An evaluation of a Stenotrophomonas maltophilia outbreak due to commercial arterial blood gas collection kit.

BACKGROUND: Stenotrophomonas maltophilia is a gram-negative bacterium that can cause hospital infections and outbreaks within hospitals. This study aimed to evaluate an outbreak of Stenotrophomonas maltophilia, caused by ready-to-use commercial syringes containing liquid lithium and heparin for arterial blood gas collection in a university hospital. METHODS: Upon detecting an increase in Stenotrophomonas maltophilia growth in blood cultures between 15.09.2021 and 19.11.2021, an outbreak analysis and a case-control study (52 patients for the case group, 56 patients for the control group) were performed considering risk factors for bacteremia. Samples from possible foci for bacteremia were also cultured. Growing bacteria were identified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. The genetic linkage and clonal relationship isolates were investigated with pulsed-field gel electrophoresis (PFGE) in the reference laboratory. RESULTS: In the case-control study, the odds ratio for the central venous catheter [3.38 (95% confidence interval [CI]: 1.444, 8.705 ; p = 0.006)], for surgery [3.387 (95% confidence interval [CI]: 1.370, 8.373 ; p = 0.008)] and for arterial blood gas collection history [18.584 (95% confidence interval [CI]:4.086, 84.197; p < 0.001)] were identified as significant risk factors. Stenotrophomonas maltophilia growth was found in ready-to-use commercial syringes used for arterial blood gas collection. Molecular analysis showed that the growths in the samples taken from commercial syringes and the growths from blood cultures were the same. It was decided that the epidemic occurred because the method for sterilization of heparinized liquid preparations were not suitable. After discontinuing the use of the kits with this lot number, the outbreak was brought under control. CONCLUSIONS: According to our results, disposable or sterile medical equipment should be included as a risk factor in outbreak analyses. The method by which injectors containing liquids, such as heparin, are sterilized should be reviewed. Our study also revealed the importance of the cooperation of the infection control team with the microbiology laboratory.

Multidrug resistance in pathogens of community-acquired urinary tract infections in Turkey: a multicentre prospective observational study

BACKGROUND: To have country-wide information about multidrug resistance (MDR) in isolates from community-acquired urinary tract infections (CAUTI) of Turkey, in terms of resistance rates and useful options. METHODS: We used a geocode standard, nomenclature of territorial units for statistics (NUTS), and a total of 1588 community-acquired isolates of 20 centres from 12 different NUTS regions between March 2019 and March 2020 were analysed. RESULTS: Of the 1588 culture growths, 1269 (79. 9%) were Escherichia coli and 152 (9.6%) were Klebsiella spp. Male sex, advancedage, and having two or more risk factors showed a statistically significant relation with MDR existence (p < 0.001, p: 0.014, p < 0.001, respectively) that increasing number of risk factors or degree of advancing in age directly affects the number of antibiotic groups detected to have resistance by pathogens. In total, MDR isolates corresponded to 36.1% of our CAUTI samples; MDR existence was 35.7% in E. coli isolates and 57.2% in Klebsiella spp. isolates. Our results did not show an association between resistance or MDR occurrence rates and NUTS regions. DISCUSSION: The necessity of urine culture in outpatient clinics should be taken into consideration, at least after evaluating risk factorsfor antibacterial resistance individually. Community-acquired UTIs should be followed up time- and region-dependently. Antibiotic stewardship programmes should be more widely and effectively administrated.

Carbapenem resistance and biofilm formation status of Enterobacterales isolated from raw milk via molecular versus phenotypic methods.

Antibiotic resistance genes can easily be transferred between bacteria in the biofilm. In the dairy industry, many bacterial species forming biofilms on the surfaces of equipment are widely reported. The experiments reported in this research paper aimed to investigate the carbapenem resistance and biofilm formation properties of Enterobacterales isolates which are spoilage microorganisms obtained from raw milk. In addition, the study determined that whether there was a relationship between the biofilm formation ability or the protein spectra of these isolates. In this study, ninety-two Enterobacterales isolates collected from 173 raw milk samples were investigated. Initially, the isolates were identified as Citrobacter braakii (n = 18), Citrobacter freundii (n = 12), Enterobacter asburiae (n = 1), Enterobacter cloacae (n = 3), Escherichia coli (n = 10), Hafnia alvei (n = 18), Klebsiella oxytoca (n = 1), Serratia fonticola (n = 24), Serratia liquefaciens (n = 4), and Serratia marcescens (n = 1) using MALDI-TOF MS. As a result, carbapenem resistance was determined in 6.5% of the isolates by CIM test, MHT, and the disk diffusion methods, but none of them had blaOXA-48, blaKPC, blaNDM-1, blaOXA23, blaOXA-58, blaOXA-51, blaVIM, and blaIMP genes. This may be due to the effect of other resistance mechanisms such as porin loss or increased flow pump activity. Furthermore, biofilm formation (weak and moderate) was detected in 97.8% of the Enterobacterales isolates. The mass spectra of the moderate biofilm producer isolate of Serratia spp. and the mass spectra of the weak biofilm producers of E.coli presented similarities.

An outbreak of Ralstonia insidiosa bloodstream infections caused by contaminated heparinized syringes.

INTRODUCTION: Ralstonia insidiosa, a gram-negative waterborne bacteria able to survive and grow in any type of water source, can cause nosocomial infections, and are considered emerging pathogens of infectious diseases in hospital settings. In this study, we report an outbreak of R. insidiosa at our center related to contaminated heparinized syringes. MATERIAL AND METHODS: The present study was conducted in a tertiary care university hospital in Turkey. An outbreak analysis was performed between September 2021 and December 2021. Microbiological samples were obtained from environmental sources and from patient blood cultures. Species identification was performed using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). To investigate the clonality of strains, all confirmed isolates were sent to the National Reference Laboratory and pulsed-field gel electrophoresis (PFGE) was used to perform molecular typing. RESULTS: Seventeen R. insidiosa isolates were identified from the blood cultures of 13 patients from various wards and intensive care units. Isolates from seven patient blood cultures and two heparinized blood gas syringes were characterized by PFGE. All isolates were found to belong to the same clone of R. insidiosa. CONCLUSION: R. insidiosa was identified as the cause of a nosocomial infection outbreak in our hospital, which was then rapidly controlled by the infection-control team. When rare waterborne microorganisms grow in blood or other body fluid cultures, clinicians and the infection-control team should be made aware of a possible outbreak.

Lactobacillus rhamnosus Sepsis Associated with Probiotic Therapy in a Term Infant with Congenital Heart Disease.

BACKGROUND: Congenital heart diseases (CHD) are the most common birth defects. Necrotizing enterocolitis (NEC) is an important cause of morbidity and mortality in premature infants, and probiotics can be used to protect NEC. CASE REPORT: We present a term infant with aortic coarctation who developed sepsis with Lactobacillus rhamnosus GG after probiotic use, successfully treated with ampicillin. The baby unfortunately died of acute cardiac arrest on the 90th day of life. CONCLUSION: Probiotic-associated sepsis may develop in infants with various risk factors such as central catheterization, long-term mechanical ventilation and in those at risk for NEC.

[The Epidemiology of Carbapenemases in Escherichia coli and Klebsiella pneumoniae Isolated in 2019 in Turkey]. / Türkiye'de 2019 Yili Içinde Izole Edilen Escherichia coli ve Klebsiella pneumoniae Izolatlarinda Karbapenemaz Epidemiyolojisi.

Antibiotic resistance is one of the most important public health problem and one of the most critical steps in preventing resistance is the monitorization of the resistance. Local, regional and global monitoring enables the spread of antibiotic resistance to be understood more clearly. In this study, it was aimed to evaluate the results of the pilot study for the establishment of molecular-based carbapenem surveillance system in Escherichia coli and Klebsiella pneumoniae isolates and to investigate the carbapenemase epidemiology in Turkey. Hospitals (n= 28) from 26 different statistical level II regions from Turkey were included in the study. The hospitals participated in the study submitted ten carbapenem susceptible and ten carbapenem resistant E.coli and K.pneumoniae isolates to our laboratory that were isolated in two different periiods of six-month either between 1 March-31 August or 1 April-30 September 2019. A total of 509 isolates were collected from 26 of the 28 participating hospitals in the study. Isolates were identified by matrix assisted laser desorptionization-time of flight mass spectrophotometry (MALDI TOF MS) (Bruker Daltonics, Germany) method and antibiotic susceptibility tests for imipenem, meropenem and colistin were studied by broth microdilution. Moreover, susceptibilities to amikacin, amoxicillin-clavulanic acid, ampicillin, aztreonam, cefepime, cefotaxime, ceftazidime, ciprofloxacin, ertapenem, gentamicin, piperacillin-tazobactam, tobramycin and trimethoprim-sulfamethoxazole were determined by disc diffusion method. The resistance genes were investigated in isolates which were found to be phenotypically resistant to carbapenem and colistin, in house method was used to investigate carbapenemase genes and a commercial colistin resistant real-time PCR kit (Biospeedy, Turkey) was used for colistin resistance genes. In total, 493 of the 509 isolates collected from hospitals were identified as E.coli (25.7%, n= 127) and K.pneumoniae (74.3%, n= 366) and included in the study. It was determined that 31% of the isolates evaluated were from community-acquired infections and 69% were either from healthcare-associated infections or from colonization sites. Among the tested isolates, 248 (50.3%) were susceptible to carbapenems and 245 (49.7%) were resistant. The types of carbapenemases in carbapenemase-producing were OXA-48 (52.2%), KPC (16.1%), NDM-1 (15%), OXA-48 + NDM-1 (12.6%), KPC + NDM-1 (2.8%) and VIM (0.5%) and OXA-48+VIM (0.5%). Resistance to colistin was detected in 23.3% of the isolates but mcr1-8 genes were not detected. It was found that all colistin resistant isolates are resistant to at least one of the carbapenems. The importance of a molecular-based antimicrobial resistance surveillance system in our country was demonstrated with this pilot study. It is thought that continuous monitoring of these epidemiological features will contribute to the management of infections due to carbapenemase-producing organisms.

[Direct Identification of Microorganisms from Positive Blood Cultures by MALDI-TOF MS Using an in-House Tween® 80 Method: Experimental and Clinical Study]. / "In-House" Tween® 80 Yöntemi ile Pozitif Kan Kültürlerinden Mikroorganizmalarin MALDI-TOF MS Yöntemi ile Dogrudan Tanimlanmasi: Deneysel ve Klinik Çalisma.

It has been reported that direct identification from blood culture bottles with positive signals and reporting the results to the clinics earlier has positive effects on mortality and morbidity. Extraction methods especially using detergents are used for the direct identification from the bottles which give positive signal. For this purpose, in-house methods developed based on the usage of saponin are widely available in the literature. In this study, it was aimed to develop a simple, easy-to-apply and reliable protocol for identifying the agent directly from the blood culture bottle that gives positive signal with the use of detergent Tween® 80, and to study the obtained protocol in clinical samples in a routine microbiology laboratory and to evaluate the results. The study was carried out in two stages, the experimental stage where the method was developed and the clinical stage where the method was applied. In the experimental stage, blood culture bottles were created with standard strains and isolates previously diagnosed with the 16S rRNA method. 10% solution of Tween® 80 was prepared with distilled water. 1 ml sample was transferred from the bottle that gave positive signal to the microcentrifuge tube, 100 µl of 10% solution of Tween® 80 was added, vortexed for 10 seconds and then incubated for 5 minutes at room temperature. The tubes were centrifuged for 5 min at 14.000 rpm, the supernatant was discarded and the pellet was washed with 1 ml of distilled water and centrifuged at 14.000 rpm for 5 minutes in three times. Samples taken from the pellets were rubbed on the slide and dried on air. Firstly, 1 µl of 70% formic acid, then 1 µl, of matrix solution was added and it was used after drying. In the second stage of the study, the method was applied to the 502 vials giving positive signal in the Microbiology Laboratory of Ankara University Faculty of Medicine Ibni Sina Hospital between 17 April 2018-31 August 2018 and the results were compared with the subculture results. The results obtained at the end of extraction in the experimental stage were compared with the subculture results and no statistical difference was found. In 383 (82.9%) bottles among 462 (92.1%) bottles with monomicrobial positive cultures, compatible results with the subculture results were obtained. Of the microorganisms correctly identified, 350 (91.3%) were bacteria and 33 (8.7%) were fungi. On the other hand, 216 (56.4%) of the bacteria were gram positive and 134 (34.9%) of them were gram negative bacteria. At least one microorganism was correctly identified in 19 (47.5%) of 40 (7.9%) bottles with polymicrobial blood cultures. Their distribution was gram negative (n= 10) and gram positive (n= 8) and yeast (n= 1). No microorganisms were identified in six bottles with polymicrobial cultures. According to the results, we believe that this in-house method developed using Tween® 80 will be a routinely applicable method for blood culture bottles that give positive signal in microbiology laboratories and it will contribute to the early diagnosis.

In vitro activity of eravacycline in combination with colistin against carbapenem-resistant A. baumannii isolates.

The synergistic activity of eravacycline in combination with colistin on carbapenem-resistant A. baumannii (CRAB) isolates was evaluated in this study. Minimum inhibitory concentrations (MICs) of eravacycline and colistin were determined by the broth microdilution method. MICs values ranged between 1 to 4 mg and 0.5 to 256 mg l-1 for eravacycline and colistin, respectively. In vitro synergy between eravacycline and colistin was evaluated by using the chequerboard methodology. Synergistic activity was found in 10% of the strains, and additive effect in 30%. No antagonism was detected. Similar activity was also observed in colistin-resistant CRAB isolates. The result of this study indicates that eravacycline and colistin combination may be a potential therapeutic option for the treatment of CRAB related infections.

High rate of colistin and fosfomycin resistance among carbapenemase-producing Enterobacteriaceae in Turkey.

When the problem with carbapenem-resistant Enterobacteriaceae (CRE) increases, the older antimicrobial agents such as colistin and fosfomycin are used for the treatment of these infections. In this study, the broth microdilution method for colistin and the agar dilution method for fosfomycin were used for a total of 147 multidrug-resistant (MDR) or extensively drug-resistant (XDR) strains of CRE. The study included Klebsiella pneumoniae (91.16%), Escherichia coli (7.48%), Enterobacter cloacae (0.68%), and Serratia marcescens (0.68%). All these strains produce various types of carbapenemase, including OXA-48, NDM, and KPC. Some of these strains also have three different carbapenemase mechanisms, including OXA-48 (78.23%), NDM (2.04%), and KPC (0.68%) or OXA-48 and NDM (10.88%), or OXA-48 and KPC (0.68%). About 76.19% of the strains and 67.35% of the strains were resistant for colistin and fosfomycin, respectively. A total of 21 out of 35 colistin-susceptible strains were found to be susceptible to fosfomycin. This study showed that the resistance rates of colistin and fosfomycin are high. The MDR and XDR strains of CRE are spreading in our region and thus a monitoring system for CRE should be followed. Moreover, the applicability of antimicrobial stewardship programs should be increased in all inpatient and outpatient settings.

Pathogenicity determinants and antibiotic resistance profiles of enterococci from foods of animal origin in Turkey.

In this study, the presence of genes responsible for the pathogenicity and antibiotic resistance profile of enterococci isolated from various foodstuffs of animal origin was investigated. The percentage prevalence of enterococci was 54.1% (203/375) and the average count was found to be 3.81 log cfu/ml-g. Species-specific primers revealed Enterococcus faecalis as the predominant species carrying one or more virulence-associated traits of efa, gelE, ace, esp and agg genetic markers. Only one E. faecium isolate (from milk) was positive for the esp gene. Regarding antibiotic resistance, the highest frequency of resistance was observed for tetracycline (21.7%), followed by quinupristin/dalfopristin (13.3%), ciprofloxacin (2.0%), penicillin (2.0%), linezolid (1.0%), ampicillin (1.0%), streptomycin (1.0%), and gentamicin (0.5%). Enterococcus faecalis showed a higher prevalence of antibiotic resistance than other enterococci. The percentage of multidrug resistance among the isolates was 3.4%. Twenty-nine E. faecalis isolates (26.6%) carrying one of the virulence-associated traits were at the same time resistant to at least one antibiotic. Our results show that foods of animal origin, including ready-to-eat products, may be reservoirs of antibiotic-resistant and potentially virulent enterococci.

[National Antimicrobial Resistance Surveillance System (NAMRSS) external quality assessment studies: 2011-2016]. / Ulusal Antimikrobiyal Direnç Sürveyans Sistemi (UAMDSS) Dis Kalite Degerlendirme Çalismalari: 2011-2016.

Establishment of sustainable and evidence-based surveillance systems are recommended for prevention of microbial resistance by the World Health Organization (WHO). As a necessity of these surveillance systems, participants are recommended to implement an external quality assessment (EQA) program. In this scope, National Antimicrobial Resistance Surveillance System (NARSS) has been established within the Public Health Institute of Turkey (PHIT) in our country since 2011. In the scope of this surveillance, NARSS EQA program has been implemented in a cycle per year and four isolates were sent to participants per cycle every year since 2011. In this study, it was aimed to evaluate the six years results of the EQA programs being implemented on NARSS participants between 2011 and 2016. The surveillance system consisted of 118 laboratories. Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus pneumoniae, Enterococcus faecium/faecalis and Acinetobacter baumannii bacteria included in scope of the surveillance were sent to participants. Identification of bacteria to the species level, verification of the antibiotic susceptibility test results and existence of specified resistance of the isolates performed with valid test methods required from the participants. Identified isolates were cultured with routine microbiological methods and sent to participants in ambient temperature in triple carrying pouches inside suitable carrying media via PTT Cargo. The results were entered by means of passwords prepared by PHIT and sent to the web based system. The analysis of results were made with SPSS program. A total of twenty-three isolates were sent to participants between 2011 and 2016. It was determined that participants commonly preferred automated systems for bacterial identification and antibiotic sensitivity test results. The use of MALDI TOF MS system was determined to be raised up to 15.65% in 2016. It has been determined that usually little mistakes were done in bacterial identification but the error rate was high especially in antimicrobial susceptibility test results with close clinical threshold values. Although not required for antibiotic susceptibility test results, it was determined that phenotypic tests have been used more widely in determining the specific resistance mechanisms that are important for epidemiological data. It was determined that 80% of participants have used EUCAST standards in 2016. As a result of this research, we have observed that EQA studies of NARSS EQA are a good performance tool for sustainable and evidence based surveillance studies, that the national antimicrobial resistance data quality is sufficiently good and that the data can be shared on international platforms. In addition, the regular maintenance of national surveillance studies shown that laboratories have positive reflections on self improvement in achieving up to date and accurate results.

[Evaluation of antibiotic susceptibilities and VISA-VRSA rates among MRSA strains isolated from hospitalized patients in intensive care units of hospitals in seven provinces of Turkey]. / Türkiye'de Yedi Ildeki Hastanelerin Yogun Bakim Ünitelerinden Izole Edilen MRSA Suslarinda VISA-VRSA Arastirilmasi ve Antibiyotik Duyarlilik Durumlarinin Saptanmasi

The aim of this study was to determine whether vancomycin resistant Staphylococcus aureus (VRSA) and vancomycin intermediate susceptible S.aureus (VISA) strains were present among methicillin-resistant S.aureus (MRSA) strains isolated from patients hospitalised at intensive care units (ICU) of hospitals located at different regions of Turkey and to determine the minimum inhibitory concentration (MIC) values of teicoplanin, linezolid, tigecycline, quinupristin-dalfopristin and daptomycin, which are alternative drugs for the treatment of MRSA infections. A total of 260 MRSA clinical strains (isolated from 113 lower respiratory tract, 90 blood, 24 wound, 17 catheter, 13 nasal swabs, two urine and one CSF sample) were collected from nine health-care centers in eight provinces [Ankara (n= 52), Konya (n= 49), Antalya (n= 40), Istanbul (n= 7), Izmir (37), Diyarbakir (n= 15), Van (n= 12), Trabzon (n= 48)] selected as representatives of the seven different geographical regions of Turkey. Methicillin resistance was determined by cefoxitin disk diffusion in the hospitals where the strains were isolated and confirmed by oxacillin salt agar screening at the Refik Saydam National Public Health Agency. Screening for VISA and VRSA was conducted using the agar screening test and E-test. Susceptibility of the MRSA strains to other antibiotics was also determined by E-test method. None of the 260 MRSA strains were determined to be VRSA or VISA. All were susceptible to teicoplanin and linezolid, and susceptibility rates to daptomycin, tigecycline and quinupristin-dalfopristin were 99.6%, 96.9%, and 95%, respectively. Absence of VISA and VRSA among the MRSA strains surveyed currently seemed hopeful, however, continuous surveillance is necessary. In order to prevent the development of VISA and VRSA strains the use of linezolid, tigecycline, quinupristin-dalfopristin and daptomycin should be encouraged as alternative agents of treatment of MRSA infections.

[The presence of extended spectrum beta-lactamase, KPC-type carbapenemase and plasmid-mediated AmpC beta-lactamase in E.coli and K.pneumoniae strains isolated from blood cultures]. / Kan Izolati E.coli ve K.pneumoniae Suslarinda Genislemis Spektrumlu Beta-Laktamaz, KPC-Tip Karbapenemaz ve Plazmid Aracili AmpC Beta-Laktamaz Varliginin Arastirilmasi

The aim of this study was to investigate the presence of extended spectrum beta-lactamase (ESBL), KPC-type carbapenemase and plasmid-mediated AmpC beta-lactamase (pAmpC) which have increased in incidence in recent years in Escherichia coli and Klebsiella pneumoniae strains isolated from the blood samples causing serious infections. Ninety nine E.coli and 114 K.pneumoniae strains which were isolated from the blood samples of patients admitted to Hacettepe University Medical Faculty, Ihsan Dogramaci Children's Hospital between January 2001 and March 2009 were investigated. The screening tests for ESBL, pAmpC beta-lactamase and KPC-type carbapenemase were performed on the same plate. Combined disk test was performed for ESBL and modified Hodge test was done for KPC-type carbapenemase confirmation according to Clinical and Laboratory Standards Institute (CLSI) guidelines. In addition the inhibitory-based test with boronic acid for KPC-type carbapenemase, pAmpC beta-lactamase and the modified Hodge test for pAmpC beta-lactamase were performed. Boronic acid inhibition test was performed to detect the co-presence of the three types of resistance. The frequency of the beta-lactamases in E.coli and K.pneumoniae isolates were as follows respectively: ESBL 26.2% and 61.4%; pAmpC 1% and 0.9% and ESBL + pAmpC 6% and 3.5%. ESBL was masked by pAmpC in an isolate. Ertapenem resistance was shown in three isolates and KPC-type carbapenemases were detected positive by the inhibitory- based test with boronic acid but found to be negative by the modified Hodge test. The results of modified Hodge test was considered valid according to CLSI comments. Since both ESBL and pAmpC were positive but modified Hodge test was negative in these three strains, ertapenem resistance was attributed to another mechanism. For the determination of ESBL and pAmpC beta-lactamases in the routine laboratory, reliable and sensitive susceptibility tests should be performed. The inhibitory-based test with boronic acid is easy for interpretation, and a practical method for the detremination of pAmpC beta lactamases. For KPC-type carbapenemases modified Hodge test which has been standardized by CLSI, is a reliable method. The results of this study showed that ESBL positivity rates are alarming and although the frequency of pAmpC is currently low, it is increasing together with ESBL. These data indicated the need for the establishment of urgent measures to control the increase in plasmid-mediated antibiotic resistance in gram-negative enteric bacteria.

Actual antibiotic resistance pattern of Brucella melitensis in central Anatolia. An update from an endemic region.

OBJECTIVE: To test in vitro susceptibilities of Brucella melitensis (B. melitensis) blood isolates obtained from an endemic region, by broth microdilution susceptibility test. METHODS: Fifty blood isolates were tested with anti-brucella antibiotics, namely, tetracycline, gentamicin, streptomycin, ceftriaxone, ciprofloxacin, levofloxacin, ofloxacin, and rifampin. All of the clinical isolates belonged to the group of B. melitensis biotype-3. This study was performed at the Clinical Microbiology Laboratory of the Medical School of Ondokuz Mayis University, Samsun, Turkey, in 2005. RESULTS: In terms of minimum inhibitory concentration-90 (MIC90) values, tetracycline (MIC90 0.25 microgram/mL) and rifampin (MIC90 0.5 microgram/mL) still continue to be the most effective antibiotics; however, ceftriaxone and streptomycin demonstrated higher MIC values, although they were still effective in vitro against B. melitensis strains with MIC90 of 8 microgram/mL. CONCLUSION: All first line, and alternative antimicrobial agents could be used in various combinations in the treatment of human brucellosis. High MIC values of ceftriaxone and streptomycin are alarming, and should be closely monitored during the therapy.