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Unusual Infections
There are many infectious diseases that present diagnostic dilemmas. Vague constitutional
symptoms are often associated with these illnesses making the diagnosis
challenging. A careful and detailed history, incorporated with physical examination,
will aid in developing a broad differential diagnosis that includes some of the more
unusual infections. Following are examples of such illnesses.
Toxic Shock Syndrome
- In 1978 a multi system illness caused by Staphylococcus aureus was described by Todd
and coworkers. They reported on seven children aged 8-17 yr who had common clinical
features of high fever, hypotension, diarrhea, erythroderma, mental confusion, and
renal failure. This entity was named toxic shock syndrome.
- In the early 1980s reports of women with toxic shock syndrome associated with menses
appeared. Menstrual toxic shock syndrome was believed to be related to hyperabsorbable
tampons and since their removal from the market the incidence of disease has decreased.
- Nonmenstrual toxic shock syndrome has become more clearly recognized as cases of
menstrual toxic shock syndrome decline. Nonmenstrual toxic shock syndrome may
occur following S. aureus colonization of the vagina and vaginal infections, the use of
contraceptives, postpartum states, or abortions. Men are also at risk following surgical
procedure where wounds may become infected, from osteomyelitis, or from respiratory
tract infections.
- The management of toxic shock syndrome requires aggressive intravenous fluid resuscitation
for hypotension.
| Table: Diagnostic criteria for toxic shock syndrome |
|---|
Temperature >38.9� C
Systolic blood pressure < 90 mm Hg
Rash with subsequent desquamation (especially palms and soles)
Involvement of ≥ 3 of the following organ systems
Gastrointestinal: vomiting, profuse diarrhea
Muscular: myalgia, or >5-fold increase in CPK
Mucous membrane hyperemia: vagina, conjunctiva, or pharynx
Renal insufficiency: at lease twice normal BUN or creatinine
Hepatic: at least twice normal bilirubin, transaminases
Blood: thrombocytopenia (< 100,000 platelett/mm3)
Central nervous system: disorientation without focal neurologic signs
Negative serologic results for Rocky Mountain spotted
fever, leptospirosis, and measles
CPK = creatine phosphokinase; BUN = blood urea nitrogen. From: MMWR Morb Mortal
Wkly Rep 1990; 39(RR-13):1, with permission. |
| Table: Frequency of signs and symptoms of toxic shock syndrome |
| Clinical Signs and Symptoms | Frequency |
| Diarrhea | 98% |
| Myalgia | 96% |
| Vomiting | 92% |
| Temperature ≥ 40� | 87% |
| Headache | 77% |
| Sore Throat | 75% |
| Conjunctival hyperemia | 57% |
| Decreased sensorium | 40% |
| Vaginal hyperemia | 33% |
| Vaginal discharge | 28% |
| Rigors | 25% |
| Note: Rash and shock are not included because they are part of the definition of toxic
shock syndrome. Adapted from: Shands KN, Schmid GP, Dan BB et al; Toxic shock syndrome
in menstruating women - Association with tampon use and staphylococcus aureus and
clinical features in 52 cases; N Engl J Med 303:1436-1442; �1980 Massachusetts Medical
Society, with permission. |
Vaginal examination should be performed early to remove any tampons and to collect
cultures, including both cervical swabs and the tampon itself.
Other potential sources of infection should be cultured and potentially infectious
material removed, i.e., drainage of abscesses or wound debridement.
Antibacterial therapy should be administered immediately with a �-lactamase resistant
antistaphylococcal antibiotic, such as intravenous nafcillin or oxacillin (2 g q 4-6 h).
Clindamycin (600-900 mg IV q 8 h) is a suggested addition to nafcillin/oxacillin due
to its ability to decrease toxin production.
With the incidence of methacillin-resistant S. aureus increasing in community acquired
infections the addition of vancomycin (1 g IV q 12 h) may be prudent prior to
culture and sensitivity testing of the pathogen.
Patients with toxic shock syndrome should be admitted to an intensive care unit.
Suggested Reading
- Todd J, Fishaut M et al. Toxic-shock syndrome associated with phage-group-1 Staphylococci.
Lancet 1978; 2:1116-8.
- Center for Disease Control and Prevention. Follow-up on toxic shock syndrome - United
States. MMWR 1980; 29:279-9.
- Waldvogel FA. Staphylococcus aureus (Including staphylococcal toxic shock syndrome)
In: Mandell GL, Bennett JE, Dolin R, eds. Mandell, Douglas, and Bennett�s Principles
and Practice of Infectious Disease. 5th ed. Philidelphia: Churchill Livingstone,
2000:2089-92.
Syphilis
- Treponema pallidum is the pathogen responsible for causing syphilis.
- The clinical course following infection evolves through stages.
- The primary stage is characterized by a painless and indurated ulcer, or chancre, at
the site of innoculation.
- Skin rash, mucocutaneous lesions, and lymphadenopathy are typical clinical findings
associated with secondary infection. Latent infection is defined as the stage
without clinical manifestations but positive serologic tests. Duration of infection of
< 1 yr is known as "early latent syphilis". "Late latent syphilis" refers to asymptomatic
infection of >1 yr.
- Tertiary syphilis is a slowly progressive disease that manifests as central nervous
system, (e.g., tabes dorsalis and general paresis), cardiovascular (e.g., aortitis), or
gummatous disease.
- Congenital syphilis may cause rhinitis, rash, jaundice, notched and widespread incisors
(Hutchinson�s teeth), and bony abnormalities (saber shins).
- Dark field examination of exudate from a mucocutaneous lesion demonstrating spirochetes
is the easiest and most rapid test for syphilis.
- The diagnosis is most commonly made by serologic testing using two general types of
tests, nontreponemal tests (Venereal Disease Research Test, or VDRL, and the Rapid
Plasma Reagin, or RPR), and treponemal tests (Fluorescent Treponemal Antibody
Absorbed, or FTA-ABS, and T. pallidum Particle Agglutination, or TP-PA).
- A positive nontreponemal test is defined as a four-fold change in titer (equivalent to
an increase in two dilutions, e.g., 1:4 to 1:16).
- Nontreponemal tests usually become nonreactive with time after treatment. False positives
may be seen with viral infections, connective tissue disease, pregnancy, and malaria.
- The VDRL test is used to assess the cerebral spinal fluid for the presence of neurosyphilis.
- Treponemal tests are specific antibody tests used to confirm the positive reactions to
VDRL or RPR. Most patients with a positive treponemal test will remain positive for
life despite treatment.
- Penicillin G is the drug of choice for all stages of syphilis. Patients with penicillin
allergy who are pregnant, who have neurosyphilis, or congenital syphilis require desensitization
and treatment with penicillin,
Arthropod-Borne Infections
- Symptoms of malaise, myalgias, headache, and the signs of fever and rash are commonly
associated with arthropod-borne infections. (Table 11.5) Ticks, mites, lice, and fleas are
common vectors. These infections have a geographic distribution based upon the habitat
of the animal reservoirs and the insects that transmit the diseases to humans.
Cat Scratch Disease
- The causative agent is Bartonella henselae.
- The disease mainly affects children and is typically benign, subsiding within several
months.
- The hallmark is regional lymphadenopathy occurring proximal to the site of a cat
scratch or bite.
| Table: Arthropod-borne infections |
|---|
| Disease | Pathogen | Signs and Symptoms | Treatment |
| RMSF | Rickettsia rickettsii | Fever, headache, rash | Doxycycline |
| Scrub typhus | R. tsutsugamushi | Fever, headache, rash | Doxycycline |
| Epidemic typhus | R. prowazekii | Fever, headache, rash | Tetracycline |
| Ehrlichiosis | Ehrlichia chaffeensis | Fever, rash, leukopenia | Doxycycline |
| Lyme Disease | Borrelia burgdorferi | Erythema chronicum migrans,
joint pains, arthritis, headache | Doxycycline |
| Tularemia | Francisella tularensis | Lymphadenopathy, cough,
pneumonitis, ulcerating lymph
nodes, oculoglandular disorder | Streptomycin |
| Babesiosis | Babesia microti | Fever, shaking chills,
arthralgias, headache,
asplenic patients high risk | Clindamycin, Quinine |
| Rocky Mountain spotted fever |
| Table: Nontuberculous mycobacteria |
| Agent | Signs and Symptoms | Treatment |
| Rapid Growing |
M. fortuitum group
M. chelonei/abscessus | Cutaneous disease | Surgical,
Resistant to anti-TB Rx
Amikacin and cefoxitin |
| Slow Growing |
MAC
(M. avium-intracellulare complex) | Pulmonary disease | Clarithromycin
Rifampin
Ethambutol
+/- Surgical |
| Disseminated disease (HIV +) | Clarithromycin
Ethambutol
+/- Rifabutin |
| M. kansasii | Pulmonary disease | Isoniazid
Rifampin
Ethambutol |
| Disseminated disease (HIV +) | Same as pulmonary |
| Intermediate Growing |
| M. marinum | Cutaneous disease | Clarithromycin OR
Rifampin and Ethambutol |
| From: Mandell: Principles and Practice of Infectious Diseases. 5/e:2632. �2000 Elsevier
Inc., with permission. |
Atypical manifestations, occurring < 5% of cases, include conjunctivitis with lymphadenopathy
(oculoglandular fever), encephalitis, myelitis, peripheral neuopathy among
others.
Treatment is with azithromycin but is usually reserved for severe disease.
The differential diagnosis of unilateral lymphadenopathy includes nontuberculosis
mycobacterial infection, tularemia, brucellosis, syphilis, histoplasmosis, vaccinations, neoplasms,
and others.
Nontuberculous Mycobacteria
- Mycobacteria species other than M. tuberculosis, M. bovis, M. africanum, and M. leprae
are considered "atypical" mycobacteria. There are over 50 species that are frequently
categorized by growth rates, rapid (< 7 days) and slow (>7 days) growing mycobacteria 95% of all human mycobacteria infections are caused by seven species, M. tuberculosis, M. leprea, M. avium-intracellulare comples, M. kansasii, M. fortuitum, M. chelonae, and M. abscessus.
Suggested Reading
- Manguina C, Gotuzzo E. Bartonellosis: Old and new. Infect Dis Clin N Amer 2000;
14:1-22.
- Brown B, Wallace Jr RJ. Infections due to nontuberculous mycobacterium. In: Mandell
GL, Bennett JE, Dolin R, eds. Mandell, Douglas, and Bennett�s Principles and Practice
of Infectious Diseases. 5th ed. Philadelphia: Churchill Livingstone, 2000:2630-6.
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