Removal of Escherichia coli and Enterococcus faecalis after Hand Washing with Antimicrobial and Nonantimicrobial Soap and Persistence of These Bacteria in Rinsates

Food handlers are important sources of contamination in the agricultural environment. This study was conducted (i) to evaluate the activity of antimicrobial soaps against Escherichia coli and Enterococcus faecalis using a hand washing model with soiled hands and (ii) to determine the survival and persistence of these bacteria in rinsates. Sterilized agricultural soil from tomato and pepper farms was inoculated with E. coli or E. faecalis at 10³ or 10⁶ CFU/g. Decontaminated hands were placed in contact with contaminated soil for 2 min and were then washed with soaps with or without antimicrobial compounds (citric extracts, chloroxylenol, triclosan, or chlorhexidine gluconate). As the control, hands were washed with sterile distilled water. The levels of bacteria remaining on the hands and recovered from the rinsates were determined using a membrane filtration method and selective media. Antimicrobial soaps removed levels of E. coli similar to those removed by distilled water and nonantimicrobial soap on hands contaminated with E. coli at 10³ CFU/g. However, when hands were contaminated with E. coli at 10⁶ CFU/g, more E. coli was removed with the chlorhexidine gluconate soap. When hands were contaminated with E. faecalis at 10³ CFU/g, bacteria were removed more effectively with soaps containing chloroxylenol or chlorhexidine gluconate. When hands were contaminated with E. faecalis at 10⁶ CFU/g, all of the antimicrobial soaps were more effective for removing the bacteria than were distilled water and nonantimicrobial soap. E. coli grew in all of the hand washing rinsates except that containing triclosan, whereas E. faecalis from the 10⁶ CFU/g treatments grew in rinsates containing chlorhexidine gluconate and in the distilled water rinsates. Washing with antimicrobial soap was more effective for reducing bacteria on soiled hands than was washing with water or nonantimicrobial soap. However, persistence or growth of bacteria in these rinsates poses health risks.

Antibacterial and antioxidant activities in extracts of fully grown cladodes of 8 cultivars of cactus pear

The antimicrobial and antioxidant activities of some cultivars of the nopal cactus have not been determined. In this study, 8 cultivars of nopal cacti from Mexico were assayed for phenolic content, antioxidant activities, and antimicrobial activities against Campylobacter Jejuni, Vibrio cholera, and Clostridium Perfringens. Plant material was washed, dried, and macerated in methanol. Minimum bactericidal concentrations (MBCs) were determined using the broth microdilution method. Antioxidant activities were quantitatively determined using spectrophotometric methods. The MCBs of the nopal cacti ranged from 1.1 to 12.5 mg/mL for c. jejuni, 4.4 to 30 mg/mL for V. cholera, and 0.8 to 16 mg/mL for C. perfringens in the cultivars Cardon Blanco, Real de Catorce, and Jalpa, respectively. High quantities of total phenols and total flavonoids were found in the Jalpa cacti (3.80 mg of gallic acid equivalent GAE/g dry weight [DW] and 36.64 mg of quercetin equivalents [QE]/g DW, respectively). 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activities (RSA) were correlated to bioactive compound contents. The Villanueva cacti had the highest %RSA at 42.31%, and the lowest activity was recorded in Copena V1 at 19.98%. In conclusion, we found that some of the 8 cactus pear cultivars studied may be used for their antioxidant compounds or antimicrobials to control or prevent the contamination of foods.

Extracts of Agave americana inhibit aflatoxin production in Aspergillus parasiticus

Toxigenic fungi invade crops prior to harvest as well as during storage and produce harmful, even carcinogenic toxins such as aflatoxins. Since consumers demand safe commodities, and due to enhanced public awareness of the dangers of many synthetic fungicides, the importance of investigating alternative, natural products to control these toxigenic fungi is clear. This study investigated the effect of aqueous extracts of Agave americana on growth, conidia and aflatoxin production. Aspergillus parasiticus strains SRRC 148, SRRC 143 (Su-1), and A. parasiticus SRRC 162, a mutant (nor-) that accumulates norsolorinic acid (NOR, an orange-coloured intermediate of the aflatoxin pathway), were first inoculated into Adye and Mateles liquid medium, then plant extracts were added, and incubated at 28 °C for 7 days. Aflatoxin and norsolorinic acid were assayed by HPLC and spectrophotometry, respectively. While the extract of A. americana stimulated growth of the studied fungi, conidiogenesis, norsolorinic acid accumulation (in the nor- mutant), and aflatoxin production were significantly affected. The reduction was produced by the extracts at concentrations higher than 5-10 mg/ml, where all types of total aflatoxin analysed (aflatoxins B1, B2, G1 and G2) were reduced from 64% to >99% in the whole culture, and a reduction of 75% of norsolorinic acid. The results of the present work indicate that extracts of A. americana may be promising safe alternatives to harmful fungicides for controlling aflatoxin contamination.

A single mutation in the IF3 N-terminal domain perturbs the fidelity of translation initiation at three levels

Bacterial translation initiation factor 3 (IF3) is involved in the fidelity of translation initiation at several levels, including start-codon discrimination, mRNA translation, and initiator-tRNA selection. The IF3 C-terminal domain (CTD) is required for binding to the 30S ribosomal subunit. N-terminal domain (NTD) function is less certain, but likely contributes to initiation fidelity. Point mutations in either domain can decrease initiation fidelity, but C-terminal domain mutations may be indirect. Here, the Y75N substitution mutation in the NTD is examined in vitro and in vivo. IF3(Y75N) protein binds 30S subunits normally, but is defective in start-codon discrimination, inhibition of initiation on leaderless mRNA, and initiator-tRNA selection, thereby establishing a direct role for the IF3 NTD in these initiation processes. A model illustrating how IF3 modulates an inherent function of the 30S subunit is discussed.

Role of ischemic preconditioning and the portosystemic shunt in the prevention of liver and lung damage after rat liver transplantation

BACKGROUND

This study evaluates whether surgical strategies such as the portosystemic shunt and ischemic preconditioning can protect against hepatic and pulmonary injury associated with liver transplantation.

METHODS

The effect of the portosystemic shunt, ischemic preconditioning, and both surgical procedures together were evaluated in rat liver transplantation. Alanine aminotransferase, hyaluronic acid levels in plasma, adenosine triphosphate and nucleotide levels in liver and edema, malondialdehyde levels, and myeloperoxidase activity were measured 24 hr posttransplantation. Plasmatic tumor necrosis factor (TNF) levels were measured as a possible proinflammatory factor responsible for hepatic and pulmonary damage associated with liver transplantation.

RESULTS

Hepatocyte and cell endothelial damage were observed in liver grafts subjected to 8 hr of cold ischemia. This was associated with increased plasma TNF levels and lung inflammatory response. Portosystemic shunt application in the recipient protected endothelial cells but did not confer an effective protection from hepatocyte damage or reduce the increased plasma TNF levels and lung damage after liver transplantation. However, preconditioning of the donor liver conferred protection against both the endothelial cell and hepatocyte damage observed after liver transplantation. Preconditioning also attenuated the increased plasma TNF release and pulmonary damage. The combination of both surgical strategies resulted in levels of liver injury, TNF, and lung damage similar to those seen after liver transplantation.

CONCLUSIONS

These findings indicate that ischemic preconditioning could be a preferred treatment to reduce hepatic and pulmonary damage associated with liver transplantation. However, this strategy may not be effective in several clinical situations requiring a portosystemic shunt.

Microbiological condition of ground meat retailed in Monterrey, Mexico

Eighty-eight samples of ground meat were randomly collected from retail stores in the metropolitan area of Monterrey, Mexico, and were analyzed for microbial contamination. Methods were those recommended by the Mexican regulation and/or the U.S. Food and Drug Administration. Over 75% of the samples contained > 10(5) total mesophilic microorganisms per g, and over 40% had >10(6) total coliforms per g. Fecal coliforms were present in most samples. Staphylococcus aureus was detected in 2.3% of the samples, Salmonella spp. in 11.4%, Listeria spp. in 62%, and L. monocytogenes in 16%. Escherichia coli was detected in 76% of samples, but none was serotype O157:H7. Shigella spp. was not found in any sample. Fusarium spp. and Mucor spp. were detected in 3.4% of the samples, and low levels of yeast in 93%. The microbiological quality of the ground meat analyzed was unsatisfactory, and the product could be an important cause of food poisoning.

Microbiological survey of retail herbs and spices from Mexican markets

In the present study, 304 samples of herbs and spices (garlic powder, cumin seeds, black pepper, oregano, and bay leaves) widely used in Mexico were analyzed for the presence of Bacillus cereus, Salmonella Typhi, Shigella dysenteriae, Escherichia coli, total and fecal coliforms, total mesophilic aerobic organisms, and fungi. Samples were nonpackaged or packaged in polyethylene bags or glass containers. High levels (10(5) to 10(7) CFU/g) of mesophilic aerobic microorganisms were found in most of the samples of garlic powder, cumin seed, and black pepper. Lower levels (<102 CFU/g) were found in oregano and bay leaves. Total and fecal coliforms counts were dependent on the type of packaging. More than 70% of the polyethylene-packaged samples had less than 10(3) CFU/g of microorganisms. Glass and nonpackaged spices showed lower levels of these microorganisms. B. cereus was present in 32 samples of which most were polyethylene packaged. The other pathogenic bacteria were not detected. Aspergillus niger was detected in 29% of the samples, Rhizopus sp. in 19%, and Penicillum sp. and Cunninghamella in 8%.