Quantitative assessment of myocardial scar heterogeneity using cardiovascular magnetic resonance texture analysis to risk stratify patients post-myocardial infarction.

AIM: To determine whether heterogeneity of cardiac scar, as assessed by cardiovascular magnetic resonance (CMR) texture analysis, may provide insight into better risk stratification for patients with previous myocardial infarction (MI). MATERIALS AND METHODS: Patients with previous MI (n=76) were followed for a median of 371.5 days after late gadolinium enhancement (LGE) CMR. The primary endpoint was a composite of ventricular tachycardia, ventricular fibrillation, or unexplained syncope. Areas of LGE were identified and manually segmented on a short-axis projection. The characteristics of the scar heterogeneity were evaluated via CMR texture analysis. This is a filtration-histogram technique, where images are filtered using the Laplacian of a Gaussian filter to extract features different sizes (2-6 mm in radius) corresponding to fine, medium, and coarse texture scales followed by a quantification step using histogram analysis (skewness and kurtosis). RESULTS: Patients suffering arrhythmic events during the follow-up period demonstrated significantly higher kurtosis (coarse-scale, p=0.005) and lower skewness (fine-scale, p=0.046) compared to those suffering no arrhythmic events. Furthermore, Kaplan-Meier analysis showed significantly higher coarse kurtosis (p=0.004), and lower fine skewness (p=0.035) were able to predict increased incidence of ventricular arrhythmic events. CONCLUSIONS: In this pilot study, indices of texture analysis reflecting textural heterogeneity were significantly associated with a greater incidence of arrhythmic events. Further work is required to delineate the role of texture analysis techniques in risk stratification post-MI.

In vitro activity of some essential oils alone and in combination against the fish pathogen Nocardia seriolae.

Microplate resazurin assay was applied to investigate the in vitro activity of four essential oils (EOs); cinnamon (Cinnamomum zeylanicum), thyme (Thymus vulgaris), lemongrass (Cymbopogon flexuosus) and tea tree (Melaleuca alternifolia) oils against 80 clinical isolates of the fish pathogen Nocardia seriolae. The checkerboard test was then used to determine the possible synergistic effect of EOs combination against reference type strains of fish nocardiosis. All tested EOs had antibacterial activity against N. seriolae isolates. Among the tested EOs, cinnamon and thyme oils both exhibited the lowest minimum inhibitory concentrations (MICs) with 5-160 and 10-160 µg/ml, respectively. The activities of lemongrass and tea tree EOs were noted to be less effective with MICs of 20-640 and 160->5120 µg/ml, respectively. The checkerboard panel of cinnamon-thyme EOs combination against N. seriolae ATCC43993 demonstrated a synergistic effect with a fractional inhibitory concentration (FIC) index of 0.75. For N. salmonicida ATCC27463, the combination panel showed an additive effect with an FIC index of 1.0. For N. asteroides ATCC19247, the combination panel demonstrated an indifference effect with an FIC index of 1.125. These results indicate that thyme and cinnamon oils alone or the combination of them at a given ratio has a promising potent clinical significance in the treatment of fish nocardiosis. Despite the promising results given by our in vitro studies, the clinical benefits of these EOs combinations can only be determined through carefully designed in vivo experimental studies.

Isolation and antibiotic susceptibility of Salmonella, Shigella, and Campylobacter from acute enteric infections in Egypt.

While Campylobacter, Salmonella, and Shigella remain major contributors to acute enteric infections, few studies on these pathogens have been conducted in Egypt. From January 1986 to December 1993, 869 Salmonella, Shigella and Campylobacter strains were isolated from stool specimens from 6,278 patients, presenting to the Abbassia Fever Hospital, Cairo, Egypt, with acute enteric infections. Salmonella predominated, totalling 465 isolates, followed by Shigella with 258 isolates, and Campylobacter with 146 isolates. Of the Shigella isolates, 124 were Shigella flexneri, 49 were S. sonnei, 47 were S. dysenteriae (mainly serotype 1, 2, and 3), and 38 were S. boydii. Campylobacter spp. comprised 92 Campylobacter jejuni and 54 C. coli isolates. Isolation of Salmonella was highest during the months of February-March, June-July, and October-November, while that of Shigella was maximal from July to October. Isolation of Campylobacter increased during May-June and again during August-October. Although Salmonella was sensitive to amikacin, aztreonam, ceftriaxone, and nalidixic acid, it was, however, resistant to erythromycin, streptomycin, ampicillin, chloramphenicol, and tetracycline. Shigella (> 80%) was sensitive to amikacin, ceftriaxone, cephalothin, sulphamethoxazole-trimethoprim (except S. sonnei), aztreonam, and nalidixic acid. Resistance (> 50%) was noted only for ampicillin, chloramphenicol, and tetracycline. C. jejuni and C. coli were resistant to cephalothin, aztreonam, and streptomycin. Some of the above antibiotics were employed to characterize the Egyptian isolates, but did not have any clinical utility in the treatment of diarrhoea. Significant differences (p < 0.05) were observed in the resistance profiles of Shigella and Salmonella between late 1980s and early 1990s. The results suggest the use of fluoroquinolones or a third-generation cephalosporin as an empirical treatment of enteric diseases. However, alternative control strategies, including the aggressive development of broadly protective vaccines, may be more effective approaches to curbing morbidity and mortality due to acute enteric infections.

Differentiation of Campylobacter isolates on the basis of sensitivity to boiling in water as measured by PCR-detectable DNA.

Differential sensitivity for the release of PCR-detectable genomic DNA upon boiling in water is reported for 45 Campylobacter jejuni and Campylobacter coli strains isolated in Egypt. All of the strains released PCR-detectable DNA when treated with proteinase K and sodium dodecyl sulfate. When DNA was extracted from these strains by boiling in water, nine (20%) of the strains were PCR negative or resistant to boiling, suggesting the presence of boiling-sensitive and boiling-resistant phenotypes.

Evaluation of antibodies reactive with Campylobacter jejuni in Egyptian diarrhea patients.

Serum and stool samples were collected from 128 individuals: 96 diarrhea patients and 32 apparently healthy controls. Stool specimens were cultured for enteric bacterial pathogens, while sera were screened by enzyme-linked immunosorbent assay for Campylobacter jejuni-reactive antibodies. Of 28 diarrhea patients who demonstrated C. jejuni-reactive antibodies (titers, > 100), 14 were culture positive for this organism. The 32 healthy controls showed significantly lower antibody titers (P < 0.05) with the exception of 10 subjects who were culture positive for C. jejuni and had reactive immunoglobulin M (IgM) (6 subjects) and IgG (7 subjects). IgA was not detected in those 10 individuals (asymptomatic). Avidity was expressed as the thiocyanate ion concentration required to inhibit 50% of the bound antibodies. The avidity was higher in symptomatic patients than asymptomatic healthy controls. IgG was less avid (0.92 M) compared to IgM (0.1 M) and IgA (1.1 M), with no correlation between antibody titer and avidity. However, the thiocyanate ion concentration required for the complete inhibition of IgG (5 M)-bound antibodies was higher than that of IgA (2 M) and IgM (3 M). This study also shows that C. jejuni antibodies were variably cross-reactive with Escherichia coli, Shigella flexneri, Shigella sonnei, and Neisseria meningitidis in addition to Campylobacter coli and Campylobacter rectus.

Enteropathogens associated with diarrhea among military personnel during Operation Bright Star 96, in Alexandria, Egypt.

This study investigated the microbial causes of diarrheal disease among U.S. troops deployed near Alexandria, Egypt, during October 1995. Bacterial causes associated with 19 cases of diarrhea included: enterotoxigenic Escherichia coli (ETEC), 42% (21% heat-stable, 11% heat-labile, and 11% heat-stable/ heat-labile producers); enteropathogenic E. coli (5.3%); and enteroadherent E. coli (42%). Four cases of diarrhea were associated with enteroaggregative E. coli based on probe analysis for enteroaggregative heat-stable enterotoxin 1. Protozoan causes included; Entamoeba histolytica (11%), E. hartmanni (5%), E. nana (5%), Blastocystis hominis (5%), Chilomastix mesnili (11%), Dientamoeba fragilis (5%), Entamoeba coli (5%), and Cryptosporidium (5%). Shigella, Aeromonas, Plesiomonas, Vibrio, Campylobacter, and Salmonella were not detected. Of the eight ETEC cases, one was colonization factor antigen (CFA)/I only, one was both CFA/I and CFA/III, three were CFA/II, two were CFA/IV, and two were CFA-negative. Antibiograms of the ETEC and enteroadherent E. coli strains showed that all isolates were susceptible to norfloxacin, ciprofloxacin, and nalidixic acid but resistant to ampicillin, tetracycline, chloramphenicol, and sulfamethoxazole.

Prevalence of antibiotic resistance among Egyptian Salmonella typhi strains.

This report describes the resistance of 537 Salmonella typhi isolates identified in Egypt between 1990-1994. Results indicated a high isolation rate for multiple resistant S. typhi (> 71% of isolates collected in 1992-93), particularly to the three standard drug regimens of the clinically relevant antibiotics; ampicillin, chloramphenicol and trimethoprim-sulfamethoxazole. This adds to the complexity and difficulty of treating infections caused by these organisms. Resistance of S. typhi was associated with a transferable 120 MD plasmid. The organism was sensitive to amikacin, aztreonam, cephalothin, ceftriaxone, gentamicin and nalidixic acid, suggesting the use of aztreonam and ceftriaxone as alternative therapeutic drugs for the treatment of multidrug-resistant S. typhi. These results may provide a clinically useful evaluation of the spread and acquisition of resistance among S. typhi strains in Egypt.