Fatma Budak

Characterization of ESBL (SHV-12) producing clinical isolate of Enterobacter aerogenes from a tertiary care hospital in Nigeria

BackgroundWe studied the beta-lactamases of an E. aerogenes isolate recovered from the blood of a two-year-old patient. The isolate demonstrated a disk-diffusion phenotype typical for an AmpC-ESBL co-producer.MethodsMicrobiology studies were performed according to standard protocols. The resistance gene was identified by transconjugation and cloning experiments.ResultsBy transconjugation only a narrow spectrum beta-lactamase (TEM-1) encoded on a small plasmid was transmitted. The ESBL was cloned and expressed in an E. coli host. Sequence analysis of the recombinant plasmid revealed blaSHV-12 associated to the insertion sequence, IS26.ConclusionThis is the first study demonstrated the occurrence of SHV-12 in Nigeria.

Emergence and spread of carbapenem-resistant Acinetobacter baumannii in a tertiary care hospital in Turkey

An intensive care unit (ICU)-based OXA-23-producing multiple-drug resistant Acinetobacter baumannii (MDRAB) outbreak was detected between October 2005 and October 2006. A total of 47 patients were infected/colonized with the outbreak strain. Clinical data were available from 37 patients. The all-cause mortality rate among the patients exposed to the epidemic strain was 35% (13/37). The outbreak strain and the resistance determinants were characterized both by microbiological methods and by molecular techniques. Cloning and sequencing experiments identified ISAbaI-associated bla(oxa-23) on the chromosome. Screening of imipenem-resistant Acinetobacter isolated from the ICU during the outbreak period with PCR identified 97 isolates as positive for the ISAbaI-bla(oxa-23) structure. Pulsed-field gel electrophoresis and plasmid analyses with selected nonrepetitive isolates revealed the clonality. Disk diffusion on cloxacillin-supplemented agar media and the real-time PCR experiments showed that outbreak isolates are overexpressing the ampC enzyme. This study highlights the occurrence of OXA-23-producing and ampC-overexpressing MDRAB in ICUs.

THE INVESTIGATION OF Chlamydophila pneumoniae IN PATIENTS WITH MULTIPLE SCLEROSIS

Totally 32 cerebrospinal fluid samples from Multiple sclerosis (MS) patients were collected. DNA was extracted by High Pure PCR Template Preparation Kit. Two genomic segments, outer membrane protein genes ompA and omp9, were targeted for the detection of C. pneumoniae DNA in the samples by PCR tests. To detect ompA, a nested-PCR assay was designed, whereas for omp9, a PCR-Enyzme immunoassay (PCR-EIA) depending on streptavidin-biotin capture and dig detection of the PCR products was performed. C. pneumoniae DNA was not detected by each assays in patient samples.

Detection of Resistivity for Antibiotics by Probabilistic Neural Networks

This paper presents the use of probabilistic neural networks (PNNs) for detection of resistivity for antibiotics (resistant and sensitive). The PNN is trained on the resistivity or sensitivity to the antibiotics of each record in the Salmonella database. Estimation of the whole parameter space for the PNN was performed by the maximum-likelihood (ML) estimation method. The expectation-maximization (EM) approach can help to achieve the ML estimation via iterative computation. Resistivity and sensitivity of the three antibiotics (ampicillin, chloramphenicol disks and trimethoprim–sulfamethoxazole) were classified with high accuracies by the PNN. The obtained results demonstrated the success of the PNN to help in detection of resistivity for antibiotics.

Efficacies of caspofungin and a combination of caspofungin and meropenem in the treatment of murine disseminated candidiasis

Disseminated candidiasis is relatively common in immunocompromised patients. The treatment protocol of these patients usually includes broad‐spectrum antibiotics and also emprical antifungals initiated due to unresponsiveness to antibiotics. In this study the efficacies of caspofungin and meropenem – separately and together – in mice with disseminated candidiasis were studied. Immunocompetent mice were infected intravenously with 2×106 CFU of Candida albicans. At 24 h postinfection, intraperitoneal therapy was initiated and was continued for 7 days. Therapy groups included those given caspofungin (0.5, 1.25, 5 mg/kg/day), meropenem (20 mg/kg/day), and a combination of the two drugs. The outcome of therapy was evaluated by kidney tissue burden studies and histologic examination. In vitro, drug susceptibilities were tested by checkerboard analysis. Kidney CFU counts showed that mice that had received both drugs had lower residual burdens. Caspofungin was effective at doses of 0.5, 1.25, 5 mg/kg compared to infected untreated controls. In vitro, MICs of caspofungin and meropenem were <0.075 μg/ml and >64 μg/ml, respectively. Synergism was observed with the combination. Histopathology showed that the degree of inflammation was 25% less and tubular necrosis was more restricted in combined therapy than monotherapy. The results indicate that concurrent caspofungin and meropenem therapy may be beneficial

Synthesis, characterization, antimicrobial activity, and QSAR studies on substituted oxadiazaboroles

This paper presents the synthesis and in vitro antimicrobial activity studies of 3,4,5-trisubstituted 4,5-dihydro-1,2,4,5-oxadiazaboroles (4) and 3,5-disubstituted 4,5-dihydro-1,2,4,5-oxadiazaboroles (7). The antimicrobial activities of the compounds were assessed against a panel of microorganisms including Staphylococcus aureus, Enterococcus faecalis, Pseudomonas aeruginosa, Escherichia coli, Streptococcus mutans, and Candida albicans. Some of the oxadiazaboroles exhibited fair activities against these microorganisms. The pMIC values of the compounds were first correlated with Hammett polar substituent constant (σ) and lipophilic constant (π) and statistically significant correlations were obtained. Additionally, the pMIC values of the compounds were correlated with σ, π, and some theoretical descriptors and fair 2D-quantitative structure–activity relationship models with clogP, surface area approx, ELUMO, µ, and EHOMO as independent variables were obtained. Application of training and test sets to quantitative structure–activity relationship models gave good results. Squared correlation matrix of the theoretical descriptors used in the quantitative structure–activity relationship study showed no correlation between the descriptors.

Prevalence and Genotypic Characteristics of ß-lactamase Negative-Ampicillin-Resistant (BLNAR) Haemophilus Influenzae in a Children's Hospital in Turkey

ABS TRACT Objective: This study’s aim is to investigate the serotypes and ampicillin resistance mechanisms in Haemophilus influenzae pediatric isolates in several clinical samples. Material and Methods: One hundred thirty nine patients’ clinic samples were examined. Serotyping using slide agglutination and antimicrobial susceptibilitiy testing using microbroth dilution test methodology were performed. Strains for which ampicillin MICs were ≥0.5 μg/mL were indiscriminately selected, and penicillin binding protein (PBP) profiles were analyzed. The blaTEM-1, blaROB-1 genes and ftsI gene mutations were examined by polymerase chain reaction (PCR) and then sequenced. Results: The serotypes in 139 serial isolates of H. influenzae were detected as serotype b (n=19; 13.7%), serotype a (n=9; 6.4%), serotype d (n=2; 1.4%), serotype f (n=2; 1.4%) and serotype c (n=1; 0.7%), serotype e (n=1; 0.7%). One hundred and five (75.5%) strains were found as nontypeable. Ampicillin, cefaclor, amoxicillin-clavulanic acid and cefotaxime resistance rates were 4.3%, 11.5%, 0%, 0%, respectively. Resistance was not detected in serotype b and e. Ampicillin resistant, beta lactamase positive four isolates (two serotype a and two nontypeable) were positive for blaTEM-1. All strains were negative for blaROB-1. A total of 4 (11.1%) serotype a, 2 (5.5%) serotype b and 30 (83.3%) nontypeable H. influenzae strains were positive for low BLNAR. Conclusion: Among pediatric isolates nontypeable H. influenzae was found to be the most common serotype. Ampicillin resistant, TEM-1 beta lactamase positive strains still involve risk in our country. Significant rate of low BLNAR positive strains in nontypeable H. influenzae is considerable. This is the first investigation on the specific gene mutations that encode PBP-3 INT and their connection with TEM-1 in low BLNAR H. influenzae strains in Turkey.