Richard H. Conklin

Prospective study of enteropathogens in children with diarrhea in Houston and Mexico

During a 22-month period, 595 children with diarrhea and 210 age-matched controls attending clinics in Houston (367 children) and Mexico (438) were prospectively evaluated for enteric pathogens. Enteropathogens associated with disease were Shigella (18%), rotavirus (14%), Salmonella (9%), toxigenic Escherichia coli (6%), and others (12%), including 14 Proteus isolates that caused rounding of adrenal cells. Enteropathogens were isolated from a greater (P less than 0.001) number of children with diarrhea (59%) than from asymptomatic controls (6%). Paired sera tested for antibody to heat-labile toxin of E. coli rarely demonstrated a fourfold rise during episodes of diarrhea. This study demonstrates: (1) more striking illness in children from Mexico; (2) more common occurrence of Shigella in Houston, and of rotavirus and Salmonella in Mexico; (3) lack of seasonal occurrence of rotavirus isolation in either population and a summertime occurrence of Shigella in Houston; (4) lack of toxigenic E. coli isolation in endemic diarrhea of either population; and (5) a significant (P less than 0.001) age-related acquisition of E. coli LT antibodies.

Enteropathogens associated with pediatric diarrhea in Mexico City

Enteropathogens were investigated as possible agents in pediatric diarrhea occurring in Mexico City during the summer of 1975. Pathogens were identified in 47 (76%) of 62 cases. Rotavirus particles were detected in 16 cases. Enterotoxigenic Escherichia coli was detected in 29 cases; 11 were positive for heat-labile enterotoxin and 18 were positive for only the heat-stable form of enterotoxin. Multiple pathogens were found simultaneously in 15 (24%) of the study population. This study indicates that the etiology of pediatric summertime diarrhea in Mexico City is diverse. ETEC and RV were the most frequently encountered pathogens, yet they frequently occurred together and with other pathogens. ST-only strains of toxigenic E. coli were as frequently recovered as LT-E. coli suggesting that both forms of ETEC must be sought in future field studies.

Comparison of Biopsy-Proven Pneumocystis carinii Pneumonia in Acquired Immune Deficiency Syndrome Patients and Renal Allograft Recipients

Pneumonia unresponsive to antibacterial agents in patients with acquired immune deficiency syndrome (AIDS) has become a new indication for lung biopsy. In 14 patients, transbronchial or open-lung biopsy demonstrated Pneumocystis carinii. An additional 12 patients, who were immunosuppressed after renal transplantation, were seen with P. carinii pneumonia. The diagnosis was established by transbronchial biopsy in the majority of patients. All patients were treated initially with trimethoprim plus sulfamethoxazole. Pentamidine was added after diagnosis if improvement did not occur. Both groups demonstrated reversal in the T cell helper: suppressor ratio. We compared these two groups of immunocompromised patients with respect to clinical presentation, lung pathology, response to therapy, and survival. Patients with AIDS were seen with a two- to three-week prodrome of fever, lymphadenopathy, weight loss, and malaise followed by hypoxia and leukopenia within 12 hours. Transplant patients became acutely ill with fever and hypoxia within 24 to 36 hours. In both groups, chest roentgenogram showed bilateral diffuse infiltrates; sputum cultures were generally negative; and lung biopsy demonstrated Gomori-Jones periodic acid-methenamine-silver-positive P. carinii. Mortality was substantially higher in patients with AIDS (50% versus 8%). This difference may be explained by the fact that the T cell defect in AIDS has an infectious cause, while the defect in the renal allograft recipient is pharmacologically mediated.

CMV and Renal Allograft Survival

A majority of renal transplant recipients become actively infected witb cytomegalovirus (CMV) (1). Most patients displaying CMV antibody preoperatively experience infections due to reactivation of latent virus. Primary CMV infections occur in preoperatively seronegative recipients due to organs from seropositive donors or to blood transfusions (2). CMV infection has serious consequences, including acute allograft rejection and patient death (1). Although CMV infection in renal allograft recipients has been thought to be associated with rejection and graft loss, there is little information concerning the relationship between tissue typing for HLA A, B and DR antigens, CMV infection, and renal allograft survival (3). In the present study the effect of CMV infection on the success of renal transplantation was assessed by serologic analysis of recipients before and following transplantation. Recipients were grouped based on the degree of incompatibility for HLA A, B and DR antigens with their donors.