas with low oxygen levels 2, 4.
• The introduction of Clostridium spores into deep tissue through traumatic injury can lead to the development of gas gangrene, characterized by the production of gas bubbles 3.
• The production of toxins by Clostridium species, such as alpha toxin, can also contribute to the development of gas bubbles in infections 3.

Treatment of Infections with Gas Bubbles

• The treatment of infections with gas bubbles often involves the use of antibiotics, such as penicillin, metronidazole, or clindamycin, which are effective against anaerobic bacteria 5, 4, 6.
• Hyperbaric oxygen therapy may also be used as an adjunctive treatment to inhibit anaerobic bacterial growth and enhance the efficacy of antibiotics 2, 4.
• Surgical debridement and removal of devitalized tissue may also be necessary to prevent the spread of infection and promote healing 2, 3.