Biomedical subjects
Publications and source records attributed to D Cahan.
A strain of Citrobacter freundii possessing the factors O:4,27 of Salmonella, without factor O:12, may be used for preparation of a diagnostic serum for identification of strains of Salmonella sub-species I belonging to O-group B, without absorption.
An antigenic scheme for Citrobacter koseri was described previously and consisted of 14 'O' antigens. Three additional antigens are now added to the scheme and type strains for these antigens are designated. Their origins and their biochemical and serological reactions are described.
An antigenic scheme, based on the determination of 17 somatic and 9 flagellar antigens, is proposed for Citrobacter koseri. Seven of the flagellar antigens constituted the specific phase (a through g), and the others (1 and 2) were nonspecific. Of the 238 theoretically possible serotypes, 48 were identified among 680 cultures examined.
A new Salmonella serovar, Salmonella eingedi, was isolated from the intestinal content of a snake, Coluber rhodorhachis, and later also from the diarrheal stools of two children.
Six new Salmonella sub-genus III serotypes (Arizona) were isolated from snakes in Israel. Their antigenic structure was established as follows: S. arizonae 16:Z52:Z35 (Ar.25:26-21); S. arizonae 18:1,v:e,n,x,z15 (Ar.7a,7b:23-28); S. arizonae 21:i:1,5(7) (Ar.22:33-30); S. arizonae 41:c:e,n,x,z15 (Ar.13:32-28); S. arizonae 51:k:z35 (Ar.1,2:29-21); and S. arizonae 53:1,v:z35 (Ar.1,4:23-21).
Forty-seven strains of Citrobacter diversus were isolated during a 12-month period from clinical material obtained from patients in a general hospital in Israel. The majority of cultures (38) were recovered from urine and wound discharges. There was one case of septicemia. The biochemical reactions of all cultures were typical for this species, except one that was anaerogenic, and they could be divided into five biotypes (a through e). Thirty-nine strains were identified serologically and found to belong to one of seven O groups described by Gross and Rowe (1974). All cultures were sensitive to tetracycline and nalidixic acid. All strains were resistant to carbenicillin and ampicillin and produced beta-lactamase.
Ninety-four (77.7%) of the 121 snakes captured during the years 1974-1975 in the Judean desert were found to carry Salmonella and/or Arizona organism. Sixty-six snakes (54.4%) harboured only one serotype. From 19 animals (15.7%) both Salmonella and Arizona organisms were isolated. From 9 snakes (7.5%) 2 or 3 serotypes of Arizona were isolated. Only 27 snakes (22,3%) harboured no detectable Salmonella nor Arizona in their intestinal contents.
A method is presented for the indirect detection of Vibrio cholerae by the multiplication of two specific bacteriophages: phiH74/64 for El-Tor vibrios, and phage group IV (Mukerjee) for classical vibrios. The product to be examined is seeded in alkaline tryptone water for enrichment, as in the classical method, and is then incubated for 6 h at 37 C. Thereafter, a loopful is transferred to each of two nutrient broth (pH 9) tubes. One of these receives a drop of phage phiH74/64; the other receives a drop of phage group IV. The stock phages are diluted so as to contain about 3,800 plaque-forming units in one drop; this is the maximum amount which, when added to 10 ml of broth, will not be detected in a loopful of 1 mm diameter. The tubes containing phage phiH74/64 are incubated at 42 C; those with phage group IV are incubated at 37 C. After 18 h the cultures are killed by agitation with chloroform, and a 1-mm loopful is deposited on a layer seeded with the detector strains: Makassar 757 for El-Tor phage and V. cholerae 154 for classical cholera phage. After 4 to 5 h at 37 C, lysis appears on the spot areas if there has been phage multiplication in the respective broth tubes. With experimentally contaminated sewage water, vegetables, or stools, 1 to 10 cholera vibrios were detected in every sample. In rare cases, false-positive results were obtained by multiplication of the phage on non-cholera vibrios.
Different vegetables were contaminated with sewage water containing large amounts of El Tor vibrios, and the viability of these vibrios was studied under defined conditions of storage. During the dry season (summer) in Jerusalem, the El Tor vibrios survived for up to 24 hr on parsley, 24 to 30 hr on tomatoes and carrots, 24 to 48 hr on cucumbers, peppers and okra and two to three days on lettuce, when the vegetables were stored at room temperature. The survival time was longer during the rainy season or during storage of the vegetables in a refrigerator. It was also prolonged on damaged vegetables. The El Tor vibrios survived for only a few hours on vegetables exposed to sunlight. The El Tor vibrios survived for 12 to 24 days in experimentally contaminated sewage water, and for up to 10 days in sewage-contaminated soil. The El Tor bacteriophage persisted for up to 36 days on phage-contaminated vegetables.
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