Ömer Küçükbasmacı

Synthesis and antimicrobial activity evaluation of new 1,2,4-triazoles and 1,3,4-thiadiazoles bearing imidazo[2,1-b]thiazole moiety

A series of 4-alkyl/aryl-2,4-dihydro-5-((6-(4-bromophenyl)imidazo[2,1-b]thiazol-3-yl)methyl)-3H-1,2,4-triazole-3-thiones (3a-i) and 2-alkyl/arylamino-5-((6-(4-bromophenyl)imidazo[2,1-b]thiazol-3-yl)methyl)-1,3,4-thiadiazoles (4a-c) were synthesized starting from 6-(4-bromophenyl)imidazo[2,1-b]thiazole-3-acetic acid hydrazide. The newly synthesized compounds were characterized by IR, (1)H NMR, mass and elemental analysis. All compounds were tested for antibacterial and antifungal activities. The antimicrobial activities of the compounds were assessed by the microbroth dilution technique. The compounds were also evaluated for antituberculosis activity against Mycobacterium tuberculosis H37Rv (ATCC 27294). The preliminary results revealed that some of the compounds exhibited promising antimicrobial activities.

Higher prevalence of toxoplasmosis in victims of traffic accidents suggest increased risk of traffic accident in Toxoplasma-infected inhabitants of Istanbul and its suburbs ☆

Reflexes of drivers who have toxoplasmosis have been shown to deteriorate from the actions of the parasitic cysts. The cysts can change the level of the neurotransmitters such as dopamine in the brain and by doing so extend the muscle response time and change personality profiles. In this study, we aimed to determine the frequency of the latent toxoplasmosis (LT) in the driver population who were either injured or died in traffic accidents reported in Istanbul and its suburbs. We compared the results with a control group and discussed the relationship between the LT and the traffic accidents. We included 218 (89.7%) non-fatal, 25 (10.3%) fatal cases in our study as study groups. A total 243 subjects, 234 (96%) male, 9 (4%) female (who were alcohol negative) compared with 191 (95.5%) male and 9 (4.5%) female subjects (control group) who had a traffic accident before but no history of toxoplasmosis were studied. Serologic tests, enzyme immunoassay (EIA) for IgG and IgM, and microimmunoflorescence (MIF) for IgG were used as the reference test, the Sabin-Feldman Dye test (SFDT) was used. According to serologic test results, LT seroprevalence in the study groups was 130 (53.5%) and in the control group 56 (28%) (p<0.0001). A LT was present in 126 out of 234 (53.8%) males in the study groups, and 54 out of 191 (28.3%) males in the control group (p<0.0001). In the 31-44 year age group, there was a significant difference with regard to toxoplasmosis between the study subjects and control groups (p<0.0001). This difference was statistically very significant in (recent and former) cases with middle-aged men (31-44 years old). The results of this retrospective study suggest that LT in drivers, especially those who are between 31 and 44 years might increase the risk for getting involved in a car accident. In a prospective study, Toxoplasma positive and negative subjects can be monitored before they are involved in a traffic accident to clarify the cause and result relationship.

New 6-(4-Bromophenyl)-imidazo[2,1-b]thiazole Derivatives: Synthesis and Antimicrobial Activity

Summary. New 4-alkyl/aryl-1-((6-(4-bromophenyl)-imidazo[2,1-b]thiazol-3-yl)-acetyl)-3-thiosemicarbazides and 3-alkyl/aryl-2-(((6-(4-bromophenyl)-imidazo[2,1-b]thiazol-3-yl)-acetyl)-hydrazono)-4-thiazolidinones were synthesized from 6-(4-bromophenyl)-imidazo[2,1-b]thiazole-3-acetic acid hydrazide. Their structures were elucidated by elemental analyses and spectroscopic data. All compounds were tested for antibacterial and antifungal activities. The antimicrobial activities of the compounds were assessed by the microbroth dilution technique. The compounds were also evaluated for antituberculosis activity against Mycobacterium tuberculosis H37Rv (ATCC 27294); they exhibited varying degrees of inhibition in the in vitro primary screening at 6.25 μg · cm−3. The most active compound was 3-(4-nitrophenyl)-2-(((6-(4-bromophenyl)-imidazo[2,1-b]thiazol-3-yl)-acetyl)-hydrazono)-4-thiazolidinone.

In vitro activity of telithromycin compared with macrolides and fluoroquinolones against Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis.

The in vitro activity of telithromycin was compared with erythromycin A, azithromycin, clarithromycin, moxifloxacin, gemifloxacin, levofloxacin, ciprofloxacin, penicillin G, ampicillin, cefuroxime and ceftriaxone against 336 consecutive strains (83 Streptococcus pneumoniae, 168 Haemophilus influenzae and 85 Moraxella catarrhalis) isolated from patients with community-acquired respiratory tract infections. Telithromycin (MIC(90), 0.008 mg/l) was the most active drug against S. pneumoniae. Telithromycin was also highly active against M. catarrhalis (MIC(90), 0.06 mg/l), but less active against H. influenzae (MIC(90), 4 mg/l).

Prevalence and Antimicrobial Resistance Patterns of Extended-Spectrum β-Lactamase-Producing Escherichia coli and Klebsiella pneumoniae Isolated from Blood Cultures in an Istanbul University Hospital

Between January 2001 and September 2006, a total of 459 Escherichia coli and 226 Klebsiella pneumoniae strains were isolated from blood samples of patients with bacteremia who were hospitalized at the Istanbul University Cerrahpasa Medical Faculty. Blood cultures were analyzed with the Bactec 9120 system (Becton Dickinson, USA). Antimicrobic resistance of the E. coli or K. pneumoniae strains was determined by the disk diffusion method according to the Clinical and Laboratory Standards Institute criteria. Extended spectrum β-lactamase (ESBL) production was examined with the double-disk synergy test. The percentage of ESBL was 40% (182/459) for E. coli and 49% (111/226) for K. pneumoniae. ESBL-producing E. coli and K. pneumoniae were highly resistant to trimethoprim/sulfamethoxazole (60 and 40.5%), amoxicillin/clavulanic acid (56.5 and 48.6%), ciprofloxacin (57.6 and 35%) and gentamicin (38 and 40.5%), respectively; however, lower resistance rates were found for amikacin (19.7 and 16%) and piperacillin/tazobactam (29.6 and 24%). None of the strains were resistant to imipenem. Our data indicated that prevalence of ESBL-producing E. coli and K. pneumoniae strains isolated from blood cultures is high and antimicrobial resistance increases. Considerable effort should be made to decrease the ESBL-positive organisms.

Synthesis, characterization, and antimicrobial evaluation of some new hydrazinecarbothioamide, 1,2,4-triazole and 1,3,4-thiadiazole derivatives

In this work, we reported the synthesis and evaluation of antibacterial and antifungal activities of three new compound series obtained from 6-(phenyl/4-chlorophenyl)imidazo[2,1-b]thiazole-3-acetic acid hydrazide: 2-{[6-(phenyl/4-chlorophenyl)imidazo[2,1-b]thiazol-3-yl]acetyl}-N-alkyl/arylhydrazinecarbothioamides (2a–d), 4-alkyl/aryl-2,4-dihydro-5-{[6-(phenyl/4-chlorophenyl)imidazo[2,1-b]thiazol-3-yl]methyl}-3H-1,2,4-triazole-3-thiones (3a–n), and 2-alkyl/arylamino-5-{[6-(phenyl/4-chlorophenyl)imidazo[2,1-b]thiazol-3-yl]methyl}-1,3,4-thiadiazoles (4a–g). The newly synthesized compounds were characterized by IR, 1H NMR, 13C NMR (APT), mass and elemental analysis. Their antibacterial and antifungal activities were evaluated against Staphylococcus aureus ATCC 29213, Pseudomonas aeruginosa ATCC 27853, Escherichia coli ATCC 25922, Candida albicans ATCC 10231, C. parapsilosis ATCC 22019, C. krusei ATCC 6258, Trichophyton mentagrophytes var. erinacei NCPF 375, Microsporum gypseum NCPF 580, and T. tonsurans NCPF 245. 3c, 3f, 3m, 3n, and 4e showed the highest antibacterial activity. Particularly 3c, 3f, 3g, 3k, 3n, 4a, 4e, and 4g showed the highest antifungal activity against tested fungi.

Comparison of in vitro activities of tigecycline with other antimicrobial agents against Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis in two university hospitals in Istanbul, Turkey.

Background: We compared the in vitro activities of tigecycline with those of other agents against 97 Streptococcus pneumoniae, 140 Haemophilus influenzae and54 Moraxella catarrhalis strains isolated in two large university hospitals in Istanbul. Methods: For analysis, the agar dilution method was used. Results: For S. pneumoniae isolates, 32% were not susceptible to penicillin (28.9% intermediate and 3.1% resistant). Cefotaxime, telithromycin, moxifloxacin and linezolid were fully active. Tigecycline had a 90% minimum inhibitory concentration (MIC90) of 0.12 μg/ml. For H. influenzae, 8.57% were not susceptible to ampicillin, among which 8 possessed β-lactamase (5.7%). Four (2.87%) H. influenzae isolates with β-lactamase-negative and ampicillin-resistant phenotype were found. All isolates were susceptible to ceftriaxone, azithromycin, ciprofloxacin, levofloxacin and moxifloxacin. MIC90 for tigecycline was 0.5 μg/ml. Of 54 M. catarrhalis isolates, 88.9% possessed β-lactamase. Tigecycline and fluoroquinolones were highly active (MIC90 ≤0.12 μg/ml). Conclusions: Linezolid, telithromycin, newer fluoroquinolones and tigecycline all have excellent in vitro activities against the 3 respiratory pathogens.

Susceptibilities of Neisseria gonorrhoeae and Ureaplasma urealyticum isolates from male patients with urethritis to several antibiotics including telithromycin.

Background: The minimal inhibitory concentrations (MICs) of erythromycin, azithromycin, clarithromycin, telithromycin, tetracycline, doxycycline, ciprofloxacin, ofloxacin, norfloxacin, levofloxacin, gemifloxacin and moxifloxacin against 78 Neisseria gonorrhoeae and 31 Ureaplasma urealyticum strains, which were isolated from patients with urethritis in Istanbul, were determined and compared. Additionally, the activities of penicillin and ceftriaxone against N. gonorrhoeae strains were explored. Methods: MICs were determined by agar and broth dilution methods for N. gonorrhoeae and U. urealyticum, respectively. Results: The susceptibility rates for penicillin and tetracycline in N. gonorrhoeae strains were 35.9 and 24.3%, respectively. All gonococcal strains were susceptible to ceftriaxone, with very low MICs (MIC90 0.008 µg/ml). Telithromycin was highly active against N. gonorrhoeae and U. urealyticum strains (MIC90 0.25 µg/ml for both). Ciprofloxacin was the most active quinolone against N. gonorrhoeae (MIC90 0.008 µg/ml) while quinolone resistance was detected in a single strain (1.3%). Conclusions: Tetracycline and penicillin should not be the option in empirical treatment of N. gonorrhoeae infections due to the very low susceptibility rates. Ceftriaxone continues to be the first choice antibiotic in the treatment of gonococcal urethritis.

Synthesis, Characterization, and Evaluation of Antimicrobial Activity of Some 1,2,4-Triazole Derivatives Bearing an Antipyryl Moiety

Summary. Some novel 4-[[2-[[5-(2-furanyl)-4-alkyl/aryl-4H-1,2,4-triazol-3-yl]thio]-acetyl/propionyl]-amino]-1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazoles were synthesized and evaluated for in vitro antibacterial activity against Staphylococcus aureus ATCC 29213, Pseudomonas aeruginosa ATCC 27853, Escherichia coli ATCC 25922, and Enterococcus faecalis ATCC 29212 and antifungal activity against Candida albicans ATCC 10231, Candida parapsilosis ATCC 22019, Candida krusei ATCC 6258, Candida parapsilosis, Trichophyton mentagrophytes var. erinacei NCPF 375, Microsporum gypseum NCPF 580, and Trichophyton rubrum using the microbroth dilution method. All of the compounds were found to be ineffective against the above bacteria within the applied MIC ranges. On the other hand, they were effective against fungi to different degrees. Three compounds showed high activity against C. parapsilosis and T. mentagrophytes var. erinacei NCPF 375 (MIC = 8 μg cm−3). The in vitro antimycobacterial activity of the new compounds was also investigated against Mycobacterium tuberculosis H37RV (ATCC 27294) in BACTEC 12B medium using a broth microdilution assay, the Microplate Alamar Blue Assay (MABA). Compounds exhibiting fluorescence were tested in the BACTEC 460 radiometric system. The most active compound was found with 66% inhibition at >6.25 μg cm−3.

Synthesis and antimicrobial evaluation of new 3-alkyl/aryl-2-[((α,α-diphenyl-α-hydroxy)acetyl)hydrazono]-5-methyl-4-thiazolidinones

New 4-thiazolidinone derivatives of benzilic acid (α,α-diphenyl-α-hydroxyacetic acid) have been synthesized and evaluated for antibacterial and antifungal activities. The reaction of 1- (α,α-diphenyl-α-hydroxy)acetyl-4-alkyl/arylthiosemicarbazides with ethyl 2-bromopropionate gave 3-alkyl/aryl-2-[((α,α-diphenyl-α-hydroxy)acetyl)hydrazono]-5-methyl-4-thiazolidinone derivatives. Their antibacterial and antifungal activities were evaluated against S. aureus ATCC 29213, P. aeruginosa ATCC 27853, E. coli ATCC 25922, C. albicans ATCC 10231, C. parapsilosis ATCC 22019, C. krusei ATCC 6258, T. mentagrophytes var. erinacei NCPF 375, M. gypseum NCPF 580 and T. tonsurans NCPF 245. 3e, 3f, 3g and 3h showed the highest antibacterial activity. Particularly 3a and 3e showed the highest antifungal activities against C. parapsilosis ATCC 22019, T. tonsurans NCPF 245 and M. gypseum NCPF 580.