Upper limb Escherichia coli cellulitis in the immunocompromised

Skin Infections

Cutaneous infections are common in immunocompromised patients. Neutropenia predisposes patients to fungal, bacterial and viral infections. Antibacterial antifungal and antiviral prophylaxis have caused a significant reduction in some of these infections.

There are two main types of cutaneous infections : primary cutaneous infections and cutaneous manifestations of a disseminated infection. In the latter, skin lesions may be the window to disseminated bloodstream infection and the first and only evidence of a disseminated life threatening infection.

The diagnosis may be at your fingertips; therefore a thorough skin exam is the clue. However, it’s also important to know the characteristic lesions associated with different infections. It will help expedite diagnosis so appropriate treatment is initiated promptly in neutropenic patients, which can be lifesaving.

In a retrospective study of 43 neutropenic febrile patients with cutaneous lesions, fungal infections were the most frequent, and nodular lesions on the lower extremities were the most prevalent (Naorungroj and Aiempanakit, J Am Acad Dermatol 74:AB166, 2016).

Skin biopsy for pathological study and culture remains the gold standard and should be obtained early to confirm the suspected diagnosis. In these immunocompromised patients the inflammatory response is altered by either the primary disease or its treatment. Therefore, routine pathogens may present in an atypical fashion, with diminished or absent induration, erythema, or pustulation in response to bacterial resulting cutaneous infection without typical cellulitis (Urabe, Clin Infect Dis 39:S53–S55, 2004). Skin lesions are evaluated not only by morphology, but also in the context of the clinical setting and biopsy result. The skin biopsy is inexpensive, relatively noninvasive and without contraindication, and may avoid the need for more invasive procedures such an open lung biopsy (Grossman, et al., Cutaneous manifestations of infection in the immunocompromised host. Springer Science+Business Media, LLC, New York, 2012).

In addition to antimicrobial therapy, surgery should not be postponed in the face of progressive skin and soft tissue infection in this population (Brzozowski and Ross, J Hand Surg Br 22:679–680, 1997).

Life-threatening Escherichia coli cellulitis in patients with haematological malignancies

Cellulitis due to Escherichia coli is rare and usually secondary to a cutaneous portal of entry. Skin and soft tissue infections (SSTI) secondary to E. coli bacteraemia have been reported exclusively in immunodeficient patients. Here, we report two cases of serious cellulitis secondary to E. coli bacteraemia in patients with haematological malignancies. Both isolated strains belonged to phylogenetic group B2 and harboured some of the main virulence factor genes commonly found in extra-intestinal pathogenic E. coli (ExPEC), including neuC, iro and fimH. Cellulitis due to E. coli seems to be linked to the immunocompromised status of patients rather than to a highly virulent clone. Nevertheless, some of the virulence factors appear to be important because both isolates belong to phylogenetic group B2. This aetiology should be considered in SSTI in patients with haematological malignancies.

Life-threatening necrotizing fasciitis due to 'bath salts' injection

Necrotizing fasciitis is an orthopedic emergency. The ability to quickly and accurately diagnose this rapidly spreading disease can save a patient's life and limb. However, the diagnosis is complex because necrotizing fasciitis usually manifests as a less severe cellulitis or abscess while the majority of the damages rage beneath the surface of the skin. Although the diagnosis is not new, the potential causes and vectors continually change. This article reports a new source of necrotizing fasciitis in an intramuscular injection of "bath salts," a rapidly emerging street drug that is legal in some states and evades authorities with its innocuous name. The patient presented 2 days after injection of bath salts with extensive cellulitis extending to the mid portion of her upper arm. The cellulitis initially responded to broad-spectrum intravenous antibiotics, but rapidly deteriorated 48 hours later, leading to a forequarter amputation with radical mastectomy and chest wall debridement to obtain healthy tissue margins and control the disease. The patient made a full recovery after further minor debridements, negative pressure dressings, directed antibiotic therapy, and skin grafting. The recent emerging popularity of this highly obtainable, injectable substance may lead to an increase in cases of necrotizing fasciitis. Orthopedic surgeons should be vigilant in diagnosing this process early and should perform an extensive debridement.

Virulence potential of Escherichia coli isolates from skin and soft tissue infections

Escherichia coli strains frequently are isolated from skin and soft tissue infections (SSTI); however, their virulence potential has not yet been extensively studied. In the present study, we characterized 102 E. coli SSTI strains isolated mostly from surgical and traumatic wounds, foot ulcers, and decubitus. The strains were obtained from the Institute of Microbiology and Immunology, University of Ljubljana, Slovenia. Phylogenetic backgrounds, virulence factors (VFs), and antibiotic resistance profiles were determined. Correlations between VFs and phylogenetic groups were established and analyzed with regard to patient factors. Further, the associations of the three most prevalent antibiotic resistance patterns with virulence potential were analyzed. Our results showed that the majority of the studied strains (64%) [corrected] belonged to the B2 phylogenetic group. The most prevalent VF was ompT (80%), while toxin genes cnf1 and hlyA were found with prevalences of 32 and 30%, respectively. None of the investigated bacterial characteristics were significantly associated with patient gender, age, type of infection, or immunodeficiency. The most prevalent antibiotic resistance pattern was resistance to ampicillin (46%), followed by resistance to tetracycline (25%) and fluoroquinolones (21%). Strains resistant to ciprofloxacin exhibited a significantly reduced prevalence of cnf1 (P < 0.05) and usp (P < 0.01). Our study revealed that E. coli isolates from SSTIs exhibit a remarkable virulence potential that is comparable to that of E. coli isolates from urinary tract infections and bacteremia.

Escherichia coli chest-wall hemorrhagic cellulitis associated with central-line placement

Cellulitis is a common clinical entity. Hemorrhagic cellulitis is distinctly unusual and is most frequent in compromised hosts. In normal or near normal hosts, hemorrhagic cellulitis may rarely complicate gram-negative sepsis. Usually, hemorrhagic cellulitis occurs below the waist. The differential diagnosis includes invasive streptococcal infection, mixed aerobic and anaerobic infection, gram-negative sepsis, and gross gangrene. We present the first-known case of Escherichia coli chest-wall hemorrhagic cellulitis associated with a central line in a patient with renal failure.