Background: Tuberculin skin testing (TST) is still the reference method for the diagnosis of latent tuberculosis infection (LTBI). Objective: To evaluate the effect of psoriasis on TST. Methods: Comparison of TST results of consecutive dermatology (n = 91) and internal medicine (n = 615) inpatients. TST was uniformly ordered, performed and evaluated according to the Mantoux method using purified protein derivative. Results: (a) Significantly larger TST indurations were measured in dermatology (median: 7 mm) compared to internal medicine inpatients (median: <1 mm; p < 0.0001). More dermatology inpatients showed ‘positive’ (>5 mm) and ‘strongly positive’ (≥15 mm) TST results (53 vs. 29% and 22 vs. 13%, respectively). (b) Among dermatology inpatients, the TST reactions were significantly larger (p < 0.01) in psoriatics (n = 28) compared to the remaining patients (n = 63). (c) In psoriatics, the TST correlated positively with the psoriasis area and severity index score (p = 0.015). Conclusion: Overt psoriasis is associated with increased TST measurements. This observation is suggestive of a possible overtreatment of these patients for LTBI.

Screening for latent tuberculosis infection (LTBI) is recommended before treatment with biologics is initiated in patients with psoriasis or inflammatory bowel disease (IBD). Our objective was to evaluate the effect of underlying disease (psoriasis or IBD) on the risk of LTBI diagnosis prior to anti-tumor necrosis factor-alpha (TNF-α) therapy. During a two-year period LTBI diagnosis rate was compared in consecutive patients with psoriasis or IBD (Crohn's disease or ulcerative colitis). IBD patients (n = 33) had significantly smaller tuberculin skin testing compared to psoriasis patients (n = 30) (p = 0.007). Applying LTBI diagnosis guidelines resulted in more psoriasis (50%) than IBD patients (24.2%) receiving treatment for LTBI prior to onset of anti-TNF-α treatment (p = 0.04). In conclusion, current recommendations for LTBI diagnosis must be re-evaluated to account for the unique tuberculin hyperactive state of the skin of patients with psoriasis.

Background/Objectives: The establishment of newborn skin flora depends on the ongoing skin maturation and the existence of potential microbial colonizers within the environment of the infant during a period of intense mother-infant physical interaction. This longitudinal study assessed culturable skin bacteria in the mother-infant dyad during the first year of life.Methods: A total of 17 mother-infant dyads were swabbed within 24 hours postpartum and at 3, 6, 9, and 12 months. Skin swabbing was performed on two anatomical areas per individual (mothers: chest-abdomen; infants: forehead-buttocks) and were incubated in five different solid culture media to optimize yield. Isolated bacterial species were identified to genus or species level using the API system (BioMeriéux, Marcy l'Etoile, France). Results:A total of 444 microbial strains were isolated belonging to 22 genera: 6 "frequent" (isolated from > 5% samples: S aureus, Proteus, Klebsiella, Pseudomonas, Enterobacter, and Enterococcus) and 16 "infrequent." Isolated genera per individual peaked at 6 months postpartum for mothers and infants (P < 0.05). Enterobacter, Enterococcus, Klebsiella, and Pseudomonas isolation rates varied significantly as a function of sampling time contrary to the rather constant isolation rates of Proteus and S aureus. The rates of concordant isolation of the same microbial species within the mother-infant dyad tended to drop from birth to the end of the first year postpartum.Conclusions: Distinct variations in the isolation rates of skin commensals from specific anatomical sites of the mother-infant dyad indicate bidirectional microbial transmission. Increasing skin flora individuality of the growing infant was recorded, manifested by declining rates of concordant isolation of the same microbial species from mother and her infant. K E Y W O R D Sfirst year of life, infant, microbiota, mother, skin | 461

It is well-established that tumour necrosis factor (TNF)-α-antagonist regimens are advisable for the control of moderate to severe psoriasis; however the application of these agents is associated with increased risk of TB reactivation. Screening for latent tuberculosis infection (LTBI) is indispensable prior to treatment inception in order to diminish the risk of active TB. Although tuberculin skin test (TST) still represents a useful tool for LTBI detection, it is difficult to be performed and read in patients with extensive psoriatic lesions. In this paper, we report the case of a 65-year-old male with severe psoriasis, who was evaluated by an interferon-gamma release assay (IGRA) for LTBI diagnosis prior to anti-TNF-α therapy. Furthermore, the physiological aspects of interferon-gamma release assays are discussed emphasizing the value of these novel immunodiagnostic tests (IGRAs) for presumable LTBI in all patients with extensive skin disorders.

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