Secondary Bacterial Infections Complicating Psoriasis

Background: Psoriasis is a chronic lifelong skin disease most commonly causing erythematous popular and scaly plaques depending on lesion type. Secondary bacterial invaders complicate such lesions. Objectives of this study were to detect the types of aerobic and anaerobic bacterial invaders commonly complicate psoriatic lesions. Patients and Methods: Swabs were taken from different lesions of different sites of patients with psoriasis. Specimens were examined bacteriologically as soon as possible (within one hour) by direct gram stained smears were examined microscopically and indirectly by cultivation aerobically and anaerobic using suitable culture media and cultivation environments. Bacterial isolates were diagnosed and confirmed using suitable diagnostic techniques. Results: Psoriasis was found higher in individuals of age group (18-40) years old and majority of them (38; 48.7%) were showing distributed psoriatic lesions whole over the body. Staphylococcus aureus took the first rank of isolation 23 (29.5%). Proteus spp. and Staphylococcus epidermidis became next 11 and 9 for each respectively. Other bacterial isolates were showed lower rate of isolation like Pseudomonas aeruginosa, Bacillus spp. Enteric bacteria were primarily isolated from children. Also, E. coli and Enterococcus fecalis. Anaerobic bacteria represented by Propionobacter spp., Fusarium spp. and Clostridium perfringens were isolated within few numbers (3, 2, 1) for each respectively. Conclusion: Secondary bacterial infections of different types complicate psoriatic lesions on different sites of the body, so we recommended the follow up of perfect sanitation and disinfection with suitable antimicrobial regimen to reduce infection hazards.


INTRODUCTION
Psoriasis is a chronic lifelong skin disease most commonly causing erythematous popular and scaly plaques depending on lesion type, Gudionsson, E. J. et al. (2003); and Guo-li, et al. 2009.Psoriasis is a chronic immunologically based inflammatory disease of the skin and joint, which has been estimated to affect 1-3% of population.The exact cause is unknown, however researches believe heredity, environment and immune system also play a role in psoriasis Gudionsson, E. J. et al. (2003).and Hwerta, C. et al. (2007).
Several overlapping clinical types of disease have been identified but the chronic plaque form (Psoriasis vulgaris) is the most common Gudionsson, E. J. et al. (2003).and Mallbris, L. et al. (2005).
Psoriasis is a common T-lymphocyte mediated inflammatory skin disease believed to have an autoimmune basis.
The link between psoriasis and infection is probably explained by the superantigen theory, that superantigens are the products of bacteria, viruses, or fungi, which can bypass normal immunological pathway and cause powerful stimulation to the immune system.Studies imply that a protein called the M protein carried by S. pyogenes acts as superantigen in provoking psoriasis, Beaker, B.S. et al. (2006).

Secondary
infected dermatosis develops when a bacterium invades compromised skin such as psoriasis, Brook, I. et al.2002.This study aimed to detect the types of aerobic and anaerobic bacterial invaders commonly complicate psoriatic lesions.

Patients and Methods
Seventy eight (78) patients with different types of psoriasis from both sexes and different residence sites of Ramadi District, West of Iraq, were included in this study.Patients were attending Ramadi General Hospital, Clinic of Skin and Venereal Diseases and Private Clinics of Dermatology in Ramadi City during the period extended from January to July 2009.
Patients were examined by Senior Dermatologist for the diagnosis and follow up of their treatment.Information about each patient was reported using questionnaire for each one.Bacteriological swabs were taken aseptically from different lesions and sites of psoriasis.Specimens were processed as soon as possible for bacteriological investigation through direct Gram stained smears and indirect examination by cultivation on blood agar, chocolate agar and MacConkey agar and incubated at 37 ºC for 24-48 hrs aerobically and anaerobically using Gas pack anaerobic Gas sheets (Oxoid).
Special culture media and techniques were employed for the diagnosis of some bacterial isolates on need.Bacterial isolates diagnosis was confirmed using morphological and culture characters following (Washington et al 7 .).
Data were reported and analyzed using SPSS Program.

Age, sex and residence
Psoriasis was found higher in individuals of age group (18-40) years old (49, 62.8%) and both sexes (28 males and 21 females) (Table1).Significant difference (P<0.05) was found between males and females in group (18-40) and (41-50) years old patients.Urban males and rural females were showing higher rate of psoriasis in age group (1-17) year (45.5%), 36.5%) for each respectively (Table1).All patients within age group > 50 years from both sexes were rural.Regarding site of psoriasis, majority of patients (38, 48.7%) were showing distributed psoriasis lesion whole over the body followed by hands and legs (26, 33.4%) (Table 2).

Bacterial Isolation
All specimens from patients were showing positive bacterial growth.The total number of bacterial isolates was (95), Seventy eight (78) of them were isolated as single bacterial isolates, while the rest (17) were showing mixed bacterial isolation (Tables3 &4).
Staphylococcus aureus took the first rank of isolation (23, 29.5%) and most of isolates were isolated from lesions on hands and legs (Table -3 (3,2,1) for each respectively (Table 3).
Enteric bacterial types were mostly isolated from hands, legs and whole of the body from children within age group (1-17) years old patients.
These findings disagree with the findings of (1) who found that psoriasis particularly psoriasis vulgaris was higher and common in individuals within (40-50) years old.Discrepancy of resulta in contrast to other investigators might be due to difference of patient samples and type of psoriasis, (guttate type) mostly mediated early with S. pyogenes recurrent tonsillitis which is most common infection in children who showed more guttate psoriasis type, Guo-li et al. (2009) and Owen, C., et al. (2001).Guttate psoriasis type is mostly mediated by S. pyogenes superantigen, Gudionsson, E. J. et al. (2003).
Residence (urban and rural) was not affecting psoriasis rate particularly patients of higher rate within age group (18-40) years old, this might be ought to the nature of psoriasis, which is primarily autoimmune triggered disease, Gudionsson, E. J. et al. 2003;Beaker, B.S. et al. 2006 andNational Psoriasis Foundation NPF National Psoriasis Foundation NPF (2010).This immune reaction leads to infiltration of inflammatory cells and increased proliferation turnover of keratinocytes, Mallbris, L. et al.All patients above 50 years old were rural, this might be due to the small sample size in this study which affects the distribution of patients regarding residence and socioeconomic status.Socioeconomic status of patients affects indirectly on the degree of effectiveness of disease via affecting immune status, sanitation and treatment.Age also affects psoriasis incidence through immune system modulation, aged individuals show decrease in CD8 T-cells and more shift to autoimmunity through break of autotoleance, National Psoriasis Foundation NPF (2010) and Rosen, S.F. 2007.In all age groups (18-40), (41-50) and (>50) years old, males were showing more psoriasis rate, this was in accordance with Hwerta et al. 2007.

Bacterial Isolation
Regarding bacterial isolation from psoriatic patient lesions of different sites, Staphylococcus aureus was predominant isolated bacteria, this was in agreement with previous referees, Gudionsson, E. J. et al. 2003;Brook, I. et al. 2002 andAbdullah, M. et al. 2007.Staphylococcus aureus was the commonest organism causing secondary infections of skin lesions, this might be attributed to the antiphagocytic effect of protein A of this organism, as well as the inhibitory effect of serum exuding from denuded skin on linolenic acid an essential fatty acid normally present on the intact skin inhibits Staphylococcus aureus colonization, Gudionsson, E. J. et al. 2003 andBrook, G.F. et al. 2007.Similarity in most of bacterial infections for psoriatic lesions and other dermatological affections like atopic dermatitis, eczema and scabies, Brook, I. et al. 2002;Rosen, S.F. 2007 and Lafi, S.A.;et al. 2008.Isolation of opportunistic pathogens from psoriatic lesions like Bacillus species.(non anthrax type) (Anthracoid spp.) and Staphylococcus epidermidis was ought to the reduced local defense factors in the lesion due to local and systemic immunosuppressant drugs like cytotoxic drugs and cortisones used for the treatment of psoriasis, Zieve, d. et al. 2008 andNational Psoriasis Foundation NPF, 2010.In addition to that, antiphagocytic activity of certain factors released by actual pathogens previously invade psoriatic lesion like Staphylococcus aureus protein A, such Staphylococcus aureus predispose invasion by opportunistic pathogens, Gudionsson, E. J. et al. 2003 andLafi, S.A. 2008.Isolation of anaerobic bacteria was different from that reported by previous researchers, Gudionsson, E. J. et al. 2003;Brook, I. 2002 andAbdullah, M. et al. 2007, lower (Brook, I. et al. 2002;Abdulla, M. et al. 2007).This was probably ought to the low personal care and sanitation criteria of patients particularly children.
The recovery of multiple organisms from psoriatic lesions of patients illustrated the polymicrobial nature of secondarily infected psoriasis and the potential for bacterial synergy between different microbial isolates, Brook, I. et al. 2002;Washington, W. J .r. et al. 2006 andHarry, J. et al. 2008.We concluded that psoriatic lesions of different types and sites of the body undergo contamination and bacterial infections and probably with other organisms like fungi, viruses, etc.So we recommend the follow up of perfect sanitation and disinfection of the lesion with suitable antimicrobial regimen to prevent complications and invader disposal.
). Proteus species.and Staphylococcus epidermidis became next (11 and 9) for each respectively.Pseudomonas aeruginosa, Bacillus species.(non anthrax) and E.coli were showing equal rate of isolation, (6) for each.Other bacterial isolates were showing lower rate of isolation (Table 3).Anaerobic bacterial types represented by Propionobacter spp.Fusarium and Clostridium perfringens were showing low number of isolation,