Listeria monocytogenes
| Listeria monocytogenes | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Listeria monocytogenes |
||||||||||||
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name | ||||||||||||
| Listeria monocytogenes | ||||||||||||
| ( Murray et al. 1926) Pirie 1940 |
Listeria monocytogenes is a non-spore-forming, gram-positive , rod-shaped, facultative-anaerobic bacterium that is mobiledue to flagella (polar or perithric flagella). It was named after the British surgeon Joseph Lister , and often referred to as impact of an infection occurring Monocytosis , a proliferation of monocytes in the blood . It is usually pathogenic and causes a number of diseases in humans and animals known as listeriosis . The most common route of infection is ingestion through contaminated food .
properties
distribution
Listeria monocytogenes is not restricted to specific host organisms or habitats and is considered ubiquitous . It has been found in a range of wildlife and domestic animals , including at least 37 species of mammals , at least 17 species of birds, and the occasional fish and shellfish . Probably about one to ten percent of all people are also infected and excrete the pathogen in the stool . In addition, Listeria monocytogenes can also be detected in the soil , in water , on plants and in other natural habitats and is able to form biofilms on many different surfaces .
Morphology and physiology
A Listeria monocytogenes cell is 0.4 to 0.5 micrometers in diameter and 0.5 to 2.0 micrometers in length. It occurs either individually or in the form of V- or Y-shaped chains and is catalase-positive as well as indole- and oxidase-negative . In addition , it does not hydrolyze urea and is not a nitrate reducer . Listeria monocytogenes forms round, blue-gray and translucent colonies up to one millimeter in size on culture plates . The morphology is similar to that of Streptococcus agalactiae , the colonies can also be confused with this species (also large, round, gray colonies with delicate β-hemolysis on Columbia blood agar).
Although Listeria monocytogenes does not form spores , the bacterium is exceptionally resistant to drought, cold, higher temperatures as well as a high salt concentration and a moderately acidic or basic pH value of 4.4 to 9.8 in the surrounding medium. The temperature optimum for growth is between 30 and 37 degrees Celsius. But even at temperatures of four to eight degrees Celsius, which are typically found in refrigerators , Listeria monocytogenes is capable of limited growth. The bacterium is safely killed by temperatures that occur, for example, during cooking , frying , sterilizing and pasteurizing .
proof
The most commonly used method for the determination of Listeria monocytogenes is an enrichment culture for 24 to 48 hours, followed by agglutination with specific antibodies . It is also possible to detect certain DNA sections with the aid of the polymerase chain reaction (PCR) and hybridization to specific DNA probes. As an alternative to the immunological and molecular biological methods, a determination can also be carried out using biochemical tests to detect certain enzyme activities . However, this detection method is very time-consuming.
Genome
The genomes of the two strains Listeria monocytogenes EGD-e (serotype 1 / 2a) and Listeria innocua CLIP 11262 (serotype 6a) were completely sequenced using shotgun sequencing . Listeria monocytogenes EGD-e has a circular chromosome with 2,944,528 base pairs and no plasmid . The GC content is 39 percent and the number of protein-coding genes is 2853. During sequencing, it was found that the functions of about 35.3 percent of the genes cannot be predicted. The Listeria monocytogenes EGD-e genome encodes several invasive proteins. The encoded proteins are very similar to those of Bacillus subtilis . A comparison between Listeria monocytogenes EGD-e and Listeria innocua CLIP 11262 found 270 (9.5 percent) genes that were specific for Listeria monocytogenes EGD-e and 149 (five percent) genes specific for Listeria innocua . The DNA sequence analysis also revealed that a close relationship between Listeria monocytogenes and Bacillus subtilis is, and both have a common ancestor. Gene transfer through transformation is responsible for most of the genome differences between the two species.
Pathogenicity
Clinical pictures
Listeria monocytogenes is a facultative pathogen . In most cases, infections are clinically inapparent , i.e. without any recognizable symptoms. Pregnancy , a change in diet and the simultaneous presence of viral or parasitic infections are favorable factors for illness . The toxin listeriolysin O (LLO) produced by the bacteria , which can be detected in a culture on blood agar , plays an important role in terms of pathogenicity. The associated gene hlyA is the most important marker of the pathogenicity of Listeria monocytogenes . In the case of a clinical manifestation, the clinical pictures are similar in humans and animals. Listeria infection is called listeriosis . She depending on the region and hygiene standards an incidence of two to 15 cases per million people per year and runs in people with an intact immune system usually with no or relatively slight symptoms in the gastrointestinal area as nausea , vomiting and diarrhea . For most patients, these are the only effects of infection.
In patients with immunodeficiency , however, depending on the site of infection, there may also be swelling of the lymph nodes and inflammation of the eye , which are known as keratitis or uveitis . Other possible places of inflammation are the throat and pharynx , the urinary bladder and the renal pelvis . In some cases, especially in the elderly, inflammation of the brain ( encephalitis ) or meninges ( meningitis ) is possible, with a mortality rate of up to 70 percent. The diseases mentioned are usually preceded by a feverish phase with symptoms similar to influenza . Infections of the genital organs in pregnant women can miscarriages and stillbirths lead, as well as to blood poisoning , swelling of the liver and spleen , respiratory problems and developmental delays in newborns. Listeriosis in newborns, which has a high mortality rate, as well as detection of the pathogen in the blood and cerebrospinal fluid of a patient are notifiable in Germany .
13 O-antigenetic patterns are known for Listeria monocytogenes . In terms of virulence intensity, Listeria monocytogenes is divided into three categories. The pathogens of line I with the highest pathogenicity , which at 98 percent most frequently cause epidemic diseases, include serotypes 1 / 2b, 3b, 4b and 4e. Serotype 4b is most clearly virulent and, at 33 to 50 percent, most frequently leads to listeriosis. Line II contains the serotypes 1 / 2a, 1 / 2c, 3a and 3c, which have an intermediate pathogenic potential and cause sporadic diseases. Line III includes serotypes 4a and 4c with a low pathogenicity.
Routes of infection and treatment
Listeria monocytogenes is transmitted through direct contact with infected animals and via contaminated food , especially dairy products , ice cream , untreated fruit and vegetables and products made from raw meat . For the spread in the body and the reaching of certain places such as the brain and the fetus in pregnant women, the uptake in phagocytes and their transport with the bloodstream is essential. The incubation time until symptoms appear in the gastrointestinal area is at least twelve hours and for symptoms in other parts of the body several days to weeks.
In a remarkable study on guinea pigs, Melton-Witt and others demonstrated that even with asymptomatic infections, colonization of the liver and reservoir formation in the microvilli can occur with constant reinfection of the Peyer's plaques .
Treatment of infections with Listeria monocytogenes is possible with various antibiotics . The drug of choice is the β-lactam antibiotic ampicillin in high doses, possibly in combination with an aminoglycoside . An alternative is cotrimoxazole . There is a natural resistance to cephalosporins . For prophylaxis , proper processing, preparation and storage of food, in particular adequate heating, and appropriate hygiene measures are necessary.
Food safety
Although Listeria are almost everywhere, the number of detected diseases appears surprisingly low (698 reports for 2018 in Germany). This could be due to the difficulty of proving listeriosis and the fact that the disease can only break out weeks later with unspecific symptoms such as fever and diarrhea. Since Listeria monocytogenes are one of the most common and dangerous pathogens in the field of food infections, EU law applies to food business operators who produce ready-to-eat foods which, such as cheese or raw ham , can pose a risk to public health caused by Listeria monocytogenes Requirements for their hygiene measures to ensure acceptable products: They have to take samples from the processing areas and equipment and have them examined for this pathogen. A measured value of no more than 100 colony-forming units / g is determined as a food safety criterion and at the same time limit value for the marketability of the food , which must be guaranteed during the entire specified shelf life. In the case of baby food, however, no listeria may be detectable and in the case of microbiologically sensitive food at least the manufacturer. Under these values, a ready-to-eat food, i.e. usually not heated before consumption, is considered unsafe, so that the entire batch of this food must be removed from the market and products that have been sold must be recalled. Anyone who nevertheless produces or markets such food is liable to prosecution in Germany for negligence.
Reporting requirement
In Germany, the direct detection of is Listeria monocytogenes in particular notifiable according to § 7 of the infection protection law , evidence of acute infection provided that indicates and it is a direct [s] evidence from blood, cerebrospinal fluid or other normally sterile substrates and from swabs of newborns is . The obligation to notify primarily concerns the management of laboratories ( § 8 IfSG).
In Switzerland, the positive and negative laboratory analytical results for Listeria monocytogene are notifiable to laboratories according to the Epidemics Act (EpG) in conjunction with the Epidemics Ordinance and Annex 3 of the EDI Ordinance on the reporting of observations of communicable diseases in humans .
Historical information
In 1911 Gustav Hülphers in Sweden reported the presence of gram-positive rod-shaped microorganisms in the liver of rabbits and named them Bacillus hepatis . Listeria monocytogenes was first described in 1923 and isolated and documented three years later by Everitt George Dunne Murray from the blood of infected rabbits, which showed a marked increase in monocytes in the blood count. During the investigation of an epidemic in rabbits and guinea pigs, test animals were also infected with the pathogen. The infection induced severe monocytosis and resulted in lesions in the lungs. Hence the pathogen was named Bacterium monocytogenes . In 1940, in South Africa , JH Harvey Pirie isolated a small gram-positive bacillus from the liver of African gerbils , which he named Listerella hepatolitica in honor of Lord Lister , the father of antiseptics . In 1952, the hygienist and microbiologist Heinz Seeliger clarified the etiology of granulomatosis infantiseptica, congenital listeriosis. Jürgen Potel previously described this as a fatal, septic, granulomatous infection in newborns and assumed to be caused by its own pathogen ( Corynebacterium infantisepticum ).
The first identified case of an infection in humans dates back to 1929. Until the 1970s, Listeria monocytogenes was primarily a problem in the farming of farm animals, in which it mainly caused encephalitis and miscarriages. With the beginning of the 1980s, however, the bacterium gained increasing importance as a pathogen in humans. The first documented epidemic took place in 1981 in Halifax ( Canada instead), with 41 patients and 17 deaths. There were other extensive epidemics from 1983 to 1987 in western Switzerland with 122 people affected and 31 deaths, 1985 in California with 142 people affected and 48 deaths, from 1989 to 1990 in Great Britain with 300 people affected (no deaths) and 1992 in France with 279 people affected and 85 deaths. In 2000, 32 people also fell ill in France, ten of whom died. According to the investigating authorities, 34 diseases, including 10 deaths between 2018 and 2020, were said to have been the result of a listeria infestation in a cheese dairy in the canton of Schwyz , Switzerland.
Individual evidence
- ↑ a b Listeriosis. RKI guide for doctors. Robert Koch Institute , August 3, 2012, accessed on February 17, 2013 .
- ↑ P. Glaser et al .: Comparative Genomics of Listeria Species (PDF; 526 kB) In: Science . Volume 294, issue 5543 of October 26, 2001, pp. 849–852
- ↑ JA Melton-Witt, SM Rafelski u. a .: Oral infection with signature-tagged Listeria monocytogenes reveals organ-specific growth and dissemination routes in guinea pigs. In: Infection and Immunity . Volume 80, Number 2, February 2012, pp. 720-732, ISSN 1098-5522 . doi: 10.1128 / IAI.05958-11 . PMID 22083714 . PMC 3264322 (free full text).
- ^ R. Leclercq et al .: EUCAST expert rules in antimicrobial susceptibility testing . In: Clinical Microbiology and Infection . tape 19 , no. 2 . Wiley-Blackwell, 2013, ISSN 1469-0691 , pp. 141-160 , doi : 10.1111 / j.1469-0691.2011.03703.x , PMID 22117544 ( wiley.com [accessed February 17, 2013]).
- ↑ RKI : Epidemiological Bulletin No. 3/2020 , from January 16, 2020, SS 18, for 2019: 591 cases, compared to 13,636 salmonellosis cases
- ↑ on this and on the following: Art. 3 Paragraph 1, Art. 5 Paragraph 2 of Regulation (EC) No. 2073/2005 of the Commission of November 15, 2005 on microbiological criteria for food (consolidated version of February 28, 2019) , in their appendix 1 numbers 1.1-1.3 to Listeria
- ↑ Art. 7 Regulation (EG) 2073/2005 "Unsatisfactory results"
- ↑ §58 Abs. 2 and §5 Abs. 1 LFGB in connection with Art. 14 VO (EG) No. 178/2002
- ↑ Heinz PR Seeliger: 50 years of experience in microbiology and hygiene. In: Würzburg medical history reports. Volume 9, 1991, pp. 207-216; here: p. 209.
- ↑ Johannes Kämer, Alexander Prange: Food microbiology . Ed .: UTB. 4th edition. No. 1421 . Eugen Ulmer KG, Stuttgart 2017, ISBN 978-3-8252-4658-7 , pp. 400 .
- ↑ Tim Wirth: The deadly cheese from original Switzerland. In: Tages-Anzeiger , August 28, 2020.
literature
- M. Hamon, H. Bierne, P. Cossart: Listeria monocytogenes: A Multifaceted Model. In: Nature Reviews. Microbiology. 4 (6) / 2006. Nature Publishing Group, pp. 423-434, ISSN 1740-1526
- G. Darai, M. Handermann et al .: Lexicon of infectious diseases in humans. Third edition. Springer, Heidelberg 2009, ISBN 978-3-540-39005-3
- S. Vadia, E. Arnett, et al. a .: The pore-forming toxin listeriolysin O mediates a novel entry pathway of L. monocytogenes into human hepatocytes. In: PLoS Pathogens . Volume 7, Number 11, November 2011, p. E1002356, ISSN 1553-7374 . doi: 10.1371 / journal.ppat.1002356 . PMID 22072970 . PMC 3207921 (free full text).
Web links
- US FDA / CFSAN Foodborne Pathogenic Microorganisms and Natural Toxins Handbook - Listeria monocytogenes (English)
- Listeriosis: highly virulent strain discovered , on scinexx.de from October 10, 2019
