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Virulence factors and mechanisms of antibiotic resistance of haemophilus influenzae


Tomislav S. Kostyanev1 / Lena P. Sechanova2
1Department of Medical Microbiology, Medical University, Sofia, Bulgaria
2Department of Medical Microbiology, Medical University, Sofia, Bulgaria
Correspondence and reprint request to: Tomislav S. Kostyanev, Department of Medical Microbiology, MedicalUniversity, Sofi a; E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.; Mob.: +359 887 602 3842 Zdrave Str., 1431 Sofi a, Bulgaria

Citation Information: Folia Medica. Volume 54, Issue 1, Pages 19–23, ISSN (Online) 1314-2143, ISSN (Print) 0204-8043, DOI: 10.2478/v10153-011-0073-y, October 2012
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Haemophilus influenzae is a small gram-negative coccobacillus known as one of the major causes of meningitis, otitis media, sinusitis and epiglottitis, especially in childhood, as well as infections of the lower respiratory tract, eye infections and bacteremia. It has several virulence factors that play a crucial role in patient infl ammatory response. Its capsule, the adhesion proteins, pili, the outer membrane proteins, the IgA1 protease and, last but not least, the lipooligosaccharide, increase the virulence of H. infl uenzae by participating actively in the host invasion the host by the microrganism. Some of these factors are used in vaccine preparations. In the post-vaccine era, an increase has been noticed in many European countries of invasive infections caused by non-encapsulated strains of H. influenzae which have a number of virulence factors, some of which are subject of serious research aiming at creating new vaccines. Numerous mechanisms of antibiotic resistance in H. infl uenzae are known which can compromise the empirical treatment of infections caused by this microorganism. The increasing incidence of resistance to aminopenicillins, induced not only by enzyme mechanisms but also by a change of their target is turning into a signifi cant problem. Resistance to other antibiotics such as macrolides, tetracyclines, chloramphenicol, trimethoprim/sulfamethoxazole, and fl uoroquinolones, commonly used to treat Haemophilus infections has also been described.

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