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Biomedical subjects

M Finland

Publications and source records attributed to M Finland.

At least 109 records · Page 6Linked to original sources

Serratia marcescens: biochemical, serological, and epidemiological characteristics and antibiotic susceptibility of strains isolated at Boston City Hospital.

The biochemical, serological, and epidemiological characteristics of 95 strains of Serratia marcescens isolated at the Boston City Hospital were examined. Several strains were shown to be endemic, and the majority of isolates were cultured from urine or respiratory secretions. Serratia species were highly resistant to polymyxin B and the cephalosporins, and various proportions were also resistant to other antibiotics including kanamycin, but all of the isolates were sensitive to gentamicin. The appearance of resistance to kanamycin and nalidixic acid among endemic strains was demonstrated. The nosocomial nature of Serratia infections, particularly those involving the urinary tract, was confirmed. Many clinical bacteriology laboratories currently fail to identify the nonpigmented strains.

Boston↗

Effect of pH of medium and size of inoculum on activity of antibiotics against group D Streptococcus (Enterococcus).

Seventy-one clinical isolates of 5 species of group D Streptococcus (Enterococcus) were tested for susceptibility to 15 antibiotics at pH 5.0, 7.4, and 8.5. Penicillin G, ampicillin, cephalothin, cephaloridine, and novobiocin were considerably more active against all strains at pH 5.0 than in the more alkaline media. On the other hand, lincomycin, clindimycin, erythromycin, and gentamicin were moderately to markedly more active at pH 8.5. No important differences were noted in the susceptibility of the strains to kanamycin and streptomycin, at the pH levels tested, but the organisms were quite resistant to them in these tests. The various species differed quantitatively in their susceptibility to the individual drugs and in the effects of pH. The size of the inoculum also had a variable effect on susceptibility, depending on the species of Enterococcus, the antibiotics, and the pH of the test medium. The data suggest that, in the antibiotic treatment of urinary tract infections caused by Enterococcus, attempts should be made to achieve the optimum pH in the urine, particularly in view of the fact that organisms of this group are often resistant to several antibiotics in the usual tests.

Anti-Bacterial Agents↗

Lysosomal and ultrastructural changes in human "toxic" neutrophils during bacterial infection.

"Toxic" neutrophils from humans with severe bacterial infections, identified by the presence of Döhle bodies, "toxic" granules, and vacuoles were shown to differ from normal neutrophils both in ultrastructure and in lysosome activity. Döhle bodies were identified as lamellar aggregates of rough endoplasmic reticulum. Toxic granules corresponded to the azurophilic granules usually identified by Romanowsky stains only in neutrophil precursors. By electron microscopy such granules were large, electron-dense, and peroxidase positive; they could usually be distinguished from the smaller, less dense, "specific" granules also present in control neutrophils, but in the latter they became visible by light microscopy only after prolonged staining or following fixation with glutaraldehyde. These observations suggest that toxic granules represent an abnormal staining reaction of the large dense granules in the toxic cells, and not phagocytized material, newly formed abnormal granules or autophagic bodies. Alkaline phosphatase activity was significantly greater in toxic neutrophils than in normal ones; 80% of the activity of both was located in the lysosome fraction. Beta glucuronidase was normal. Total acid phosphatase was normal, but the percentage located in the nonlysosome fraction of toxic neutrophils was increased, suggesting that lysosomes were "labilized." Formation of neutral red vacuoles in supravitally stained preparations, an index of lysosome activity, occurred more rapidly in toxic neutrophils. This reaction paralleled degranulation and the formation of clear vacuoles in unstained wet mounts and could be blocked by colchicine, a lysosome stabilizer, or enhanced by procedures which activate lysosomes. "Autophagic" vacuoles were observed by electron microscopy in some toxic neutrophils. These observations are discussed in relation to the concept that the "toxic" neutrophils in severe bacterial infection reflect cellular immaturity and/or stimulation or degeneration.

Alkaline Phosphatase↗