The International Journal of Mycobacteriology

: 2019  |  Volume : 8  |  Issue : 1  |  Page : 22--24

Drug resistance profile of Mycobacterium tuberculosis isolates from patients referred to tuberculosis reference laboratory in Kosovo

Rrezarta Bajrami1, Gjyle Mulliqi1, Arsim Kurti2, Greta Lila1, Lul Raka1,  
1 Department of Microbiology, National Institute of Public Health of Kosovo; Department of Microbiology, University of Prishtina “Hasan Prishtina,” Faculty of Medicine, Prishtina, Kosovo
2 Department of Microbiology, National Institute of Public Health of Kosovo, Prishtina, Kosovo

Correspondence Address:
Lul Raka
National Institute of Public Health of Kosovo, Rrethi i Spitalit, P. N. 10000, Pristina


Background: Drug-resistant tuberculosis (TB) continues to threaten TB control and remains a major global public health concern. The poor patient adherence in TB treatment is the cornerstone of emerging multidrug-resistant TB (MDR-TB). The aim of this study was to evaluate the resistance of Mycobacterium tuberculosis to the first-line TB drugs among isolates from clinical specimens. Methods: A laboratory-based study was conducted in the Department of Microbiology, within the National Institute of Public Health of Kosovo, from January 2017 to September 2018. Sputum and other clinical specimens were obtained from patients with pulmonary and extrapulmonary TB. The specimens were stained with Ziehl–Neelsen, inoculated on Löwenstein–Jensen media for 6–8 weeks, and tested for sensitivity against the first-line TB drugs (isoniazid [INH], rifampicin [RIF], ethambutol [EMB], and streptomycin [SM]). Results: Of the 316 M. tuberculosis isolates collected, 31.6% showed resistance to first-line TB drugs. Among these resistant isolates, 31% showed resistance to at least one of the first-line TB drugs and 0.3% showed MDR. Resistance to EMB, INH, RIF, and SM was seen in 17%, 8%, 3%, and 72% of isolates, respectively. Polyresistance was seen in 3% of the isolates. Conclusion: Our study confirms that resistance to streptomycin was the most common phenomenon. The resistance pattern identified in this study could assist clinicians in providing appropriate treatment regimen to TB patients and improve their clinical outcome.

How to cite this article:
Bajrami R, Mulliqi G, Kurti A, Lila G, Raka L. Drug resistance profile of Mycobacterium tuberculosis isolates from patients referred to tuberculosis reference laboratory in Kosovo.Int J Mycobacteriol 2019;8:22-24

How to cite this URL:
Bajrami R, Mulliqi G, Kurti A, Lila G, Raka L. Drug resistance profile of Mycobacterium tuberculosis isolates from patients referred to tuberculosis reference laboratory in Kosovo. Int J Mycobacteriol [serial online] 2019 [cited 2020 May 30 ];8:22-24
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Tuberculosis (TB) remains a global public health problem, representing the second cause of death among communicable diseases.[1] According to the World Health Organization (WHO), in 2017, 10 million people developed TB and 1.6 million died from this disease. Over 95% of TB deaths occurred in developing countries.[2]

TB treatment, prevention, and control have been seriously jeopardized in the last decade due to the increasing rate of multidrug-resistant (MDR) and extensively drug-resistant (XDR) TB. At the global level, there were 558,000 new TB cases with resistance to rifampicin.[3] China, India, and the Russian Federation covered 47% of total TB-resistant cases worldwide. The fastest decline in TB incidence was noted in the WHO European Region (4.6% from 2015 to 2016). The most affected MDR-TB areas in Balkan area are Rumania, Bulgaria, and Bosnia.[4]

Kosovo, with a population of 1.7 million, is located in the southeast of Europe. Healthcare in Kosovo is still under transition period facing many challenges, of which the most important are limited resources and lack of health insurance system.[5]

The burden of TB in Kosovo remains high, despite the decreasing trend of TB-reported cases. The number of registered TB cases decreased from 1443 new cases in 2002 (69 per 100,000 population) to 721 in 2017, with an annual median decline of 3.5%. The Global Fund to Fight AIDS, TB, and malaria supported Kosovo with grants which resulted in substantial reduction in a number of TB cases. The prevalence of TB drug resistance was unknown in Kosova until the establishment of the National Tuberculosis Program (NTP) in 2000.[6]

Routine monitoring of MDR-TB is very important because of the limited availability of first-line TB drugs, the high price of second-line TB drugs, and lack of facilities in most health-care centers in Kosovo that could detect MDR-TB or have access to the second-line TB treatment. Therefore, data on local TB drug resistance are essential for patient management and selection of appropriate regimen for patients suspected to have the resistance strain, as this helps prevent the spread of resistant TB.[2],[7]

The aim of this study was to evaluate the resistance of Mycobacterium tuberculosis to the first-line TB drugs from clinical specimens in Kosovo.


The study was conducted in the Department of Microbiology within the National Institute of Public Health of Kosovo. Epidemiological and microbiological data of M. tuberculosis from various clinical specimens and its resistance to the first-line TB drugs were retrospectively collected from January 2017 to September 2018.

Sputum samples were collected early morning on 3 consecutive days. Other collected specimens included bronchial fluid, cerebrospinal fluid, and urine. The diagnosis of pulmonary and extrapulmonary TB was based on anamnesis, physical examination, chest radiography, positive acid-fast smear, and culture.[8],[9]

The drug-susceptibility testing (DST) against the first-line TB drugs was carried out using the proportional method after inoculating the specimens on Löwenstein–Jensen (LJ) medium and incubating them at 37°C. The LJ medium was observed two times a week, for 8 weeks, to check for possible growth of microbial colonies.[10] Resistance was expressed as the percentage of colonies that grew on the following critical concentrations of the drugs: 0.2 μg/mL for isoniazid (INH), 2.0 μg/mL for ethambutol (EMB), 4 μg/mL for streptomycin (STM), and 40 μg/mL for rifampicin (RMP). Interpretation was made according to the critical proportion of 1% for all drugs.

Any drug resistance was defined as resistance to one or more first-line TB drugs (INH, RIF, EMB, and SM). Resistance to only one first-line TB drug was defined as monoresistance, whereas resistance to at least two or more first-line TB drugs except the INH and RIF combination was defined as polyresistance.[11],[12] MDR-TB was defined as resistance to the two key first-line TB drugs, INH and RIF.

The study was conducted after approval by the Ethics Review Committee of the Medical School of University of Prishtina, No = 1/445, issued on July 21, 2014.


Of the 3038 clinical specimens received, 316 (10.4%) were positive for MTB culture. The results showed that 100 (31.6%) strains were resistant to at least one or more anti-TB drugs. One hundred and seventy-three patients were male (54.7%) and 143 (45.2%) were female.

Among clinical samples with positive growth of M. tuberculosis, sputum samples predominated with 307 (97.1%) followed by four samples of bronchial fluids, three cerebrospinal fluid, and two pus samples.

The proportion of resistance to the first-line TB drugs during 2-year observation period is presented in [Table 1]. There were three isolates of MDR-TB. Eight isolates were resistant against INH, 17 expressed resistance only to EMB, three isolates were resistant to RIF, and 72 isolates (72%) were resistant to SM. Polyresistance to EMB and INH was noted in 3% of the isolates; EMB and INH were noted in 2% of the isolates. Three specimens (3%) were resistant to INH and rifampin (MDR-TB).{Table 1}


DST for TB is an effective tool to control MDR-TB. The early diagnosis and prompt treatment of MDR-TB patients can prevent disease transmission and reduce the risk of developing the drug resistance.[13]

The first study conducted in Kosovo covered 2112 patients during 10 years and three regions.[7] Based on the first survey, the prevalence of total resistance to any of the four drugs tested was 20.6%. The drug to which the resistance was most frequent in new cases was streptomycin 15.2%, and less resistance rates were, respectively, EMB 2.3%, rifampicin 2.0%, and INH 0.4%. In previously treated cases, the resistance rates were, respectively, 17.6% streptomycin, EMB 6.9%, rifampicin 3.2%, and INH 0.5%. The prevalence of MDR was 1.2%. The current survey shows an increase in resistance rates although the study sample is smaller.

The percentage of MDR in Kosova is low. The MDR data analysis shows that MDR is not a problem for the time being and this is one of the best indicators proving that TB situation and TB program are performing well.

In 2016, 50 countries in the WHO European Region reported on the first-line anti-TB DST results. The percentage of confirmed MDR-TB cases among 86,797 new pulmonary TB cases tested for first-line DST in the region was 17.7%. XDR-TB was reported for 20.1% of 984 MDR-TB cases tested for the second-line drug susceptibility.[14]

Pulmonary MDR-TB cases notification rate for Kosovo was 0.9%, and it is similar to some neighboring countries – Albania (2.5%), Macedonia (1.4%), and Serbia (1.5%). This proportion was much higher in some other countries of European area: Lithuania (20.7%), Kyrgyzstan (32.7%), Moldova (33.4%), and Russia (44.8%). The average rate in the European Union/ European Economic Area (EU/EEA) countries was 2.4%.

The above-mentioned rates are much lower than in countries of other continents. For example, in South Africa, MDR-TB resistance rate is 58.4%.[15] Data from national reference laboratories in India show that 40%–58% of MDR-TB suspects are confirmed to have MDR-TB by DST.[16]

In our study, 31.6% of M. tuberculosis isolates were resistant to at least one first-line TB drug. The main contributor to this figure was resistance to streptomycin, which can be related to the use of this drug for other treatment purposes against bacterial infections besides TB.

In 2011, Jenkins et al. produced the first analysis of global INH resistance data from 131 countries reported to the WHO. Of the submitted nationwide data, the former Soviet Union countries reported the highest percentages of TB cases with INH resistance reaching 44.9%. Across the rest of the world, 13.9% of TB cases had some form of INH resistance.[17]

The percentage of INH resistance above 10% is a predictor of the development of MDR-TB. Therefore, M. tuberculosis culture with DST for at least INH and RIF should be performed for all TB patients before the start of treatment. Langendam et al. showed that patients treated with inappropriate TB therapy were on a 27-fold higher risk to develop MDR-TB.[18]

Our study had some limitations. The sample size was relatively small. To determine the level of MDR pattern, a larger population is needed for the survey. Another limitation is potential misclassification between new and retreatment cases.


Resistance to streptomycin and EMB was the most common resistance profile identified by this survey. The MDR-TB rate is currently low in Kosovo, but this does not mean that the key stakeholders involved in the NTP should underestimate the potential risk of resistance to TB drugs. The resistance profile from this study could assist clinicians for appropriate TB treatment and improvement of patient's clinical outcome. Continuous monitoring of resistance trends should be a priority of NTP.

Financial support and sponsorship


Conflicts of interest

There are conflicts of interest.


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