Yogurt containing bioactive molecules produced by Lactobacillus acidophilus La-5 exerts a protective effect against enterohemorrhagic Escherichia coli in mice.

An active fraction extracted from Lactobacillus acidophilus La5 cell-free spent medium (LAla-5AF) was incorporated in a dairy matrix and tested to assess its antivirulent effect against enterohemorrhagic Escherichia coli (EHEC). Mice in experimental groups were fed for 4 days with yogurt supplemented with LAla-5AF. On the fifth day, mice were challenged with a single dose (10(7) CFU per mouse) of E. coli O157:H7. The clinical manifestations of the infection were significantly less severe in mice fed the yogurt supplemented with LAla-5AF. EHEC attachment and colonization was attenuated by LAla-5AF. Tumor necrosis factor alpha production was down-regulated, which might indicate a protective effect in the kidney during EHEC infection. To investigate the mechanisms associated with the in vivo effects observed, LAla-5AF was tested by reverse transcription real-time PCR to confirm its effects on the expression of several virulence genes of EHEC O157. The results showed that these fractions were able to down-regulate several virulence genes of EHEC, including stxB2, qseA, luxS, tir, ler, eaeA, and hlyB.

Studies of metabolites in diarrheal stool specimens positive for Klebsiella, Serratia, and Proteus spp. by frequency-pulsed electron-capture gas chromatography.

Diarrheal stools from infants from which Klebsiella pneumoniae, Serratia liquefaciens, and Proteus mirabilis were isolated as possible causative agents of diarrhea were studied. These stools, along with control stool specimens which were collected from infants in the same village of Tamooh (near Cairo, Egypt), were analyzed by frequency-pulsed electron-capture gas chromatography (FPEC-GC). Watery stools and formed stools, to which distilled water was added, were centrifuged, and the supernatant was extracted with organic solvents and derivatized with specific functional group reagents to form electron-absorbing derivatives of carboxylic acids, hydroxy acids, alcohols, and amines. Results from the study showed distinct differences in FPEC-GC profiles of stools positive for K. pneumoniae, S. liquefaciens, and P. mirabilis. The major differences found were that diarrheal stools from which K. pneumoniae was isolated contained acetoin, a hydroxy acid-labeled peak F, and an unidentified amine, peak A. S. liquefaciens diarrheal stools had FPEC-GC profiles like the controls with the exception that an amine, peak A, was detected. The diarrhel stools containing P. mirabilis produced a distinct amine profile.

Frequency-pulsed electron-capture gas-liquid chromatographic studies of chemical changes in sera of patients with schistosomiasis.

Sera from well documented cases of Schistosoma mansoni and S. haematobium infections as well as controls, were studied by frequency-pulsed electron-capture gas--liquid chromatography (FPEL-GLC) and mass spectrometry for detection of carboxylic acids and amines. Many carboxylic acids and unidentified peaks were detected. In a few serum specimens from infected patients, putrescine and cadaverine were detected. Indications are that in these few patients with high egg counts enough diamines were present to possibly produce amine toxicity. Following the initial investigation, the basic chloroform extractions, which contained amines, were further studied by FPEC-GLC with the aid of splitless injection and a capillary column. Several amines were detected which seemed to be related to schistosomiasis. Mass spectra were obtained on an unidentified schistosamine peak. The possible significance of the data is discussed.

Studies of metabolites in diarrheal stool specimens containing Shigella species by frequency-pulsed electron capture gas-liquid chromatography.

Eleven diarrheal stool specimens and 10 control stool specimens from Cairo, Egypt, were studied by frequency-pulsed electron capture gas-liquid chromatography (FPEC-GLC). Four cases involving Shigella sonnei, three cases involving Shigella boydii, and four cases involving Shigella flexneri were studied. The aqueous stools were centrifuged, extracted with organic solvents, and derivatized to form specific electron-capturing derivatives of carboxylic acids, alcohols, hydroxy acids, and amines. Analyses were performed on high-resolution glass columns with an instrument equipped with an extremely sensitive electron capture detector that is specific for the detection of electron-capturing compounds. The diarrheal stools studied had specific FPEC-GLC profiles and contained metabolic markers that readily distinguished between the Shigella spp. studied and Escherichia coli producing heat-stable or heat-labile enterotoxins. S. sonnei stools contained hexanoic acid, 2-hydroxy-4-methylmethiobutyric acid, and some unidentified alcohols that distinguished this organism from other enteric pathogens. S. boydii produced an acid that was unique for this species, and S. flexneri produced alcohols that could be used to distinguish between it and other enteric organisms. The FPEC-GLC profiles obtained during this study were also very different from those reported earlier for Clostridium difficile and rotavirus. This study presents further evidence that the selectivity and sensitivity of FPEC-GLC techniques can be used to rapidly identify causative agents of diarrhea and detect physiological changes that occur in the gut during the course of diarrheal illness.

Rapid differentiation of enterotoxigenic Escherichia coli that produce heat-stable and heat-labile toxins by frequency-pulsed electron capture gas-liquid chromatography analysis of diarrheal stool specimens.

Thirty-three stool specimens from infants in the village of Tamooh near Cairo, Egypt, were studied by frequency-pulsed electron capture gas-liquid chromatography (FPEC-GLC). In 13 of the diarrheal cases, the suspected causative agent isolated was Escherichia coli which produced heat-stable toxin (ST), and in 10 other cases E. coli that produced heat-labile toxin (LT) were isolated. Ten control stool samples, collected from infants from whom no pathogenic organisms were isolated, were analyzed at the same time. Comparisons also were made against healthy control stools from individuals in the United States who had been previously analyzed by FPEC-GLC (Brooks et al., J. Clin. Microbiol. 20:549-560, 1984). The stools were suspended in water and centrifuged, and the supernatant was extracted with organic solvents and derivatized to form electron-capturing derivatives of carboxylic acids, hydroxy acids, alcohols, and amines. Results from the study showed distinct differences among the FPEC-GLC profiles of E. coli ST-positive stools, of E. coli LT-positive stools, and of the control stool samples. An unidentified compound appearing in the ether-soluble hydroxy acid fraction from E. coli ST-positive stools was tentatively identified by mass spectrometry as 6-methoxy-2-hydroxyhexanoic acid. 6-Methoxy-2-hydroxyhexanoic acid was found in all stools that contained E. coli ST but was not present either in stools from which E. coli LT was isolated or in control samples. 6-Methoxy-2-hydroxyhexanoic acid may prove to be an important marker for use in the identification of E. coli ST. In addition to 6-methoxy-2-hydroxyhexanoic acid, the carboxylic acid, alcohol, and amine FPEC-GLC profiles obtained from stools were very different between these two organisms. The data indicate that FPEC-GLC analysis of diarrheal stool specimens might be a rapid way to distinguish diarrhea caused by E. coli ST, E. coli LT, Clostridium difficile, and rotavirus.

Identification of diethylene glycol in sera from Egyptian children by frequency-pulsed electron-capture gas-liquid chromatography.

Sera taken from fifteen patients (from Kerdasa village near Cairo, Egypt) infected with Schistosoma haematobium, with eggs present in the urine, were studied by frequency-pulsed electron-capture gas-liquid chromatography (FPEC-GLC). Some of the patients were treated with metrifonate and again studied by FPEC-GLC. Diethylene glycol was detected in the sera of untreated patients infected with S. haematobium. This compound was identified by negative chemical ionization and electron-impact mass spectrometry. Initially we suspected that the build-up of diethylene glycol in these patients was caused by schistosomiasis infection. However, in a follow-up blind-coded study using FPEC-GLC, which included 37 sera from Kerdasa and Tamooh villages near Cairo, Egypt, we detected diethylene glycol in eleven samples, four of which were controls from the villages. These latter findings indicate that the source of diethylene glycol might be the environment or foodstuffs, but the specific source has not been determined. Regardless of the source, diethylene glycol could affect the health of these Egyptian children by causing a narcotic effect, increased bladder stones, and increased numbers of bladder tumours.

Assessment of efficacy of praziquantel against Schistosoma mansoni infection.

In order to assess the efficacy of praziquantel against Schistosoma mansoni infection, a clinical trial was carried out in Namool village in patients with different intensities of infection according to the geometric mean egg count. Different doses were given (20, 30, 40 mg/kg body weight). A parasitological follow-up was carried out after 1 and 6 months from treatment. The percentage of cure was high and reached 89.4% among the low-egg-count group who received 40 mg/kg body weight. A high percentage of reduction was noted in the mean egg count of the non-cured cases which reached 92.6% in the high-egg-count group who received 40 mg/kg body weight of praziquantel. Mild side effects increased in frequency as dosage increased, abdominal disturbance, vomiting and fever. Praziquantel seems to be an ideal drug against Schistosoma mansoni infection especially for mass treatment as it is given in a single oral dose.