Other
infections (nonviral)
Candidiasis
Candida
albicans (formerly called Monilia) is a yeast, frequently present in
small numbers in the healthy bowel and mouth. It may cause primary infection in
the newborn or supeninfection when flora are disturbed by antibiotic treatment.
In thrush (candidal stomatitis) white patches are seen in the mouth; it may
occur in infants, in postoperative patients, and with ill-fitting dental plates.
Vaginitis is common in pregnancy and diabetes. Candida may infect moist
skin under breasts and the nailfolds, and cause severe intertnigo.
Administration
of broad-spectrum antibiotics often results in proliferation of Candida in
the respiratory tract and bowel, and may be responsible for digestive upsets.
Systemic candidiasis with invasion of lung and bloodstream is a complication
of immunosuppression in transplantation surgery, and in the chemotherapy of
malignant disease. Oral thrush also occurs in AIDS.
Candida
infections are treated by the topical
antibiotic nystatin or by gentian violet. Treatments for vaginal candidiasis
include pessary treatment with clotrimazole (Canesten), miconazole nitrate (Gynodaktanin),
econazole (Ecostatin) or tsoconazole nitrate (Travogyn) from 1 to 6 days or
nystatin for 14 days. Ketoconazole 200 mg twice daily for 5 days and
fluconazole 150 mg (single dose) are more recent oral treatments. In all cases
of treatment failure, the male partner should be investigated for
balanoposthitis, easily cured with clotnimazole or nystatin ointments locally.
Aspergillus
Aspergillus
species can cause a variety of
clinical syndromes.
Asthma
A type I hypersensitivity reaction.
Allergic
broncho pulmonary aspergillosis
May be due to a type I and type III hypersensitivity reaction. Asthma
and a chronic cough with sputum production occur and bronchiectasis may result.
Aspergilloma
A chronic infection in a previously damaged area of lung, e.g. an old
tuberculous cavity, producing a characteristic radiographic appearance.
Haemoptysis may result and surgical removal may be necessary.
Disseminated
aspergillosis
Usually found in immunocompromised patients such as those undergoing
chemotherapy for leukaemia. Treatment involves the use of amphotenicin B.
Chancroid (soft sore)
This infection is rare in Western countries. It is caused by the
Gram-negative bacillus Ducrey (I-Iaemophilus ducreyi). Two to 5 days
after infection, sores, often multiple, appear on the genitals. They become
pustular and ulcerate, forming rounded, painful, soft, readily bleeding ulcers
with undermined edges. Inguinal adenitis follows, the swollen nodes being hard
and tender causing a feeling of stiffness in the groin. Resolution may occur at
this stage, but suppuration may follow, the nodes becoming matted together
forming a fluctuant unilocular abscess (hobo) with red overlying skin, in one or
both groins. The bubo should never be incised since healing is very slow.
Aspiration is correct. Phagedaena (a rapidly destructive ulceration) sometimes
occurs.
Treatment. Any antibiotic which may
prevent the identification of 717 pallidum in a case of concomitant
syphilitic infection, or when the aetiology of the lesion is in doubt, is
contraindicated. The mainstay of treatment has been co-trimoxazole 960 mg twice
daily or erythromycin 500 mg four times daily for 1 week. However, resistance to
cotrimoxazole is now appearing. Ciprofloxacin 500 mg twice daily for 3 days is
an alternative. Regular daily cleaning of ulcers with isotonic saline is
recommended.
Gonorrhoea
This venereal disease is discussed in relation to the genitourinary
system in Chapters 67 and 68.
Lymphogranuloma
venereum
This is described in Chapter 67.
Granuloma inguinale
This is described in Chapter 67.
Erysipelas
Erysipelas is a spreading inflammation of the skin and subcutaneous tissues due to an infection by Streptococcus pyogenes (j3-haemolytic streptococcus Lancefield group A). Poor hygienic living conditions, recurrent upper respiratory tract infections, debilitating illness and extremes of life are predisposing causes, and the lesion develops around a scratch or abrasion which is the site of inoculation of the streptococcus. A rapid toxaemia associated with the local infection and a rose-pink rash extending over the adjacent skin rapidly develops. The rash has a very clear edge and considerable oedema occurs (Fig. 8.13) over some tissues when infected, e.g. orbit or scrotum. Following the fading of the rash, a brown discoloration of the skin remains. The S. pyogenes remains fully sensitive to penicillin (see also ‘Antimicrobial chemotherapy’)
Anthrax
Bacillus
anthracis is a large, Gram-positive, aerobic, spore-forming rod. It is very
resistant to heat and antiseptics. The disease is found in cattle and is likely
to appear in people who handle carcasses, wool, hides, hair and bone meal.
The
cutaneous type is the commonest human variety; the incubation period is from 3
to 4 days. The lesion usually commences on an exposed portion of the body, such
as the hands, forearms or face. An itching papule (Fig.
8.14) occurs, around
which a patch of induration soon becomes evident. The papule suppurates and is
replaced by a black slough, and a ring of vesicles appears on the surrounding
indurated area. This stage comprises the typical ‘malignant pustule’. A
brawny, congested area of induration develops around the site of infection. The
regional lymph nodes are involved. Toxaemia is always in evidence. A smear of
vesicle fluid is used to confirm the diagnosis by culture and animal
inoculation.
Treatment.
Penicillin is the treatment of choice.
Prevention.
This must include precautiOns to sterilise potentially infected animal products
and wool from countries where the disease is endemic. A vaccine is available for
those at special risk of exposure.
Differential
diagnosis. The condition is easily mistaken for a severe furuncle (Chapter 37).
Other
forms of anthrax are rarely, if ever, now seen, e.g. wool-sorter’s disease, a
pneumonia due to inhalation of spores, and an alimentary type, following
ingestion of spores.
Actinomycosis
This disease is caused by Actinomyces israelli, an anaerobic,
Gram-positive, branching, filamentous organism which sometimes lives as a
harmless parasite in the tonsillar crypts and dental cavities of the otherwise
normal mouth. It is popularly supposed that it occurs in corn and grasses, but
the pathogenic bacillus does not. If the organism invades tissue, it causes a
subacute pyogenic inflammation with considerable induration and sinus formation.
Trauma and the presence of carious teeth are important predisposing factors in
the development of lesions in the mouth.
Diagnosis
depends on finding the organism in pus or in tissue section. Pus should be
collected in a sterile tube (a swab is usually insufficient) and inspected in a
good light for the presence of pinhead-sized ‘sulphur granules’. On
microscopy, the granules are seen to consist of Gram-positive branching
bacilli. The peripheral filaments radiate4 from the central part of
the granule and may be surrounded by Gram-negative tissue clubs.
Culture.
The presence of secondary organisms often makes this difficult.
The
lesions are characterised by the formation of a firm, indurated mass, the edges
of which are indefinite. Lymph nodes are not affected, but if a vein is invaded,
pyaemia is likely.
There
are four main clinical forms of actinomycosis.
• Faciocervical is the commonest.
The lower jaw is more frequently affected, often adjacent to a carious tooth.
The gum becomes so indurated that it simulates a bony swelling. Nodules appear,
which soften and burst; the overlying skin of the face and neck becomes
indurated and bluish in colour, softening occurs in patches. Abscesses burst
through the skin and sinuses follow.
• Thorax. The lungs and pleura are infected, either by aspiration of
the bacillus or by direct spread from the pharynx or neck, or even upwards
through the diaphragm. The chest wall, in the late stages, becomes riddled with
sinuses. An empyema is not uncommon, and the infection can easily spread through
the diaphragm to the liver and the subphrenic spaces.
• Right iliac fossa (see Chapter 5’).
• Liver (see Chapter 52).
Treatment.
Actinomyces is usually sensitive to penicillin, ret racycline and some
other antibiotics, e.g. lincomycin, but the sensitivity should be checked in the
laboratory. A prolonged intensive course of penicillin (10 megaunits reducing to
4 megaunits daily) is usually the best treatment until all signs of the disease
have disappeared.
Madura
foot (and hand). See (Fig. 8.15) and Chapters 30 and 31.
Parasitic
diseases
• Filariasis. See Chapter 17.
• Hydatid disease. See Chapter 52.
• Bilharziasis. See Chapter 65.
• Amoebiasis. See Chapter 57.
• Dracunculus medinensis. See Chapter 12.