Characterization of carbapenem-resistant Escherichia coli and Klebsiella: a role for AmpC-producing isolates

Aim: This study aimed to investigate the role of AmpC enzymes in carbapenem resistance among AmpC/extended-spectrum β-lactamase (ESBL)-producing clinical isolates of Escherichia coli and Klebsiella spp. Methods: Fifty-six bacterial strains that were AmpC producers were examined. The antibiotic susceptibility test was performed by the disk diffusion and E-test. The prevalence of the plasmid carbapenemase was determined using PCR. Results: The resistance to meropenem in the AmpC⁺/ESBL⁺ group was 64%, higher than that reported for the AmpC^-/ESBL⁺ group. Ten isolates of the carbapenem-resistant AmpC producers were negative for carbapenemase-encoding genes. Conclusion: Carbapenem resistance among AmpC-producing isolates with negative results for carbapenemase-encoding genes potentially demonstrates the role of AmpC enzymes among these isolates.

Allylphenols as a new class of human 15-lipoxygenase-1 inhibitors

In this study, a series of mono- and diallylphenol derivative were designed, synthesized, and evaluated as potential human 15-lipoxygenase-1 (15-hLOX-1) inhibitors. Radical scavenging potency of the synthetic allylphenol derivatives was assessed and the results were in accordance with lipoxygenase (LOX) inhibition potency. It was found that the electronic natures of allyl moiety and para substituents play the main role in radical scavenging activity and subsequently LOX inhibition potency of the synthetic inhibitors. Among the synthetic compounds, 2,6-diallyl-4-(hexyloxy)phenol (42) and 2,6-diallyl-4-aminophenol (47) showed the best results for LOX inhibition (IC₅₀ = 0.88 and 0.80 μM, respectively).

High prevalence of blaCMY AmpC beta-lactamase in ESBL co-producing Escherichia coli and Klebsiella spp. clinical isolates in the northeast of Iran

OBJECTIVE

The production of β-lactamase enzymes such as AmpC β-lactamases and extended-spectrum β-lactamases (ESBLs) is among the main mechanisms for resistance to expanded-spectrum cephalosporins. The present study was conducted to investigate the prevalence and molecular epidemiology of plasmid-mediated AmpC beta (β)-lactamase in ESBL co-producing Escherichia coli (E. coli) and Klebsiella spp. (Klebsiella pneumoniae and Klebsiella oxytoca) clinical isolates in the northeast of Iran.

METHODS

A total of 602 E. coli and Klebsiella spp. clinical isolates were collected from three hospitals in Mashhad (northeast of Iran). A combination disk test (CDT) was performed for the phenotypic detection of ESBLs. Screening for the detection of AmpC β-lactamases was performed by a susceptibility test to a cefoxitin disc among ESBL producing isolates. A confirmatory test for AmpC β-lactamases was performed using the Mast® D68C test. Identification of plasmid-mediated AmpC cluster genes was done by multiplex polymerase chain reaction (PCR).

RESULTS

Among 336 ESBL-producing strains, 230 (68.4%) isolates were resistant to cefoxitin. Results of the Mast® D68C test showed that 30% (69/230) of cefoxitin-resistant isolates simultaneously exhibited ESBL and AmpC activity and 22% (51/230) of isolates probably showed multi-drug resistant (MDR) phenotype. Results of multiplex PCR among ESBL-positive isolates showed that, 16.7% (56/336) of isolates were positive for plasmid-borneampC cluster genes, and CMY (38%) was the most frequent genotype of plasmid mediated AmpC.

CONCLUSION

Findings of the study revealed that an increase in the prevalence of ESBL and AmpC co-producer in E. coli and Klebsiella spp. strains may become an important public health issue. Therefore, there is a vital need for surveillance of spread of these clinical isolates.

Designing and Construction Pcdna3.1 Vector Encoding Cfp10 Gene of Mycobacterium tuberculosis

Background:

Pathogenic mycobacteria are a major cause of human morbidity and mortality. Mycobacterium tuberculosis is an etiological agent of human tuberculosis (TB). Designing new vaccines, including DNA vaccines, may be a useful strategy for preventing TB.

Objectives:

The purpose of this study was to design and construct an eukaryotic expression vector containing M. tuberculosis.

Materials and Methods:

Genomic DNA of M. tuberculosis H37Rv cultured on Lowenstein Jensen medium was extracted, and cfp10 was amplified by PCR. After digesting the PCR product and the plasmid, the cfp10 fragment was ligated into the vector pcDNA3.1 (+). Correct insertion was confirmed by colony PCR, restriction enzyme digestion, and sequencing.

Results:

Electrophoresis of the PCR product on gel showed a 303-bp target fragment. Colony PCR, restriction enzyme digestion, and Sequencing methods confirmed the accuracy of the gene cloning. Colony PCR and restriction enzyme digestion confirmed the cloning.

Conclusions:

Cloning of cfp10 of M. tuberculosis into an eukaryotic expression vector was performed successfully. We propose this recombinant plasmid for inducing immunity in animal models in future studies. This recombinant vector can also be used in the construction of fusion proteins.

Sequence Analysis of lip R: A Good Method for Molecular Epidemiology of Clinical Isolates of Mycobacterium tuberculosis

Advances in DNA sequencing have greatly enhanced the molecular epidemiology studies. In order to assess evolutionary and phylogenetic relation of Mycobacterium tuberculosis isolates several gene targets were evaluated. In this study, appropriate fragments of 5 highly variable genes (rpsL, mprA, lipR, katG, and fgd1 genes) were sequenced. The sequence data were analyzed with neighbor-joining method using mega and Geneious software. The phylogenetic trees analyzes revealed that the discriminatory power of lipR is much stronger than that observed in the other genes. lipR could distinguish between more clinical isolates. Therefore, lipR is a promising target for sequence analyzes of M. tuberculosis.

Synthesis and SAR studies of 3-allyl-4-prenyloxyaniline amides as potent 15-lipoxygenase inhibitors

15-Lipoxygenases are one of the nonheme iron-containing proteins with ability of unsaturated lipid peroxidation in animals and plants. The critical role of the enzymes in formation of inflammations, sensitivities and some of cancers has been demonstrated in mammalians. Importance of the 15-lipoxygenases leads to development of mechanistic studies, products analysis and synthesis of their inhibitors. In this work new series of the 3-allyl-4-allyoxyaniline amides and 3-allyl-4-prenyloxyaniline amides were designed, synthesized and their inhibitory potency against soybean 15-lipoxygenase were determined. Among the synthetic amides, 3-allyl-4-(farnesyloxy)-adamantanilide showed the most potent inhibitory activity by IC(50) value of 0.69 μM. SAR studies showed that in spite of prenyl length increases, the effects of the amide size and its electronic properties on the inhibitory potency became predominant. The SAR studies was also showed that the orientation of allyl and prenyloxy moieties toward Fe core of the SLO active site pocket is the most suitable location for enzyme inhibition.

Malignant gliomas of the brain. A retrospective study

A retrospective study of 72 consecutive and nonrandomized patients with malignant glial tumors is presented. The influence of age, sex, location of tumor, initial presenting symptoms, symptomatic preoperative interval, reoperation, extent of tumor removal, histological subtype of tumor, lymphocyte infiltration, and different treatments upon survival time has been evaluated and statistically analyzed. Age was inversely associated with survival with a strong statistical significance (p = 0.0001). Headache was the most common (67%) initial symptom; aphasia and seizure were both present in 45.3% of patients. Initial presenting symptoms had no effect upon survival. Parietal lobe and lymphocyte infiltration had marginally negative effects upon survival (p = 0.097 and p = 0.10 respectively). The amount of tumor removal was marginally associated with an improved survival (p = 0.07). Radiation therapy was strongly associated with an improved survival time (p = 0.0007). The addition of chemotherapy did not affect the survival (perhaps reflecting the small number of patients and inadequate chemotherapy). There was an obvious beneficial effect of reoperation upon survival time, if the patient lived and underwent reoperation later than 16 months after the initial operation (slow-growing tumor). Although median and mean survival times (10 and 20.34 months respectively, SD 7.45 months) were similar to most series reported, our rates of survival (20%, 12.5%, and 7.5% at 2, 3, and 5 years, respectively) were notably higher.

Intraarterial 1,3-bis(2-chloroethyl)-1-nitrosourea chemotherapy for the treatment of malignant gliomas of the brain: a preliminary report

In a clinical trial, 10 patients with malignant gliomas underwent partial resection of their tumors and were treated by intraarterial 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) chemotherapy. The drug was given at least 1 month after the completion of postoperative radiotherapy in total doses of 270-280 mg/m2 in two sessions separated by a 48-hour interval (the two sessions with interval were equal to one course). This therapy was repeated every 8-10 weeks. Four patients had three courses and the other six patients had two courses of chemotherapy. This therapy was the only antitumor chemotherapy for this group of patients. Our preliminary results demonstrate the safety of this new procedure and suggest that intraarterial BCNU chemotherapy may be more effective, and has a better tolerance and less toxicity, than intravenous BCNU chemotherapy. Furthermore, it was demonstrated that, in the case of one patient, higher antitumor activity resulted from intraarterial BCNU chemotherapy as compared to intravenous BCNU therapy.

Microsurgical anatomy and related techniques to an anterolateral transthoracic approach to thoracic disc herniations

The microsurgical anatomy and related techniques of a modified anterolateral transthoracic approach to the thoracic disc space is presented. This procedure was performed on at least three thoracic levels of 12 cadavers within a few hours after death. Such an approach allows a safe decompression of the spinal cord and roots under full visual control. There is minimal risk to radiculomedullary vessels, minimal osteoligamental resection, and no compromise of stability of the spinal column. Therefore, this procedure does not require surgical stabilization of the spinal column, postoperative bracing, or prolonged bed rest. The difference between this approach and anterolateral transthoracic, posterolateral, and transpedicular approaches is discussed.

Prognostic value of round cell (lymphocyte) infiltration in malignant gliomas

The biopsy specimens of 342 patients with malignant glioma were evaluated to determine the extent and prognostic significance of round cell infiltration within these representative tissues: (a) tumor, (b) peritumoral, (c) hypervascular, (d) necrotic, and (e) normal tissue. Thirty-six percent of all biopsy specimens showed at least one tissue area with round cell infiltration. Patients in age groups 0 to 25 years and 71 years and older tended to show less round cell infiltration than did patients 41 to 55 years old. The presence of round cell infiltration in tissue was associated with a poor prognosis. Patients showing any infiltration had mean survival times of 8.4 months as opposed to 11.9 months for those showing no infiltration. The relationship between round cell infiltration and poor prognosis is true, irrespective of postoperative therapy, sex, and age.

Radiation necrosis of the brain: time of onset and incidence related to total dose and fractionation of radiation

Clinical deterioration during or after brain irradiation may be due to progression of neoplasm or radiation induced necrosis of the neoplasm and/or of normal brain tissues, or a combination of all. Eight patients with histologically documented radiation induced lesions of the brain are included in this study. The radiation therapy included the fractional schedule, group A, who received 280 to 300 rads daily, to a total dose of 4500 to 5000 rads and weekly exposure did not exceed 900 rads. Group B patients were exposed to 850 rads, daily dose on day 1, 3, 21 and 23 to a total dose of 3400 rads. The incidence of radiation induced lesions of brain was 3.4% in patients group A and 8.7% in group B patients (without statistical significance). The median time of onset of these lesions after completion of radiation therapy was significantly shorter in group B patients (8.5 months) as opposed to group A patients (21 months).

Possible influence of cerebrospinal fluid pressure on the growth of a third ventricle choroid plexus papilloma

A case of histologically proven benign choroid plexus papilloma of the third ventricle in a 4-month-old male child is reported. The clinical symptoms and the neuroradiologic findings were those of a supratentorial hydrocephalus. A shunting procedure was performed after refusal by the family of a direct surgical approach. Subsequently there was a four- to fivefold increase in volume of this tumor in less than 4 months under decreased cerebrospinal fluid pressure. The purpose of this report is first to add a case to 27 cases of papilloma of the choroid plexus of third ventricle reported in the medical literature. Secondly to underline a possible influence of intraventricular pressure on the growth of a histologically benign intraventricular papilloma. Subsequently, the question of radiation therapy may be raised, if total removal of the papilloma is not obtained, especially in view of decreased cerebrospinal fluid pressure provided by the previous shunting procedure.

Multifocal brain radionecrosis masquerading as tumor dissemination

The authors report on an autopsy-proven case of multifocal widespread radionecrosis involving both cerebral hemispheres and masquerading as tumor dissemination on a CT scan done 13 months after complete resection of an oligodendroglioma followed by radiation therapy. This case demonstrates that radiation damage may be present in a CT scan as a multifocal, disseminated lesion. Since the survival of brain-tumor patients who have undergone radiation therapy is prolonged by aggressive therapy, the incidence and variability of radiation-induced complications in such cases is likely to increase. For similar reasons, the radionecrosis in such cases should be taken into consideration. A short review of the CT scan findings and diagnostic and therapeutic considerations in a case of widespread radionecrosis is presented. The need for appropriate diagnosis and subsequent life-saving management is emphasized.

Subacute necrotizing polioencephalopathy

A previously healthy 20-year-old woman died of a progressive cerebral disease that involved the brain stem and the cerebral hemispheres successively. The illness ran its course in 80 days. Postmortem examination showed a multifocal necrotizing encephalopathy that chiefly affected gray matter structures and that was mainly located in the brain stem and cerebral cortex. The cause and pathogenesis remain unknown.