Streptococcus pneumoniae is the most frequent bacterial cause of pneumonia, otitis media, and bacteremia and is the third most common cause of meningitis in infants and children. Infants have the highest rates of pneumococcal disease. Recent studies showed that the peak incidence of meningitis occurs among infants three to five months of age, that of otitis media occurs among infants six to 12 months of age, and that of hospitalization for pneumonia occurs among infants 13 to 18 months of age. A predominance of males was noted in most studies of pneumococcal disease. Blacks have higher rates of bacteremia and meningitis than do whites; this difference is explained only in part by the greater susceptibility to infection of children with sickle cell disease. However, the incidence of otitis media is lower in blacks than in whites. The predominant pneumococcal serotypes change with age, with time, and with geographic location. Certain serotypes are responsible for most cases of bacteremia or meningitis. Types present in the pneumococcal vaccine currently available represent 85% to 97% of the strains that have caused disease in the United States in recent years.

Age Factors↗

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Use of pneumococcal vaccine for prevention of recurrent acute otitis media in infants in Boston. The Greater Boston Collaborative Otitis Media Study Group.

The efficacy of pneumococcal polysaccharide vaccine for children suffering from recurrent acute otitis media (AOM) was determined by administration, in a randomized double-blind fashion, of one of two polyvalent vaccines to 124 children aged five to 21 months. The octavalent vaccine contained serotypes commonly associated with AOM: 1, 3, 6A, 7F, 14, 18C, 19F, and 23F. The heptavalent control contained serotypes not commonly associated with AOM: 2, 4, 5, 8, 9N, 12F, and 24F. Recipients of the octavalent vaccine experienced significantly (P less than 0.05) less AOM due to serotyes contained in the octavalent vaccine than did children who received the control vaccine. Although the recipients of octavalent vaccine suffered less from AOM due to types in that vaccine than did controls, their clinical experience with AOM was not different. Both groups of children were equally likely to experience at least one episode of AOM after vaccination (70% for octavalent vaccine and 78% for heptavalent vaccine). The mean numbers of episodes of AOM after vaccination also were similar (2.1 for octavalent vaccine and 2.3 for heptavalent vaccine). Similarly, the period of effusion in the middle ear after pneumococcal AOM was identical for both groups. Although immunization with pneumococcal vaccine appeared to reduce the number of episodes of AOM due to serotypes contained in octavalent vaccine, the clinical experience of the children was not favorably affected by this vaccine.

Acute Disease↗

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Interactions of rifampin and trimethoprim in vitro.

Combination of rifampin and trimethoprim (TMP) has been suggested as a means of preventing the emergence of bacterial resistance to the individual agents and of achieving synergistic antimicrobial activity. By means of standard techniques of antimicrobial susceptibility testing, combinations of rifampin and TMP were tested against clinical isolates of a variety of aerobic bacteria. Synergism was defined as a fourfold or greater decrease in the minimal inhibitory concentration (MIC) of the more active agent in the combination. Antagonism was defined as a fourfold or greater increase in the MIC of the more active agent. No change or, at most, a twofold change was considered to represent indifference. Combinations of rifampin and TMP in ratios of 7:1, 7:2, and 1:1 demonstrated synergistic activity against 12%, 13%, and 28% of 440 isolates, respectively. Antagonism was observed in 10%, 9%, and 8% of strains tested against the above ratios. Killing curves determined with selected organisms failed to demonstrate synergistic antibacterial activity. Combinations of rifampin and TMP failed to prevent the emergence of resistance to both drugs when selected strains of various bacteria were exposed to serial, subinhibitory concentrations. Thus, synergism of rifampin and TMP was observed in only a minority of strains tested, and combination of the two agents failed to prevent the emergence of drug resistance in vitro.

Bacteria↗

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Selection of antimicrobial agents for treatment of neonatal sepsis.

The incidence of sepsis among neonates born in the United States varies from less than one to more than eight per 1,000 live births. Bacterial meningitis occurs in about one-third of infants with sepsis and is more frequent during the first month of life than during any subsequent period. The clinical diagnosis of sepsis in newborn infants is difficult since signs are subtle and nonspecific. Because of the difficulty of diagnosis, many infants receive treatment although few significant bacterial infections are subsequently documents; approximately 5%-10% of neonates born in the United States receive parenteral antibiotics. The choice of antimicrobial agents for treatment of bacterial infections in neonates is based on knowledge of the responsible organisms and their patterns of antimicrobial susceptibility. Group B Streptococcus and Escherichia coli are currently the bacterial pathogens most often responsible for sepsis and meningitis in the United States. A penicillin and an aminoglycoside are the drugs usually used for initial therapy in infants with suspected sepsis. Present regimens are not optimal, however; mortality from sepsis and meningitis varies from 10% to 50%. Many survivors have significant sequelae. In addition, dose-related toxicity of the aminoglycosides is a concern. New beta-lactam antibiotics with increased efficacy against gram-negative enteric bacilli and with minimal or no dose-related toxicity warrant careful evaluation in newborn infants.

Anti-Infective Agents↗

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Infectious diseases and day care.

Infectious diseases often occurring in epidemics, are to be expected in group day care because of the susceptibility of infants and toddlers to infection and the ready transmission of infection in the day care setting. Children in day care have more respiratory and gastrointestinal infections and are at higher risk for meningitis due to Haemophilus influenzae than are children in home care. Infections acquired by the child in the day care center may spread to members of the household and to the community. Illness in the child in day care may necessitate care at home and a change in plans of the parents; family stress may result. Infections in the day care center can be limited by appropriate use of the physical facilities, education of personnel in standards of hygiene, and maintenance of recommended immunizations of children and adult care givers. Simple techniques of infection control, such as hand washing, are the most effective.

Child↗