Groups of BALB/c mice were orally immunized with Chlamydia trachomatis serovar L2/434/Bu in order to characterize the nature and kinetics of the chlamydial antibody response in the cervix and other mucosal sites. These animals were subsequently challenged intravaginally to determine whether oral immunization offers protection against chlamydial antigen shedding in the genital tract. Following oral immunization, immunoglobulin A antibody activity was detected in the genital tract as well as other mucosal sites. Subsequent intravaginal challenges exhibited booster effects on preexisting antibody activity in the genital tract. Significant protection against challenge infection in the genital tract was observed by oral immunization. This was indicated by the absence of any chlamydial antigen shedding in cervical secretions. On the other hand, passively administered chlamydial-specific serum immunoglobulin G antibody did not significantly influence the course of cervical shedding of the organism and did not confer any protection against a subsequent intravaginal challenge. It is concluded that prior oral immunization can induce a secretory antibody response in the genital tract and provide protection against subsequent infection.

Twenty-two clinical isolates of Haemophilus species were studied within two passages of their original isolation for the presence of fimbriae by negative-staining electron microscopy. Six isolates were identified as fimbriated, including three strains of nontypable Haemophilus influenzae, one strain of Haemophilus parainfluenzae, and two strains of Haemophilus haemolyticus. In fresh isolates of fimbriated strains of nontypable H. influenzae, approximately 40%-50% of cells had fimbriae; after five passages in vitro, less than 1% of the cells had fimbriae. Thus, a variety of Haemophilus species that colonize the human respiratory tract can be fimbriated, and this fimbriation is rapidly lost on passage in vitro.

Children with catheter-associated bacteremia were evaluated for the type of bacteria recovered and the relationship of the bacteria to the predisposing disease. A previously unrecognized observation was that gram-negative isolates, namely, Escherichia coli and Klebsiella sp., were almost exclusively recovered (11 of 12 isolates [92%]) from children with short bowel syndrome (SBS) compared with those from children with other underlying diseases, such as inflammatory bowel disease, malignancies, and other disorders (P < 0.001). Furthermore, children with SBS had a higher frequency of repeated infection (3.1 catheter-associated infections compared with 1.3 catheter-associated infections in children with other disorders during the same period). Only gram-positive bacteria were isolated from children with malignancies and other predisposing disorders. The very high frequency of catheter-associated gram-negative bacteremia in children with SBS compared with that in children with other bowel disorders, malignancies, and other predisposing diseases requires attention by the clinician in the management of patients in this group.