Abstract
Background
Photosensitivity to Chlamydia trachomatis has been described in almost 50% of chronic cases of lymphogranuloma venereum (LGV) caused by L1, L2 or L3 serovars. Photosensitivity in non LGV strains of C trachomatis has not been studied. We studied the association of various photosensitive dermatoses with C trachomatis infection in non LGV cases.
Methods
Sera of all the cases of photosensitivity, melasma, chronic actinic dermatitis (CAD), polymorphic light eruption (PLE), actinic prurigo (AP) and rosacea were tested for the presence of IgM, IgG and IgA antibodies to C trachomatis by ELISA method. The results were compared with 30 healthy controls.
Result
Seventeen (25.53%) of 57 cases of photosensitivity as against two (6.67%) controls were seropositive for IgM/IgG/IgA antibodies, a statistically significant difference (χ2 6.18, p 0.013). Similarly, significantly higher seropositivity was observed in 12 (25.53%) of 47 cases of melasma (χ2 4.38, p 0.0363) and six (46.15%) of 13 cases with CAD (χ2 6.91, p 0.0086). Although higher proportion of patients of rosacea [five (31.25%) of 16 cases] and PLE [four (25.0%) of 16 cases] were seropositive, the difference was not statistically significant (χ2 3.23, p >0.05, OR 6.36, CI 95% 0 to 48 and χ2 3.09, p 0.078, OR 4.67, CI 95% 5 to 41 respectively). There was no association of AP.
Conclusion
The observations suggest that C trachomatis infection in non LGV cases is an important cause of PS, melasma and CAD. It appears to be an important cause of rosacea and PLE. We recommend that all cases of photosensitivity, melasma, CAD, PMLE and rosacea and their spouses/sexual contacts be investigated for C trachomatis infection.
Key Words: Photosensitivity, Melasma, Chronic actinic dermatitis, Polymorphic light eruptions, Rosacea, Actinic prurigo, Chlamydia trachomatis
Introduction
Melasma is an acquired hypermelanosis, which occurs in sun-exposed areas and is exacerbated by light. Women are usually affected, but it may be occasionally seen in men. The exact cause of this disorder was not known. Melasma was earlier associated with pregnancy [1] or consumption of oral contraceptives [2]. Photosensitivity to C trachomatis has been described in almost 50% of chronic cases of lymphogranuloma venereum (LGV) caused by L1, L2 or L3 serovars [3]. We found chronic pelvic inflammatory disease in almost 60% of cases of melasma [4], suggesting that melasma may be due to photosensitivity to C trachomatis in clinical or sub clinical chronic genitourinary infection in a large proportion of cases. This was later confirmed by the presence of antichlamydia IgM antibodies in significant number of patients of melasma [5]. Photosensitivity (PS), polymorphic light eruptions (PLE), rosacea, chronic actinic dermatitis (CAD), actinic prurigo (AP) like photosensitive skin diseases, the exact cause for which is not known, may be precipitated by C trachomatis infection and hence this study was done.
Material and Methods
All the patients of PS and photosensitive disorders like melasma, CAD, PLE, AP and rosacea reporting to out patient department were included, while those of known cause of photosensitivity like DNA repair defective disorders and cases of porphyrias were excluded.
Patients were diagnosed as cases of photosensitivity, if they complained of discomfort, burning and/or erythema in the exposed areas on sun exposure without any other skin lesion. PLE was diagnosed clinically in cases with papular, papulovesicular, vesicobullous or plaque lesions in the sun exposed areas, which are transient in nature and appear during spring or summer season. CAD was diagnosed clinically in cases with persistent eczematous lesions in photo distribution without history of use of any topical photosensitizing agent. AP was again diagnosed clinically in cases with erythematous itchy papules and nodules on exposed parts in the absence of antinuclear antibodies. Skin biopsy was performed in doubtful cases, which could support the clinical diagnosis. Diagnosis of melasma and rosacea was again clinical. Informed consent was obtained and sera of all the patients were tested for the presence of IgM, IgG & IgA antibodies to Chlamydia trachomatis by enzyme-linked immunosorbent assay (ELISA) method using the kits supplied by Vircell S I, Granada, Spain. The test had sensitivity of 96% for IgG, 90% for IgM and 95% for IgA with a specificity of 100% for IgM, IgG and 98% for IgA.
Thirty healthy age and sex matched controls were also tested. The study was cleared by the hospital Ethics Committee. χ2 test was used as a test of significance.
Results
There were 47 cases with melasma, of which 44 (93.62%) were females and three (6.38%) males, with an average age of 40.0 years (SD ± 8.26) . The average duration of melasma was 5.36 years (Range 8 months to 24 years, SD ± 4.41). The control group had an average age of 41.20 years (SD ± 2.95), of which 29 were females and one male (Table 1). The difference in mean age of the patients and controls was not significant (SE 1.32). The difference in positivity for C trachomatis between cases and controls was found statistically significant (χ2 4.38, p 0.0363).
Table 1.
Chlamydia trachomatis antibodies in photosensitive disorders
| Group | Number | Positive (%) | IgM positive (%) | IgG positive (%) | IgA positive (%) | χ2 | p |
|---|---|---|---|---|---|---|---|
| Melasma | 47 | 12 (25.53) | 3 (6.38) | 4 (8.51) | 5 (10.64) | 4.38 | 0.0363 |
| Photosensitivity | 57 | 17 (25.53) | 7 (12.28) | 8 (14.04) | 5 (8.77) | 6.18 | 0.013 |
| Chronic actinic dermatitis | 13 | 6 (46.15) | 3 (23.08) | 3 (23.08) | 3 (23.08) | 6.91 | 0.0086 |
| PLE | 16 | 4 (25.0) | 2 (12.5) | 1 (6.25) | 1 (6.25) | 3.09 | 0.078 |
| Rosacea | 16 | 5 (31.25) | 0 | 3 (18.75) | 2 (12.5) | 3.23 | >0.05 |
| Actinic prurigo | 11 | 1 (9.01) | 0 | 1 (9.01) | 0 | - | >0.05 |
| Controls | 30 | 2 (6.67) | 2 (6.67) | 0 | 1 (3.33) |
PLE = Polymorphic light eruptions
There were 57 cases of PS, with an average age of 45.27 years (SD ± 11.48). Seventeen (29.82%) were males and 40 (70.18%) females. Average duration of photosensitivity was 5.20 years (SD ± 4.37). The difference in positivity for C trachomatis between cases and controls was statistically significant (χ2 6.18, p 0.013).
There were 13 cases of CAD, with an average age of 48.68 years (SD ± 10.21 years), of which five (38.46%) were males and eight (61.54%) females. Average duration of disease was 6.36 (SD ± 9.89) years. The difference in positivity for C trachomatis between cases and controls was statistically significant (χ2 6.91, p 0.0086).
There were 16 cases of PLE, with an average age of 38.38 years (SD ± 12.20 years). Eight (50%) cases each were males and females. Average duration of disease was 3.18 (SD ± 4.05) years. Although higher percentage of patients of PLE had antibodies to C trachomatis, the difference was not statistically significant [χ2 3.09, p 0.078, OR 4.67, Confidence Interval (CI) 95% -5 to 41], possibly due to small sample size.
There were 16 cases of rosacea, with an average age of 50.06 years (SD ± 13.43 years). Ten (62.5%) of them were males and six (37.5%) were females. Average duration of disease was 4.12 years (SD ± 3.62). Although higher percentage of patients of rosacea had antibodies for C trachomatis, the difference in positivity was not statistically significant (χ23.23, p >0.05), possibly because of small sample size. Odds Ratio (OR) was 6.36 and CI 95% was 0 to 48.
There were 11 cases of AP, with an average age of 38.91 years (SD ± 15.51). Two (18.18%) of them were males and nine (81.82%) females. Average duration of the disease was 2.56 years (SD ± 3.25). The difference in positivity for C trachomatis between the cases and controls was not statistically significant (p> 0.05).
Discussion
Photosensitivity to C trachomatis has been described in almost 50% of chronic cases of lymphogranuloma venereum [3]. We found that even in non-LGV cases of photosensitivity, there was significantly higher percentage of seropositivity to C trachomatis, thereby suggesting that even non-LGV strains of C trachomatis cause photosensitivity. Majority of our patients with photosensitivity were females. This suggests that deep seated pelvic infection with C trachomatis may be an important cause of photosensitivity in women. Melasma has been associated with chronic pelvic inflammatory disease (PID) due to C trachomatis [4, 5], which is in agreement with this study.
The mechanism underlying the transition from photoallergy to CAD, in cases where this is a precursor, remains unclear. Norris et al [6], felt that in the initial phases of photoallergy, local reaction begins with UVA-dependant covalent photochemical binding of hapten to endogenous protein, followed by an eczematous delayed-type hypersensitivity (DTH) response. With progression to CAD, UVA+/-UVB irradiation alone may trigger the immune response at any site, possibly by the continuing formation of antigenic photo products from the ubiquitous endogenous carrier protein alone. In cases where there is no preceding history of photoallergy, CAD may represent an end stage of a number of predisposing conditions like allergic contact dermatitis to substances with phototoxic potential, endogenous eczema [7], photosensitivity from oral medication, possibly PLE and human immunodeficiency virus infection [8]. Finally CAD also appears to arise de novo in normal subjects [9]. A significant association was found between chronic actinic dermatitis and C trachomatis seropositivity, suggesting that some product of metabolism of C trachomatis may be acting as a hapten for inducing DTH response in CAD.
PLE has been postulated to be a delayed type hypersensitivity reaction to ultraviolet radiation [10]. Attempted isolation of the inducing antigen in PLE has been unsuccessful but precipitation of the condition following allergic contact dermatitis to Fentichlor suggests an endogenous Fentichlor-like antigen as one possibility [11]. Recently heat-shock protein 65 has been isolated from the lesions of PLE [12]. Much of the chlamydial disease is due to delayed hypersensitivity reaction to specific heat shock proteins [13].
Some reports suggested that patients with rosacea have increased incidence of Helicobacter pylori infection, although other have failed to confirm this association [14]. Role of infestation of skin with tiny mite Demodex folliculorum, has also received little support [15]. However there is no disagreement on improvement in rosacea with tetracycline, erythromycin or metronidazole, which suggests a bacterial aetiology. A high Odds Ratio in rosacea suggests that C trachomatis induced photosensitivity may have a role in this dermatoses. Actinic prurigo did not have any association suggestive of C trachomatis infection.
We recommend further studies in a larger group of patients to establish the aetiology of rosacea and PLE. In the meantime all cases of PS, melasma, CAD, PLE, rosacea and their spouses/sexual contacts should be investigated and treated for C trachomatis infection.
Conflicts of Interest
None identified
Intellectual Contribution of Authors
Study Concept : Col MPS Sawhney, Wg Cdr S Arora, Col A Khetarpal
Drafting & Manuscript Revision : Col MPS Sawhney, Wg Cdr S Arora, Col A Khetarpal
Statistical Analysis : Col MPS Sawhney
Study Supervision : Col MPS Sawhney
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