Etta Macdonald

Tinea capitis caused by Trichophyton tonsurans.

Abstract: Children with tinea capitis caused by Trichophyton tonsurans often have a lifetime of association with the organism and, in spite of intermittent therapy, as adults pass the infection to successive generations. While most current treatment regimens are directed at treating the individual patient, our study supports the need to evaluate and possibly treat all family members and their home environment.

A description of the stages in the life cycle of the filarial worm litomosoides carinii.

The life history of the filarial worms has been known in a general way for many years, but a study of a complete life cycle in the laboratory has only been possible since Litomosoides carinii, a parasite of the cotton rat, became available. In connection with experiments on immunity in this species, it has been necessary to identify anatomical characters by which the degree of development of individual worms can be readily determined. These characters and certain other details of development are described in this paper. These observations in addition to those already published complete the description of all the stages and the intervening molts. METHODS The stages in the intermediate host were obtained from mites raised on uninfected white rats. When the mites were hungry enough to feed readily they were placed on an infected cotton rat and recovered as they dropped off 2 or more hours later. They were then kept under conditions of high humidity at temperatures controlled within a range of 5o C. The mean temperature for each series of mites was constant but varied for different series from 180 to 240 C. The infected mites were dissected in one-half strength Tyrodes solution and the larvae were measured while alive in the same solution, or in the case of the third stage larvae, after the application of sufficient heat to paralyze but not kill them. The definitive host stages were obtained by introducing infective larvae dissected from mites into a subcutaneous pocket of an etherized cotton rat. The developing worms were recovered from saline washings of the pleural cavity of the rat. They were fixed in 70 per cent ethyl alcohol at 700 C., and after gradual changes to glycerin, were mounted in glychrogel and measured. For brevity we shall use the term age of the worms to mean the time from entrance into the intermediate or definitive host, as the case may be. RESULTS

Exophiala jeanselmei infection in a postrenal transplant patient

We report a case of Exophiala jeanselmei infection in a postrenal transplant patient. He had verrucous lesions on the thigh and abdomen in which clinical and histologic changes resembled those characteristic of chromoblastomycosis. However, the morphologic features of the fungus seen in the tissue sections made it necessary to diagnose this case as phaeohyphomycosis. The patient was treated successfully by complete excision of the lesion on the abdomen and with oral ketoconazole.

Actinomycetoma Caused by Nocardiopsis dassonvillei

We report a case of mycetoma caused by Nocardiopsis dassonvillei in a 39-year-old man. He had multiple nodules and draining sinuses on the anterior aspect of his right leg just below the knee. Few cream-colored granules were seen in the exudate. The biopsy specimen showed gram-positive, non-acid-fast granules with distinct borders. An aerobic actinomycete isolated from the lesion was identified as N dassonvillei. We think that this is the first reported case of mycetoma caused by N dassonvillei.

Erythrasma: Overlooked or Misdiagnosed?

When erythrasma was described over 100 years ago,’ little was known about the causative agent, and the disease was considered to be a fungal infection. The organism was originally called Microsporum minutissirnurn and has been known by various fungal and bacterial names. In 1961, when the organism was proved to be a gram-positive bacillus in the diphtheroid group, it was named Corynebacterium minutissimum.2 Since then, several studies on erythrasma have appeared in the English literature describing its incidence, bacteriology, and treatment, and the disease has finally been accepted as a bacterial infection. The organism, C. minutissimum, is a short grampositive rod with subterminal granules. It is best cultured in a medium containing 20% fetal bovine serum, 2% agar, and 78% tissue culture medium 199. Growth occurs within 12-24 hours as small, shiny, moist, translucent, greyish-white colonies that fluoresce various tones of coral red to orange under Wood’s light. The fluorescence of the colony persists for 2-4 days. The organism can also grow on blood agar and occasionally on other media, but the colonies may not fluoresce. There seems to be no doubt that this organism is a member of the normal skin flora. The conditions for multiplication of the organisms on the skin and tor subsequent clinical infection are unknown. Moisture, obesity, and diabetes are some ot the predisposing factors. The lesions of erythrasma are asymptomatic, welldefined patches ot irregular shape and size. At first the color i s red but later becomes brownish. The surfaces are rather smooth but tend to be finely scaly and wrinkled. The lesions are most commonly tound in the body folds, particularly the groin, axillary, intergluteal, and, in the female, the inframammary areas (Figs. 1, 2). Lesions in the toewebs are also trequent and show scaling, iissuring, and marceration. The generalized form, referred to

The cotton swab technic for the culture of dermatophyte infections — its efficacy and merit

A set of three comparison studies under varying conditions was performed to determine the efficacy of a cotton swab technic for obtaining material for culture of dermatophyte infections. Matched fungal cultures, one by swab and one by scrape, on each of 110 subjects showed that there was no difference in the two methods. The merits of this culture technic are explored and the conclusion is drawn that the cotton swab is an efficient and reliable adjunct to the practice of dermatology.

Comparative experiments with a Florida strain of Litomosoides carinii in Eastern and Texas cotton rats.

Abstract Eastern cotton rats, Sigmodon hispidus hispidus, and Texas cotton rats, Sigmodon hispidus texianus, were infected with a strain of filarial worms, Litomosoides carinii, derived from eastern cotton rats. During the first 23 days worms of a primary infection developed equally well in either strain of rats. Worms of superimposed infections were retarded in growth and development to a statistically significant degree in either strain of cotton rats harboring worms from a single previous infection.

Experimental necrotic dermatosis induced by group G streptococci in mice

SummarySelf healing necrotic lesions were produced on the backs of laboratory mice by injecting group G streptococci into the skin. The incidence and severity of necrotic dermatosis was dose related. When 1×101 colony forming units (cfu) were injected subcutaneously, lesions developed on three of 16 mice 4 days post inoculation. Injection of 1×103 cfu produced lesions on five of 16 mice and 1×105 cfu produced lesions on seven of 15 mice 3 days post inoculation. An inoculation of 1×107 cfu produced lesions on all of 16 mice 2 days post inoculation. Lesions produced by the 1×101 inoculum were smaller and had healed by the 15th day post inoculation, whereas lesions produced by the 1×107 inoculum persisted until the 24th day post inoculation. No mortality could be attributed to experimental design and all lesions healed without the use of medication or antibiotics.

Susceptibility and acquired immunity of two subspecies of cotton rats to their respective strains of filarial worm parasites

Abstract Two subspecies of cotton rats, Sigmodon hispidus hispidus and S. h. texianus appear to be equally susceptible to primary infections of the two strains of filarial worms, Litomosoides carinii , which they harbor in nature. Acquired immunity as measured by retarded growth and development of worms of challenging infections as compared with those of primary infections, appears to develop equally in either strain of rat with either strain of worms. When the two strains of rats were immunized and challenged with the two strains of worms in all possible combinations, some slight differences were observed between strains of rats and between strains of parasites. The differences were large, however, when worms from immunized rats were compared with those from non-immunized rats, regardless of the strains of rats or the strain of immunizing or challenging worms. There may be some evidence of slight differences between the strains of worms in their adaptation to their respective geographically isolated hosts. The comparability of work using different strains, which has been published to date, does not appear to be invalidated. In future experiments comparisons should be made within strains and not between strains.

Comparison of skin changes induced on mice by either group A type 12 or group G streptococci

Abstract Adult Swiss webster mice were injected with 3× 106 colony‐form inc units (cfu) of group G or 2. 5 × 106 cfu of group A streptococci at intradermal injection sites on the right and left paralumbar areas of the back. The mice were sacrificed at intervals between 4 hours and 14 days post‐injection (p. i.) and full thickness biopsies of skin 10 mm in diameter encompassing the sites of injection were taken. One tissue specimen was homogenized in PBS and plated to determine the number of cfu, while another was used for histopathological studies. The number of viable group A and group G streptotocci in the tissue increased to 3 × 109 cfu by 96 hours p. i. after 192 hours p. i. the group A cells had declined to 2. 7 × 106 cfu compared to 1. 1 × 108 cfu for group G cells. No streptococci of either group were detected at 336 hours (14 days p. i.). Gross edematous lesions induced by either streptococcus group were evident on all animals at 24 hours (p. i.). Group G streptococci lesions were larger and persisted longer than lesions induced by group A. Histological examination consistently revealed more inflammation and necrosis in tissue sections from mice injected with group G streptococci.