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P N Lowry

Publications and source records attributed to P N Lowry.

11 recordsLinked to original sources
PubMed1978

Significance of hemolytic streptococci for Nashville school children: clinical and serologic observations.

The results of this study (1969-1971 confirm previous findings that incidence rates for hemolytic and group A streptococci in Nashville school children fluctuate sporadically. During these two years, there was a significant decrease in streptococcal incidence and in typability of group A streptococci. A positive throat culture was not associated significantly more often with symptoms of an infection of the upper respiratory tract than when symptoms were absent. The larger the number of group A streptococci present in the throat culture, the more likely was a streptococcal antibody increase to occur. Nevertheless, some children with small numbers of group A streptococci had an antibody increase, and the degree of positivity of the throat culture was not a very accurate indication of whether an antibody response would occur. Epidemiologic factors such as age, sex, race, or crowding in the home did not seem to play a highly significant role in rates. Seasonal influences were marked in 1969-1970 but not in 1970-1971. Regarding socioeconomic background, the rates were consistently lower in Clemons school, which serves a predominantly black neighborhood of higher socioeconomic level, than in the other two schools. Our findings confirm that the incidence of acquisition of the hemolytic streptococcus is a continually changing, dynamic process among school children.

Antibodies, Bacterial↗
PubMed1976

Further studies of some "nontypable" group A streptococci.

Thirty-two strains of group A hemolytic streptococci which could not be M typed with the available typing sera in Nashville, Tenn., were reinvestigated at the Streptococcus Reference Laboratory in Colindale, England, in order to estimate the efficacy of other antisera not available in Nashville and newer techniques (the opacity factor inhibition test) of typing strains not isolated in England. Fifty percent were eventually typed and all but four contained enough M protein to suggest that they would have been typed had the appropriate typing sera been available. The results indicate that group A streptococci truly lacking M protein were seldom isolated from the Nashville children from whom the streptococci were cultured. Several factors responsible for nontypability were considered, including the nonavailability of the necessary type-specific antisera and loss of M protein due to a change from Matt to glossy colonial types in the laboratory.

Animals↗
PubMed1974

Streptococcal L forms and phage. A clinical-epidemiologic study.

This study showed that streptococcal L forms could not be isolated from children who were either carriers of group A streptococci or had disease due to this pathogen. It was possible to induce L colony formation in 15 strains of group A. Streptococcal bacteriophages were demonstrated in 20% of group A streptococci isolated from school children who were carriers, but did not have clinical evidence of streptococcal disease, and from 44.9% of children whose physicians considered they had acute streptococcal upper respiratory infections. Lysogeny (bacteriophage) was demonstrated more frequently during 1969-70 when carrier rates were high and from children who had manifest streptococcal disease, suggesting a possible positive relationship between lysogeny, high carrier rates, and infection in the children studied. Lysogeny and erythrogenic toxin production by group A streptococci occurred simultaneously in approximately half of the strains of group A streptococci tested, suggesting that lysogeny is not a sine qua non for erythrogenic toxin production.

Bacteriophages↗
PubMed1969

Significance of hemolytic colonies in throat cultures.

These studies indicate that a single strain of hemolytic streptococci almost exclusively predominates the bacterial flora in patients with streptococcal infections and in the carrier state. One can proceed with confidence that, in isolating streptococci from throat swabs cultured on blood-agar plates, only a single hemolytic colony need be picked for serological grouping and typing.

Carrier State↗
PubMed1967

Effect of Streptococcus pyogenes on tissue cells.

Human tissue cell lines from each of the three primary germinal sources, ectoderm (conjunctiva and carcinoma of the buccal mucosa), entoderm (intestine and liver), and mesoderm (heart and monocytes) were inoculated with group A Streptococcus pyogenes, Staphylococcus aureus, and group D streptococci and were then observed. In addition, the effect of these bacteria on mouse fibroblasts was studied. All of the cell lines appeared to be equally susceptible to damage, but damage to the cells by S. pyogenes occurred only when living, actively multiplying bacteria were in contact with the tissue cells. Streptococcal products in the form of "used" growth medium had no observable effect on the cells. Cytopathogenic effects were first noticed about the time one would expect the bacteria to have reached the end of the log phase of growth. No damage to the tissue cells was noted when group A streptococci were separated from the cells by membrane filter diffusion chambers or dialyzing membranes, but a membrane did not protect cells from deleterious effects of staphylococci or group D streptococci. Group A streptococci survived in the tissue culture medium, but multiplication did not occur unless living tissue cells were present.

Carcinoma↗
PubMedDate not supplied

Acquisition of group A streptococcal M protein antibodies.

Seventy-five children who acquired positive throat cultures for Group A streptococci among 250 cultured weekly were studied during the school years 1972-1973 and 1973-1974 in order to investigate streptococcal M protein antibodies. Eleven (14.7%) of the children had strain-specific serum M protein antibodies at the time a positive throat culture was first detected or 6 weeks previously. Eight of 64 (12.5%) children acquired strain specific serum M protein antibodies within 6 weeks and another 6 of 46 (13%) did so within 1 year of infection. The presence of strain-specific serum M protein antibodies did not appear to be protective. One-third of the 75 children who acquired positive throat cultures had a significant rise in anti-streptolysin O or anti-hyaluronidase antibody titers. Among those who acquired Group A streptococci, 25 children had positive cultures on 7 or more culture dates.

Antibodies, Bacterial↗
PubMedDate not supplied

Serologic groups of Neisseria gonorrhoeae recovered from patients in Nashville, Tennessee, 1971--1976.

The objective of this study was to develop and apply a serologic method for identification of different strains of Neisseria gonorrhoeae. Several procedures for preparation of cell-free extracts were tried; the most satisfactory was that with phosphate-buffered saline solution. Both capillary tube and immunodiffusion precipitin techniques were evaluated, and the latter proved preferable. Serologic grouping was attempted for 704 strains of N. gonorrhoeae isolated during 1971--1976. Groupable strains shifted from a predominance of group A to a predominance of group B strains. The percentages of isolates of groups C and D increased, and group E appeared occasionally. Nongroupable strains were much more common after 1973. Four of six strains that were etiologic for recrudescent gonococcal urethritis belonged to the same serogroup that had caused the initial infection; two of six were different. The partners in nine male and female sexual pairs were infected by the same serogroups, four pairs by nongroupable strains, and the partners of five pairs harbored differed serogroups. The immunodiffusion technique described should be useful in clinical and epidemiologic studies of gonorrhea. The antigenic material was shown to be a high-molecular-weight polysaccharide.

Antigens, Bacterial↗