Impaired neutrophil functions in the pathogenesis of an outbreak of recurrent furunculosis caused by methicillin-resistant Staphylococcus aureus among mentally retarded adults

Staphylococcus aureus and Host Immunity in Recurrent Furunculosis

Staphylococcus aureus is one of the severest and most persistent bacterial pathogens. The most frequent S. aureus infections include impetigo, folliculitis, furuncles, furunculosis, abscesses, hidradenitis suppurativa, and mastitis. S. aureus produces a great variety of cellular and extracellular factors responsible for its invasiveness and ability to cause pathological lesions. Their expression depends on the growth phase, environmental factors, and location of the infection. Susceptibility to staphylococcal infections is rooted in multiple mechanisms of host immune responses and reactions to bacterial colonization. Immunological and inflammatory processes of chronic furunculosis are based on the pathogenicity of S. aureus as well as innate and acquired immunity. In-depth knowledge about them may help to discover the whole pathomechanism of the disease and to develop effective therapeutic options. In this review, we focus on the S. aureus-host immune interactions in the pathogenesis of recurrent furunculosis according to the most recent experimental and clinical findings.

Recurrent furunculosis - challenges and management: a review

Furunculosis is a deep infection of the hair follicle leading to abscess formation with accumulation of pus and necrotic tissue. Furuncles appear as red, swollen, and tender nodules on hair-bearing parts of the body, and the most common infectious agent is Staphylococcus aureus, but other bacteria may also be causative. In some countries, methicillin resistant S. aureus is the most common pathogen in skin and soft tissue infections which is problematic since treatment is difficult. Furunculosis often tends to be recurrent and may spread among family members. Some patients are carriers of S. aureus and eradication should be considered in recurrent cases. Solitary lesions should be incised when fluctuant, whereas patients with multiple lesions or signs of systemic disease or immunosuppression should be treated with relevant antibiotics. The diagnostic and therapeutic approach to a patient suspected of staphylococcosis should include a thorough medical history, clinical examination, and specific microbiological and biochemical investigations. This is particularly important in recurrent cases where culture swabs from the patient, family members, and close contacts are mandatory to identify and ultimately control the chain of infection. Focus on personal, interpersonal, and environmental hygiene issues is crucial to reduce the risk of contamination and recurrences.

Recurrent furunculosis: a review of the literature

BACKGROUND

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is increasing in incidence and manifests as skin and soft tissue infections including furuncles. The majority of studies have focused on the epidemiology of single furuncles and not recurrent disease. There is a lack of data concerning the incidence of furunculosis outside the U.S.A.

OBJECTIVES

This report reviews the literature of recurrent furunculosis and the impact of CA-MRSA on the disease.

METHODS

Article citations were searched within PubMed. Search terms used were 'furunculosis', 'recurrent furunculosis', 'skin abscess' and 'recurrent boils'. Articles were discarded if they did not refer to furunculosis secondary to S. aureus.

RESULTS

A total of 1515 articles were initially retrieved with the term 'furunculosis', 77 with the term 'recurrent furunculosis', 2778 with the term 'skin abscess', and 1526 with the term 'recurrent boils'. After excluding articles not referring to S. aureus furunculosis, 86 articles were included for this review.

CONCLUSIONS

Furunculosis is increasing within the U.S.A. secondary to the CA-MRSA epidemic and the resistant organism's close association with the Panton-Valentine leucocidin (PVL) virulence factor. PVL is associated with follicular infections in general, having its strongest association with furunculosis and its recurrence. The majority of furuncles in the U.S.A. are caused by CA-MRSA, while elsewhere in the world they are caused by methicillin-sensitive S. aureus. Nasal carriage of S. aureus is the primary risk factor for recurrent furunculosis and occurs in 60% of individuals.

Immunomodulatory activity of Toxicodendron pubescens in experimental models

BACKGROUND

Toxicodendron pubescens is a botanical name of Rhus toxicodendron (Rhus tox). This plant is widely used in its homeopathically diluted form in the treatment of inflammatory and edematous conditions. In this study, various dilutions of Rhus tox including its crude form have been evaluated for their effects on immune response in the in vivo and in vitro experimental models.

METHODS

Rhus tox in the form of mother tincture, 6cH, 30cH, 200cH and 1000cH dilutions was tested through in vivo models including sheep red blood cells (SRBCs) induced cellular and humoral immune response in C57/BL6 mice. The effects of Rhus tox dilutions were also evaluated in vitro on the functions of human polymorphonuclear (PMN) cells such as phagocytosis and intracellular killing of Candida albicans, chemotaxis, and reduction of nitroblue tetrazolium (NBT) dye.

RESULTS

Rhus tox was found to intensify SRBCs induced antibody titer and delayed type hypersensitivity response in mice. Even higher dilutions such as 200cH and 1000cH were found to affect the immune response; however, the crude form, mother tincture, 6cH and 30cH dilutions revealed more potent effects than the 200cH and 1000cH dilutions. In in vitro assays, all the dilutions exerted stimulation of phagocytosis, candidacidal activity and chemotaxis of human PMN cells. The NBT dye reduction assay revealed that oxidative processes in the PMN cells are accelerated in the presence of Rhus tox. This study shows that Rhus tox possesses immunostimulatory activity in its crude form as well as in homeopathically diluted forms. These effects appeared to be concentration dependent as higher dilutions had less potent effects.

The impact of vector-mediated neutrophil recruitment on cutaneous leishmaniasis

The dynamic process of pathogen transmission by the bite of an insect vector combines several biological processes that have undergone extensive co-evolution. Whereas the host response to an insect bite is only occasionally confronted with the parasitic pathogens that competent vectors might transmit, the transmitted parasites will always be confronted with the acute, wound-healing response that is initiated by the bite itself. Invariably, this response involves neutrophils. In the case of Leishmania, infection is initiated in the skin following the bite of an infected sand fly, suggesting that Leishmania must possess some means to survive their early encounter with recruited neutrophils at the bite site. Here, we review the literature regarding the impact of neutrophils on the outcome of infection with Leishmania, with special attention to the role of the sand fly bite.

Skin and Soft Tissue Infections

Primary skin infections (ie, pyodermas) typically are initiated by some breach in the epidermis, resulting in infection by organisms, such as Streptococcus pyogenes and Staphylococcus aureus, that normally colonize the skin. Host-associated factors, such as immunosuppression, vasculopathy, neuropathy, or decreased lymphatic drainage, may predispose to skin infection. The clinical syndromes associated with skin infections are often characteristic and are defined most simplistically by anatomic distribution. Although often mild and self-limited, skin infections can be more aggressive and involve deeper structures, including fascia and muscle. This article discusses skin and soft tissue infections, including impetigo, hair follicle-associated infections (ie, folliculitis, furuncles, and carbuncles) erysipelas, cellulitis, necrotizing fasciitis, pyomyositis, septic bursitis, and tenosynovitis.