Infections of the chest wall, although uncommon, are important problems for thoracic surgeons. The severity of these infections can range from relatively minor and inconvenient problems to life-threatening situations that require urgent and aggressive care. Since most surgeons will see only a small number of cases in their careers, an organized approach to management is essential. In this chapter, we present our preferred methods of classification, and we review the various aspects of management. Specific topics of significant importance, for example, poststernotomy sternal infections and mediastinitis, are covered in other chapters in this text.

A review of recent review of the literature suggests that there is no standard or ideal way to categorize chest wall infections. In our experience, classification according to type of organism, anatomic location, and the presence or absence of necrosis is most helpful for organizing the majority of clinical presentations of chest wall infections.

Bacterial

Bacterial infection is among the most common type of chest wall infection. Although diagnosis may be straightforward on culture, this may not be the case with certain fastidious organisms or if the patient has already received antibiotic therapy. Infections may be mono- or polymicrobial. Staphylococcus spp. is a common organism that produces typical features of infection and can vary in appearance from small abscesses to destructive chest wall masses. Although Staphylococcus spp. infections may develop without any warning or history, they most commonly arise as a complication of surgical procedures or trauma. Streptococcal spp. such as pneumoniae and milleri are also common culprits and can be related to underlying empyema. Anaerobic organism infections (e.g., Bacteroides spp.) can be life-threatening and may arise from the oral cavity as a result of poor dentition with extension into the head and neck, mediastinum, and chest wall. Invasion of the chest wall from an underlying lung infection is not unusual and can be difficult to distinguish from a primary pulmonary malignancy with chest wall invasion. These infections are more common in immunocompromised patients such as diabetics.

Unusual organisms, such as Actinomyces spp., can arise in the oropharynx and affect the chest wall and underlying thoracic structures. The most common of these organisms is Actinomyces israelii. Aspiration is the most common cause with lower lobes being the predominant area affected. Pulmonary infection from Actinomyces spp. may also result in an empyema which in turn may extend into the chest wall.¹ Sulfur granules are pathognomonic of Actinomyces infection and are composed of colonies of organisms surrounded by neutrophils.²

Fungal

Fungal infections of the chest wall are quite uncommon and typically arise in immunocompromised individuals either as a primary infection or as part of a disseminated infection (see Chapter 103). Occasionally, these types of infection occur after surgical procedures. Fungal organisms that may cause infection include Aspergillus, Candida, Rhizopus, Mucor, Absidia, and Phycomyces spp.³ Fungal infections can be extremely difficult to eradicate and may require multiple surgical procedures and prolonged antifungal therapy.

Mycobacterial

As with other pathology of the chest, tuberculosis must always be part of the differential diagnosis in chest wall infections. Although the chest wall is not a common initial presentation, cultures to rule out tuberculosis infection should always be sent. Immigration from other parts of the world or a history of immunocompromise should raise the possibility of a tuberculosis infectious etiology.

Parasitic

A high degree of suspicion is necessary to diagnose chest wall parasitic infections. Hydatid disease, leishmaniasis, and cutaneous myiasis are examples of parasitic infections that are difficult to diagnose in patients traveling outside of their endemic regions.

Bone

Although osteomyelitis can affect any part of the chest skeleton, it more commonly affects the sternum than other parts of the chest wall. Primary infection is rare, with most cases occurring post-sternotomy. Sternal infections after cardiac surgery are well described elsewhere in this text. Primary infections in the absence of surgical intervention are uncommon but can be seen in drug addicts and patients with underlying pulmonary infections with extension into bone. These infections result in destruction of the cancellous bone and impairment of blood supply. Untreated, these infections will result in bone death. Osteomyelitis of the rib is usually localized and associated with procedures, such as chest tube insertion or chest trauma.

Cartilage

Infections of the cartilage arise most commonly after surgical interventions, including cardiac surgery, thoracotomy, and chest tube insertion. Primary infections are extremely uncommon but can be seen, particularly with Mycobacterium. Cartilages five through nine are contiguous and therefore an infection arising in any cartilage may spread and be particularly difficult to manage. Common organisms include Staphylococcus and Streptococcus, but Escherichia coli and Pseudomonas aeruginosa may also be cultured. The patient presents generally with a draining sinus which is associated with pain and tenderness. Imaging, both computed tomography (CT) of the chest and bone scan, can be helpful. Such infections can be very resistant to therapy and frequently require open debridement and prolonged antibiotic therapy. Large defects can occur if the contiguous cartilages of the costal margin are involved.