Haemophilus
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Haemophilus influenzae colonies in a blood agar |
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Haemophilus is a genus of rod-shaped Gram - negative bacteria fromthe Pasteurellaceae family . The 16 types of these bacteria are immobile rods that sometimes live in the mucous membranes of humans and animals and can cause diseases. Almost all Haemophilus species are able to survive without oxygen (optionally anaerobic ); however, they are mostly more aerobic . The name of the group comes from their particular preference for culture media with added blood or hemoglobin on which they can be kept in culture.
Medically significant species
Haemophilus influenzae
The bacterium, also known as Pfeiffer influenza bacteria , formerly also influenza bacillus or Bacillus influenzae , was first detected in 1892 by the bacteriologist Pfeiffer , considered to be the causative agent of " influenza " and is the most famous representative of the Haemophilus species. This made it particularly popular increased that it was the first living being to be completely sequenced in 1995 and thus represents a milestone in genome research .
The cocoid rod bacterium is differentiated into eight biotypes (types I to VIII) on the basis of various characteristics (such as a different enzymatic structure ). There are Haemophilus influenzae strains that form a capsule . Depending on the composition of the capsule (different levels of polysaccharides ), these strains are divided into serotypes a to f. Encapsulated, H. influenzae is an obligate pathogen ; type b most often leads to invasive infections. The capsule provides resistance to phagocytosis , making it the most important virulence factor. In addition to IgA - proteases formed what the local immune response to H. influenzae diminishes.
This is to be distinguished from the unencapsulated bacteria variant, which is part of the normal flora of humans. It accounts for around 1.8% of the total flora in children and 0.15% in adults. The unencapsulated variant is only available under certain circumstances, e.g. B. with epithelial damage caused by toxins such as nicotine, pathogenic. A chronic infection of the bronchial mucosa can contribute to the "smoker's cough". Since H. influenzae can absorb DNA from the environment ( competence ), both encapsulated strains can lose their capsule and vice versa, unencapsulated strains can form a capsule ("switch").
H. influenzae lives exclusively in the mucous membranes of humans, as part of the oral flora , especially in those of the upper respiratory system ( nose , throat or oropharynx , trachea ) and can cause inflammatory diseases there and in the lower respiratory tract ( sinusitis , epiglottitis , bronchitis , pneumonia but also otitis , endocarditis and osteomyelitis ). The bacterium is mainly transmitted as a droplet infection by sick or healthy germ carriers, outside the mucous membranes it is only viable for a short time. Due to its presence, especially in the case of flu, it was previously thought to be the causative agent of the flu, until the flu virus could be identified as the actual cause. H. influenzae is therefore seen as a causative agent of secondary symptoms in the flu, benefiting from the weakening of humans by the viruses . Especially in (unvaccinated) small children, this bacterium is also the causative agent of meningitis ( meningitis ) and other inflammatory diseases. As prophylaxis one is vaccination against Haemophilus influenzae type b infection , the HIB recommended. In 2000, before the widespread establishment of HIB vaccination in early childhood in the WHO member states , an estimated 371,000 children under the age of 5 died of this vaccine-preventable infection every year. The death toll in countries where the HIB vaccination is now carried out as standard (183 countries, including Germany) has fallen by up to 90%.
Evidence is provided from sputum , blood and liquor by culturing. Ideally, this is done on cooked blood agar . Bacitracin is also added to the culture medium to prevent the growth of other bacteria. Alternatively, the often additionally used "wet nurse" Staphylococcus aureus creates ideal growth conditions ( wet nurse growth ) when using blood agar through strong NAD + and hemin production . After 1 to 2 days of incubation at 37 ° C, smooth, slightly transparent colonies can be seen. The special diagnosis is then carried out biochemically or via MALDI-TOF , the capsule typing by slide agglutination and via PCR .
In Germany, direct or indirect evidence of Haemophilus influenzae must be reported by name in accordance with Section 7 of the Infection Protection Act , if the evidence indicates an acute infection. In Switzerland, the positive laboratory analytical finding is to Haemophilus influenzae notifiable and that after the Epidemics Act (EpG) in connection with the epidemic Regulation and Annex 3 of the Regulation of EDI on the reporting of observations of communicable diseases of man .
Haemophilus ducreyi
Haemophilus ducreyi is known as the Streptobacillus of the soft chancre (also ulcus molle ) and is the causative agent of this sexually transmitted disease, which is not notifiable in Germany - in contrast to Austria . The disease and thus its pathogen occur mainly in the tropical (and poor) regions of Africa , Southeast Asia and Latin America . Visible symptoms are rounded ulcers on the labia and in the vaginal vestibule of women or on the glans and penis shaft of men. The genome of this bacterium has also been known since 2003 .
Haemophilus aegyptius
Haemophilus aegyptius , also known as Koch-Weeks-Bacillus , cannot be distinguished morphologically from H. influenzae . It is mainly in North Africa spreads and other tropical and subtropical continents and is the causative agent of known as purulent conjunctivitis conjunctivitis .
Haemophilus parainfluenzae
Haemophilus parainfluenzae occurs only very rarely as a pathogen in a form of endocarditis (inflammatory changes in the lining of the heart).
Haemophilus vaginalis
This is an old name for the bacteria now known as Gardnerella vaginalis , which occur quite often in non-specific inflammations of the vagina and uterus . The bacterium is probably not always pathogenic, however, as it is often found in healthy women.
Haemophilus haemolyticus
Unlike the other representatives of the genus, Haemophilus haemolyticus is able to split and use the hemoglobin of the blood. However, this species is not known to play a role as a pathogen.
Haemophilus parasuis
The causative agent of Glässer's disease in pigs. Feverish polyserositides and polyarthritis dominate the clinical picture. However, the pathogen is also detected on the mucous membranes of non-diseased animals. Pronounced clinical pictures usually occur under the influence of stress. The cultural pathogen detection succeeds particularly well from the liquor cerebrospinalis , taking into account species-specific growth requirements.
Haemophilus paragallinarum
The causative agent of the contagious chicken flu ( Coryza contagiosa ). The most noticeable clinical symptom is the "owl's head", which can be traced back to the accumulation of secretion in the paranasal sinuses .
Former representatives
Haemophilus somnus was taxonomically questionable for the division into the genus Haemophilus. According to Bergey's manual, it belongs to the species incertae sedis . The independence from both the X and the V factor contradicts the classification in the genus Haemophilus. The bacteria described as Haemophilus agni and Histophilus ovis were therefore combined with H. somnus in the new species Histophilus somni . It is the causative agent of ISTME ( infectious, septicemic, thrombosing meningoencephalitis ) in cattle. Symptoms are febrile general illnesses with central nervous symptoms. The pathogen can also be involved in endometrids, mastitis, abortions and the birth of weak calves.
therapy
The therapy of choice are the antibiotics amoxicillin (possibly together with a beta-lactamase inhibitor such as clavulanic acid , e.g. as a combination preparation) or moxifloxacin.
Other antibiotics that can be used against Haemophilus (influenzae) are ampicillin, cefuroxime (-Axetil), cefotiam, cefpodoxime-proxetil, cefotaxime , doxycycline, ceftriaxone , meropenem (especially for meningitis), ciprofloxacin and levofloxacin . Ceftriaxone, cefotaxime, quinolones , ertapenem , imipenem , levofloxacin and meropenem are particularly suitable for severe infections . Haemophilus is primarily resistant to 1st generation cephalosporins.
literature
- Keywords “Haemophilus”, “Haemophilus”, “Haemophilus aegypticus”, “Haemophilus ducreyi”, “Haemophilus haemolyticus”, “Haemophilus influenzae”, “Haemophilus parainfluenzae”, “Haemophilus vagembel medical dictionary ” in Pschyr. 257th edition, Walter de Gruyter, Berlin 1993; P. 588
- Medical microbiology, infection and disease theory, Rolle / Mayr, 8th edition, 2006
Web links
- Haemophilus influenzae - information from the Robert Koch Institute
Individual evidence
- ↑ Manfred Vasold: Influenzabazillus (Haemophilus influenzae). In: Werner E. Gerabek , Bernhard D. Haage, Gundolf Keil , Wolfgang Wegner (eds.): Enzyklopädie Medizingeschichte. De Gruyter, Berlin / New York 2005, ISBN 3-11-015714-4 , p. 671.
- ↑ Richard Pfeiffer: The Aetiology of Influenza. In: Journal of Hygiene and Infectious Diseases. Volume 13, 1893, pp. 357-386.
- ↑ a b c Ulrich Heininger: Haemophilus influenzae type b . In: Heinz Spiess, Ulrich Heininger, Wolfgang Jilg (Eds.): Impfkompendium . 8th edition. Georg Thieme Verlag, 2015, ISBN 978-3-13-498908-3 , p. 173 f .
- ↑ a b c d Herbert Hof and Rüdiger Dörries: Medical Microbiology . 5th edition. Thieme, Stuttgart 2014, ISBN 978-3-13-152965-7 , pp. 426-428 .
- ↑ Marianne Abele-Horn (2009), p. 264.
- ↑ Watt et al. Burden of disease caused by Haemophilus influenzae type b in children younger than 5 years: global estimates. The Lancet, Volume 374, Issue 9693, Pages 903-911. doi : 10.1016 / S0140-6736 (09) 61203-4
- ^ Haemophilus influenzae type b (Hib) »Kinderaerzte-im-Netz. Retrieved March 1, 2019 .
- ^ A b Thiên-Trí Lâm and Ulrich Vogel: Haemophilus . In: Sebastian Suerbaum, Gerd-Dieter Burchard, Stefan HE Kaufmann, Thomas F. Schulz (eds.): Medical microbiology and infectious diseases . Springer-Verlag, 2016, ISBN 978-3-662-48678-8 , pp. 285 , doi : 10.1007 / 978-3-662-48678-8_33 .
- ^ Marianne Abele-Horn: Antimicrobial Therapy. Decision support for the treatment and prophylaxis of infectious diseases. With the collaboration of Werner Heinz, Hartwig Klinker, Johann Schurz and August Stich, 2nd, revised and expanded edition. Peter Wiehl, Marburg 2009, ISBN 978-3-927219-14-4 , pp. 194 and 264.