Characterization of integrons, extended spectrum beta lactamases and genetic diversity among uropathogenic Escherichia coli isolates from Kerman, south east of Iran

Background and Objectives

The study aimed to investigate the distribution of genes encoding integrons, extended spectrum beta-lactamase (ESBL) in E. coli isolated from UTIs, as well as the genetic diversity among the isolates.

Materials and Methods

E. coli isolates were recovered from the patients with UTI in Kerman Iran. Antibiotic susceptibility was done according to CLSI guidelines. The presence of ESBL genes and integrons was evaluated using PCR. PCR and sequencing were applied for the evaluation of cassette content of integrons. Genotyping of the isolates was performed by multiple-locus variable-number tandem repeat analysis (MLVA).

Results

Imipenem was the most effective antibiotic, while the highest resistance was observed to streptomycin. In total 40.2% of isolates were ESBL producers. Of 69 integron-positive isolates, 59 only had class I integrons, 4 only had class II integrons and 6 had both types. The most common gene cassette found within class I integrons was dfrA17-aadA5 (n=27). The E. coli isolates were divided into 16 MLVA clusters.

Conclusion

The current study demonstrated the simultaneous presence of class I integrons and ESBLs involved in the resistance of UPEC isolates to antibacterial agents. Our finding also revealed that the E. coli isolates belonged to diverse clones.

[Clinical application of STR genotyping diagnosis for hydatidiform mole and nonmolar gestation]

Objective: To investigate the value of short tandem repeat (STR) genotyping in the diagnostic workup of molar and non-molar gestations with correlation of histological characteristics. Methods: Six hundred and fifty-six cases were selected based on clinically suspected hydropic abortion and/or molar pregnancy from July 2015 to September 2017 at Beijing Obstetrics and Gynecology Hospital. DNA was extracted from dissected chorionic villi and paired maternal endometrial FFPE tissue samples by Simplex OUP™ FFPE DNA Tissue Kit. STR genotyping was performed by PowerPlex 16 HS system. Results: DNA genotyping was informative in 649 of 656 cases, leading to identification of 215 hydatidiform mole gestations and 434 non-molar gestations. Most of non-molar gestations (375 cases, 86.4%) were diploid hydropic abortion. Various trisomy syndromes were found (53 cases, 12.2%), including trisomy 2, 3, 4, 7, 8, 13, 16 and 21. Only 2(0.5%) digynic triploid gestations were detected. Moreover, 4 cases (0.9%) of uniparental disomies (homologous or heterologous) were found. There were 196 cases with histologic diagnostic suspicious of hydatidiform moles were accurate sub-classified. Among them, 59 cases hydatidiform moles were under-diagnosed as diploid hydropic abortions, and 28 cases diploid hydropic abortions were over-diagnosed as hydatidiform moles.Compared with partial moles(PHM), there were no specific histomorphological features between the various types of non-molar gestations and partial moles for definitive diagnostic separation. There was no significant difference in the expression of p57(kip2) among PHM, trisomy and diploid hydropic abortions group (P=0.247). Conclusions: STR genotyping can distinguish non-molar gestations from early hydatidiform moles, and efficiently avoid misdiagnosis based only on histological evaluation. Therefore, using STR genotyping, not only can the overdiagnosis of non-molar pregnancy be avoided, but also individualized management can be offered to patients including monitoring of serum hCG.

Quantification of mixed chimerism allows early therapeutic interventions

Hematopoietic stem cell transplantation is the curative option for patients with myelodysplastic syndrome; however, it requires a long post-transplantation follow-up. A 53-year-old woman with a diagnosis of myelodysplastic syndrome underwent related donor allogeneic hematopoietic stem cell transplantation in July 2006. Three months after transplantation, a comparative short tandem repeat analysis between donor and recipient revealed full chimerism, indicating complete, healthy bone marrow reconstitution. Three years and ten months after hematopoietic stem cell transplantation, the patient developed leukopenia and thrombocytopenia. Another short tandem repeat analysis was carried out which showed mixed chimerism (52.62%), indicating relapsed disease. A donor lymphocyte infusion was administered. The purpose of donor lymphocyte infusion is to induce a graft-versus-leukemia effect; in fact, this donor's lymphocyte infusion induced full chimerism. Successive short tandem repeat analyses were performed as part of post-transplantation follow-up, and in July 2010, one such analysis again showed mixed chimerism (64.25%). Based on this finding, a second donor lymphocyte infusion was administered, but failed to eradicate the disease. In September 2011, the patient presented with relapsed disease, and a second related donor allogeneic hematopoietic stem cell transplantation was performed. Subsequent short tandem repeat analyses revealed full chimerism, indicating complete bone marrow reconstitution. We conclude that quantitative detection of mixed chimerism is an important diagnostic tool that can guide early therapeutic intervention.

Facioscapulohumeral dystrophy: the path to consensus on pathophysiology

Although the pathophysiology of facioscapulohumeral dystrophy (FSHD) has been controversial over the last decades, progress in recent years has led to a model that incorporates these decades of findings and is gaining general acceptance in the FSHD research community. Here we review how the contributions from many labs over many years led to an understanding of a fundamentally new mechanism of human disease. FSHD is caused by inefficient repeat-mediated epigenetic repression of the D4Z4 macrosatellite repeat array on chromosome 4, resulting in the variegated expression of the DUX4 retrogene, encoding a double-homeobox transcription factor, in skeletal muscle. Normally expressed in the testis and epigenetically repressed in somatic tissues, DUX4 expression in skeletal muscle induces expression of many germline, stem cell, and other genes that might account for the pathophysiology of FSHD. Although some disagreements regarding the details of mechanisms remain in the field, the coalescing agreement on a central model of pathophysiology represents a pivot-point in FSHD research, transitioning the field from discovery-oriented studies to translational studies aimed at developing therapies based on a sound model of disease pathophysiology.