Dorothy J. Clark

Failure of penicillin to eradicate group B streptococcal colonization in the pregnant woman. A couple study.

Prophylactic treatment of couples with oral penicillin has been recommended as a means of eradicating GBS from the parturient female. In 1977 and 1978 this hypothesis was tested in an investigation of couples from a middle and upper socioeconomic group in Houston, Texas. A group of 40 women, known to be colonized with GBS during the third trimester of pregnancy, and their husbands were treated simultaneously with oral penicillin. Patients were recultured 3 weeks following completion of therapy and at the time of delivery. At the time of delivery 67% of the women remained colonized with GBS. This percentage does not differ substantially from that obtained in a series of untreated colonized women. This study demonstrates that oral penicillin treatment of couples is not an effective means of reducing maternal colonization at the time of delivery.

The natural history of group B streptococcal colonization in the pregnant woman and her offspring

A longitudinal study of colonization by group B streptococcus (GBS) was conducted in 93 pregnant women and 92 of their infants. Positive cultures were obtained from vaginal swab specimens on at least one occasion during pregnancy from 20.4% of the women. Three types of carriage were observed: chronic, transient, and intermittent. At the time of delivery, 12.9% of the mothers were colonized by GBS. GBS colonization occurred in 41.7% of the infants of the mothers colonized intrapartum. Only 1.2% of infants intrapartum culture-negative mothers were colonized. Infants colonized at birth were culture negative by 4 months of age. This study suggests that interruption of vertical transmission of GBS from mother to infant not only would influence the incidence of early-onset GBS disease but also might reduce the incidence of late-onset GBS disease.

A 12 year review of the antibiotic managementof Hemophilus influenzae meningitis

The medical records of 253 children with Hemophilus influenzae meningitis treatedfrom 1959 through 1970 were reviewed. One hundred and sixteen patients received ampicillin alone, and 112 patients received chloramphenicol alone or in combination with other antibiotics. The children in the two treatment groups were matched as to sex, race, and severity of illness, but there were more young infants in the chloramphenicol group than in the ampicillin group. The over-all frequency of bacteriologically positive spinal fluid cultures after initiation of antimicrobial therapy was identical in the two groups (4.5 per cent). However, “late-convalescent” spinal fluid cultures were positive in four of the patients treated with chloramphenicol and in none of the group treated with ampicillin. The mortality rate and incidence of complications (subdural effusion and/or neurologic sequelae) were similar in the two treatment groups.

Influence of several antibiotics, singly and in combination, on the growth of listeria monocytogenes

Three strains of Listeria monocytogenes were studied for their in vitro susceptibility to five antibiotics alone or in various combinations. Penicillin or ampicillin plus kanamycin or gentamicin gave earlier and more complete killing than any of the agents alone. Penicillin and tetracycline together were no more effective than tetracycline alone and the combination was less effective than penicillin alone. The possibility of in vivo synergism of various commonly used antibiotic combinations should be further investigated since many patients with listeriosis receive such combinations for broad antibacterial coverage until the specific etiologic diagnosis is made.

Expression of the functional cone phototransduction cascade in retinoblastoma.

Retinoblastoma is a malignant intraocular tumor that primarily affects small children. These tumors are primitive neuroectodermal malignancies, however some of them show morphologic evidence of differentiation into photoreceptors. Phototransduction cascades are a series of biochemical reactions that convert a photon of light into a neural impulse in rods and cones. The components of these cascades are uniquely expressed in photoreceptors and, although functionally similar, distinct components of these cascades are expressed in rods and cones. Using HPLC anion exchange chromatography, Western blot analysis, and specific monoclonal and polyclonal antibodies, we found that the cone but not the rod cGMP phosphodiesterase is functionally expressed in all six primary retinoblastomas examined and in three continuous retinoblastoma cell lines. Morphologic evidence of differentiation did not correlate with the expression of the enzyme. Furthermore, GTP analogues could activate the phosphodiesterase activity suggesting that an intact phototransduction cascade is present in the tumors. The presence of the cone phototransduction cascade in retinoblastoma confirms that this tumor has biochemically differentiated along the cone cell lineage.

Incidence of kanamycin resistance among Escherichia coli isolates from neonates

The antimicrobial susceptibilities of 368 E. coli strains isolated from well neonates, well pediatric outpatients, and ill neonates were determined, and the incidence of antibiotic-resistant strains was correlated with epidemiologic data. Ninety-five per cent of these isolates were susceptible to kanamycin and 98 per cent to gentamicin. Most of the difference in susceptibility of these E. coli strains to kanamycin and gentamicin appeared to be on the basis of weight for weight activity. Kanamycin-susceptible strains were isolated from 96 per cent of well neonates and well outpatients, and 94 per cent of ill neonates, age three days or less. An increase in the incidence of resistance to kanamycin, streptomycin, and ampicillin among strains isolated from neonates was related to prolonged hospitalization and/or prior antibiotic therapy. This study demonstrates the need for analyzing antimicrobial susceptibility data from newborn nurseries in an epidemiologic context.

Comparison of Mueller-Hinton Agar and Oxoid Sensitivity Test Medium in Antibiotic Susceptibility Testing of Escherichia coli

The in vitro activity of five antibiotics against 368 strains of Escherichia coli was determined by use of Mueller-Hinton agar and Oxoid sensitivity test medium. Minimal inhibiting concentrations were essentially identical with both media.