PARIS Not only are patients with cutaneous T-cell lymphoma more likely to be colonized with Staphylococcus aureus, compared with healthy individuals, but S. aureus colonization appears to be directly related to the body surface area involvement, according to a study of 100 adults.
Researchers at Northwestern University, Chicago, compared colonization rates for 50 CTCL patients, 25 patients with psoriasis, and 25 healthy controls enrolled from a single dermatology clinic. S. aureus colonization was found in 44% of CTCL patients, 48% of psoriasis patients, and 28% of healthy controls.
Colonization with S. aureus was significantly associated with increased body surface area involvement of CTCL, Dr. Victoria Nguyen reported at the annual congress of the European Academy of Dermatology and Venereology.
Healthy controls were seen for routine skin examination. Patients with CTCL and psoriasis had to have active lesions in order to be included in the study.
The control participants were matched with case patients by age, sex, and anatomical skin site.
Potential participants were excluded if they had active infections, had taken antibiotics in the previous 3 months, or had undergone decolonization in the last 6 months. Patients who had HIV infection, were on chemotherapy, or were otherwise immunocompromised were also excluded.
Culture swabs were obtained from nares and lesional skin or normal skin in the healthy control group. Body surface examination was performed on CTCL patients.
Of the patients found to have S. aureus colonization, the majority was community associated (68%, 83%, and 71% for the CTCL, psoriasis, and control groups, respectively). The rate of methicillin-resistant S. aureus colonization was 2% in the CTCL group, 12% in the psoriasis group, and 8% in the healthy control group.
"Our study is likely an underestimation of S. aureus colonization, given that our excluded population [of CTCL patients] did have a greater rate of S. aureus colonization, up to 80%," noted Dr. Nguyen.
Infection is a common complication of CTCL, with S. aureus being the most common pathogen behind these infections, said Dr. Nguyen, who is a dermatology resident at Northwestern.
The reason for this predisposition to infection among CTCL patients may be threefold. First, these patients have an impaired skin barrier. They also have a decreased repertoire of normal circulating T cells. Lastly, these patients may also be immunosuppressed.
"CTCL is a Th-2-mediated pathway. So, similar to atopic dermatitis, there's perhaps a decrease in antimicrobial peptides in these patients, predisposing them to Staphylococcus aureus colonization," she said.
"The reason for the similarity in the colonization rates among the CTCL and psoriasis groups may be because these patients have an impaired skin barrier; both groups may have more frequent visits to the clinic; and hospitalizations and procedures may be higher in these groups," she added.
Prior studies have shown in vitro stimulation of CTCL cell lines with staphylococcal toxins, positive S. aureus cultures in half of Sézary syndrome patients, and the improvement of Sézary syndrome with antibiotic use.
"It may be that perhaps treating the colonization and infection in CTCL patients may improve severity," said Dr. Nguyen.
At Northwestern, she and her colleagues have treated S. aureus colonization in CTCL patients with resulting improvements in severity.
"We do recommend for our patients, who look like they've got crusting or excoriation, that they get sodium hypochlorite bathsa quarter cup of 6% sodium hypochlorite in a bath tubdaily or weekly to decrease colonization," she concluded.