DEPARTMENT OF INFECTIOUS MICROBIOLOGY
Assoc. Prof. Hristo Najdenski, DVM, PhD
Head of Department
E-mail: hnajdenski@abv.bg
Tel: (+359 2) 979 31 61
Annotation
Studies on factors and mechanisms of bacterial virulence are of common and
traditional interest of the Department Infectious Microbiology. The basic topics of
investigation are related with: 1) characterisation of bacterial-host interactions in
socially important zoonoses and others emerging infections; 2) molecular analysis
of Mycobacterium tuberculosis e.g. multidrug resistant strains and monitoring the
burden and transmission of tuberculosis in Bulgaria; 3) in vitro determination of
antibacterial and antifungal activities of substances with organic and non-organic
origin; 4) photobiology and photodynamics inactivation of bacterial pathogens.
Laboratories
Zoonoses and Bacterial Virulence
Genetics and Drug Resistance of Mycobacteria
Antimicrobial Agents
Laboratory Zoonoses and Bacterial Virulence
Head :
Staff
Hristo Najdenski, DVM, PhD, Associate Professor,
hnajdenski@abv.bg, tel: (+359 2) 979 31 61
Zoia Yordanova, MS, Research Assistant,
yordanovazoia@gmail.bg, tel: (+359 2) 979 31 70
Radka Georgieva, Laboratory Assistant
Main Research topics

Epidemiology, epizootology, and prevention of yersiniosis

Detection, enumeration and typing of socially important food-borne zoonoses
in products of animal origin by using the polymerase chain reaction
methodology

Bacterial virulence factors and immune pathogenesis of genetically designed
live vaccinal vectors
Current Projects



Role of migrating birds and their feeding ticks on the dissemination of some
medically important zoonotic pathogens along the East-European flyway
(ACIP A-08-2010)
Microbiological quality and safety control of cow’s milk and yogurt by using
PCR methodology (FWO-BAS VS.012.08N) VS.012.08N)
Development of vaccine against Chlamidia trachomatis (Ocuvac/2010)
Achievements

Yersinia outer membrane proteins have been isolated and used in improved
ELISA and immunoblot tests for routine laboratory diagnosis of natural
yersiniosis in humans and animals.

Bacterial-host interactions (invasion, persistence, intracellular survival,
immune response, pathomorphology) were characterized with contribution to
pathogenesis of experimental melioidosis, listeriosis, and yersiniosis, by using
different animal models.

Clinical, immunological, and pathomorphological examinations were followed
after experimental oral infections of pigs with two wild and four genetically
constructed mutant strains of Yersinia enterocolitica O:8. A lower virulence
and bacterial load of the viscera, weaker morphological changes, better
immunogenicity and well expressed tissue tropism to the lymphoid tissue of
the mutant strains wzzGB and sodA-314 in comparison with mutants 8081-R2,
wbcEGB and wild strains WA-314 and 8081-L2 were established.

The role of outer membrane proteins YopK and YpkA during experimental oral
pig model with Yersinia pseudotuberculosis was studied. It was established
that these mutant strains are less virulent in comparison with wild type strain.
Nevertheless the strains were characterized with high immunogenic potential
and ability to colonize the lymphoid tissues. This ability was the highest in
yopK mutant strain.

The method of PCR-DGGE was optimized and successfully applied for direct
detection and typing of Campylobacter jejuni and Campylobacter coli in caecal
samples of broilers without preliminary enrichment. This method allows
reliable and fast detection and identification of pathogenic Campylobacters
being causative agent №1 of food infections in humans.

Real-time PCR is developed for detection and quantification of pathogenic
Yersinia in raw milk by using different virulence encoding genes as a target for
primer design
Patent
Najdenski, H., E. Golkocheva-Markova, A. Vesselinova. Outer membrane proteins as
specific antigens for diagnosis of yersiniosis, No 65927/2010
Recent Publications

Bonovska, M., Tzvetkov, Y., Najdenski, H., Bachvarova, Y. (2005): PCR for detection of
Mycobacterium tuberculosis in experimentally infected dogs. J. Vet. Med. 52 (10), 5-8.

Najdenski, H., Golkocheva, E., Kussovski, V., Ivanova, E., Manov, V., Iliev M., Vesselinova,
A., Bengoechea, J.A., Skurnik, M. (2006): Experimental pig yersiniosis to assess attenuation
of Yersinia enterocolitica O:8 mutant strains. FEMS Immunol. Med. Microbiol. 47, 425-435.

Golkocheva, E., Stoilov, R., Najdenski, H. (2006): Serological findings in blood sera of patients
with Yersinia-triggered arthritis. Clin. Microbiol. Infect. 12 (s4), P1739.

Golkocheva-Markova, E., Christova, I., Stoilov, R., Najdenski, H. (2008): Cross-reaction
between Yersinia outer membrane proteins and anti-Borrelia antibodies in sera of patients
with Lyme disease. Clin. Microbiol. Infect., 14, 873-875.

Iliev, M.V., Najdenski, H.M. (2008): Monitoring of plasmid dissociation and pathogenic
potential among Yersinia enterocolitica and Yersinia pseudotuberculosis during storage of
refrigerated pork meat. Ann. Microbiol. 58, 4, 623-632.

Najdenski, H., Heyndrickx, M., Herman, L., Messens, W. (2008): Fla-DGGE analysis of
Campylobacter jejuni and Campylobacter coli in cecal samples of broilers without cultivation.
Vet. Microbiology, 127: 196-202.

Iliev, M.V., Najdenski, H.M., Stals, A., Werbrouck, H., Herman, L., Van Coillie, E. (2008):
Optimization of Real-Time PCR protocol for detection of pathogenic Yersinia enterocolitica
strains. Bulg. J. Vet. Med., 11, 3, 179-184.

Najdenski, H., Golkocheva-Markova, E., Kussovski, V., Vesselinova, A., Garbom, S., WalfWatz, H. (2008): Attenuation and preserved immunogenic potential of Yersinia
pseudotuberculosis mutant strains evidenced in oral pig model. Zoonoses Public Health, (in
press).

Iliev, M., H. Najdenski. (2008) Optimisation of PCR protocol for detection and differentiation of
pathogenic serotypes of Yersinia enterocolitica in milkComp. Rend. Acad Bul. Sci, 10(61),
1271-1278.

Carballeira, N.M., Oyola, D., Ivanova, A., Tsvetkova, I., Najdenski, H., Seizova, K. Stefanov,
K. (2008): The fatty acid composition of a Virgibacillus marismortui strain isolated from lake
Pomorie in Bulgaria. Compt. Rend. Acad. Bulg. Sci., , 61, 1:49-54.

Orozova, P., Chikova, V., Kolarova, V., Nenova, R., Konovska, M., Najdenski, H. (2008):
Antibiotic resistance of potentially pathogenic Aeromonas strains. Trakia J. Sci., 6, 71-77,.

Najdenski, H., E. Golkocheva-Markova, V. Kussovski, A. Vesselinova, S. Garbom, H. WalfWatz. (2009): Attenuation and preserved immunogenic potential of Yersinia
pseudotuberculosis mutant strains evidenced in oral pig model. Zoonoses Public Health, , 56,
4, 157-168.

Golkocheva-Markova, E., Najdenski, H. Bondarenko, V. (2009): Screening of pathogenic and
nonpathogenic Yersinia strains for the presence of chromosomal virulence markers. Compt.
Rend. Acad. Bulg. Sci., , 3(62), 349-354.

Orozova, P., V. Chikova, V. Kolarova, R. Nenova, M. Konovska, H. Najdenski. (2010):
Antibiotic resistance of pathogenic to fish isolates of Aeromonas pp. Bulg. J. Agricult. Sci., 16,
3, 377-388.
LABORATORY OF GENETICS AND DRUG RESISTANCE OF
MYCOBACTERIA
Head of laboratory: Nadya Markova, MD, PhD- Associate Professor
nadya.markova@gmail.com; markn@bas.bg tel: (+359 2) 979 31 68
Staff
Violeta Valcheva, PhD, Research Scientist violeta_valcheva@mail.bg tel: (+359 2)
979 31 68
Georgi Slavchev, MS, PhD student slavchevg@gmail.com tel: (+359 2) 979 31 68
Albena Cherneva; Research Assistant albenacherneva@abv.bg tel: (+359 2) 979 31
68
 Mycobacterial
Main Research topics
pathogenesis, basic and fundamental molecular biological
research on tuberculosis and mechanisms of latent tuberculosis
 Molecular mechanisms of drug resistance in M.tuberculosis
 Molecular
epidemiology
mycobacteria
of
tuberculosis,
phylogeny
and
evolution
of
 Immunomodulators against tuberculosis
The laboratory is equipped with recently acquired, state-of-the art equipment for
molecular genetics and basic mycobacteriology experiments.
Current Projects
•
FP7- EUMEDNETvs TB-245872 ”Building a cooperative strategy between
Europe and Mediterranean Countries for upgrading tuberculosis research and
control” (2010-2013); Nadya Markova, Partner Country Group Leader;
http://www.eumednet-tb.org/institution.html
•
Grant ID 03/27, National Science Fund, Bulgaria (2010-2012); Challenges of
Latent Tuberculosis- untraditional model for interdisciplinary investigations;
project leader- Nadya Markova
•
Grant DMU 02/1, National Science Fund, Bulgaria (2010-2012); Rapid
detection of drug-resistant M.tuberculosis strains by molecular-genetic
methods; project leader Violeta Valcheva
•
Grant DMU 02/3, National Science Fund, Bulgaria (2010-2012); Development
of new anti-tuberculosis agents; project leader for Institute of microbiology Violeta Valcheva
Achievements
 Monitoring the burden and transmission of tuberculosis in Bulgaria using
advanced molecular epidemiological methods and population structure
analysis.
 Study on incidence and transmission of multidrug-resistant Mycobacterium
tuberculosis strains in Bulgaria by genotypic detection of drug resistant
mutations.
Recent Publications
 Valcheva V., Mokrousov I., Panaiotov S. , Bachiiska E , Zozio T, Sola C. Markova N.,
Rastogi
N.
(2010);
Bulgarian
specificity
and
controversial
phylogeography
of
Mycobacterium tuberculosis spoligotype ST 125__BGR. FEMS Immunology & Medical
Microbiology; 59: 90-99.
 Markova N. Hidden face of tuberculosis. (2009); Bioscience Hypothesis. 2: 441-442.
 Valcheva V, Mokrousov I, Narvskaya O, Rastogi N, Markova N. (2009); Genetic Diversity
Mycobacterium tuberculosis Population in Bulgaria. In “Genetic Diversity”, Nova Publishers,
Hauppauge, New York, USA.
 Valcheva V, Markova N, Rastogi N, Narvskaya O, Mokrousov I. (2009); Drug Resistant
Tuberculosis in Bulgaria: Molecular Insights. In “Drug-Resistant Tuberculosis: Causes,
Diagnosis and Treatments”, Nova Publishers, Hauppauge, New York, USA
 Markova N., Michailova L., Kussovski V., Jourdanova M. (2008); Formation of Persisting Cell
Wall Deficient Forms of Mycobacterium bovis BCG during interaction with peritoneal
macrophages in guinea pigs. Electronic Journal of Biology, 4 : 1-10
 Markova N., Michailova L., Jourdanova M., Kussovski V., Valcheva V., Mokrousov I., T
Radoucheva T. (2008); Exhibition of persistent and drug-tolerant L-form habit of
Mycobacterium tuberculosis during infection in rats. Central European Journal of Biology,
3 : 407–416.
 Valcheva V., Mokrousov I., Narvskaya O., Rastogi N., Markova N (2008); .Мolecular snapshot
of drug-resistant and drug-susceptible Mycobacterium tuberculosis strains circulating in
Bulgaria. Infect Genet Evol., 8, 657-63.
 Valcheva V., Mokrousov I., Narvskaya O., Rastogi N., Markova N. (2008). Utility of New 24locus VNTR Typing for Discriminating Mycobacterium tuberculosis Clinical Isolates in
Bulgaria. J. Clin. Microbiol., 46, 3005-11.
 Valcheva V., Mokrousov I., Rastogi N., Narvskaya O., Markova N. (2008): Molecular
characterization of Mycobacterium tuberculosis isolates from different regions of Bulgaria.
J. Clin. Microbiol., 46, 1014-8.
 Mokrousov, I., Jiao,W.W., Valcheva, V., Vyazovaya, A., Otten, T., Ly, H. M., Lan, N. N.,
Limeschenko, E., Markova, N., Vyshnevskiy, B., Shen, A.D., Narvskaya O. (2006); Rapid
Detection of the Mycobacterium tuberculosis Beijing genotype and its ancient and modern
sublineages by IS6110-based inverse PCR. J. Clin. Microbiol. 44, 2851–2856.
 Mokrousov, I., Jiao, W.W., Sun, G.Z., Liu, J.W., Valcheva, V., Li, M., Narvskaya, O., Shen,
A.D. (2006); Evolution of drug resistance in different sublineages of Mycobacterium
tuberculosis Beijing genotype. Antimicrob. Agents and Chemotherapy 50, 2820-2823.
 Markova N, Michailova L., Kussovski V, Jourdanova M, Radoucheva T. (2005); Intranasal
application of lentinan enhances bactericidal activity of rat alveolar macrophages against
Mycobacterium tuberculosis. Pharmazie 60, 42-8.
 Drandarska,
I,
Kussovski,
V.,
Nikolaeva,
S.,
Markova,
N.
(2005);
Combined
immunomodulating effects of BCG and Lentinan after intranasal application in guinea pigs.
International Immunopharmacology 5, 795-803.
 Michailova, L, Kussovski, V., Radoucheva, T., Jourdanova, M., Berger, W., Rinder, H.,
Markova, N. (2005); Morphological variability and cell wall deficiency of Mycobacterium
tuberculosis in “heteroresistant” strains isolated from newly diagnosed tuberculosis patients.
The International Journal of Tuberculosis and Lung Disease, 9, 907-14.
Laboratory Antimicrobial Agents
Staff
Head: Vesselin Kussovski, PhD, Associate Professor,
veselinkussovski@yahoo.com tel: (+359 2) 979 31 74
Mariana Ninova, MS, Research Scientist,
bomarsa@abv.bg, tel: (+359 2) 979 31 48
Iva Tzvetkova, MS, Research Assistant,
likovska@abv.bg, tel: (+359 2) 979 31 48
Main Research topics

Antibacterial and antifungal in vivo and in vitro activities of naturally derived or
newly synthesized substances

Photophysical and photosensitizing properties of phthalocyanine complexes
as antibacterial and antiviral agents. Vesko opravi tova!!!
Achievements

Antibacterial activity in vitro is found from a metabolite (usnic acid) isolated
from the Antarctic lichen of Neuropogon spp

Chemical composition, antibacterial, and antifungal activities are proved at
essential oil from Achillea collina (Becker), Achilea asplenifolia (Vent.), Ruta
graveolens, green alga Cladophora rivularis (L.) Hoek, propolis from Europe,
Brasilia, Malta, etc.

Four tetra alkyl-substituted cationic phthalocyanines with different hydrocarbon
chains on pyridyloxy-group were synthesized and used as photodynamic
photosensitizers. Antimicrobial activity against multidrug-resistant strain of
Aeromonas hydrophila was found emphasizing its potential for application in
antimicrobial photodynamic therapy.

It was found that the methicilin-resistant and methicilin-sensitive strains of
Staphylococcus aureus as well as Pseudomonas aeruginosa and Candida
albicans can be effectively photoinactivated with the cationic phthalocyanine
ZnPeMe. Anionic phtalocyanine ZnPcS and cationic phthalocyanine ZnPeMe
are effective virucidal photosensitisers for the studied DNA-viruses – Herpes
virus simplex type I and Vaccinia virus.
Current Projects
New microalgal strains – potential producers of economical and medical important
products. (DO02-299/08)
Wild small fruit species in Bulgaria – a valuable resource for human helth (DО02334/08)
New method for treatment of pathogens in oral cavity with photodynamic complexes
(DVU01/0016)
Photodynamic inactivation of pathogenic bacteria and viruses with phtalocyanines:
ecological and medical aspects (Б-1534/05)
Analytical service
Microbiological analysis of drug substances, foods, drinks, etc.
Recent Publications

Batovska, D., Parushev, St., Slavova, A., Bankova, V., Tsvetkova, I., Ninova, M., Naydenski,
Ch. (2007): Study on the substituents’ effects of a series of synthetic chalcones against the
yeast Candida albicans. Eur. J. Med. Chem., 42: 87-92.

Popova. M., Bankova, V., Bogdanov, S., Tsvetkova, I., Naydenski, H., Marcazzan, G. L.,
Sabatini, A.-G. (2007): Chemical characteristics of popular type propolis of different
geographic origin. Apidologie, 38, 306-311.

Batovska, D., St. Parushev, B. Stambolijska, I. Tsvetkova, M. Ninova, H. Najdenski. (2009):
Examination of growth inhibitory properties of synthetic chalcones to which antibacterial
activity was predicted. Eur. J. Med. Chem., 44, 5, 2211-2218. (I.F. – 3.269)

Kamenarska, Z., J. Serkedjieva, H. Najdenski, K. Stefanov, I. Tsvetkova, S. DimitrovaKonaklieva, S. Popov. Antibacterial, antiviral, and cytotoxic activities of some red and brown
seaweeds from the Black Sea. Botanica Marina, 2009, 52, 80-86. (I.F. 2009 – 1.09)

Batovska, D.I., I.T. Todorova, I.V. Tsvetkova, H. Najdenski. Antibacterial study of the medium
chain fatty acids and their 1-monoacylglycerides: individual effects and synergistic
relationships. Polish J. Microbiol., 2009, 58, 1, 43-47.

Ivanova, A., M. Bozhanka, H. Najdenski, I. Tsvetkova, I. Kostova. Chemical composition and
antimicrobial activity of wild garlic Allium ursinum of Bulgarian origin. Nat. Product
Communicat., 2009, 4, 8, 1059-1062.

Petrova, A., M. Popova, C. Kuzmanova, I. Tsvetkova, H. Naydenski, E. Muli, V. Bankova. New
biologically active compounds from Kenyan propolis, Fitoterapia, 2010, 81, 6, 509-514.

Trusheva, B., I. Todorov, M. Ninova, H. Najdenski, A. Daneshmand, V. Bankova, Antibacterial
mono– and sesquiterpene esters of benzoic acids from Iranian propolis. Chem. Cent. J., 2010,
4 (8), 1-5.

Popova, M., B. Trusheva, D. Antonova, S. Cutajar, D. Mifsud, C. Farrugia, I. Tsvetkova, H.
Najdenski, V. Bankova. The specific chemical profile of Mediterranean propolis from Malta.
Food Chemistry, 2011, 126, 1431-1435.