Biomedical subjects
Publications and source records attributed to H D Isenberg.
Primary osteomyelitis in a teen-aged boy that mimicked Ewing's tumor radiologically showed small Gram-negative rods on the original smear. The organism isolated was an obligately anaerobic bacterium, finally identified as Clostridium sphenoides. This finding underlines the need for microbiologic analysis of orthopedic lesions.
A model system for the study of inflammation in vivo has been developed using the 16-h polyvinyl sponge implant in the rat. This system allows for simultaneous measurement of in vivo chemotaxis, volume of fluid influx, and fluid concentrations of lysosomal and lactic dehydrogenase (LDH) enzymes. In addition, the enzyme content of inflammatory fluid neutrophils may also be determined. A parallel time course of neutrophil and lysosomal enzyme influx into sponge implants was observed. This was characterized by an initial lag phase and a rapid increase between 5 and 16 h. The origin of supernatant LDH and lysosomal enzymes was studied with anti-neutrophil serum to produce agranulocytic rats. Inflammatory fluid in these rats was almost acellular and contained decreased concentrations of beta glucuronidase (-96%) and LDH (-74%). In control rats all of the supernatant beta glucuronidase could be accounted for by cell death and lysis, as estimated from measurements of soluble DNA. Only 15-20% of the LDH activity could be accounted for on the basis of cell lysis. The remainder was derived from neutrophil-mediated injury to connective tissue cells. Large intravascular doses of methylprednisolone markedly inhibited neutrophil influx into sponges and adjacent connective tissue. Secondary to decreased neutrophil influx, fewer neutrophils were available for lysis, and lysosomal enzyme levels in inflammatory fluid decreased. No evidence for intracellular or extracellular stabilization of neutrophil lysosomal granules by methylprenisolone was found.
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This cooperative study between a large clinical laboratory and a reference laboratory evaluated the performance of the expanded r/b system for identifying Enterobacteriaceae. The 2,200 cultures isolated in the normal hospital routine presented no problem of identification to the r/b system. About 250 "atypical" cultures which were exchanged between the collaborating laboratories were also identified accurately. The expanded r/b system was found to perform as well as most biochemical-physiological identification systems, and when used appropriately was highly satisfactory as a system for identification of Enterobacteriaceae.
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Clindamycin palmitate and potassium phenoxymethyl penicillin were evaluated in 103 children with upper respiratory illnesses and pharyngeal group A streptococci, from November 1970 to July 1971. The children were assigned randomly by weight to one of the antibiotic regimens given orally for 10 days. Clindamycin palmitate and potassium phenoxymethyl penicillin dosages were 75 and 125 mg, respectively, in 5 ml tid for children weighing less than 25 kg, and 150 and 250 mg, respectively, in 10 ml bid for children weighing 25 kg or more. Recurrences of the original streptococcal group A, M, and T types within 3 weeks after the end of treatment were classified as failures. The failure rates were: clindamycin palmitate, 10% (5 of 52), and potassium phenoxymethyl penicillin, 18% (9 of 51). Possible drug-related rashes were observed in 8 of 52 clindamycin palmitate-treated patients. The geometric mean minimal inhibitory concentrations of clindamycin and penicillin against 103 isolates of group A streptococci were 0.033 and 0.007 mug/ml, respectively. The serum concentrations about 70 min after ingesting 150 mg of clindamycin palmitate averaged 3.8 mug/ml and after 250 mg of potassium phenoxymethyl penicillin averaged 0.9 mug/ml. Clindamycin palmitate was as effective as potassium phenoxymethyl penicillin in eradicating group A streptococci from the pharynx in tid and bid regimens. Nevertheless, because of its rash-producing tendency in some patients and higher cost, clindamycin palmitate should not be preferred to penicillin for treatment of streptococcal sore throat in the non-penicillin-allergic patient.
The reactions elicited in this evaluation of the improved Enterotube indicate the efficacy of using this device for the differentiation of the members of the family Enterobacteriaceae.
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Primary grouping of more than 2,000 members of Enterobacteriaceae, freshly isolated from clinical specimens, was performed on the basis of eight conventional laboratory tests used routinely in this laboratory and by the R/B system. Results indicate that both systems perform well in this first step in the identification of various medically significant species of the family. Difficulties encountered with certain reactions of the R/B system were corrected with a physical modification of the tubes. An additional 100 representatives of Enterobacteriaceae were compared with conventional methods and the modified R/B system. Results indicate improvement in observing and interpreting findings with the R/B system.
A completely automated system for the performance of antibiotic susceptibility tests in the clinical laboratory is described. With a modicum of personnel involvement, data on 40 specimens tested against 13 antibiotics are obtained every hour after an initial 3-hr period. The step by step explanation of the functioning of this prototype system, based on a thoroughly tested manual model, is presented. The system compares well with the standard diffusion test and has a potential for application to other endeavors of the clinical microbiology laboratory with a comparable saving in time and labor.
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Lancefield group D streptococci are involved with appreciable frequency in a variety of infectious processes. The presumptive recognition of these bacteria on initial culturing of clinical specimens is an objective not attained readily by selective media available in the clinical laboratory. Selective Enterococcus agar was evaluated with emphasis on its ability to sequester enterococci from specimens with many microbial components. In addition, the sensitivity of this new agar was compared with Trypticase Soy agar containing sheep blood and Mitis Salivarius agar. All enterococci isolated from clinical material were classified in accordance with accepted biochemical and immunochemical criteria. The enterococci grew on the new medium as distinctive colonies surrounded by a black zone. Only Listeria monocytogenes presented similar colonial morphology after 48 hr. Most other bacteria did not grow at all or appeared markedly different. The sensitivity of the new agar was of the same order of magnitude as on blood or Mitis-Salivarius agars, but its selectivity was superior.
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