Fever and rash, bacterial causes

Rickettsiosis and dengue are frequent causes of cutaneous rash and fever after a trip in the (sub)tropics. Septicaemia due to meningococci is life-threatening. A disease that occurs after a trip does not necessarily need to have an exotic aetiology.

A distinction is often made between scarlatiniform, morbilliform, roseoliform, vesicular and petechial cutaneous rashes. As the same organism can cause different cutaneous abnormalities, an aetiological survey is given here.

• Typhus or spotted fever (rickettsiosis) occurs quite frequently. An inoculation chancre can be found in tick-bite fever and in scrub typhus. Transient leucopenia and thrombocytopenia characterise the disease. Rocky Mountain spotted fever and epidemic spotted fever are very serious diseases.

• Typhoid fever is a consequence of infection with Salmonella typhi. Roseola typhosa are discrete maculopapular lesions. They are rare and are usually difficult to detect. If they do occur they are found on the thorax and the abdomen.

• Secondary syphilis is accompanied by a maculopapular rash. Lesions occasionally appear simultaneously on the oral mucosa. Condylomata lata and alopecia areata should be looked out for. Serology is essential for diagnosis.

• Scarlet fever (scarlatina) is caused by infection with group A streptococci that produce an erythrogenic toxin. The disease resembles a classical streptococcal pharyngitis, with red tongue (strawberry tongue). There is also a diffuse redness of the skin. The erythema will disappear by pressure. A typical perioral pallor is described. Pastia's lines are dark red lines in skin folds. After the acute phase desquamation will occur. Acute rheumatic fever is a serious complication. Kawasaki syndrome is an important differential diagnosis.

• Bartonellosis initially causes a haemolytic anaemia with fever. This can be followed by nodular or verrugous skin lesions (verruga peruviana).

• Meningococcal septicaemia is a medical emergency. Purpural skin lesions are caused by massive intravascular coagulation (DIC) due to infection with Neisseria meningitidis. Shock and multi-organ failure can rapidly develop. There is a risk of complications with gangrene and destruction of the adrenal glands (Waterhouse-Friderichsen syndrome).

• Chronic gonococcaemia (Neisseria gonorrhoeae) causes intermittent fever, arthritis of the large joints and recurrent skin lesions on the hands, forearms, calves and feet. The petechiae are usually isolated, though they sometimes occur in small groups. There is a central vesicle (blister), surrounded by a red halo. This lesion develops into a haemorrhagic pustule and subsequently heals.

• Subacute bacterial endocarditis can cause petechiae. These are frequent in the nailbed. Osler noduli, Roth spots, a cardiac murmur, haematuria and Janeway lesions may be present. Blood cultures are extremely important. Echocardiography (preferably transoesophageal) should be carried out to detect valve lesions.

• Leptospirosis can occasionally (10%) be accompanied by cutaneous rash, e.g. on the calves (Fort Bragg fever). In typical cases other clinical data (fever, icterus, kidney infection, "aseptic" meningitis, red conjunctivae, tendency to bleeding) will suggest the diagnosis.

• Acute rheumatic fever may be accompanied by erythema marginatum. This is however a rare clinical sign. Erythema marginatum is transient and is considered one of the major Jones’ criteria for the diagnosis of acute rheumatic fever. The lesions are usually very short-lived, but usually reappear on the torso and proximal parts of the limbs. The other major criteria are carditis, arthritis, chorea and subcutaneous noduli. All these symptoms do not occur at the same time.

• Rat bite fever. This term covers 2 different diseases.

• Infection with Streptobacillus moniliformis, a pleomorphic Gram-negative bacillus, can follow after an infected rat or mouse bite or after drinking unpasteurised infected milk (Haverhill fever). After healing of the initial bite wound an abrupt "viral" syndrome occurs, with fever, headache, vomiting and muscle and joint pain (arthritis). A morbilliform petechial rash develops on hands and feet. There is no lymphadenopathy in Haverhill fever. The history and bacterial culture will guide the diagnosis.

• Sodoku is an infection caused by Spirillum minus, a Gram-negative, short, spiral-shaped organism. Lymphangitis, lymphadenopathy, recurrent fever and a recurrent roseola-urticarial rash follow. Sodoku does not lead to arthritis. It has not yet been possible to culture the organism in vitro. There is a high risk of complications involving endocarditis. Treatment is with penicillin or tetracycline.

• Cutaneous anthrax When someone comes into contact with animal fur or hides contaminated with anthrax bacteria, an infection of the skin can follow. After a short incubation period, a small spot appears on the skin at the site of infection. This can initially itch somewhat. Vesicles or blisters will usually form around the central lesion. This is followed by a central ulceration that nevertheless develops painlessly. The ulcer is dry (no pus formation) and there is often a black scab (Greek: "anthrax" = charcoal). Red oedema can occur around the lesion. Regional lymphadenopathy and moderate fever can occur. There is no peripheral leucocytosis. The skin lesion heals slowly. Sometimes the infection will spread, with generalised anthrax as a consequence.

• Pseudomonas aeruginosa septicaemia is accompanied in 13-39% of cases by various cutaneous abnormalities (petechiae, vesicular lesions, nodules, erythema, gangrene = ecthyma gangrenosum).

• Brucellosis. This disease is only rarely accompanied by cutaneous abnormalities (maculopapular rash, erythematous lesions). Persistent fatigue, recurrent fever, neurological problems, bone pain, lymphadenopathy and splenomegaly can occur. Serology and various cultures are necessary for the diagnosis.

• Mycoplasma pneumoniae infection is, in addition to respiratory abnormalities, sometimes accompanied by erythema multiforma.

Category: Medicine Notes