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Biomedical subjects

M S Simberkoff

Publications and source records attributed to M S Simberkoff.

At least 109 records · Page 6Linked to original sources
PubMed1975

Nosocomial infection caused by gentamicin-resistant, streptomycin-sensitive Klebsiella.

Resistance to gentamicin increased abruptly among nosocomial isolates of Klebsiella and Enterobacter at the New York Veterans Administration Hospital in 1973 and 1974. A prospective clinical survey revealed a greater incidence of true infection caused by Klebsiella than by Enterobacter. The initial site of implantation was usually the urinary tract. Multiple serotypes were involved, and one of these was found in rectal swabs of patients treated with antibiotics. Gentamicin resistance declined rapidly after the use of this antibiotic was restricted and increased several months after restrictions were removed. Gentamicin-resistant strains of Klebsiella were uniformly sensitive to amikacin; 75% were sensitive to polymyxin B and 70% to streptomycin. Antibiotic sensitivity among gram-negative pathogens might be preserved by a program in which the use of highly effective agents is periodically rotated.

Ampicillin↗
PubMed1975

Fungal endocarditis: analysis of 24 cases and review of the literature.

Fungal endocarditis occurs in heroin addicts, patients who have undergone cardiovascular surgery, and patients who are treated for prolonged periods with intravenous fluids and broad spectrum antibiotics. The organisms associated with endocardial infection differ in each of these groups. Candida parapsilosis is the fungal species most commonly isolated from narcotics addicts, Aspergillus species are most frequently found in patients after cardiovascular surgery, and Candida albicans occurs most frequently in patients who have received prolonged courses of intravenous fluids and antibiotics. Despite the availability of antifungal antibiotics and surgery, over 80% of patients with documented fungal endocarditis die of this infection. Thus, early diagnosis of fungal invasion and prevention of established endocardial infection are essential. Antifungal therapy and/or careful followup should be considered in patients in whom "transient fungemia" is documented by blood culture and serological and untrasonic techniques should be further evaluated as a means of early diagnosis.

Adolescent↗
PubMed1974

Synergy between cephalosporin and aminoglycoside antibiotics against Providencia and Proteus.

Clinical isolates of Providencia and Proteus with relative aminoglycoside resistance were tested for susceptibility to combinations of gentamicin or tobramycin with cephalothin or cefazolin. The minimal bactericidal concentration of aminoglycoside for one-third of the strains was reduced by fourfold or more in the presence of one-fourth of the minimal bactericidal concentration of either cephalosporin. This effect was achieved by clinically attainable concentrations of cephalothin or cefazolin.

Aminoglycosides↗
PubMed1973

In vitro bactericidal effectiveness of four aminoglycoside antibiotics.

The antibacterial activity of four aminoglycoside antibiotics (gentamicin, Sch 13706, tobramycin, and sisomicin) was tested against eight gram-negative and three gram-positive species. A total of 323 strains were studied by the broth dilution technique. Tobramycin and sisomicin had greater bacteriostatic and bactericidal activity against Pseudomonas strains than did gentamicin and Sch 13706. Of the four antibiotics, sisomicin was most active against Klebsiella, Enterobacter, Escherichia coli, indole-negative and -positive Proteus, and Streptococcus pyogenes. Gentamicin was most effective against Serratia. A fourfold or greater difference existed frequently between the minimal inhibitory and bactericidal concentrations of all antibiotics against Enterobacter and Serratia. This difference was greatest with tobramycin. Staphylococcus aureus was highly susceptible, Providencia relatively resistant, and enterococcus uniformly resistant to the antibiotics studied. Agar diffusion susceptibility testing with gentamicin and tobramycin showed that organisms susceptible to less than 6.2 mug/ml usually yielded zones 17 to 26 mm in diameters. Zones of 15 to 16 mm represented intermediate susceptibility which varied with the organism and antibiotic. Several Serratia strains required 6.2 to 12.5 mug of gentamicin/ml or 25 to 50 mug of tobramycin/ml for bactericidal activity despite minimal inhibitory concentrations of 0.09 to 3.1 mug/ml and zone sizes greater than 13 and 17 mm, respectively. Studies with Enterobacter and tobramycin yielded similar results.

Aminoglycosides↗
PubMed1971

The interaction in vitro between polymorphonuclear leukocytes and mycoplasma.

The interaction, between mycoplasma (PPLO) and human or rabbit leukocytes was examined in vitro. Upon incubation of M. hominis or M. arthritidis for 2 hr with rabbit peritoneal exudate granulocytes or leukocytes from human peripheral blood, no killing of mycoplasma was observed either in the presence or absence of type-specific antiserum. However, (14)CO(2) production from glucose-1-(14)C was stimulated up to 10-fold in the presence of live or heat-killed PPLO. The extent of stimulation depended upon the number of organisms and the presence of type-specific antiserum. The stimulation of (14)CO(2) production seems not because of tight adherence of PPLO to the leukocytes, since PPLO were quantitatively recovered in the medium after sedimenting the granulocytes. The enhanced conversion of medium lysolecithin to cellular lecithin that accompanies phagocytosis of polystyrene particles was significantly reduced when PPLO were also present. Mycoplasma alone elicited no stimulation of lecithin formation. Killing of E. coli, a microorganism readily engulfed and killed by leukocytes in vitro, was diminished when the leukocytes were preincubated with mycoplasma. These findings indicate that M. hominis and M. arthritidis are not ingested by granulocytes to any detectable extent, but that these organisms affect the leukocytes' metabolism and also impair phagocytosis of E. coli.

Animals↗
PubMed1969

Studies of PPLO infection. V. Inhibition of lymphocyte mitosis and antibody formation by mycoplasmal extracts.

Extracts of five arginine-utilizing mycoplasmas inhibit PHA-induced lymphocyte mitosis, while extracts of five glucose-utilizing mycoplasmas do not. Evidence is presented supporting the view that the inhibitory factor is the enzyme arginine deiminase. This enzyme inhibits the reactions of human lymphocytes to antigens as well as PHA, and the secondary production of antibody by rabbit lymph node fragments in vitro. Addition of enzyme to the cells several days after the initial mitotic or antigenic stimulus reduces, but does not abolish, further cellular activity. The production of serum proteins by hepatoma cells is totally unaffected by the mycoplasmal extract. It is concluded that arginine is an essential amino acid for the small lymphocyte, but not for the transformed cell nor for a number of other cell types. Suggestive evidence has been obtained that other enzymes similarly affect lymphocyte reactions.

Animals↗