Treatment of childhood pneumonia in developing countries requires knowledge of susceptibility patterns for Streptococcus pneumoniae and Haemophilus influenzae. Between October 1991 and April 1993, a surveillance survey of antimicrobial resistance was performed at two fever hospitals in Egypt; nasopharyngeal swab and blood specimens obtained from 1,635 children with pneumonia were cultured for these organisms. Susceptibility testing of these organisms was performed. At least one of these organisms was isolated from nasopharyngeal swab specimens from 73% of the children; 3.7% of blood cultures were positive. For S. pneumoniae strains, 70.9% of nasopharyngeal isolates were calculated to be susceptible to penicillin vs. 77.6% of blood isolates; the percentages of isolates susceptible to co-trimoxazole were 73.0% and 75.0%, respectively. For H. influenzae strains, 93.0% of nasopharyngeal isolates were calculated to be susceptible to ampicillin vs. 100% of blood isolates; the percentages of isolates susceptible to co-trimoxazole were 84.9% and 100%, respectively. Although most S. pneumoniae and H. influenzae strains associated with childhood pneumonia in Cairo were susceptible to penicillins and co-trimoxazole, antimicrobial resistance did not occur.
Eleven Escherichia coli strains, crossreactive with the capsular polysaccharide (CPS) of Neisseria meningitidis group A (GrA), were detected among 645 stool isolates from healthy families in Cairo, Egypt. 10 of these strains were of the O107:K93:H27 or O107:K93:SP serotypes and may be considered descendents of a single bacterium or as a clone. The remaining crossreactive strain was of the O7:K51:H18 serotype. None of the 11 strains produced enterotoxins and none were enteroinvasive. The purified CPS of these E. coli strains, as well as a polysaccharide (PS) from B. pumilis, strain Sh17, precipitated with equine GrA (H49) antiserum. A partial identity between the E. coli K93, K51 and Sh17 PS on the one hand and the GrA CPS on the other was observed by double immunodiffusion when reacted against the H49 antiserum. Four K93 strains and one K51 strain were found among 320 E. coli strains from patients at the Clinical Center, National Institutes of Health, and three K93 strains were found in 105 stool samples from children in Copenhagen. The data from these three surveys suggest that these crossreactive E. coli are common organisms and could serve as a stimulus for "natural" GrA CPS antibodies. Quantitative precipitation analysis showed that K51, K93, and Sh17 PS precipitated 25, 46.8, and 50% of H49 antibodies, respectively. Absorption of H49 antiserum with the GrA CPS removed its precipitating activity with the E. coli K93, K51, and Sh17 PS. Absorption of H49 antiserum with either K51 CPS or Sh17 PS removed the homologous crossreactivity only, whereas K93 CPS absorbed both K93 and K51 reactivities. Antibodies, raised by intravenous injection of formalinized E. coli K93 or K51 cells into rabbits, precipitated with GrA CPS and were bactericidal against GrA meningococci. The crossreaction between the E. coli K93 and the GrA CPS was unexpected since these two CPS are compositionally so dissimilar.
A prospective study of spread of M-type 1, 2, 13, 14, 25 and 60 group A Streptococcus in 64 families in Qalyub, Egypt, in 1972-1974 showed that type-specific serum bactericidal antibody does not protect against pharyngeal acquisition of homologous organisms. The presence of type-specific antibody also does not appear to affect duration of carriage of the organism. Type-specific immunity must be mediated in another way, such as by local antibody or trough prevention of infection (as evidenced by a host response) following acquisition. This study also confirms the observations of others that administration of penicillin lowers the probability that a person who acquires group A Streptococcus will develop type-specific antibody.
Immunization of C57Bl/6 mice with gamma-irradiated Schistosoma mansoni cercariae induces highly significant protection against subsequent challenge with unattenuated living cercariae. The antigens that evoke T cell-mediated immunity in this model are vaccine antigen candidates since T lymphocytes mediate antibody-independent immune responses and control the production of most antibodies. To identify these antigens, spleen cells of mice immunized twice with gamma-irradiated cercariae were tested for proliferative responsiveness and production of interleukins (Il) and interferon-gamma (IFN-gamma) following incubation with separated soluble schistosomular (SSA) and adult worm (SAWA) antigens in T cell western assays. Data obtained at 3, 4, 5, and 6 wk post-secondary immunization in 2 experiments indicated that SSA and SAWA bands of 62-60, 50, and 45 kDa reproducibly elicited T cell proliferation and production of Il-2, Il-4, and IFN-gamma by spleen cells from immunized, but not unimmunized, mice. Bands of 72-68, 29.5, and 28 kDa elicited proliferation and production of Il-2 and Il-4, but not IFN-gamma. Bands of 35-33 and 24 kDa induced either proliferation or Il production at some intervals.
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