Molecular diversity of Klebsiella pneumoniae clinical isolates: antimicrobial resistance, virulence, and biofilm formation.

One of the mechanisms responsible for antibiotic resistance in Klebsiella pneumoniae is the enzymes produced by the bacteria; another important mechanism is the ability to form biofilm. In this study, antibiotic resistance, genes associated with virulence, and biofilm-forming properties of K. pneumoniae strains were investigated. A total of 100 K. pneumoniae isolates were obtained from different clinical samples identified by Matrix-Assisted Laser Desorption/Ionization time-of-flight Mass Spectrometry. Antimicrobial susceptibility testing was performed with the Phoenix 100 apparatus. The biofilm forming properties of strains were determined by the microtiter plate method. For molecular analysis, genes encoding the carbapenemase enzyme (blaOXA-48, blaNDM-1, blaIMP, and blaVIM) and biofilm-related genes (treC, luxS, mrkA, and wza) were investigated by polymerase chain reaction (PCR). While 76% of clinical isolates were resistant to three or more antimicrobials, 24% were classified as non-multidrug resistant (non-MDR). When biofilm-forming capacities of clinical isolates were tested, it was determined that the resistant-isolates produced 59.2% strong biofilm, and susceptible-isolates produced 12.5% strong biofilm. According to PCR results, carbapenemase genes were determined as follows: blaOXA-48-70%, blaNDM-49%, and blaKPC-19%, blaOXA-48/blaNDM/blaKPC-12%, blaOXA-48/blaNDM-26%, and blaOXA-48/blaKPC-4%. The biofilm-associated genes in bacterial isolates were determined as follows: luxS-98%, treC-94%, mrkA-88%, and wza-15%. In addition, Hierarchical Clustering Tree and Heatmap analysis revealed an association between isolates that lacks resistance genes and isolates lacks biofilm-formation related genes that were included in MDR or non-MDR classes. As a result, biofilm should be considered in the treatment of MDR infections, and therapy should be planned accordingly. In addition, pursuing the data and genes of antibiotic resistance is significant for combating resistance.

Molecular epidemiological investigation of carbapenem resistant Klebsiella pneumoniae isolated from intensive care unit patients of six geographical regions of Turkey.

INTRODUCTION: Klebsiella pneumonia causes serious infections in hospitalized patients. In recent years, carbapenem-resistant infections increased in the world. The molecular epidemiological investigation of carbapenem-resistant K. pneumoniae isolates was aimed in this study. METHODOLOGY: Fifty carbapenem-resistant K. pneumoniae isolates from six geographical regions of Turkey between September 2019-2020 were included in the study. The disk diffusion method was used for the antibiotic susceptibility testing. The microdilution confirmed colistin susceptibility. Genetic diversity was investigated by MLST (Multi-Locus Sequence Typing). RESULTS: The resistance rates were as follows: 49 (98%) for meropenem, 47 (94%) imipenem, 50 (100%) ertapenem, 30 (60%) colistin and amoxicillin-clavulanate, 49 (98%) ceftriaxone, 48 (96%) cefepime, 50 (100%) piperacillin-tazobactam, 47 (94%) ciprofloxacin, 40 (80%) amikacin, 37 (74%) gentamicin. An isolate resistant to colistin by disk diffusion was found as susceptible to microdilution. ST 2096 was the most common (n:16) sequence type by MLST. ST 101 (n:7), ST14 (n:6), ST 147 and ST 15 (n:4), ST391 (n:3), ST 377 and ST16 (n:2), ST22, ST 307, ST 985, ST 336, ST 345, and ST 3681 (n:1) were classified in other isolates. In Istanbul and Ankara ST2096 was common. Among Turkey isolates, the most common clonal complexes (CC) were CC14 (n:26) and CC11 (n = 7). CONCLUSIONS: In Turkey, a polyclonal population of CC14 throughout the country and inter-hospital spread were indicated. The use of molecular typing tools will highlight understanding the transmission dynamics.

Synergistic efficacy of meropenem, ciprofloxacin and colistin antibiotics against planktonic and biofilm forms of Myroides odoratimimus bacterial isolates.

PURPOSE: In this study, it was aimed to investigate the combined synergistic efficacy of colistin (CT), meropenem (MEM), and ciprofloxacin (CIP) antibiotics on planktonic and biofilm forms in Myroidesodoratimimus strains isolated from various clinical specimens. METHODS: Antibiotic susceptibility was determined by the Kirby-Bauer disk diffusion method. In addition, minimum inhibitory concentrations (MIC) of CIP, MEM, and CT were studied using the standardized broth microdilution method. In vitro synergistic activity of antibiotics against M. odoratimimus planktonic bacteria strains was studied by the Micro Broth Checkerboard method. The microtiter plate (MtP) method was used to determine the effectiveness of antibiotics on M. odoratimimus biofilm formation. RESULTS: A zone of inhibition was not observed against other antibiotics used except amikacin and linezolid in all strains. While CT/MEM and CT/CIP combinations have a synergistic effect on all strains, the combination CIP/MEM has an additive effect. According to the biofilm inhibition results, all three antibiotics inhibited biofilm formation. However, the efficacy of MEM (60.3-76.5%) and CIP (60.2-77.8%) was approximately two times higher than that of CT (25.4-34.5%). In addition, the effectiveness of combinations of antibiotics on biofilm formation was examined and the percentage of inhibition was 30.8% when CT was used alone, while the biofilm inhibition rates of CT/MEM and CT/CIP were 92.4% and 91.7%, respectively. MEM/CIP combination was inhibited biofilm formation by 75.7%. CONCLUSIONS: This study is the first report showing the efficacy of CT, MEM and CIP antibiotics, which are frequently used in clinical practice, in combination on M. odoratimimus planktonic and biofilm forms. The findings of our study are particularly guiding for combined antibiotic treatment options in immunosuppressed patients admitted to an intensive care unit (ICU). The CT/MEM combination is currently used frequently. In addition, these results are important in terms of supporting in vitro that CT/CIP and MEM/CIP combinations can also be used as a treatment option in M. odoratimimus related infections.

Which scoring system is effective in predicting mortality in patients with Crimean Congo hemorrhagic fever? A validation study.

We aimed to decide which scoring system is the best for the evaluation of the course of Crimean-Congo Hemorrhagic Fever (CCHF) by comparing scoring systems such as qSOFA (quick Sequential Organ Failure Assessment), SOFA (Sequential Organ Failure Assessment), APACHE II (Acute Physiology and Chronic Health Evaluation II) and SGS (Severity Grading System) in centers where patients with CCHF were monitored. The study was conducted with patients diagnosed with CCHF in five different centers where the disease was encountered most commonly. Patients having proven PCR and/or IgM positivity for CCHF were included in the study. The scores of the scoring systems on admission, at the 72nd hour and at the 120th hour were calculated and evaluated. The data of 388 patients were obtained from five centers and evaluated. SGS, SOFA and APACHE II were the best scoring systems in predicting mortality on admission. All scoring systems were significant in predicting mortality at the 72nd and 120th hours. On admission, there was a correlation between the qSOFA, SOFA and APACHE II scores and the SGS scores in the group of survivors. All scoring systems had a positive correlation in the same direction. The correlation coefficients were strong for qSOFA and SOFA, but poor for APACHE II. A one-unit rise in SGS increased the probability of death by 12.818 times. qSOFA did not provide significant results in predicting mortality on admission. SGS, SOFA and APACHE II performed best at admission and at the 72nd and 120th hours.

Antimicrobial synergism and antibiofilm activities of Pelargonium graveolens, Rosemary officinalis, and Mentha piperita essential oils against extreme drug-resistant Acinetobacter baumannii clinical isolates.

Rosemary officinalis L., Pelargonium graveolens L., and Mentha piperita L., essential oils are used by complementary medicine specialists simultaneously with traditional antibiotics for treatment purposes. The chemical composition of essential oils was analyzed by the gas chromatography-mass spectrometry method. In vitro antibacterial and antibiofilm activities of the essential oils were tested against extreme drug-resistant (XDR) colistin-resistant and colistin susceptible Acinetobacter baumannii clinical strains. The synergistic activities between essential oils and colistin antibiotics were investigated by the checkerboard method. The highest antibacterial effect was detected in mint essential oil (2.5-5 µl/ml), followed by pelargonium essential oil (5-20 µl/ml) and rosemary essential oil (5-20 µl/ml). The combination of rosemary essential oil or pelargonium essential oil with colistin showed strong synergistic activity in most of the bacterial strains tested (fractional inhibitory concentration index ≤ 0.5; synergy). As a result of the combination of mint essential oil and colistin, an indifferent effect was observed in only two bacterial strains, and other strains could not be evaluated. No antagonistic effects were observed in any of the tested essential oils. As a result of the effectiveness of the combination, the minimum inhibitory concentration (MIC) values of colistin in XDR-A. baumannii clinical isolates decreased 2-32 fold. Additionally, the sub-MIC concentration of essential oils exhibited an inhibitory effect (48-90%) against the biofilm layer of tested A. baumannii strains.

[COVID-19 Co-infection in a patient with Crimean Congo Hemorrhagic Fever: A Case Report]. / Kirim Kongo Kanamali Atesi Hastasinda COVID-19 Ko-enfeksiyonu: Bir Olgu Sunumu.

Crimean-Congo Hemorrhagic Fever (CCHF) is an acute viral zoonotic disease. Coronavirus disease-2019 (COVID-19) is a newly emerging viral disease and it is caused by "severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2)". In this article, a case diagnosed with CCHF and COVID-19 coinfection confirmed by the polymerase chain reaction (PCR) method and its management was presented. A thirtyfive years old female patient admitted to the hospital with the complaint of fever for one day and common body pain. It was learned that three days before the onset of her complaints, she removed a tick adhering to the anterior abdominal wall with no precaution. Her body temperature was 38°C degrees and her respiratory rate was 22 per minute. The leucocyte count was 3660/mm³ and the platelet count was 138.000/mm³. It was determined that prothrombin time was 15.4 seconds, international normalized ratio (INR) was 1.35 seconds, and D-dimer level was 1310 ng/ml. The patient was hospitalized with prediagnosis of CCHF. Supportive treatment was started. On the second day at the clinical follow-up of the patient, complaints of sore throat and cough without sputum started. A combined nasopharyngeal and throat swab sample was taken from the patient because of the suspicion of COVID-19. COVID-19 PCR test result was reported as positive. Favipiravir treatment was started. The CCHF-PCR test, which was studied from the serum sample sent to the Microbiology Reference Laboratories was reported as positive. From the third day of favipiravir treatment; the patient did not have a fever and her complaints regressed. On the ninth day of her hospitalization, she was discharged. In this case; it is important to show that both diseases, especially in regions where CCHF disease is endemic, can be confused due to the similarity of the clinical picture with COVID-19 and to know that they can coexist.

Evaluation of the diagnostic performance of the Xpert® MTB/RIF assay in pulmonary and extrapulmonary samples.

INTRODUCTION: This study aimed to evaluate the performance of the Xpert MTB/RIF assay in the identification of M. tuberculosis in pulmonary and extrapulmonary clinical samples by taking the results of the BACTEC MGIT 960TB culture system as a reference. MATERIALS AND METHODS: A total of 11,341 specimens sent to Sivas Cumhuriyet University Application and Research Hospital Tuberculosis Laboratory for microbiological examination with suspicion of tuberculosis infection between January 2013 and December 2019 were examined, and 6847 clinical specimens that underwent culture (BACTEC MGIT 960TB), Xpert MTB/RIF and AFB (Acid-fast bacilli) testing were selected and included in our study. Of the samples included in the study, 5096 samples were pulmonary, and 1751 were extrapulmonary samples. RESULT: In our study, sensitivity, specificity, PPV and NPV values of Xpert MTB/ RIF and AFB were calculated by taking TB culture test as reference test. The sensitivity of the Xpert MTB/RIF assay was calculated as 96.1%, specificity as 99.7%, positive predictive value (PPV) as 88.2%, and negative predictive value (NPV) as 99.9%. These values for pulmonary samples were determined as 98.3%, 99.7%, 89.9%, and 99.9%, respectively. For extrapulmonary samples, the sensitivity of the assay was found as 89.4%, specificity as 99.5%, PPV as 82.9%, and NPV as 99.7%. The sensitivity and PPV values for AFBpositive samples were found to be 99.0% and 97.1%, respectively. For AFB negative samples, the sensitivity, specificity, PPV, and NPV values were determined as 90.5%, 99.7%, 73.8%, and 99.9%, respectively. CONCLUSIONS: A large number of clinical samples were studied with the Xpert MTB/RIF test in our study. It can be a guide in determining the performance of the test under the conditions of our country. Especially in the diagnosis of extrapulmonary TB, the effectiveness of the Xpert MTB/RIF assay has not been certainly proven in countries having a moderate prevalence of TB, such as Turkey. In most of the published studies, only a small part of the samples is extrapulmonary samples. So, our study provides valuable results in terms of evaluating a large number of extrapulmonary samples.

Clinical, Neurophysiological and Neuroimaging Findings of Critical Illness Myopathy After COVID-19.

Hypoxemic respiratory failure caused by coronavirus disease 2019 (COVID-19) may lead to prolonged intensive care unit stay and mechanical ventilation. Critically ill patients often develop intensive care unit acquired weakness (ICUAW), which is an umbrella term that encompasses critical illness polyneuropathy and critical illness myopathy. The aim of this paper is to report the clinical, neurophysiological, and radiological findings suggesting critical illness myopathy in three patients with critical COVID-19. Muscle magnetic resonance imaging may serve as a diagnostic tool for critical illness myopathy. Weaning failure and generalized muscle weakness with preserved sensation and cranial nerve function should alert physicians for ICUAW.

Understanding the pathophysiological changes via untargeted metabolomics in COVID-19 patients.

Coronavirus disease 2019 (COVID-19) is an infectious respiratory disease caused by a new strain of the coronavirus. There is limited data on the pathogenesis and the cellular responses of COVID-19. In this study, we aimed to determine the variation of metabolites between healthy control and COVID-19 via the untargeted metabolomics method. Serum samples were obtained from 44 COVID-19 patients and 41 healthy controls. Untargeted metabolomics analyses were performed by the LC/Q-TOF/MS (liquid chromatography quadrupole time-of-flight mass spectrometry) method. Data acquisition, classification, and identification were achieved by the METLIN database and XCMS. Significant differences were determined between patients and healthy controls in terms of purine, glutamine, leukotriene D4 (LTD4), and glutathione metabolisms. Downregulations were determined in R-S lactoglutathione and glutamine. Upregulations were detected in hypoxanthine, inosine, and LTD4. Identified metabolites indicate roles for purine, glutamine, LTD4, and glutathione metabolisms in the pathogenesis of the COVID-19. The use of selective leukotriene D4 receptor antagonists, targeting purinergic signaling as a therapeutic approach and glutamine supplementation may decrease the severity and mortality of COVID-19.

[Klebsiella pneumoniae Infections in the Intensive Care Unit: Risk Factors Related to Carbapenem Resistance and Patient Mortality]. / Yogun Bakim Ünitesinde Gelisen Klebsiella pneumoniae Enfeksiyonlari: Karbapenem Direnci ve Hasta Mortalitesi ile Ilgili Risk Faktörleri.

Klebsiella pneumoniae is the cause of complicated and difficult-to-treat nosocomial infections such as sepsis, urinary tract infection, catheter related infections, pneumonia and surgical site infections in intensive care units. The biggest problem in infections with K.pneumoniae is that treatment options are limited due to multiple antibiotic resistance and consequently the increased morbidity and mortality. The widespread and improper use of carbapenems can lead to epidemics that are difficult to control, especially in intensive care units because of the acquired resistance to this group of antibiotics. Outbreaks and sporadic cases caused by carbapenem resistant K.pneumoniae (CRKP) species have been reported all over the world in recent years with increased frequency. The aim of this study was to determine the risk factors related to carbepenem resistance and mortality caused by K.pneumoniae infections in a university hospital anesthesia intensive care unit. The study was conducted between January 1st, 2016, and December 31st, 2018. Retrospective data were obtained from the patient and laboratory-based surveillance records. Adult patients (≥ 18 years) with K.pneumoniae growth in the blood, urine, abscess and tracheal aspirate samples collected 48 hours after admission to the intensive care unit were considered as the relevant infection locus-related agent and treated with antibacterial therapy. Clinical samples collected from patients were inoculated onto 5% sheep blood and eosin-methylene-blue (EMB) agar except the blood samples. Blood samples were cultured in blood culture bottles and incubated in an automated system. Gram staining was performed for the samples showing growth signal within five days and then inoculated onto 5% sheep blood and EMB agar media and were incubated for 18-24 hours at 35.5-37°C. Identification of the isolates was performed using Bruker IVD MALDI Biotyper 2.3 (Bruker Daltonik GmbH, Bremen, Almanya) based on "matrix-assisted laser desorption/ionization time-of-mass spectrometry (MALDI-TOF MS)". K.pneumoniae isolates were identified by obtaining reliability scores of 2.0 and above in the study. Antibiotic susceptibility tests were performed with Phoenix 100 (BD, New Jersey, ABD) automated system. Interpretations were made according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST) guidelines. Combination disk diffusion test and polymerase chain reaction based tests were used to show the presence of carbapenemase in CRKP isolates. A total of 88 patients with K.pneumoniae infection were included in the study. The mean age of the patients was 74 ± 15 (range= 21-93) years and 60.2% were female. CRKP was detected in 32 patients (36.4%) and carbapenem-sensitive K.pneumoniae (CSKP) was detected in 56 patients. The presence of OXA-48 was found to be 68.8% in the carbapenem screening test performed by combination disc method in patients with CRKP. Multivariate logistic regression analysis showed that previous use of colistin [Odds ratio (OR)= 19.108; 95% confidence interval (CI)= 2.027-180.133; p= 0.010] and aminoglycoside (OR= 12.189; 95% CI= 1.256-118.334; p= 0.031) was an independent risk factor in terms of CRCP among the patients with K.pneumoniae infection. The 28-day mortality rates were 71.9% in the CRKP group (23/32) and 37.5% in the CSKP group (21/56). Presence of CRKP in terms of 28-day mortality (OR= 5.146; 95% CI= 1.839-14.398; p= 0.002) was an independent risk factor. The data obtained in this study will guide for conducting effective and continuous surveillance studies and implementing rational antibiotic programs to prevent the increase in CRKP.

[A Case of Meningitis Caused by Globicatella sanguinis in a Patient with a Lumbo-peritoneal Shunt]. / Lumbo-peritoneal Santli Hastada Globicatella sanguinis'e Bagli Menenjit Olgusu.

Globicatella sanguinis is catalase-negative, alpha-hemolytic, nonmotile, facultative anaerobic grampositive cocci, identified as a new species in 1992. Since the colony morphology in blood agar and microscopic appearance resembles streptococci, it is thought that some of the isolates previously identified in the Streptococcus viridans group were G.sanguinis species. G.sanguinis has been isolated from various clinical specimens, its species identification and antibiotic susceptibility have been tested since the year it was identified. Clinical specimens in which it is isolated include various mucosal surfaces, blood, urine, wound and cerebrospinal fluid. In this report, considering also the literature information, a case of G.sanguinis which is thought to cause meningitis was presented. Our case is a 39-year-old female patient with a lumboperitoneal shunt. The patient was admitted to the neurosurgery clinic with a headache and vision loss and was hospitalized in the service with a pre-diagnosis of pseudotumor cerebri. Neurological examination revealed no pathological findings. Eye examination revealed mild papillary edema, local retinal hemorrhage, and bilateral expansion in retinal vascularization. There was no pathologic findings in the brain magnetic resonance imaging. The colonies resembling alpha hemolytic streptococci were isolated from the cerebrospinal fluid taken upon the development of neck stiffness, fever, and tachycardia on the 10th day of hospitalization of the lumbo-peritoneal shunt administered patient. The identification of the isolate was determined in Bruker IVD MALDI Biotyper 2.3 (Bruker Daltonik GmbH, Bremen, Germany), available in our laboratory and it was identified as G.sanguinis (KJ680157.1) with a score of > 2. The definite identification of the isolate at the species level was made by 16S rDNA sequence analysis and it was determined that the bacterium was G.sanguinis with 100% similarity and coverage. The minimum inhibitory concentration (MIC) for some of the antibiotics was determined by the agar gradient method. The MIC values were found as; linezolid 0.50 µg/ml, vancomycin 0.75 µg/ ml, imipenem 0.75 µg/ml, meropenem 3 µg/ml, penicillin G 6 µg/ml and cefotaxime > 32 µg/ml. It is known that these rare isolates can be isolated in greater numbers along with the introduction of MALDITOF MS-based devices in many laboratories. Following greater numbers of isolation of this rare species of bacteria, our knowledge about its clinical significance, placement in the flora and antibiotic susceptibility will also be expanded.

[Analysis of intestinal ameobiasis in patients with diarrhea by adhesin antigen test and direct microscopy]. / Ishalli Hastalarda Baðýrsak Amebiyazýnýn Adezin Antijen Testi ve Direkt Mikroskopi ile Incelenmesi.

OBJECTIVE: In this study, we aimed to research the frequency of intestinal amebiasis in patients who applied with diarrhea retrospectively for a year and compare direct microscopic analysis and ELISA adhesin antigen test for Entamoeba histolytica procedures. METHODS: The fecal matter sample of 259 patients with diarrhea who applied to the Sivas Numune Hospital Microbiology Laboratory between February 2012 and March 2013 were studied. Samples were evaluated with direct microscopic analysis and Entamoeba histolytica adhesin antigen test (E. histolytica II, Techlab, Blacksburg, USA). RESULTS: In the patients who applied to our laboratory with an amebiasis diagnosis, the mean age was detected as 40.12±19, and the positivity range of the Entamoeba histolytica adhesin antigen test was detected as 25.1% (n=65). In ELISA adhesin test-positive patients 24.6% (n=16) trophozoites, cyst, abundant leukocytes and erythrocytes were detected, and in 6 patients (3.1%), ELISA adhesin antigen test was negative. There was no difference between males and females (p>0.05), but between-season difference was detected (p<0.05). CONCLUSION: Direct microscopic analysis may be inadequate in the differential diagnosis of E. histolytica/ and E. dispar and discrimination of Entamoeba cyst and/or trophozoites from other cellular elements (esp. leukocytes). Furthermore, we thought that the E. histolytica monoclonal ELISA adhesin test is useful for the differential diagnosis of pathogenic E. histolytica and nonpathogenic E. dispar.

[Sternal tuberculosis]. / Sternum tüberkülozu.

Isolated involvement of the sternum is rare, representing less than 1% of tuberculous osteomyelitis. In this report, a 51-years-old woman who was admitted to the hospital with a localized solid mass in the sternum has been presented. A soft, painful mass measuring 3 cm in diameter in the lower sternum was detected during physical examination. Radiological investigation revealed presternal soft tissue and bone expansion in the posterior side of lower sternum. The patient was treated with non-specific antibiotics for a suspected diagnosis of osteomyelitis but the lesion did not show any regression. Since the microbiological analysis of fine needle aspiration fluid demonstrated acid-fast bacilli in direct microscopy and Mycobacterium tuberculosis was isolated from the culture, anti-tuberculous therapy consisting of isoniazid (INH), rifampicin (RIF), pyrazinamide (PZA), and ethambutol (ETM) was started. Sputum and urine cultures of the patient yielded negative results in terms of tuberculosis. After the first month of the therapy, her skin lesion was completely healed. Since the strain was found to be resistant to isoniazid, the maintenance therapy has been applied as INH + RIF + PZA for nine months. The history of the patient indicated that one of her relatives had skin tuberculosis on the face. As a result the patient has been successfully treated with anti-tuberculosis combination therapy together with surgical debridement.

Antituberculotic drug resistance in a Turkish state hospital with national data.

Antituberculosis drug resistance is a major factor threatening the success of tuberculosis control programmes. The aim of this study was to reveal the patterns of antituberculosis drug resistance in a secondary hospital in Turkey and to compare with national data. The results of BACTEC MGIT 960 system for susceptibility testing were retrospectively analysed on 76 clinical Mycobacterium tuberculosis complex isolates from different patients. The mean age of 48 men (63.2%) and 28 women was 37 and 39, respectively. Overall resistance rate to isoniazid was 14.5%, followed by streptomycin 9.2%, ethambutol 6.9% and rifampin 5.3%. Female sex and diabetes mellitus but not the presence of cavitary lesion or radiological involvement was a risk factor for the development of drug resistance. Anemia, leukocytosis or thrombocytosis was not associated with the drug resistance. In conclusions, further studies should be conducted regularly to monitor drug resistance in Turkey in order to manage effectively national tuberculosis control efforts.

[Resistance rates to antituberculous drugs in Sivas province]. / Sivas ilinde antitüberküloz ilaçlara direnç oranlari.

Infections caused by drug-resistant Mycobacterium tuberculosis strains represent a serious public health problem in recent years. The aim of this retrospective study was to investigate the resistance rates of M. tuberculosis complex strains isolated from clinical specimens in the laboratories of Cumhuriyet University and Numune State Hospitals in Sivas province (located in the middle Anatolia), between May 2004-May 2006 period, to the major antituberculous drugs. A total of 158 M. tuberculosis complex strains which were isolated from sputum, bronchial lavage fluid, stomach fluid, urine, pus, peritoneal fluid and cerebrospinal fluid samples, each of which from different patients were included to the study. The identification of the isolates and antituberculosis drug susceptibility testing were performed by MGIT (Mycobacteria Growth Indicator Tube) 960 system in both of the laboratories. Of 158 isolates 42 (26.6%) were found resistant to at least one of the drugs, while 116 (73.4%) were susceptible to all of the tested antimycobacterials. The overall resistance rates were found as 17.7% (28/153) for isoniazid, 11.4% (18/153) for streptomycin, 4.4% (7/153) for rifampicin, and 5.1% (8/153) for ethambutol. The rate of multidrug resistant isolates characterized with resistance to isoniazid+rifampicin were 3.8% (6/158). As a result, the most common resistance patterns observed in our region were found as single isoniazid resistance (13/158; 8.2%), single streptomycin resistance (8/158; 5.1%) and combined isoniazid+streptomycin resistance (8/158; 5.1%), respectively, with lower resistance rate to rifampicin (4.4%) in comparison to the previous results reported from Turkey.