Papers by Mihaela Obrovac
Lijec̆nic̆ki vjesnik, May 1, 2007
The best known members of genus Mycobacterium belong to M. tuberculosis complex. Other mycobacter... more The best known members of genus Mycobacterium belong to M. tuberculosis complex. Other mycobacteria are known as nontuberculous mycobacteria (NTM). NTM less commonly cause a disease (mycobacteriosis), more often colonising respiratory tract. The presence of NTM is more common in immunocompromised patients and in those with a previous lung disease. The decrease in the incidence of tuberculosis is followed by increased incidence of NTM. Since tuberculosis has been declining in Croatia over the last 50 years, increasing incidence of NTM is expected. Growing incidence of chronic obstructive pulmonary disease (COPB) is contributing to this increase. NTM are ubiquitous and inhaling of aerosol particles constitutes the dominant route of infection. They are not transmitted via interhuman contact. In addition to pulmonary and skin infections, disseminated infections are also described. The treatment of mycobacteriosis is difficult and long. Besides using antituberculotic drugs such as rifampin and ethambutol, the therapies use fluoroquinolones; the introduction of macrolides has significantly improved the outcome of treatment.
PubMed, 2004
Mycobacterium (M.) tuberculosis is the most common individual causative agent of infectious disea... more Mycobacterium (M.) tuberculosis is the most common individual causative agent of infectious disease in the world. It is responsible for 26% of preventable deaths in adulthood. Because the number of new cases grows at an annual rate of 2%, in 1993 WHO proclaimed tuberculosis a global health problem. The immediate cause for this was coinfection with causative agents of tuberculosis and human immunodeficiency virus, and spread of resistant and multiresistant strains of M. tuberculosis (MDR TB). It is estimated that 50 million people are infected with resistant strains of M. tuberculosis. Tuberculosis has emerged as a major public health problem for its high mortality (50%-80%) in the first 4-16 weeks of the disease and 100 times more expensive therapy for drug-resistant than for drug-susceptible tuberculosis. Mycobacteriologic laboratories play a fundamental role in the detection, combat and control of tuberculosis, especially in preventing the spread of drug-resistant tuberculosis. In this connection, there is an increased need of a rapid and reliable determination of the susceptibility of isolated strains of M. tuberculosis to the first- and second-line antituberculotic drugs.
Pathogens, Apr 26, 2022
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Veterinární medicína, 2012
An outbreak of tuberculosis among bovines and pigs caused by Mycobacterium caprae is described in... more An outbreak of tuberculosis among bovines and pigs caused by Mycobacterium caprae is described in this paper. After tuberculin skin tests with bovine purified protein derivates (PPD) six cattle and one sow, own by a small family farm, tested positive whilst three pigs were suspected in 2004. All animals were euthanised and checked for gross pathological lesions. Generalised lesions were found in five cattle and two sows; however one calf and two gilts had lesions that were localised in the submandibular lymph nodes. Mycobacteria were isolated from tissue samples of six cattle and four pigs. Mycobacterial isolates were identified using classical biochemical tests and molecular methods (PCR, GenoType MTBC) as M. caprae. Mycobacterial Interspersed Repetitive Unit (MIRU) typing of isolated mycobacteria showed an identical number of repeats in 12 different loci. Results of the research confirmed the domination of M. caprae among infected cattle in Croatia; however this pap...
Scandinavian Journal of Infectious Diseases, Nov 25, 2013
Mycobacterium tuberculosis still represents a serious cause of morbidity and mortality worldwide.... more Mycobacterium tuberculosis still represents a serious cause of morbidity and mortality worldwide. The aim of this study was to determine the transmission rate and genetic lineages of M. tuberculosis circulating in Croatia during a 3-y period, between 2009 and 2011. A total of 1587 M. tuberculosis strains (1 strain per tuberculosis patient) isolated in Croatia from 2009 to 2011 were genotyped using 15-locus mycobacterial interspersed repetitive units-variable number of tandem repeats (MIRU-VNTR) analysis. The majority of tested isolates (66.73%) belonged to the Euro-American global lineage. The most prevalent sub-lineages were Haarlem (48.64%), followed by S (6.05%), Cameroon (3.72%), and Latin American-Mediterranean (3.4%). Among the total 1587 tested isolates, 996 (63%) were included in 1 of 236 clusters. The cluster size ranged from 2 (114 clusters) to 45 (1 cluster) patients, the mean cluster size being 4.2. These results indicate that 47.83% of tuberculosis cases during the period analyzed were the result of recent transmission. The most prevalent global lineage in Croatia is Euro-American (sub-lineages Haarlem, S, Cameroon, and Latin American-Mediterranean). The high clustering rate and high medium clustering size of 4.2 tuberculosis cases could indicate a possible failure in interrupting the transmission of infection and points to the need for improvements in national and local tuberculosis control activities. This is the first study describing the molecular epidemiology of tuberculosis in Croatia.
American Academy of PediatricsItasca, IL eBooks, 2020
PubMed, 2004
Drug resistant and multidrug resistant tuberculosis is a consequence of human activity. Resistant... more Drug resistant and multidrug resistant tuberculosis is a consequence of human activity. Resistant strains of M. tuberculosis are mainly prevalent in regions with weak national TB programs or poor socioeconomic environment. Therefore an effective surveillance of the resistance patterns of TB bacilli is an essential tool for the quality of tuberculosis control programs and a demanding task in all countries. Surveillance of tuberculosis in Croatia is based on individual notifications of every newly diagnosed patient by the physicians, followed by laboratory notifications. Data are collected at the Epidemiology Service, National Institute of Public Health Tuberculosis Register (TR). TR is part of the World Health Organization informational system and Surveillance of Tuberculosis in Europe (EuroTB). The results of the ten-year surveillance of the prevalence of drug resistant (5.7%) and multidrug resistant (1.6%) tuberculosis show that Croatia has a favorable situation which should be kept up strictly following the measures of the national TB program.
Aim: To detect mutations in katG and inhA genes in Mycobacterium tuberculosis (M. tuberculosis) c... more Aim: To detect mutations in katG and inhA genes in Mycobacterium tuberculosis (M. tuberculosis) clinical isolates resistant to isoniazid (INH). Methods: A total of 103 isolates collected from 1999 to 2006 in Croatia and identified as INH-resistant M. tuberculosis strains by standard susceptibility testing proportion method according to Canetti were investigated. Multiplex PCR method was used to detect an AGC to ACC mutation in the katG gene and an inhA C-15T mutation in the regulatory region of the mabA-inhA operon. Results: Genetic basis of INH resistance was found for 76 (75%) of total 103 M. tuberculosis strains investigated. There was a correlation between mutation in 315 codon of katG gene and acquisition of resistance to other antituberculous drugs. Conclusions: Mutation in katG gene in INH resistant M. tuberculosis strains is highly predictive for acquisition of resistance to other antituberculous drugs.
PubMed, Jun 1, 2007
Setting: This paper describes an outbreak of human and related bovine tuberculosis (TB) caused by... more Setting: This paper describes an outbreak of human and related bovine tuberculosis (TB) caused by Mycobacterium caprae in Croatia. A 13-year-old boy clinically presented enlargement of cervical lymph node with consecutive isolation of M. caprae. His 7-year-old sister, who had no clinical signs of disease, hyper-reacted to the purified protein derivative (PPD) test (>25 mm) and peribronchial infiltration was found by radiology. The children came from a family that ran a small-sized cattle dairy farm. Design: All cattle on the farm were subjected to cutaneous TB testing: six of the 14 reacted positive, while three were suspicious. The entire herd was slaughtered, their carcasses examined and collected material subjected to pertinent diagnostic procedures. Results: Gross examination findings consistent with TB were observed in the PPD-positive cows. Mycobacteria isolated from the boy and cattle were identified by classical and molecular methods, confirming M. caprae as the causative agent. Conclusion: Although not bacteriologically proven, consumption of raw milk or non-pasteurised milk products from infected dairy cattle was suspected as the source of infection in humans. Our findings confirm the domination of M. caprae among cattle in Croatia and represent the first evidence of M. caprae infection in humans in Croatia.
Hrvatski časopis za javno zdravstvo, Nov 23, 2013
Infektološki glasnik, Jun 30, 2013
Mihaela OBROVAC 1) , dr. sc., mag. medicinske biokemije Ljiljana @MAK 1) , dr. sc., dr. med., spe... more Mihaela OBROVAC 1) , dr. sc., mag. medicinske biokemije Ljiljana @MAK 1) , dr. sc., dr. med., specijalist medicinske mikrobiologije s parazitologijom Vera KATALINI]-JANKOVI] 1) , prim., dr. med., specijalist medicinske mikrobiologije s parazitologijom 1) Hrvatski zavod za javno zdravstvo, Zagreb Klju~ne rije~i tuberkuloza genotipizacija MIRU-VNTR molekularna epidemiologija
Tuberculosis (TB) is the leading infectious cause of death worldwide. Croatia takes place among t... more Tuberculosis (TB) is the leading infectious cause of death worldwide. Croatia takes place among the countries with still high incidence of tuberculosis (33/100, 000 in 2002). Several countries around the world have registered outbreaks of mono- and even multidrug resistance (MDR) TB. Croatia has a low incidence of both (3% and 0.6%, respectively). MDR is defined as resistance to at least rifampin (one of the major first line anti-TB drug) and isoniazid, with or without resistance to other drugs. As to rifampin associated genetic modification in M. tuberculosis strain, this is the initial and precursory event of MDR. The objective of this study was to compare the classical drug susceptibility test (DST – proportion method on Loewenstein-Jensen medium) and the reverse hybridization-based line probe assay (INNO-LiPA Rif.TB, Innogenetics). The DST enables the differentiation for established resistance to rifampin, isoniazid, ethambutol and streptomycin, while INNO-LiPA Rif.TB enables the recognition of early genetic mutation of rifampin resistance region of the beta-subunit of the RNA polymerase (rpoB). Herein, we examined 39 M. tuberculosis strains of which 1 sensitive and 2 resistant only to rifampin, both by DST and INNO-LiPA Rif.TB. Among 20 rifampin and other anti-TB drugs resistant (MDR) strains by DST, INNO-LiPA Rif.TB allowed the identification of 19 strains resistant to rifampin, of which one was identified as mixture of the mutant strain (R4a) and the wild type (WT), while the remaining one was identified as only WT. Fourteen out of 16 samples resistant to anti-TB drugs other than rifampin were confirmed by INNO-LiPA Rif.TB, while 2 were identified as resistant to rifampin. The overall concordance of the two tests represents 92.3%. DST is very informative assay on TB drug resistance but it is time consuming and the interpretation of the results could be ambiguous contrary to INNO-LiPA Rif.TB. Beside that, INNO-LiPA Rif.TB assay is very reliable and simple to perform. Moreover, it allows the identification of genetic mutation before the appearance of phenotypic changes of the bacteria. Thus, it could be considered as the screening test for drug resistance for M. tuberculosis strains.
Hrvatski časopis za javno zdravstvo, Nov 12, 2015
Tuberkuloza je i nadalje jedan od glavnih javnozdravstvenih problema u cijelom svijetu. Nakon kon... more Tuberkuloza je i nadalje jedan od glavnih javnozdravstvenih problema u cijelom svijetu. Nakon kontakta s bacilom tuberkuloze, djeca imaju povecani rizik za razvoj bolesti te je zbog toga važno djecu testirati ukoliko postoji sumnja na infekciju. Do prije nekoliko godina jedini nacin testiranja kontakata na izloženost bacilu tuberkuloze bio je kožni PPD test koji ima iznimno nisku osjetljivost i specificnost. Napredak u probiru kontakata ucinjen je uvođenjem IGRA (od engl. Interferon gamma release assay) testova, kod kojih je osjetljivost i specificnost bolja nego kod kožnog testa. Osnovni cilj ovoga rada bio je procijeniti dijagnosticku vrijednost ex vivo određivanja koncentracije IFN-γ u djece s pojacanom reakcijom nakon redovnog PPD testiranja. U istraživanje je ukljuceno 120 BCG-irane djece koji su prilikom redovitog PPD testiranja bili hiperreaktori. Od ukupnog broja testiranih samo je 15 (12,5%) djece imalo pozitivan IGRA test, dok je cak 105 (87,5%) imalo negativan. Nije bilo statisticki znacajne razlike u velicini PPD probe između skupina (21,5 mm u IGRA+, 20,9 mm u IGRA- skupini, p=0,458). Postojala je razlika u skupinama u odnosu na koncentraciju IFN-g nakon stimulacije s antigenima specificnim za M. tuberculosis , dok nije bilo razlike kako u bazicnoj koncentraciji IFN-g tako i u koncentraciji IFN-g nakon stimulacije mitogenom. Prije bi sva djeca PPD hiperreaktori bila ukljucena u dijagnosticki algoritam za dokaz tuberkuloze, te bi velikom broju bila prepisana preventivna terapija izonijazidom kroz vise mjeseci. Međutim, dodatnim IGRA testiranjem pokazali smo kako je samo manji broj ove djece zaista i bio u kontaktu s bacilom tuberkuloze. Gotovo 90% djece koja su prije bila podvrgnuta dijagnostickim i terapijskim postupcima ovim je novim testom iskljuceno iz daljnje obrade. Zakljucno, ukljucivanje IGRA testiranja u djece kod koje se sumnja na infekciju s bacilom tuberkuloze pridonosi boljem odabiru pacijenata kojima je potrebna obrada i profilaksa.
American Journal of Infection Control, Apr 1, 2017
Mihaela OBROVAC 1) , dr. sc., mag. medicinske biokemije Ljiljana @MAK 1) , dr. sc., dr. med., spe... more Mihaela OBROVAC 1) , dr. sc., mag. medicinske biokemije Ljiljana @MAK 1) , dr. sc., dr. med., specijalist medicinske mikrobiologije s parazitologijom Vera KATALINI]-JANKOVI] 1) , prim., dr. med., specijalist medicinske mikrobiologije s parazitologijom 1) Hrvatski zavod za javno zdravstvo, Zagreb Klju~ne rije~i tuberkuloza genotipizacija MIRU-VNTR molekularna epidemiologija
... Journal. Authors: Katalinić-Janković, Vera; Obrovac, Mihaela. ... Source: U: Knjiga saetaka:... more ... Journal. Authors: Katalinić-Janković, Vera; Obrovac, Mihaela. ... Source: U: Knjiga saetaka: I. Hrvatski kongres preventivne medicine i unapređenja zdravlja. Zagreb, 2003 / Strnad, Marija (ed). - Zagreb : Depol komunikacije, Medicinski fakultet Zagreb , 2003. 54. ...
Genotyping of M. tuberculosis isolates has been used to support investigations of local outbreaks... more Genotyping of M. tuberculosis isolates has been used to support investigations of local outbreaks. Molecular methods have revolutionised our understanding of the transmission of tuberculosis showing that clustered cases indicate recent transmission while distinctive genotypes represent a reactivation of the past infection. The aim of our study was to investigate a connection between M. tuberculosis strains isolated from potentially linked cases. A total of 12 isolates originating from three local outbreaks, one hospital and two communities (a family and a shared household) were included in the study. Isolates were analysed by a high-resolution typing method, MIRU-VNTR analysis (Mycobacterial Interspersed Repetitive Units - Variable Number Tandem Repeats). Twelve MIRU loci vary in tandem repeat numbers and, in most, sequence between repeat units. PCR-based genotyping of these12 MIRU loci yields different patterns that can be used for the comparison of M. tuberculosis strains. In the hospital outbreak there were more than one genotype present, indicating that there was no common source of infection. Transmission was confirmed only for the cases of the shared household but not the family. In conclusion, our results suggest that genotyping by means of MIRU-VNTR analysis can be a useful adjunct to standard contact investigations and can be used to identify unsuspected transmission and broaden the scope of contact investigations.
Nastanak rezistencije na antimikrobna stredstva kod prije osjetljivih mikroorganizama posljedica ... more Nastanak rezistencije na antimikrobna stredstva kod prije osjetljivih mikroorganizama posljedica je njihove uporabe u lijecenju zaraznih bolesti ljudi i životinja. Sve veca, pritom i neracionalna upotreba antibiotika dovela je do povecanja broja rezistentnih sojeva kod svih mikrooganizama. Unatrag desetak godina u cijelom svijetu zabilježen je porast rezistencije M. tuberculosis na antituberkulozne lijekove. Rezistentna tuberkuloza je ubikvitarna: prema procjeni Svjetske zdravstvene organizacije (SZO) približno je 50 milijuna ljudi inficirano rezistentnim sojem M. tuberculosis. U suradnji s Međunarodnom unijom za borbu protiv tuberkuloze SZO prati pojavu, kretanje i sirenje rezistentne i multirezistentne tuberkuloze (MDR TB – rezistencija najmanje na izoniazid i rifampicin) u svim dijelovima svijeta. Rezistencija bacila tuberkuloze na antituberkulotike je rezultat utjecaja covjeka. Nastaje amplificiranjem spontanih mutacija gena odgovornih za rezistenciju bilo primjenom neadekvatnih terapijskih režima, sto dovodi do sprjecavanja rasta osjetljivih bacila uz razmnožavanje onih otpornih, bilo losom suradnjom bolesnika i neredovitim uzimanjem lijekova. To je stecena rezistencija, za razliku od primarne rezistencije gdje se osoba inficirala vec prije rezistentnim sojem. Pojava rezistentne tuberkuloze direktno utjece na provođenje mjera nacionalnih programa za suzbijanje i sprjecavanje tuberkuloze. U Hrvatskoj je 1993. godine u Odjelu za bakteriolosku dijagnostiku tuberkuloze Hrvatskog zavoda za javno zdravstvo osnovan Sredisnji laboratorijski registar rezistentne tuberkuloze. Godisnjim izvjestajem o radu laboratorija prikupljaju se podaci o rezistentnim sojevima i rezistentnim bolesnicima u Hrvatskoj. Test osjetljvosti izvodi se kod svih izoliranih sojeva M. tuberculosis. Broj rezistentnih sojeva ima silazni trend i kretao se od 10, 4% u 1993. godini do 6, 9% u 2001. godini. Od 2001. godine uveden je i podatak o primarnoj i stecenoj rezistenciji. U razdoblju od 1993. do 2001. godine, stopa prevalencije rezistentne tuberkuloze je imala silazni trend i kretala se između 4/100.000 stanovnika u 1993. godini do 1, 5/100.000 stanovnika u 2001. godini. U isto vrijeme stopa multirezistentnih bolesnika se kretala između 0, 9 i 0, 4/100.000 stanovnika. Zabilježeno je da se među monorezistentnim bolesnicima i dalje najcesce javlja rezistencija na izoniazid i streptomicin, antituberkulotike koji su najdulje u primjeni. Ipak, rezistencija na rifampicin kao prekursor multi-drug rezistencije je rijetka. Desetogodisnji rezultati pracenja rezistentne i multirezistentne tuberkuloze u Hrvatskoj pokazuju da nasa država ima prihvatljivu situaciju koju treba strogom primjenom svih mjera Nacionalnog programa za suzbijanje i sprjecavanje tuberkuloze i zadržati.
Background Over the last 10 years, multidrug resistant Acinetobacter baumannii has been spreading... more Background Over the last 10 years, multidrug resistant Acinetobacter baumannii has been spreading worldwide as emerging microorganisms that negatively impact on the outcome of in-hospital patients. Methods Between 2007 and 2016, all isolates of patients of the Vienna General Hospital (VGH), tested positive for multidrug resistant Acinetobacter baumannii (MDR A. baumannii) strains, were investigated with respect to their genetic relationship. Patient medical histories were reviewed in order to collect discriminating factors related to MDR A. baumannii colonization or infection. Results A total of 79 isolates of 76 patients were obtained. For 44 of them (55.7%) the first diagnosis ward was an intensive care unit (ICU). A total of 10 genotype clusters were identified and 35 cases (44.3%) of in-hospital acquisition in our institution could be detected. Multidrug resistant Acinetobacter baumannii isolates were acquired before admission to our hospital in 44 cases (55.7%) and in 31 (70.5%) they belonged to patients who had previous exposure to the healthcare setting of high prevalence countries for MDR A. baumannii. Conclusion Patients admitted to our hospital with a previous healthcare contact in a high prevalence country for multidrug resistant Acinetobacter bau
The genus Mycobacterium currently has more than 140 species, including M. tuberculosis complex, M... more The genus Mycobacterium currently has more than 140 species, including M. tuberculosis complex, M. leprae and other organisms referred to as nontuberculous mycobacteria (NTM). In recent years, there has been a marked increase in the number of cases of human disease due NTM that seem to be related to the geographic distribution of these species in the environment. A wide range of diseases is caused by NTM, including lung disease, lymphadenitis, skin and soft tissue infections, osteoarticular disease and disseminated disease. In Croatia, TB diagnostics is conducted in 14 laboratories that use Lowenstein-Jensen and MGIT media for the recovery of mycobacteria from clinical specimens. Full-grown AFB cultures, negative for M. tuberculosis, are sent to Croatian National Institute of Public Health where the identification is performed by means of GenoType Mycobacterium CM/AS kits (Hain Lifescience) and/or by phenotypical methods. Of total of 39, 580 clinical isolates isolated in Croatia from 2000 to 2008, 37, 426 (94.55%) were identified as belonging to M. tuberculosis complex and 2, 154 (5.45%) as NTM. During that period, NTM prevalence increased steadily, starting with 4.2% in 2000 and rising to 9.9% in 2008. Total of 95 patients with NTM isolates met microbiologic criteria for mycobacteriosis. After M. xenopi (n=36 ; 37.89%) and MAC (n=31 ; 32.63%), most patients had M. kansasii (n=15 ; 15.79%) isolated. M. fortuitum was isolated in 5 patients (5.26%), M. abscessus in 3 (3.16%), while M. chelonae, M. celatum, M. scrofulaceum, M. gordonae, M. peregrinum and M. marinum were isolated in one patient each (1.05%). With TB notification rate of 19/100.000, Croatia is a middle-incidence country and TB is still a public health problem. Nevertheless, the incidence of NTM, as well as number of mycobacteriosis patients, is steadily rising and the key role of the laboratory is increasing the awareness of NTM as potential pathogens. The correct and rapid identification of NTM is at the basis of the proper therapeutic modality.
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Papers by Mihaela Obrovac