Listeriosis overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [2]
Overview
Listeriosis is a bacterial infection caused by a gram-positive, motile bacterium, Listeria monocytogenes.[1] Listeriosis is relatively rare and occurs primarily in newborn infants, elderly patients, and patients who are immunocompromised.[2]
Historical Perspective
Listeria monocytogenes (formerly Bacterium monocytogenes) was isolated in 1926 by Everitt Murray and renamed Listeria monocytogenes in 1940 after Joseph Lister, in honor of his discovery of sterilization to prevent surgical infection. Initially described as a bacteria of laboratory animals, the first human cases were described in 1929 by Nyfeldt, in Denmark.
Classification
Clinical syndromes caused by Listeria monocytogenes include: infection in pregnancy, neonatal infection, bacteremia, central nervous system infection (meningitis, encephalitis, rhombencephalitis, brain abscess, spinal cord infection), endocarditis, localized infection, and febrile gastroenteritis.
Pathophysiology
Listeria monocytogenes is able to enter de body through the gastrointestinal lining, causing infection in otherwise sterile sites. The pathogenesis of L. monocytogenes is centered on its ability to survive and multiply within phagocytic host cells, which it uses to travel to difference sites in the body. Listeria monocytogenes is transmitted through contaminated food and causes infection particularly in immunosuppressed patients, elderly, and pregnant women. Microscopically, the infected sites are characterized by the occurrence of inflammation, with exudate and presence of multiple neutrophils.
Causes
Listeria monocytogenes is a Gram-positive, facultative intracellular parasite, anaerobe, nonsporulating bacillus. Motile via flagella, L. monocytogenes can move within eukaryotic cells by explosive polymerization of actin filaments (known as comet tails or actin rockets). The name monocitogenes derives from the strong monocytic activity this organism produces in rabbits, which however, does not happen in humans.[3] Different strains of the bacteria show different pathogenic tropisms towards different tissues. It is commonly found in soil, water, vegetation and fecal material.[4]
Differential Diagnosis
Listeriosis is associated with different clinical syndromes; therefore, it should be differentiated from a wide range of diseases. Differential diagnoses of listeriosis include febrile gastroenteritis, parenchymal brain infections, subcortical brain abscesses, and fever during the last trimester of pregnancy.[5]
Epidemiology and Demographics
In 2013, the average annual incidence of listeriosis in the United States was 0.26 cases per 100,000 individuals.[6] The disease has a worldwide distribution, with sporadic incidence affecting mostly immunosuppressed patients, pregnant women, neonates, and elderly subjects.[7]
Risk Factors
The ingestion of uncooked meats and vegetables, unpasteurized (raw) milk and cheeses, processed (or ready-to-eat) meats, and smoked seafood is a risk factor for listeriosis.[8] Immunosuppressed patients, neonates, pregnant women, and elderly patients have higher risk of contracting listeriosis.[9]
Natural History, Complications and Prognosis
Listeriosis is commonly transmitted through contaminated food. The clinical presentation of the disease depends on the baseline health status of the patient. Although asymptomatic carriers may be identified, the disease is commonly manifested as a febrile gastroenteritis. Other more invasive manifestations include sepsis of unknown origin, bacteremia, central nervous system (CNS) infection, endocarditis, and focal infections. Possible complications of listeriosis include acute respiratory distress syndrome (ARDS), rhabdomyolysis, acute renal failure, and pneumonia. The prognosis of listeriosis depends on the health status of the host, where healthy older children and adults show the lowest death rate.[7]
Diagnosis
History and Symptoms
The clinical manifestation of listeriosis is host-dependent. Immunocompetent persons may experience acute febrile gastroenteritis or no symptoms. Among older adults and immunocompromised persons, the most common clinical presentations are septicemia and meningitis. Pregnant women may experience a mild flu-like illness, followed by fetal loss, or bacteremia and meningitis in the newborns.
Physical Examination
The findings on the physical examination depend on the clinical manifestation of listeriosis (febrile gastroenteritis, sepsis, infection in pregnancy, central nervous system infection, or endocarditis). Common findings include fever, tachycardia, pallor. Signs of neurological involvement may range from altered mental state, to paralysis, respiratory failure, and coma.
Laboratory Findings
For symptomatic patients, diagnosis is confirmed only after isolation of Listeria monocytogenes from a normally sterile site, such as blood, spinal fluid (in the setting of nervous system involvement), or amniotic fluid/placenta (in the setting of pregnancy). Stool samples are of limited use and are not recommended. Listeria monocytogenes can be isolated readily on routine media, but care must be taken to distinguish this organism from other Gram-positive rods, particularly diphtheroids. Selective enrichment media improve rates of isolation from contaminated specimens. The cultures take 1-2 days for growth. Importantly, a negative culture does not rule out infection in the presence of strong clinical suspicion. Serological tests are unreliable, and not recommended at the present time. There is no clinical value in performing laboratory testing on asymptomatic patients, even if higher risk.[7]
MRI
Although both MRI and CT scan may be used to help in the diagnosis of Listeria monocytogenes lesions, MRI is a more sensitive method to detect listerial lesions in the cerebellum, brainstem and cortex.[10] High-signal lesions on T2-weighted images and enhancing lesions on T1-weighted images can be identified in the cerebral parenchyma on MRI following administration of IV contrast. Since brainstem involvement on MRI coupled with proper clinical setting is strongly suggestive of infection by Listeria monocytogenes, it is helpful to use contrast MRI in all patients presenting with listerial meningitis, listerial bacteremia, CNS signs and symptoms or suspicion of intracranial listeriosis.
Other Diagnostic Studies
For symptomatic patients, diagnosis is confirmed only after isolation of Listeria monocytogenes from a normally sterile site, such as blood, spinal fluid (in the setting of nervous system involvement), or amniotic fluid/placenta (in the setting of pregnancy). Importantly, a negative culture does not rule out infection in the presence of strong clinical suspicion. Serological tests exist but they are unreliable and not recommended at the present time.
Treatment
Medical Therapy
Ampicillin, with or without gentamicin, is the preferred antibiotic for the treatment of listeriosis. Patients intolerant to penicillins may be managed with trimethoprim-sulfamethoxazole. The suggested minimum duration of therapy depends on the clinical syndrome. Listerial gastroenteritis is frequently self-limited but a short course of oral ampicillin may be considered in individuals with impaired cell-mediated immunity or those who have ingested food implicated in outbreaks. Listeria bacteremia requires at least 2 weeks of treatment, meningitis 3 weeks, endocarditis 4 to 6 weeks, and brain abscess or rhombencephalitis 6 weeks.
Surgery
The treatment of listeriosis is based on an adequate antibiotic regimen. Surgery may be indicated for complications of listeriosis, such as central nervous system (CNS) complications or valve damage caused by endocarditis.
Primary Prevention
General recommendations for the primary prevention of infection with Listeria include appropriately washing and handling of food, maintaining a clean and safe kitchen and environment, cooking meat and poultry thoroughly, safely storing foods, and choosing safe foods. In addition to the general recommendations on how to prevent an infection with Listeria, there are additional recommendations specifically for persons who are at higher risk, such as pregnant women, elderly, and individuals with compromised immune systems. Besides the primary prevention measures, there is no prophylaxis for listeriosis.
References
- ↑ Ryan KJ; Ray CG (editors) (2004). Sherris Medical Microbiology (4th ed. ed.). McGraw Hill. ISBN 0-8385-8529-9.
- ↑ Hof H (1996). Listeria Monocytogenes in: Baron's Medical Microbiology (Baron S et al, eds.) (4th ed. ed.). Univ of Texas Medical Branch. (via NCBI Bookshelf) ISBN 0-9631172-1-1.
- ↑ Mandell, Gerald L.; Bennett, John E. (John Eugene); Dolin, Raphael. (2010). Mandell, Douglas, and Bennett's principles and practice of infectious disease. Philadelphia, PA: Churchill Livingstone/Elsevier. ISBN 0-443-06839-9.
- ↑ "Risk assessment of Listeria monocytogenes in ready-to-eat foods" (PDF).
- ↑ Lorber, B. (1997). "Listeriosis". Clinical Infectious Diseases. 24 (1): 1–11. doi:10.1093/clinids/24.1.1. ISSN 1058-4838.
- ↑ CDC. Incidence and Trends of Infection with Pathogens Transmitted Commonly Through Food — Foodborne Diseases Active Surveillance Network, 10 U.S. Sites, 2006–2013. MMWR Morb Mortal Wkly Rep. 2014;63(15);328-332
- ↑ 7.0 7.1 7.2 "Listeria Stattistics".
- ↑ Listeria (Listeriosis) Sources. CDC.gov accessed on 7/25/2014 [1]
- ↑ Lorber, B. (1997). "Listeriosis". Clin Infect Dis. 24 (1): 1–9, quiz 10-1. PMID 8994747. Unknown parameter
|month=ignored (help) - ↑ Armstrong RW, Fung PC (1993). "Brainstem encephalitis (rhombencephalitis) due to Listeria monocytogenes: case report and review". Clin Infect Dis. 16 (5): 689–702. PMID 8507761.