Long-term bacterial profile of refrigerated ground beef made from carcass tissue, experimentally contaminated with pathogens and spoilage bacteria after hot water, alkaline, or organic acid washes

The effects of 2% (vol/vol) lactic acid (LA), 2% (vol/vol) acetic acid (AA), 12% (wt/vol) trisodium phosphate (TSP), 72 degrees C water (HW), and 32 degrees C water (W) washes on bacterial populations which were introduced onto beef carcass surfaces after wash treatments were determined up to 21 days of storage at 4 degrees C of packaged ground beef prepared from the treated and inoculated carcasses. Beef carcass necks were collected from cattle immediately after harvest and subjected to the above treatments or left untreated (control). Neck meat was then inoculated with low levels (ca. <2 log10) of Listeria innocua, Salmonella typhimurium, Escherichia coli O157:H7, and Clostridium sporogenes contained in a bovine fecal cocktail. In general, growth of these four bacteria, aerobic bacteria, lactic acid bacteria, and pseudomonads was suppressed or not observed in the ground beef when LA, AA, or TSP treatments were used as compared to the untreated control. HW or W washes offered little suppression of growth of pathogens during subsequent storage of ground beef when these bacteria were introduced onto beef tissue posttreatment. Of the treatments used, a final LA or AA wash during the processing of beef carcasses offers the best residual efficacy for suppression of pathogen proliferation in ground beef during long-term refrigerated storage or short-term abusive temperature storage if these bacteria contaminate the carcass immediately after carcass processing.     

Long-term effect of alkaline, organic acid, or hot water washes on the microbial profile of refrigerated beef contaminated with bacterial pathogens after washing

One hundred consecutive patients (81 male and 19 female) with unstable angina pectoris undergoing coronary angiography were divided according to Braunwald's clinical classification. Seventeen (17%) patients had new onset angina (class I), 68 (68%) sub-acute angina (class II) and 15 (15%) had acute rest angina (class III). Twenty-seven (27%) patients had secondary unstable angina pectoris (class A), 49 (49%) primary unstable angina (class B) and 24 (24%) had post-infarction unstable angina (class C). ST-T wave changes on ECG were present in 54 (54%) while absent in 46 (46%) patients. On coronary angiography, 26 (26%) patients had single vessel disease, 30 (30%) double vessel disease and 39 (39%) patients had triple vessel disease. Five (5%) patients were found to have normal coronaries. Classification of patients according to Braunwald's clinical classification showed single vessel disease to be higher in class I as compared to class II (47% vs 22%; p = 0.04) and classes III (47% vs 20%; p<0.01). Single vessel disease was found to be higher in class C as compared to class B (41.7% vs 16.4; p = 0.01). Double vessel disease was higher in class B as compared to class A (40.8% vs 18.5%, p = 0.04). Triple vessel disease incidence was not found to be significantly different among different clinical classes. Morphology of coronary artery lesions was classified according to Ambrose's classification. Out of the total of 248 lesions in the whole study group, there were 68 (27.42%) concentric lesions, 55 (22.18%) eccentric type I lesions, 23 (9.27%) eccentric type II lesions, 42 (16.94%) multiple irregularity lesions and 60 (24.19%) totally occluded lesions. Concentric lesions were found to be higher in class C as compared to class B (40% vs 19.8%; p = 0.014). Statistically significant difference was not present in the distribution of other morphological type of lesions among different clinical classes. In the whole study group, intra-luminal thrombus was found to be present in 17 (17%) of patients. Distribution of intra-luminal thrombus according to Braunwald's classification showed that none of the patients in class I had intra-luminal thrombus, while 13 (19.1%) patients in class II and 4(26.7%) in class III had intra-luminal thrombus. The difference in the occurrence of intra-luminal thrombus between class I and class II (p = 0.004) and class I and class III (p = 0 .03 was found to be significant. Thus, majority of patients undergoing coronary angiography had primary sub-acute rest angina. Single vessel disease was higher in new onset angina. Patients with unstable angina pectoris and ST-T changes on ECG had higher number of lesions per patient and higher eccentric type I lesions. Intra-luminal thrombus was more frequently encountered with acute rest angina. However, the distribution of different morphological type of lesions on coronary angiography did not differ significantly in different clinical classes of unstable angina pectoris divided according to Braunwald's classification.