1. Pitted keratolysis, erythrasma, trichomycosis appear to be related to cortyneforms or dephteroids

2. The Corynebacteria
The Corynebacteria are a diverse group of gram-positive bacilli which include Corynebacterium diphtheriae as well as a bewildering number of species that are found on the skin as part of the normal flora. These latter organisms are usually referred to as diphtheroids or coryneforms.
Three skin conditions appear to be related to an overabundance of these coryneforms: pitted keratolysis, erythrasma, trichomycosis. Interestingly, all three have been reported to coexist in the same person.
Gram Stain from the Blood agar showing characteristic Gram-positive short rods with Chinese letter arrangement of the diphtheroid (×1000)

3. Non-diphtherial Corynebacteria, which are also referred to as Diphtheroids, are a widely diverse collection of bacteria. Up to now, the pathogenic potential of coryneform bacteria has been underestimated. Although frequently considered as contaminants, these organisms have been associated with invasive disease, particularly in immunocompromised patients. Species like C. amycolatum, C. jeikeium, C. minutissimum, and C. urealyticum are being reported with increasing frequency in recent years. These organisms have been implicated in multiple infections like catheter-associated blood stream infections, endocarditis, prosthetic valve infections, meningitis, neurosurgical shunt infection, brain abscess, peritonitis, osteomyelitis, septic arthritis, urinary tract infections, empyema, and pneumonia

4. Actinomycetes Actinomycetes
Pitted keratolysis was first reported in a Ceylonese patient in 1910, by Castellani under the term "Keratoma plantare sulcatum", a disease limited to the soles and characterized by small pits which coalesced and formed sulci. In 1930 Acton and McGuire described eight cases of Keratoma plantare sulcatum from Bengal. They stated that the pits were associated with an organism belonging to the actinomycetes group and named it Actinomyces keratolytica sp. nov . Acton and McGuire renamed the disease "Keratolysis plantare sulcatum", since the condition in reality is a partial loss of the stratum corneum rather than a hyperkeratosis as Castellani's "Keratoma" implied. In 1931, Acton and McGuire ( Ind. M. Gazette 66: 65, 1931)suggested that Actinomyces keratolytica was the causative agent. Zaias et al (Arch. Derm. 92: 151, 1965), observing the erosion of the horny layer of the plantar surfaces, assigned the condition its current name, "Pitted keratolyis."
Actinomycetes

5. 10 toes on one foot.

6. Part I pitted keratolysis

7. pitted keratolysis
This condition is characterized by numerous shallow, discrete pits on the plantar surface of the feet, usually in the weight-bearing areas. Although the condition is asymptomatic, there is usually hyperhidrosis and the feet may be malodorous. Painful erosions may occur. The condition is caused by Micrococcus species. Topical clindamycin or topical erythromycin is the treatment of choice.

8. Pitted keratolysis What is the cause of pitted keratolysis?
Pitted keratolysis is caused by several bacterial species, including corynebacteria, Dermatophilus congolensis, Kytococcus sedentarius, actinomyces and streptomyces.
In moist conditions, the bacteria proliferate. The pitting is due to destruction of the horny cells (stratum corneum) by protease enzymes produced by the bacteria.
The bad smell is due to sulfur compounds produced by the bacteria.
How is the diagnosis of pitted keratolysis made?
Pitted keratolysis is usually diagnosed clinically. Swabs may be helpful to identify causative organisms, and skin scrapings are often taken to exclude fungal infection. The diagnosis is sometimes made by skin biopsy revealing characteristic histopathological features of pitted keratolysis.
Treatment of pitted keratolysis
Pitted keratolysis can be successfully treated with topical antibiotics such as fusidic acid cream, or with oral erythromycin.
It will quickly recur unless the feet are kept dry.

9. Pitted Keratolysis Pitted keratolysis forming sulci on the heel.
Pitted Keratolysis is caused by Corynebacterium species, Actinomyces  or Micrococcus.

10. Pitted keratolysis with hyperkeratosis on the heel.
Classic pits of pitted keratolysis on the plantar aspect of the phalanges.

11. Pitted Keratolysis
A large plaque-like lesion of Pitted keratolysis on the large toe.
A case of inflammatory pitted keratolysis

12. pitted keratolysis or keratolysis punctata caused by Corynebacterium of Taplan.

13. Pitted Keratolysis
, Histological evaluation of hematoxylin and eosin (H&E)–stained plantar skin reveals a crater limited to the stratum corneum (see the image below).
Histopathology reveals a crater limited to the thick stratum corneum of the epidermis.
The microorganisms, cocci, and filamentous forms may be seen with H&E staining, but they are detected more easily with Gram stain, periodic acid-Schiff stain, or methenamine silver stain. In 2000, Wohlarb et al reported 2 histologic types. The superficial minor type is coccoid bacteria found extracellularly on the surface of the stratum cornea. The classic or major type is coccoid and septated bacterium forms intracorneocytically in the horny layer. In patients with associated foot pain and with erythematous-to-violaceous macular lesions and pits, histological examination reveals only a mild dermal inflammatory reaction. In 2000, de Almeida et el studied pitted keratolysis with electron microscopy and noted transverse septated bacterium in tunnellike openings on the floor of the pits.
Histopathology reveals a crater limited to the thick stratum corneum of the epidermis.

14. The use of the VOLAR CORNEAL BIOPSY (VCB), i. e
The use of the VOLAR CORNEAL BIOPSY (VCB), i.e., the use of the cornified scrapings or clippings from the foot (or hand) for histologic examination, instead of a KOH preparation.
Not only fungi can be identified. It is not uncommon that Corynebacterium minutissimum, the agent of the underestimated pitted keratolysis of the soles, can be detected. The defining thin granules and filaments making the diphtheroid will stand up in the PAS stain
Subungual Horn, Filamentous Corynebacteria, PAS Stain

15. Part II Erythrasma

16. Erythrasma
Erythrasma is a bacterial infection caused by Corynebacterium minutissimum (Gram positive bacteria). , Obesity& diabetic people are more likely to develop Erythrasma infection caused by bacteria.
Causes :
The infection is more common in people who live in warm climate. The predisposing factors that cause Erythrasma are obesity, diabetes, poor hygiene, hyperhidrosis and age. .
Diagnosis :
Scraping culture test for confirming the infection may be needed. Wood’s lamp investigation is done for diagnosing the illness. UV rays of the lamp when passed on to the infected skin layer, makes it coral red.
Treatment :
Taking antibiotic medications like erythromycin can cure the bacterial infection. Topical ointments that contain fusidic acid and imidazole are prescribed for controlling infection. Antibacterial drugs and anti-infective medications are given for the patient depending on the intensity of infection and his health condition. Erythromycin, Clarithromycin and Miconazole are prescribed for controlling infection and inflammation.

17. Erythrasma 

18. ERYTHRASMA

20. Erythrasma 

21. ERYTHRASMA

22. Erythrasma 
The pink-red fluorescence of corynebacteria, an infection of the body folds known as erythrasma, shown under a "woods lamp" in a dark room.

23. Predisposing conditions to erythrasma
Erythrasma is typically located in moist folds as:
Under the arms (axillae)
In the groin and inner thighs
Between the toes, especially between the 4th and 5th toes .
Predisposing conditions to erythrasma
Diabetes
Obesity
Excessive sweating
Poor hygiene
Immune deficiency

24. Gram Stain from the Blood agar showing characteristic Gram-positive short rods with Chinese letter arrangement of the diphtheroid

25. Corynebacterium minutissimum

26. Corynebacterium minutissimum
Erythrasma is a cutaneous bacterial infection caused by Corynebacterium minutissimum. It was named in 1961 and is a lipophilic, Gram-positive, non–spore-forming, aerobic, catalase-positive diphtheroid that makes up to 50% of the normal flora of the skin.
Epidemiology
Erythrasma is a common infection present in the toe webs of up to 44% of diabetics; it is also seen in patients with advanced age, obesity, poor hygiene and hyperhidrosis. Erythrasma is the most common interdigital infection of the foot, presenting as fissuring, scaling and maceration of the web spaces.
Clinical Presentation
Erythrasma typically affects warm and moist intertriginous areas such as the axilla, groin and inframammary area. It presents as a confluent brownish patch, which later develops into a red-brownish plaque with minimal scale that is usually asymptomatic but can be pruritic. In addition to erythrasma, C. minutissimum has less commonly caused abscess formation, bacteremia, catheter-related infection and ophthalmologic infection.
Erythrasma is often mistaken for tinea corporis. Therefore, a negative KOH examination to exclude dermatophytosis may be helpful.
Erythrasm can be diagnosed by visualizing coral-red fluorescence under Wood’s light examination of the effected area. This color results from the porphyrins produced by C. minutissimum.
Histology/Pathogenesis
Hematoxylin and eosin staining of a skin biopsy may appear normal. However, the Gram, the periodic acid-Schiff and the methenamine silver stains reveal the rod-like shape of C. minutissimum in the stratum corneum.

27. Corynebacterium minutissimum

28. Corynebacterium minuti- ssimum bacterium
False-colour transmission electron micrograph (TEM) of Corynebacterium minutissimum, showing a single bacterium of the Gram positive, non- sporing, aerobic species of bacilli (rod-shaped bacteria). The Corynebacterium genus includes an important human pathogen, C. diphtheriae the causative agent of diphtheria; other species cause suppurative (pus forming) diseases of animals. An assortment of non- pathogenic species, known as diptheroid bacilli, occur as normal flora of human skin, upper respiratory tract, external ears and conjunctivae (mucous membranes of eye & inner eyelid). Magnification: X 26,500 at 35mm size

30. Scheme of hair microscopy

31. ORS: outer root sheath, CP: companion cell, IRS: inner root sheath, He henle’s layer, Huxley layer, Ci: cuticle of IRS, Ch: cuticle of hair shaft, CO cortex of hair shaft, Me medulla, DP dermal papilla Pattern of antibodies against protein are shown

32. The human keratin family comprises 54 members, 28 type I & 26 type II
The human keratin family comprises 54 members, 28 type I & 26 type II. Out of the 28 type I keratin , 17 are epithelial & II are hair keratins . Similarly the 26 type I members comprises 2O epithelial & 6 hair keratins. Out of 26 hair specific keratins only 5 have , at present ( Schweizer,J. Experimental cell research 313 ,page 2O1O: 2OO7) been associated with inherited hair disease

34. Part III TRICHOMYCOSIS AXILLARIS Int. J. Trichology 5: 12, 23O13
Trichomycosis axillaris is a benign, relatively common superficial bacterial infection of the axillary hair shafts and to a lesser extent, pubic hair (trichomycosis pubis).. It is caused by the overgrowth of several species of the gram-positive diphtheroid Corynebacterium (mostly Corynebacterium tenuis). Trichomycosis is a misleading term because the infection is not caused by a fungus as the name may imply. The source of the organism is the skin, where Corynebacteria are plentiful.
Corynebacterium prefers moist areas of the body thus mainly affects hair shafts in sweat gland-bearing areas, such as the armpits and the pubic area.
Superficial infection results in 1- to 2-mm adherent yellow, black or red granular nodules or concretions that surround and stick to each hair shaft, making it appear beaded or thicker. The concretions consist of tightly packed bacteria and are most common on the central portion of axillary hair.
The different color may be attributable to the species of Corynebacterium or to the changes in chemical environment of these organisms) The insoluble cement substance elaborated by the bacteria adheres to the hair shaft and, occasionally, invades and destroys cuticular and cortical keratin. The hair shaft may become brittle and thus, more easily broken, but this is rare.
Yellow concretions are the most common, whilst red and black are seen most often in tropical climates (the black the rarest). Sweat may be coloured according to the colour of the concretions and therefore clothing can be the same color. The underlying skin usually is normal. It occurs in both temperate and tropical climates: it is a trivial disease of worldwide occurrence. It is not limited by race or sex: nevertheless it appears to be more common in men than women but this is because many women shave their axillary hair. It can affect any age group from puberty through adulthood.
all that is noticed are sweaty, smelly armpits. Dermatologists are searched for the malodorous sweat and hyperhidrosis of the underarm area.
The treatment consists of  daily cleansing with soap and water and application of benzoyl peroxide (gel or wash formulations). Topical antibiotic preparations such as clindamycin or erythromycin are occasionally required to eliminate the infection. "Drying" powders may assist treatment. But the fastest method  to get rid of the problem is to clip  or to shave the affected hairs. Once treated, it may recur if preventive measures are not taken: the area has to be kept clean (with antibacterial soap) and dry. Regular use of antiperspirants (such as anhydrous aluminium chloride) provide an effective means of prevention by reducing sweating.
Shaving or trimming axillary hair usually is beneficial.

35. Trichomycosis (trichobacteriosis) Int. J. Trichology 5:L 12, 2O13
Initial trichomycosis pubis (var. flava)

36. Trichomycosis (trichobacteriosis) Int. J. Trichology 5:L 12, 2O13
Trichomycosis, a more correct term would be trichobacteriosis or bacterial trichonodosis is a superficial infection, primarily of the axillary hair, which can exhibit three different clinical presentations: The most common clinical variant is trichomycosis flava (yellow), while rubra (red) and nigra (black) variants occur much less frequently. From the earliest reported cases of trichomycosis, the causative agent was classified as C. tenuis. In light of the new taxonomic position of the genus Corynebacterium, however, that particular species is no longer considered, and thus, the majority of the reports are left as Corynebacterium sp. However, some studies have shown that the causative agent belongs to the so-called group 2 (LD2) (also referred to as the CDC-G/LD group), that it corresponds to the C. flavescens species, and that it is related to the flava variant.
Yellow‑fluorescence of trichomycosis pubic' hairs (Wood light)

37. Trichomycosis (trichobacteriosis) Int. J. Trichology 5: 12, 2O13
Trichomycosis infection begins when the causative agent comes in contact with the hair shaft, and the bacteria adhere to the surface, or the cuticle, of the hair, using a cement-like substance, the chemical composition of which is not yet known, that is insoluble in water as well as in the other principal solvents (i.e., acetone, ethanol). Electron microscopy studies have clearly shown that the microorganism does not penetrate to the medulla's cortex of the hair; instead, it only adheres strongly to the surface of the hair and develops slowly until it forms concretions around the hair shaft.

38. Culture of Corynebacterium sp. , in chocolate‑blood agar plate Int. J
Culture of Corynebacterium sp., in chocolate‑blood agar plate Int. J. Trichology 5: 123, 2O13

39. Trichomycosis (trichobacteriosis) An. Bras. Dermat.87 nO. 2, 2Oi2
Trichobacteriosis, trichomycosis axillaris or trichomycosis palmellina belongs to the group of cutaneous corynebacteriosis as well as erythrasma and pitted keratolysis.
It is mostly caused by Coryne bacterium tenuis and is clinically characterized by yellowish, reddish or blackish sticky concretions surrounding the hair shaft of the axillary or pubic region.
Hyperhidrosis and improper hygiene are the main predisposing factors.
Despite its symptomless condition, treatment may be based on cleansing methods. Sometimes topical antibiotics (erythromycin 2% or clyndamicin 1%) or benzoyl peroxide may be required. The differential diagnosis includes white piedra, black piedra and hair casts

40. Trichomycosis (trichobacteriosis)

41. Trichomycosis (trichobacteriosis)

42. Case of Trichomycosis Axillaris and Erythrasma J. drugs Dermat. 1O: no
Case of Trichomycosis Axillaris and Erythrasma J. drugs Dermat. 1O: no.12, 2O11