A comparison of antibiotic resistance patterns of Gram negative aerobic bacilli from St. John's, Antigua and Rochester, New York

Available information indicates that antibiotic resistance is increasing throughout the world and that it is a greater problem in developing countries than in the more developed countries. A comparison of antibiotic susceptibility of gram negative aerobic bacilli from Holberton Hospital in St. John's, Antigua and Genessee Hospital in Rochester, New York, USA was undertaken to test that hypothesis. Escherichia coli, Klebsiella spp and Enterobacter spp isolates had antibiotic susceptibility tested by the disk diffusion method. Antibiograms of isolates from similar sources from both institutions from 1992 to 1995 were compared: ampicillin, gentamicin and cotrimoxazole. Results reveal that E. coli isolates in Antigua in 1992 had a higher prevalence of resistance to ampicillin (71 percent vs 31 percent, p=0.001) and no significant difference in resistance to gentamicin (4 percent vs 2 percent, p=NS) or co-trimoxazole (20 percent vs 11 percent, p=NS) compared to Rochester. By 1995, the prevalence of resistance was significantly greater for all three drugs (ampicillin 76 percent vs 31 percent, p=0.001, gentamicin 21 percent vs 2 percent p=0.001, co-trimoxazole 34 percent vs 9 percent, p=0.001) in Antigua compared with Rochester. Klebsiella and Enterobacter isolates in Antigua had a higher rate of resistance early and late compared with Rochester. Isolates from Holberton Hospital in Antigua developed a higher prevalence of resistance between 1992-3 and 1994-5, with E. coli having more resistance to gentamicin (4 percent vs 20 percent, p=0.01) and Klebsiella having more resistance to gentamicin (16 percent vs 43 percent, p=0.001) and co-trimoxazole (34 percent vs 57, p=0.001). In no instance did the resistance of any bacilli to any antibiotic improve significantly in that interval in Antigua. These data show that antibiotic resistance in Antigua is more prevalent than in Rochester and that the gap is widening.(AU)

Septicemia due to multiple biotypes of Escherichia coli.

BACKGROUND: Polymicrobial bacteremias with different biotypes of the same organism have not been reported as a cause of bacteremia in any patient. CASE: A 37-year-old gravida had a cesarean delivery performed after a failed vacuum extraction. On the second postoperative day, she developed a septicemia with temperature to 39.4C. Three different biotypes of Escherichia coli with different antibiotic susceptibilities were isolated from her blood. A fourth biotype was isolated from the urinary and genital tracts; therefore, the source of her bacteremia was not apparent. She was treated successfully with cefoxitin and gentamicin. CONCLUSION: Accurate selection of colonies from microbiological isolation plates allowed identification of four different E. coli biotypes (three in the blood) from a bacteremic patient. Rapid identification of antibiotic susceptibility is important in such patients.

Comparison of fluorescent antibody, bacitracin susceptibility, latex agglutination, coagglutination, and API 20S for identifying group A streptococci.

A total of 200 beta-hemolytic streptococci, isolated from clinical specimens submitted to our laboratory, were identified as group A versus non-A using the fluorescent antibody technique (FA), bacitracin susceptibility (BBL, Difco, and Raven disks), SeroSTAT, Streptex, Phadebact, and the API 20S system. Of the 122 group A isolates, all methods except SeroSTAT and Phadebact yielded 92-99% agreement when compared with the Lancefield precipitin test. Phadebact yielded an 84% agreement and SeroSTAT changed from 83 to 98% after trypsinization. Numerous false positives were obtained and only FA (91%) and API 20S (96%) yielded better than 90% agreement on non-A identification when compared with the Lancefield test. The most false positives were obtained (45%) using the SeroSTAT reagents. Considering accuracy, our data suggests the FA technique to be the method of choice for identifying group A streptococci.

Inhibition of transformation in group H streptococci by lysogeny.

Group H streptococcal strains Challis and WE4 were lysogenized with a bacteriophage isolated from strain Channon, after which their capacity for transformation to streptomycin and rifampin resistance was reduced by three orders of magnitude. The probable reason is the inability of the lysogenized strains to bind deoxyribonucleic acid irreversibly, even though they exhibit earlier stages of competence development during a competence regimen.

Isolation of bacteriophages from group H streptococci.

Temperate phages were isolated from 5 of the 17 strains of group H streptococci tested.

Intergroup lysis and transduction by streptococcal bacteriophages.

Bacteriophages from streptococci of groups A, E, and G lysed streptococci distributed among serogroups A, C, G, H, and L; propagated in some, but not all, of these; and transduced streptomycin resistance within group A or (by A phages only) from group A to group G streptococci.

Lysis and lysogenization of groups A, C, and G streptococci by a transducing bacteriophage induced from a group G Streptococcus.

A temperate bacteriophage, designated GT-234, was isolated from a group G Streptococcus after ultraviolet irradiation. After several single-plaque passages in a group G indicator strain, this phage formed plaques in 3 of 14 group A strains, in 3 of 15 group C strains, and in 4 of 13 group G strains-but not in some representatives of several other serogroups. After propagation in each of the sensitive strains, the progeny from each was shown to be the same phage by (i) adsorption and plaque formation in each of the other groups, (ii) lysogenization in each of the other groups, (iii) high titers on infection of each serogroup, regardless of the group of propagating strain, and (iv) neutralization of infection in each of the other groups by antiserum against the phage propagated in group G. Phage GT-234 is serologically related to virulent group A phage A25, from which it is morphologically indistinguishable. Like A25, it is a transducing phage. Other studies showed that A25, as well as a group A temperate transducing phage (AT-298), could also infect strains of group C and G. These results indicate a need for reassessment of group specificity and phage receptors among streptococci of groups A, C, and G and raise possibilities for intergroup transduction.