One-Year Post-Vaccination Longitudinal Follow-Up of Quantitative SARS-CoV-2 Anti-Spike Total Antibodies in Health Care Professionals and Evaluation of Correlation with Surrogate Neutralization Test.

Numerous vaccines have been generated to decrease the morbidity and mortality of COVID-19. This study aims to evaluate the immunogenicity of the heterologous boosts by BioNTech against homologous boosts by CoronaVac at three-month intervals in two health care worker (HCW) cohorts, with or without prior COVID-19, for one year post-vaccination. This is a prospective cohort study in which the humoral responses of 386 HCWs were followed-up longitudinally in six main groups according to their previous COVID-19 exposure and vaccination status. Anti-SARS-CoV-2 spike-RBD total antibody levels were measured and SARS-CoV-2 neutralization antibody (NAbs) responses against the ancestral Wuhan and the Omicron variant were evaluated comparatively using international standard serum for Wuhan and Omicron, as well as with the aid of a conversion tool. The anti-SARS-CoV-2 spike-RBD total Ab and Nab difference between with and without prior COVID-19, three months after two-dose primary vaccination with CoronaVac, was statistically significant (p = 0.001). In the subsequent follow-ups, this difference was not observed between the groups. Those previously infected (PI) and non-previously infected (NPI) groups receiving BioNTech as the third dose had higher anti-SARS-CoV-2 spike total Ab levels (14.2-fold and 17.4-fold, respectively, p = 0.001) and Nab responses (against Wuhan and Omicron) than those receiving CoronaVac. Ab responses after booster vaccination decreased significantly in all groups at the ninth-month follow-up (p < 0.05); however, Abs were still higher in all booster received groups than that in the primary vaccination. Abs were above the protective level at the twelfth-month measurement in the entire of the second BioNTech received group as the fourth dose of vaccination. In the one-year follow-up period, the increased incidence of COVID-19 in the groups vaccinated with two or three doses of CoronaVac compared with the groups vaccinated with BioNTech as a booster suggested that continuing the heterologous CoronaVac/BioNTech vaccination, revised according to current SARS-CoV-2 variants and with at least a six-month interval booster would be an effective and safe strategy for protection against COVID-19, particularly in health care workers.

Quantitation of antibodies against SARS-CoV-2 spike protein after two doses of CoronaVac in healthcare workers.

Quantitation of antibodies to the spike protein of severe acute respiratory syndrome coronavirus 2  (SARS-CoV-2) was performed for the detection of adaptive immune response in healthcare workers (HCWs) vaccinated with CorovaVac. We prospectively recruited HCWs from a university hospital in Turkey. Serum samples from 1072 HCWs were obtained following 28 days of the first, and 21 days of the second dose. Detection and quantitation of SARS-CoV-2 antispike antibodies were performed by the chemiluminescent microparticle immunoassay (SARS-CoV-2 IgG II Quant; Abbott). Results greater than or equal to the cutoff value 50.0 AU/ml were reported as positive. After the first dose, antispike antibodies were detected in 834 of 1072 (77.8%) HCWs. Seropositivity was higher among females (84.6%) than males (70.6%) (p < 0.001) and was found to be highest in both women and men between the ages of 18-34. After the second dose, antibodies were detected in 1008 of 1012 (99.6%) HCWs. Antibody titers were significantly higher in those who had coronavirus disease-2019 before vaccination than those who did not (p < 0.001). Antibody positivity and median antibody titers were significantly less in HCWs with chronic diseases compared to those without (p < 0.05 and p < 0.001, respectively). In conclusion, our findings indicated that a relatively high frequency (99.6%) of humoral immunity was produced in HCWs aged 18-59 after two doses of CoronaVac. Quantitation of antibodies may help facilitate longitudinal monitoring of the antibody response, which will be especially useful in deciding the dose of the vaccine in vulnerable groups such as those over 60 years of age and those with chronic diseases.

Determination of genotypic varieties and genotyping of multiple drug-resistant tuberculosis by the RFLP and spoligotyping methods.

BACKGROUND/AIM: The purpose of the present study was to determine the distribution and epidemiological features of mycobacteria with molecular methods. MATERIALS AND METHODS: Fifty-five culture-positive samples were analyzed by polymerase chain reaction-restriction enzyme length polymorphism (PCR-RFLP) at species level, and their molecular typing was performed with spoligotyping. The IS6110 region and the locus of gene coding for Hsp65 were amplified. RFLP profiles were obtained by cutting the Hsp65 region with the Hae III and BstE II (Eco91I) enzymes. Spoligotyping was carried out by commercial kit. The H37Rv strain was used as the control. RESULTS: All samples showed the same cutting pattern with the H37Rv strain. The RFLP profiles of 9 strains identified as "mycobacteria other than tuberculosis" were compatible with the M. tuberculosis complex. Spoligotyping of 55 isolates detected 13 different genetic profiles. The Beijing genotype was not detected. One isolate was described as an orphan strain according to the SpolDB4 database. The most frequently detected family was T1 with 32 strains (64%), followed by 9 isolates (18%) belonging to the LAM7 TUR family. CONCLUSION: PCR-RFLP is a specific, rapid, and effective method in routine diagnosis of mycobacteria. Spoligotyping is an ideal method in the determination of genotypic varieties of mycobacteria.

Prevalence and genotype distribution of human papillomavirus in non-neoplastic cervical tissue lesion: cervical erosion.

Human papillomavirus (HPV) infection is the commonest sexually transmitted infection, which is associated with various clinical conditions, ranging from asymptomatic infection to malignant disease of the cervix. The aim of this study was to evaluate the prevalence and genotypic distribution of HPV in women with cervical erosion and to compare the results with those in women with a clinically normal cervix. A further aim was to establish the association between HPV infection and cervical cytology results in women with and without cervical erosion. Cervical samples were collected by liquid-based method and consecutively evaluated for the presence of HPV DNA and for cervical cytology. HPV DNA was tested by a nested polymerase chain reaction (PCR) and typed by reverse dot blot genotyping. Cytological classification was made according to Bethesda 2001 criteria. The overall HPV prevalence was 16.9%; HPV DNA was positive in 20.2% of women with cervical erosion and 12.8% in women with normal cervix (P < 0.05). Multiple infections were found in 34.1% of the HPV-positive women. Commonest types were HPV 18 (32.9%), HPV 16 (29.5%), HPV 54 (20.5%), and HPV 6 (17%). Cervical cytology results were abnormal for 5.2% of women with cervical erosion and for 1.3% with clinically normal cervix (P < 0.05). This study detected a high prevalence of HPV infection in women with cervical erosion compared to women with a normal cervix. This data may contribute to the HPV epidemiology in the southeastern Turkey. It is recommended that women with cervical erosion should be given priority in HPV screening programs.

Determination of antimicrobial susceptibility patterns and inducible clindamycin resistance in Staphylococcus aureus strains recovered from southeastern Turkey.

BACKGROUND: In this study, we determined the susceptibility patterns of Staphylococcus aureus strains to various antimicrobials and prevalence of inducible clindamycin resistance (ICR) in these isolates. METHODS: Two hundred and one S aureus strains, isolated from various clinical samples, were included in the study. Antibiotic susceptibilities were studied by disc diffusion method on the basis of the guidelines by the Clinical and Laboratory Standards Institute. The disc diffusion induction test (D test) was applied to determine ICR resistance among erythromycin-resistant S aureus isolates. RESULTS: Of the 201 S aureus strains, 101 (50.2%) were resistant to methicillin. All strains were susceptible to vancomycin, teicoplanin, quinupristin/dalfopristin, and linezolid. It was found that 54 (53.4%) methicillin-resistant S aureus (MRSA) strains were erythromycin resistant, and 40 (39.6%) of them showed constitutive clindamycin resistance. ICR was detected in seven (6.9%) MRSA strains. It was found that 13 (13.0%) methicillin-susceptible S aureus (MSSA) strains were erythromycin resistant. Constitutive clindamycin resistance was seen in one (1.0%) MSSA strain, and ICR was detected in 10 (10.0%) cases. CONCLUSION: There was a high rate of methicillin resistance among S aureus strains in our hospital. However, no statistically significant difference of ICR was observed between MRSA and MSSA strains (p=0.434) or between inpatients and outpatients (p=0.804). It was concluded that ICR should be routinely evaluated in each S aureus case to avoid therapy failure among patients.

Demonstration of Chlamydophila pneumoniae, Mycoplasma pneumoniae, Cytomegalovirus, and Epstein-Barr virus in atherosclerotic coronary arteries, nonrheumatic calcific aortic and rheumatic stenotic mitral valves by polymerase chain reaction.

OBJECTIVE: The aim of this study was to investigate whether bacterial and viral infectious agents can be demonstrated in atherosclerotic lesions of patients with coronary artery disease (CAD) as well as in stenotic aortic and mitral valves from patients undergoing heart valve replacement. METHODS: In this cross-sectional study, the presence of Chlamydophila pneumoniae, Mycoplasma pneumoniae, Cytomegalovirus (CMV), and Epstein-Barr virus (EBV) was investigated by polymerase chain reaction in atherosclerotic and non-atherosclerotic vascular samples taken from patients undergoing coronary artery bypass surgery due to CAD, and from patients undergoing aortic (AVR) and/or mitral valve replacement (MVR) secondary to valvular stenosis. For statistical analyses ANOVA, Chi-square test or Fisher's exact test were used. RESULTS: The presence of C. pneumoniae, M. pneumoniae, and CMV in atherosclerotic versus non-atherosclerotic samples was as follows: 30% vs. 16.7% (p=0.222), 6.7% vs. 3.3% (p=0.554), and 10% vs. 0% (p=0.076), respectively. In valve group, same pathogens were present in AVR and MVR patients as follows: 24.2% vs. 21.4% (p=0.773), 9.1% vs. 7.1% (p=0.758), and 21.2% vs. 11.9% (p=0.275). EBV DNA was not detected in any of vascular specimens, but in one (3%) patient with AVR (p=0.256). CONCLUSION: Our results suggest that C. pneumoniae, M. pneumoniae, and CMV are present with similar frequency both in atherosclerotic and non-atherosclerotic vessels. We conclude that although non-atherosclerotic, vascular samples of CAD patients are invaded by infectious agents as like as atherosclerotic vessels. We further conclude that C. pneumoniae, M. pneumoniae, and CMV are present in stenotic aortic and mitral valves and atherosclerotic tissues with similar frequency indicating that atherosclerosis and valvular stenosis might share a common etiology related to infection.

The prevalence of Chlamydia trachomatis and Neisseria gonorrhoeae in the endocervical swab specimens of symptomatic, asymptomatic and infertile women in Turkey.

PURPOSE: To investigate C. trachomatis and N. gonorrhoeae prevalence in three different female populations in Turkey. METHODS: A total of 370 women, 170 symptomatic, 100 asymptomatic, and 100 infertile, were included. Of the endocervical specimens collected from all women using a Dacron swab, the first one was taken to Stuart's transport medium to culture, while the second one was transferred onto slides to perform direct fluorescent antibody test (DFA) and Gram staining, and the third specimen was used for Becton Dickinson BDProbeTec ET system (BDPT). RESULTS: C. trachomatis was detected in 5.16% of symptomatic, 1.11% of asymptomatic, and 2.15% of infertile women with BDPT. Sensitivity and specificity of the DFA test were 72.73 and 97.85%, respectively. N. gonorrhoeae was detected in 2.42% of symptomatic and in 1.02% of infertile women. N. gonorrhoeae was not detected in any asymptomatic women. In N. gonorrhoeae-positive patients, sensitivity and specificity of culture were 60 and 100%, respectively, while they were 80 and 100% for BDPT. CONCLUSIONS: Prevalence of N. gonorrhoeae and C. trachomatis was detected to be low in Turkish women, and the difference between the groups was not significant. Both agents were more prevalent in subjects over 25 years of age.

[Comparison of disc diffusion, E-test, and broth microdilution methods for the determination of resistance to colistin, polymyxin B, and tigecycline in multi-resistant Acinetobacter baumannii isolates]. / Cogul dirençli Acinetobacter baumannii izolatlarinda kolistin, polimiksin B ve tigesiklin direncinin saptanmasinda disk difüzyon, E-test ve buyyon mikrodilüsyon yöntemlerinin karslastirilmasi.

The increased rate of antimicrobial resistance in Acinetobacter baumannii made it necessary to reconsider old antibiotics such as polymyxins and develop new drugs such as tigecycline. The aim of this study was to investigate the susceptibility rates of multi-drug resistant A. baumannii clinical isolates to colistin, polymyxin B, and tigecycline by three different methods in microbiology laboratory of Gaziantep University Research Hospital, between September 2006 and April 2008. A total of 200 A. boumannii strains isolated from various clinical samples (tracheal aspirate, blood, sputum, surgical wound, catheter, pleural fluid, urine, and others) were included to the study. Identification of bacteria was performed by conventional microbiological methods and by an automatized identification system (Vitek 2, bioMerieux, France). Antimicrobial susceptibility pattern of A. baumannii isolates was determined by disc diffusion method and 95 multiple resistant A. baumannii isolates were identified. Susceptibilities of these multiple resistant bacteria to colistin, polymyxin B, and tigecycline were tested with disc diffusion, E-test, and broth microdilution methods. All of the isolates (100%) were sensitive to colistin with all three methods. Ninety-two (96.8%) of them were sensitive to polymyxin B with both disc diffusion and broth microdilution methods, and 90 (94.7%) of them were sensitive to polymyxin B with E-test. Eighty-three (87.4%) of them were sensitive to tigecycline by disc diffusion method, 78 (82.1%) by E-test, and 90 (94.7%) by broth microdilution method. No statistically significant difference was detected for the three methods in terms of susceptibility testing for polymyxin B (p > 0.05). However, while no significant difference wa detected for tigecycline susceptibility testing by disk diffusion and broth microdilution (p > 0.05), statistically significant difference was determined for broth microdilution and E-test methods (p = 0.000). In conclusion, comparison of disc diffusion, E-test, and broth microdilution methods yielded that all three methods were concordant to each other in terms of susceptibility testing of polymyxins. Susceptibility rate to tigecycline was found lower by E-test method than that obtained by other methods. These results emphasized that antimicrobial activities of colistin, polymyxin B and tigecycline against A. baumannii isolates obtained in our hospital were high, however, for tigecycline susceptibility testing against A. boumannii, disk diffusion or broth microdilution methods would rather be preferred.

Prevalence of human cytomegalovirus co-infection in patients with chronic viral hepatitis B and C: a comparison of clinical and histological aspects.

BACKGROUND: Human cytomegalovirus (HCMV) is a common pathogen of severe disease in patients with impaired immune functions. Reactivation of HCMV in immunocompetent host is usually asymptomatic, but may deteriorate the prognosis of patient with chronic illness. OBJECTIVES: This study was conducted to detect HCMV infection in patients with chronic hepatitis B virus (HBV) and chronic hepatitis C virus (HCV) infections and to point out the effects of HCMV-HBV and HCMV-HCV co-infections on liver histology. STUDY DESIGN: Expression of HCMV DNA was determined in liver tissue biopsies by real-time quantitative polymerase chain reaction (qPCR) method. There were 44 chronic HBV, and 25 chronic HCV patients within the study group. Control group consisted of 36 patients with hepatologic malignancies. RESULTS: HCMV infection was demonstrated in 52.3% of chronic HBV, and 36% of chronic HCV patients. Although alanine aminotransferase (ALT) levels of HCMV-infected HBV patients were decreased slightly, they were increased in HCV patients. Histologic activity scores (necroinflammation and fibrosis) of HCMV-positive patients were higher than that of HCMV-negatives in both HBV and HCV groups. Intrahepatic HBV DNA or HCV RNA loads of the corresponding study groups were decreased in HCMV-infected patients. CONCLUSION: We conclude that HCMV infection is common in chronic HBV and HCV patients, who can be regarded as patients at high risk for HCMV disease. Though the histological changes were more marked in liver, replication of HBV and HCV were inhibited in HCMV-positive cases.

Prevalence of hepatitis B and C viruses in patients with lymphoproliferative disorders.

The etiology of most lymphoproliferative disorders remains unclear, though several hypotheses have been proposed. One of the conjectured mechanisms is infection of a tumor clone by an oncologic virus. Recently, evidence has arisen implicating both hepatitis B and, even more so, hepatitis C viruses in the pathogenesis of lymphoproliferative disease. Based on this information, we surveyed the prevalence of hepatitis B and C virus in patients with lymphoproliferative disease. A total of 334 newly-diagnosed lymphoproliferative disease patients (200 males, 134 females) and 1,014 (133 females, 881 males) healthy controls were randomly recruited from the university blood bank. Serologic evaluation for hepatitis B and C viruses was conducted and confirmed using PCR analyses. Those with hepatitis B and/or C, controls, and subgroups of patients with lymphoproliferative disease were compared using Pearson Chi-square analysis. Among patients with lymphoid tumors, the seropositivity of HbsAg and/or anti-HCV was 8.7% (29/334), and among the controls 6.1% (49/802), however this difference did not achieve statistical significance (P = 0.23, OR: 1.36, 95% CI: 0.82-2.26). We found no significant gender- or age-related differences for either hepatitis B or C seropositivity. There were no significant differences between the seropositivity rates of hepatitis B, C, or both in either NHL or Hodgkin's lymphoma. However, in the diffuse large cell lymphoma and follicular lymphoma subgroups, the HbsAg seropositivity rate was significantly higher than that in the controls (P = 0.017, P = 0.048, respectively), as was the seropositivity rate for hepatitis C in those with diffuse B cell lymphoma versus controls (P = 0.008). We did not identify any significant difference in the combined prevalence of hepatitis B or C seropositivity between patients with lymphoproliferative disorders and controls. However, significant differences were revealed among certain patient subgroups versus the controls. These two viruses could play a role in the development of certain specific lymphoproliferative disorders. Nevertheless, larger epidemiological studies are necessary and should focus, particularly on specific patient subgroups.

Real-time polymerase chain reaction assay for detection of Streptococcus pneumoniae in sputum samples from patients with community-acquired pneumonia.

BACKGROUND AND PURPOSE: A quantitative real-time polymerase chain reaction (PCR) method targeting the pneumolysin gene of Streptococcus pneumoniae in sputum specimens from patients with community-acquired pneumonia (CAP) was evaluated for the identification of pneumococci. METHODS: The applicability of the assay to clinical samples was evaluated by studying 140 sputum specimens from patients with CAP. Of the specimens, 96 (68.6%) were found to be positive by real-time PCR. The results were compared to culture findings. RESULTS: The sensitivity and specificity of the real-time PCR assay developed in this study as compared to those of the culture method were 97.2% and 60.9%, respectively. CONCLUSION: Real-time PCR assay was found to be a rapid and sensitive method for the detection of pneumococci.

Tuberculosis verrucosa cutis in a patient with long-standing generalized lichen planus: improvement of lichen after antitubercular polychemotherapy.

Tuberculosis verrucosa cutis (TBVC) is a rare form of skin tuberculosis in Western communities, and is generally seen in certain risk groups. A 52-year-old housewife with recalcitrant generalized cutaneous and mucosal lichen planus (LP) of more than a 20-year duration presented with an erythematous-edematous plaque with a warty surface containing deep hemorrhagic fissures and numerous orifices draining purulent material on the back of her left hand. On the basis of clinical, histological and bacteriological findings, TBVC was diagnosed. The patient was successfully treated with isoniazid, rifampicin, ethambutol and pyrazinamide. Interestingly, all lichen lesions improved completely with this therapy. To the best of our knowledge, this is the first documented case of TBVC associated with LP, which was cured by antitubercular polychemotherapy. The case is presented because it reflects a possible reciprocal causal relationship between two cutaneous conditions of different natures.

Patterns of antimicrobial resistance in a surgical intensive care unit of a university hospital in Turkey.

BACKGROUND: Several studies have reported higher rates of antimicrobial resistance among isolates from intensive care units than among isolates from general patient-care areas. The aims of this study were to review the pathogens associated with nosocomial infections in a surgical intensive care unit of a university hospital in Turkey and to summarize rates of antimicrobial resistance in the most common pathogens. The survey was conducted over a period of twelve months in a tertiary-care teaching hospital located in the south-eastern part of Turkey, Gaziantep. A total of 871 clinical specimens from 615 adult patients were collected. From 871 clinical specimens 771 bacterial and fungal isolates were identified. RESULTS: Most commonly isolated microorganisms were: Pseudomonas aeruginosa (20.3%), Candida species (15%) and Staphylococcus aureus (12.9%). Among the Gram-negative microorganisms P. aeruginosa were mostly resistant to third-generation cephalosporins (71.3-98.1%), while Acinetobacter baumannii were resistant in all cases to piperacillin, ceftazidime and ceftriaxone. Isolates of S. aureus were mostly resistant to penicillin, ampicillin, and methicillin (82-95%), whereas coagulase-negative staphylococci were 98.6% resistant to methicillin and in all cases resistant to ampicillin and tetracycline. CONCLUSION: In order to reduce the emergence and spread of antimicrobial-resistant pathogens in ICUs, monitoring and optimization of antimicrobial use in hospitals are strictly recommended. Therefore local resistance surveillance programs are of most value in developing appropriate therapeutic guidelines for specific infections and patient types.

A rare cause of anemia and thrombocytopenia in a newborn: congenital malaria.

A newborn with fever and jaundice was referred to our hospital with anemia and thrombocytopenia of unknown origin. The patient's mother suffered from malaria infection during the third trimester of her pregnancy, but she did not accept medical therapy. On physical examination the newborn showed mild splenomegaly and jaundice. Laboratory tests revealed marked anemia with a hemoglobin value of 7.7 g/L and thrombocytopenia with platelet numbers of 17,000/mm3. Plasmodium vivax was detected in blood smear. Oral therapy with chloroquine and primaquine was started. This patient is the second case of congenital malaria reported from Turkey, and shows that the diagnosis of congenital malaria should be considered in infants with suspected congenital infection who are born to mothers with a history of malarial disease. We emphasize the importance of adequate antenatal medical therapy during pregnancy.

Automatized PCR evaluation of Mycobacterium tuberculosis complex in respiratory and nonrespiratory specimens.

In this study, Mycobacterium tuberculosis complex isolates recovered from respiratory and nonrespiratory specimens with culture were evaluated using an automatized PCR method. Specimens with suspected tuberculous disease were decontaminated and concentrated using the standard N-acetyl-L-cysteine NaOH method and were inoculated onto glycerol-supplemented Löwenstein-Jensen media and BACTEC B12 vials. Forty-one specimens with typical colonies on solid media and 127 specimens identified as M. tuberculosis complex in a BACTEC system were selected as the study group. As the control group, 46 specimens without growth on either culture media were selected. The PCR results were positive in 33 (80.5%) and 87 (68.5%) samples that were culture-positive on solid and liquid media, respectively. All (100%) culture-negative specimens within the control group were also negative in the COBAS AMPLICOR Mycobacterium tuberculosis (MTB) PCR method. In conclusion, although it is a fast method for identifying M. tuberculosis complex isolates from clinical specimens, the COBAS AMPLICOR MTB PCR method is found to be less sensitive than culture techniques, we propose therefore that it should only be used in combination with culture results in the clinical diagnosis of tuberculosis.

Evaluation of negative results of BacT/Alert 3D automated blood culture system.

Although automated continuous-monitoring blood culture systems are both rapid and sensitive, false-positive and false-negative results still occur. The objective of this study, then, was to evaluate negative results occurring with BacT/Alert 3D blood culture systems. A total of 1032 samples were cultured with the BacT/Alert 3D automated blood culture system, using both aerobic (FA) and anaerobic (FN) [corrected] media, and 128 of these samples yielded positive results. A total of 904 negative blood samples were then subcultured in 5% sheep blood agar, eosin methylene blue, chocolate agar, and sabouraud-dextrose agar. Organisms growing on these subcultures were subsequently identified using both Vitek32 (bioMerieux, Durham, NC) and conventional methods. Twenty four (2.6%) of the 904 subcultures grew on the subculture media. The majority (83.3%) of these were determined to be gram-positive microorganisms. Fourteen (58.3%) were coagulase-negative staphylococci, two (8.3%) were Bacillus spp., one (4.2%) was Staphylococcus aureus, and one (4.2%) was identified as Enterococcus faecium. Streptococcus pneumoniae and Neisseria spp. were isolated together in two (8.3%) vials. Gram-negative microorganisms comprised 12.5% of the subcultures, of which two (8.3%) were found to be Pseudomonas aeruginosa, and one (4.2%) was Pseudomonas fluorescens. The other isolate (4.2%) was identified as Candida albicans. We conclude that the subculture of negative results is valuable in the BacT/Alert 3D system, especially in situations in which only one set of blood cultures is taken.

Synergy tests by E test and checkerboard methods of antimicrobial combinations against Brucella melitensis.

Two different synergy testing methods, the checkerboard and the E test methods, were used to compare the in vitro efficacies of various antimicrobial combinations against 16 Brucella melitensis strains isolated from blood cultures. The rate of agreement of the E test and checkerboard methods was found to be 55%. The most concordant results were found for the streptomycin-doxycycline combination in 12 (75%) tests, in which four strains showed synergistic activity by E test and antagonistic activity by the checkerboard method and in which one strain showed antagonistic activity by both methods. Even though each of these methods uses different conditions and endpoints, the results of both methods frequently agreed.