Contribution of plasmid-encoded fimbriae and intimin to capacity of rabbit-specific enteropathogenic Escherichia coli to attach to and colonize rabbit intestine.

Attachment to the intestinal mucosa is an essential step in the pathogenesis of diarrhea caused by enteropathogenic Escherichia coli (EPEC). Fimbriae and intimin, the outer membrane protein product of the chromosomal eae gene, contribute to this process, but their relative roles and the nature of their interaction are not known. The aim of this study was to determine the relative contribution of plasmid-encoded fimbriae, termed Ral, and intimin to the capacity of rabbit-specific EPEC (REPEC) to attach to the intestinal mucosa of rabbits. To achieve this, we constructed a series of mutants in REPEC strain 83/39 (O15:H-), in which the ralE and eae genes were insertionally inactivated. These strains were then inoculated into ligated loops of rabbit ileum, which were resected 18 h later and examined by light and electron microscopy. The results showed that intimin, but not Ral, is essential for the elicitation of attaching-effacing lesions by REPEC. Nevertheless, a delta eae Ral-bearing mutant adhered to the intestinal epithelium to the same extent as its eae-positive parent and far more extensively than an eae(+) delta ral strain. To examine the contribution of Ral and intimin to colonization of rabbit intestine, we fed these strains to weanling rabbits, which were killed 4 days later, so that the number of bacteria in various regions of the intestine could be determined. The results indicated that strain 83/39 requires both Ral and intimin to colonize the intestine successfully and that a delta eae delta ralE double mutant was incapable of colonizing the intestine. Taken together, these findings indicate that Ral and intimin act independently as adhesion factors of REPEC strain 83/39 and that this strain carries no other significant colonization factor. When both Ral and intimin are present, they appear to act cooperatively, with Ral-mediated adhesion preceding that mediated by intimin.

Identification of a novel genetic locus that is required for in vitro adhesion of a clinical isolate of enterohaemorrhagic Escherichia coli to epithelial cells.

Enterohaemorrhagic Escherichia coli (EHEC) are food-borne intestinal pathogens with a low infectious dose. Adhesion of some EHEC strains to epithelial cells is attributed, in part, to intimin, but other factors may be required for the intestinal colonizing ability of these bacteria. In order to identify additional adherence factors of EHEC, we generated transposon mutants of a clinical EHEC isolate of serotype O111:H-, which displayed high levels of adherence to cultured Chinese hamster ovary (CHO) cells. One mutant was markedly deficient in CHO cell adherence, human red blood cell agglutination and autoaggregation. Sequence analysis of the gene disrupted in this mutant revealed a 9669 bp novel chromosomal open reading frame (ORF), which was designated efa1, for EHEC factor for adherence. efa1 displayed 28% amino acid identity with the predicted product of a recently described ORF from the haemolysin-encoding plasmid of EHEC O157:H7. The amino termini of the putative products of these two genes exhibit up to 38% amino acid similarity to Clostridium difficile toxins A and B. efa1 occurred within a novel genetic locus, at least 15 kb in length, which featured a low G+C content, several insertion sequence homologues and a homologue of the Shigella flexneri enterotoxin ShET2. DNA probes prepared from different regions of efa1 hybridized with all of 116 strains of attaching-effacing E. coli (AEEC) of a variety of serotypes, including enteropathogenic E. coli (EPEC) and EHEC, but with none of 91 non-AEEC strains. Nevertheless, efa1 was not required for the attachment-effacement phenotype, and the efa1 locus was not physically linked to the locus for enterocyte effacement (LEE) pathogenicity island, which is responsible for this phenotype in EPEC. These findings suggest that efa1 encodes a novel virulence-associated determinant of AEEC, which contributes to the adhesive capacity of these bacteria.

Percutaneous needle biopsy of mediastinal masses using a computed tomography-guided extrapleural approach.

This study was conducted to determine the reliability of mediastinal biopsy using a computed tomography-guided extrapleural approach. Twenty patients (16 men and 4 women) between the ages of 30 to 79 years underwent 22 percutaneous biopsies. The sampled masses ranged in size from 1.6 to 8 cm. A coaxial 17-gauge needle system was advanced into the fascia subjacent to the parietal pleura. An extrapleural fluid collection was created using a 20%/80% ratio of 1% lidocaine and normal saline. The blunt cannula was then advanced through the fluid to the edge of the lesion, and core or cytologic specimens were obtained. A diagnosis was obtained in 18 of 20 patients (90%). There were 10 malignant and 8 benign diagnoses. Complications included pneumothorax (1), vasovagal reactions (1), intercostal neuritis (1), and transient Homer's syndrome (1). In this series, both a high diagnostic yield as well as a low complication rate were obtained.

Hemiballism-hemichorea: unusual neurologic presentation in acquired immunodeficiency syndrome.

A patient with hemiballism-hemichorea as the initial manifestation of the acquired immunodeficiency syndrome is described. Movement disorders in AIDS have not been frequently reported. Possible etiologies and therapeutic trials are presented. To our knowledge this is the first case report of hemiballism-hemichorea as the initial presenting feature of an AIDS patient in Puerto Rico.

Rotator cuff sonography: a reassessment.

This study is both a retrospective and prospective evaluation of the clinical usefulness of shoulder sonography. Ninety-eight patients suspected of having rotator cuff tears underwent sonography of both shoulders. Sixty-two patients underwent double-contrast arthrography performed on the same day as sonography, and 38 patients underwent surgery after sonography. A comparison of the results from ultrasound and arthrography, using published diagnostic criteria, demonstrated a sensitivity of 75% and a specificity of 43% for detection of a rotator cuff tear. In this study, use of more restricted criteria, a subset of the published criteria, yielded a sensitivity of 68% and a specificity of 90%. A comparison of sonography with surgery, using this study's criteria, demonstrated a sensitivity of 57% and a specificity of 76%. This report shows that shoulder sonography is less reliable than previously reported and appears to have a very limited role in the evaluation of rotator cuff injuries.

Supralevator abscess: evaluation with transrectal sonography.

Transrectal ultrasound was used in 2 patients with supralevator perirectal fluid collections. In one instance, this technique was used to diagnose and plan surgical drainage of a perirectal abscess. In another patient needle aspiration under sonographic guidance was performed for removal of a septated fluid collection.

Endometrial echo and its significance in female infertility.

The sonographic appearance of the endometrium was evaluated in 97 infertile women, 51 from a fertility unit (FU) and 46 from an in vitro fertilization (IVF) program. Three groups of patients were identified: those with normal findings, those with an incomplete endometrial echo, and those without any endometrial echo. Findings were correlated with the type of ovulation induction protocol, the peak estradiol level, and the number of successful pregnancies. In the IVF group, 72% of the patients did not exhibit normal endometrial echoes but had adequate estradiol levels, compared with 62% of the FU patients with normal endometrial echoes but significantly lower estradiol. The data suggest that IVF patients have a nonresponsive endometrium rather than inadequate estrogen stimulation and therefore that an endometrial abnormality may be an important cause of their infertility. Ultrasound may be used as a screening method to identify such patients.