Listeriosis

Other Names: Listeriosis; Listeria monocytogenes infection

Listeriosis is a serious infection usually caused by eating food contaminated with the bacterium Listeria monocytogenes.

Cause

A listeria infection or listeriosis is an infection caused by a bacteria known as Listeria monocytogenes. Listeria can be spread by several methods. A common cause is ingestion (food-borne transmission) of unpasteurized milk or contaminated vegetables. It can also be transmitted from mother to fetus during pregnancy or directly to the newborn at the time of delivery.

Riskfactors

Listeria is most likely to sicken pregnant women and their newborns, adults aged 65 or older, and people with weakened immune systems. Other people can be infected with Listeria, but they rarely become seriously ill.

Symptoms

People with invasive listeriosis usually report symptoms starting 1 to 4 weeks after eating food contaminated with Listeria; some people have reported symptoms starting as late as 70 days after exposure or as early as the same day of exposure. Listeriosis can cause a variety of symptoms, depending on the person and the part of the body affected. Listeria can cause fever and diarrhea similar to other foodborne germs, but this type of Listeria infection is rarely diagnosed. Symptoms in people with invasive listeriosis, meaning the bacteria has spread beyond the gut, depend on whether the person is pregnant.

Pregnant women: Pregnant women typically experience only fever and other flu-like symptoms, such as fatigue and muscle aches. However, infections during pregnancy can lead to miscarriage, stillbirth, premature delivery, or life-threatening infection of the newborn. People other than pregnant women: Symptoms can include headache, stiff neck, confusion, loss of balance, and convulsions in addition to fever and muscle aches. Sometimes listeriosis involves many organs and presents with masses filled with pus (microabscesses or granulomas). Older children with Listeria infections frequently develop meningitis.

Diagnosis

Listeriosis is usually diagnosed when a bacterial culture (a type of laboratory test) grows Listeria monocytogenes from a body tissue or fluid, such as blood, spinal fluid, or the placenta.

Treatment

Treatment include antibiotics such as ampicillin and aminoglycosides. The antimicrobial regimen should be the standard therapy for listeriosis, typically including IV ampicillin and gentamicin for 14 to 21 days for nonallergic patients.

In invasive listeriosis, the bacteria have spread to the bloodstream and central nervous system. Treatment includes intravenous delivery of high-dose antibiotics and hospital care of duration which depends on how widespread the infection is, but usually no less than 2 weeks. Ampicillin, penicillin, or amoxicillin are often given for invasive listeriosis, and gentamicin is often added in patients with compromised immune systems. Trimethoprim-sulfamethoxazole, vancomycin, and fluoroquinolones can be used in cases of allergy to penicillin. For treatment to be effective, the antibiotic must penetrate the host cell and bind to penicillin-binding protein 3 (PBP3). Cephalosporins are not effective for treatment of listeriosis.

Prevention

Preventing listeriosis as a foodborne illness requires effective sanitation of food contact surfaces. Ethanol is an effective topical sanitizer against Listeria. Quaternary ammonium can be used in conjunction with alcohol as a food-contact safe sanitizer with increased duration of the sanitizing action.

Keeping foods in the home refrigerated below 4 °C (39 °F) discourages bacterial growth. Unpasteurized dairy products may pose a risk. Cooking all meats (including beef, pork, poultry, and seafood) to a safe internal temperature, typically 73 °C (165 °F), will kill the food-borne pathogen.

Epidemiology

Every year, about 1,600 people get listeriosis in the United States. A few outbreaks of listeriosis are identified most years. Even though most cases of listeriosis are not part of recognized outbreaks, outbreak investigations help show which foods are sources of listeriosis.

NIH genetic and rare disease info

• NIH info on Listeriosis

Listeriosis is a rare disease.

Listeriosis Resources
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