Listeriosis I

Listeriosis I

OVERVIEW:

Infection caused by the ubiquitous, weakly hemolytic, gram positive bacillus, Listeria monocytogenes, which is pathogenic to many animal species. Occurs most often in fetuses (disseminated infantile listeriosis), in neonates, and in immunosuppressed patients. Majority of adult patients have pre-existing disease (cirrhosis, lymphomas, solid tumors, AIDS, cancer therapy). Usual course - acute.
• In 1998-1999 at least 50 illnesses were reported from eleven states resulting from contaminated hot dogs and deli meats.

System(s) affected: Pulmonary, Endocrine/Metabolic, Gastrointestinal, Renal/Urologic, Hemic/Lymphatic/Immunologic, Nervous
Genetics: No known genetic pattern
Incidence/Prevalence in USA:
• 1,850 cases a year (425 deaths)
• Pregnant women are about 20 times more likely than healthy adults to get listeriosis
• Persons with AIDS are almost 300 times more likely to develop infection
Predominant age: Neonates, elderly
Predominant sex: Male > Female

SIGNS AND SYMPTOMS:

• Asymptomatic
• Abdominal pain
• Adult respiratory distress syndrome
• Cervical lymphadenopathy
• Chills
• Conjunctivitis
• Decreased fetal movement
• Diarrhea
• Dysuria
• Fatigue
• Fever
• Hepatosplenomegaly
• Malaise
• Myalgia
• Nausea
• Pharyngitis
• Urinary frequency
• Vomiting
• Findings suggestive of meningitis - fever, headache, nausea and vomiting, stiff neck, delirium, coma
• Findings suggestive of sepsis - high fever and generalized severe illness without evidence of localized infection (in patients with alcoholism, malignancies, immunosuppression, AIDS)

CAUSES:

Listeria monocytogenes, a small gram-positive bacillus; infection with other species of Listeria are rare. Illnesses can begin 2-8 weeks after eating contaminated food.

RISK FACTORS:

• Age - fetus, neonates, elderly
• Metastatic malignant disease
• HIV infection
• Alcoholism
• Renal hemodialysis
• Pregnancy
• Immunosuppressed
• Exposure to infected animals (veterinarians, butchers, etc.). Animal-to-human transmission is rare.
• Ingesting contaminated food or drink (e.g., soft Mexican style cheese or feta cheese)

DIAGNOSIS

DIFFERENTIAL DIAGNOSIS:

• Other infections - Staphylococcal, gram negative Klebsiella, Candida, cryptococcosis, viral
• Infantile listeriosis, E. coli, Group B streptococci
• Infectious mononucleosis

LABORATORY:

• CSF
• Gram stain - may reveal small, gram-positive rods or coccobacillary forms with tumbling motility. (Sometimes difficult to identify since organisms are not present in large numbers and may be confused with diphtheroids and other bacteria.)
• Cell count - in most cases, the predominant cell type is the neutrophil; however, mononuclear cells may predominate. Counts range from 0-1200/mm3. RBC's frequently seen.
• Protein concentration - within normal limits to 735 mg/dL
• Glucose - within normal limits to undetectable
• CSF cultures - demonstrates beta-hemolysis (L. monocytogenes grows well on 5% sheep's blood or chocolate agar)
• Counterimmunoelectrophoresis (CIE) latex agglutination (LA) - possibly useful for differential diagnosis
• Other tests
• Blood cultures should be done
• CBC - peripheral WBC may show an elevated neutrophil count and/or left shift
• Other cultures in newborn - cervical vaginal secretions and lochia from the mother; cord blood; grossly abnormal portions of the placenta, meconium, and exudate expressed from an incised skin papule of the neonate

Drugs that may alter lab results: Antibiotics
Disorders that may alter lab results: Cultures may be confusing in patients with mixed infections

PATHOLOGICAL FINDINGS:

• Gross - multi-organ miliary granulomatosis
• Micro - nodular focal abscess
• Micro - necrotic amorphous basophilic debris
• Micro - increased tissue macrophages
• Micro - gram-positive bacilli
• Motile bacilli
• Chinese-letter aggregates

SPECIAL TESTS:

Specimens for serologic testing should be submitted to the local public health laboratory. In outbreaks, serotyping may be desirable.

IMAGING:

MRI with any patient having central nervous system symptoms

DIAGNOSTIC PROCEDURES:

Lumbar puncture

TREATMENT

APPROPRIATE HEALTH CARE:

Inpatient during acute phase

GENERAL MEASURES:

• Bedrest
• Isolation if immunosuppressed
• Secretion precautions
• Respiratory assistance (if apneic, or CNS depressed)

SURGICAL MEASURES:

N/A

ACTIVITY:

Bedrest

DIET:

• Acute case, total parenteral nutrition, nasogastric tube, or softer diet if tolerated
• As a preventive, avoid eating raw or partially cooked foods and soft cheeses. Warm leftovers thoroughly and wash raw vegetables before cooking.

PATIENT EDUCATION:

• Dietary guidelines for avoidance in high risk patients
• CDC - National Center for Infectious Diseases; www.cdc.gov/ncidod/ncid.htm/
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Medical Diagnosis » L » Listeriosis I