Biomedical subjects

S Kadis

Publications and source records attributed to S Kadis.

33 records · Page 2Linked to original sources

PubMed1982

Enterotoxin production and resistance to antimicrobial agents in porcine and bovine Escherichia coli strains.

A select group of porcine and bovine Escherichia coli strains capable of causing diarrheal disease in neonatal pigs and calves, respectively, were tested for enterotoxin production and resistance to 23 different antimicrobial agents. Thirty-four of the 39 porcine strains tested were enterotoxigenic; that is, they synthesized heat-stable (ST), together with heat-labile (LT), enterotoxin; ST toxin alone, or LT toxin alone. Fourteen of the 15 bovine strains tested produced ST toxin only, whereas 1 strain elaborated LT toxin only. All of the strains were multiple drug resistant. Among the porcine strains, 2 were resistant to 6 of the antimicrobial agents, and 1 was resistant to 18 of the drugs. All of these strains were resistant to cloxacillin, lincomycin, and penicillin G. None of them was resistant to chloramphenicol, colistin, gentamicin, polymyxin B, or nalidixic acid. One of the bovine strains was resistant to 7 of the drugs, and 1 strain was resistant to 17 of these antimicrobial agents. All of the bovine strains exhibited resistance to cloxacillin, lincomycin, novobiocin, pencillin G, sulfathiazole, sulfamethizole, and triple sulfa (sulfadiazine, sulfamerazine, and sulfamethazine). None of these strains showed resistance to gentamicin, nalidixic acid, nitrofurazone, or nitrofurantoin.

Animals↗

PubMed1981

Evaluation of penicillin in conjunction with acetohydroxamic acid in treatment of experimental Corynebacterium renale pyelonephritis.

The therapeutic efficacies of procaine penicillin G and acetohydroxamic acid, when administered alone or in combination, were evaluated in rats with experimentally induced pyelonephritis at 24 h and 4 days after intrabladder inoculation with Corynebacterium renale. Penicillin alone prevented the development of pyelonephritis when administered in a once daily dose of 50,000 units for 5 days beginning within 24 h of infection challenge. However, if therapy was not initiated until the 4th day after induction of infection, pyelonephritis ensued which could not be differentiated from untreated rat pyelonephritis. Acetohydroxamic acid, when administered by itself in a once daily dose of 100 mg for 5 days, was completely ineffective whether therapy was started at 24 h or 4 days after initiation of infection. On the other hand, the combination of penicillin and acetohydroxamic acid prevented progression of pyelonephritic infection and facilitated healing when rat kidneys were examined at 14 and 30 days after initiation of infection. The kidneys of those rats sacrificed at 30 days after cessation of treatment revealed the presence of increased interstitial fibrous connective tissue in the renal medulla suggesting prior damage followed by recovery and repair. In vitro studies on the action of penicillin and acetohydroxamic acid against C. renale revealed no signs of synergism or antagonism.

Animals↗

PubMed1979

Antibody formation in Corynebacterium renale-induced experimental pyelonephritis in the rat.

The immune defense system of the kidney was studied by inducing ascending pyelonephritis in rats with Corynebacterium renale. With the fluorescent antibody technique, C renale organisms were observed in the renal pelvis, but were not coated with antibody until they reached the medulla. Histopathologic evaluation of renal tissues collected serially after inoculation confirmed the presence of infection in the medulla when antibody coating occurred. Serum anti-C renale antibody concentrations increased after antibody-coated bacteria appeared in the urine and kidney. Free anti-C renale antibody was not detected in urine from infected rats, using the microagglutination assay. Antibody coating appears to occur only after C renale organisms invade the medulla during ascending pyelonephritis.

Animals↗

PubMed1978

Influence of iron on Corynebacterium renale-induced pyelonephritis in a rat experimental model.

Growth of Corynebacterium renale in vitro on low-iron medium (1.34 micron) was only slightly less than that on high-iron media (7.16 and 9.85 micron). However, studies on C. renale-induced pyelonephritis using the rat as an experimental model revealed that C. renale cultivated in high-iron media was capable of producing pyelonephritis, but when grown on low-iron medium, these bacteria were noninfective. This apparent avirulence of the bacteria cultivated on low levels of iron could be reversed by injecting the rats intramuscularly with ferric ammonium citrate.

Animals↗

PubMed1978

Minimal nitrogen requirements of Corynebacterium renal strains.

Corynebacterium renale strain 10849 was grown in a chemically defined medium containing glucosamine, ammonium sulfate, and 5 amino acids as possible nitrogen sources. Although glucosamine was slightly stimulatory, its omission from the medium had a minimal effect on growth, and washed cells introduced into glucosamine-free medium grew readily through 10 serial transfers, demonstrating that this compound was not required for growth. Individual omissions of isoleucine, valine, methionine, and glutamine resulted in lengthened lag periods and reduced growth rates in initial transfers, but recovery occurred in subsequent serial transfers so that by the 3rd or 4th transfer, growth rates and cell crops were only slightly less than in control cultures in complete medium. Omission of cystine resulted in a permanently low growth rate and reduced cell crop, but this was remedied by substituting various nonnitrogenous compounds containing reduced sulfur. Strain 10849 and 6 additional strains were then serially cultured in a minimal defined medium in which sodium thioglycolate provided reduced sulfur and ammonium sulfate served as sole nitrogen source. Since only ammonium ion was required as the nitrogen source, it could be concluded that C renale, which rapidly hydrolyzes urea, should find an adequate source of nitrogen for growth in the urinary tract of animals.

Ammonia↗

PubMed1977

Experimental Rat model for Corynebacterium renale-induced pyelonephritis.

The laboratory rat was able to serve as a model for ascending pyelonephritis after implantation of a zinc disk coated with Corynebacterium renale into the urinary bladder because it satisfied three different criteria for infection. The production of an alkaline urine and the presence of significant numbers of C. renale in the kidneys, as well as distinct pyelonephritic lesions as revealed by histological examination, were observed in all rats infected with C. renale. Control rats that harbored sterile disks in their urinary bladders exhibited none of the above effects.

Animals↗

PubMed1977

Influence of acetohydroxamic acid on experimental Corynebacterium renale pyelonephritis.

The role of Corynebacterium renale urease in the establishment of pyelonephritis was studied by the oral administration of acetohydroxamic acid (AHA), a urease inhibitor, to experimentally infected rats. The bacteria were introduced by surgical insertion of a zinc disc containing 1 X 10(6) colony-forming units of C-renale into the urinary bladder whereas sterile discs were implanted in the bladders of the control animals. Daily administration of AHA via the drinking water did not halt the development of pyelonephritis. Larger doses, given by gavage, did accomplish this goal; that is, the pH of the urine was lowered, the number of colony-forming units of C. renale in the kidney was reduced drastically, and pyelonephritic lesions were observed in the kidney by light-microscopic examination. All experimental rats developed cystitis in varying degrees of severity. About 70% of the intact AHA given by gavage was excreted in the urine 24 h after administration of this compound. Rats implanted with a urease-negative mutant of C. renale displayed no signs of pyelonephritis but did develop cystitis.

Animals↗

PubMed1976

Effect of hydroxamic acids on growth and urease activity in Corynebacterium renale.

Studies were conducted on the effect of four different hydroxamic acids (HA), hydroxyurea, acetohydroxamic acid, p-flurobenzoylhydroxamic acid and sorbylhydroxamic acid, on the growth and urease activity of Corynebacterium renale. The addition of each of these HA, at concentrations ranging form 10(-3) to 10(-5) M, to medium containing urea as the sole nitrogen source resulted in a lengthened lag period of growth the extent of which depended upon the concentration of each HA tested as well as the structure of the compound; that is, the size and (or) complexity of the side chain attached to the common terminal group of the molecule. However, the maximal growth levels achieved following conclusion of the exponential phase were not affected by the HA. Investigations on the effect of these HA on the urease activity of intact cells as well as cell-free extracts revealed that in each case the enzymatic activity was inhibited by each of the HA tested. The extent of inhibition with the intact cells was aobut one-half of that observed with cell-free extracts. Direct incubation of cell-free extracts as well as intact cells with each of the HA tested was required for maximal inhibition.

Cell-Free System↗

PubMed1974

Urea utilization by Leptospira.

One representative of each of five different pathogenic serotypes of Leptospira as well as one saprophytic strain were capable of growing on medium containing urea in place of an ammonium salt as a nitrogen source. Growth of all of the organisms tested on 1% urea was substantial, but only those that exhibited strong urease activity could grow to any appreciable extent on urea at a concentration as high as 2%. Intact urea-grown cells of the pathogenic serotypes tested (grippotyphosa and icterohaemorrhagiae) exhibited urease activity, with the level of activity of the former being considerably greater. No urease could be detected in cells of the saprophytic strain. When the pathogenic leptospires were sonicated or treated with toluene, the urease activity was greatly enhanced. When cultivated on NH(4)Cl, neither intact nor disrupted cells of any of the strains tested exhibited any urease activity. Cells of the grippotyphosa and icterohaemorrhagiae strains exhibited diauxic growth when cultivated in the presence of both NH(4)Cl and urea, whereas only monophasic growth could be detected for the saprophytic test strain. The experimental data on urea utilization and urease activity, when considered in the light of previously reported findings on leptospiral pathology, renal physiology, and the role of urease in other bacterial infections, suggests a significant role for leptospiral urease (in addition to other factors) in determining localization of the organism in the kidney and contributing to the resultant kidney pathology.

Ammonium Chloride↗

PubMed1971