Identifying transmission routes of Streptococcus pneumoniae and sources of acquisitions in high transmission communities.

Identifying the transmission sources and reservoirs of Streptococcus pneumoniae (SP) is a long-standing question for pneumococcal epidemiology, transmission dynamics, and vaccine policy. Here we use serotype to identify SP transmission and examine acquisitions (in the same household, local community, and county, or of unidentified origin) in a longitudinal cohort of children and adults from the Navajo Nation and the White Mountain Apache American Indian Tribes. We found that adults acquire SP relatively more in the household than other age groups, and children 2-8 years old typically acquire in their own or surrounding communities. Age-specific transmission probability matrices show that transmissions within household were mostly seen from older to younger siblings. Outside the household, children most often transmit to other children in the same age group, showing age-assortative mixing behavior. We find toddlers and older children to be most involved in SP transmission and acquisition, indicating their role as key drivers of SP epidemiology. Although infants have high carriage prevalence, they do not play a central role in transmission of SP compared with toddlers and older children. Our results are relevant to inform alternative pneumococcal conjugate vaccine dosing strategies and analytic efforts to inform optimization of vaccine programs, as well as assessing the transmission dynamics of pathogens transmitted by close contact in general.

Pyogenic arthritis caused by capnocytophaga gingivalis in an immunocompetent three-year-old male.

Capnocytophaga gingivalis is most often isolated as normal oral flora or with periodontal disease. This organism is also associated with sepsis usually in immunocompromised hosts. We identified pyogenic arthritis caused by C. gingivalis in a 3-year-old immunocompetent male, whose clinical course closely resembled monoarticular onset pauciarticular juvenile rheumatoid arthritis. This is the first report of C. gingivalis septic arthritis in the world literature, but there are increasing reports of infections with this carbon dioxide-loving organism at other sites in non-immunocompromised individuals. The subacute presentation of the monoarthritis with this organism of low virulence led to a long delay in diagnosis and treatment. Any monoarthritis must continue to raise concern about infection.

Predictors of infectious complications after burn injuries in children.

BACKGROUND: Infections are the major life-threatening complication of burn injury and occur with the greatest frequency in children. Knowledge of their occurrence and management, however, is extrapolated from studies in adults. We performed a prospective study of infectious complications in burned children. OBJECTIVE: To delineate epidemiology, risk factors and microbiology of infections in burned children where burn care and surgical interventions are optimal. METHODS: Children hospitalized for burns were entered into prospective study. Characteristics of the burn injury were assessed, and active surveillance for infections was performed. RESULTS: Seventy patients were entered [mean age, 42 months; mean total body surface area (TBSA), burn 15%]. Twenty-seven percent of patients developed 39 infections: 13 involved the burn wound (burn wound sepsis, 6; graft loss, 5; and cellulitis, 2); 13 were catheter-associated septicemia; 13 involved other sites (i.e. pneumonia, 4; urinary tract infection, 3; bacteremia, 2; endocarditis, 1; myocardial abscess, 1; toxin-mediated syndrome, 1; and otitis media, 1). Twenty-three infections were caused by a single organism, 9 infections by more than 1 organism and in 7 infections defined by CDC criteria no organism was recovered. Organisms causing infection were: Staphylococcus aureus, 19; Candida albicans, 4; Pseudomonas aeruginosa, 4; coagulase-negative Staphylococcus, 4; Enterococcus sp., 3; Escherichia coli, 1; Klebsiella oxytoca, 1; Serratia marcescens, 1; Streptococcus pneumoniae, 1; Streptococcus pyogenes, 1; Aspergillus fumigatus, 1; and Candida parapsilosis, 1. Burn mechanism (flame and inhalation), extent (TBSA >30%) and depth (full thickness) were risk factors for infection; young age and site of burn were not. CONCLUSION: The most common infections occurring in burn children are burn wound infections and catheter-associated septicemia. Characteristics of burn injury predict risk of infection. Children with flame and inhalation injury, TBSA burned >30% and full thickness burns are at high risk of infectious complications.

In vitro activity of gemifloxacin and other antimicrobial agents against isolates of Bordetella pertussis and Bordetella parapertussis.

We investigated the activity of the novel quinolone agent gemifloxacin (SB-265805) and a panel of comparator agents against Bordetella pertussis and Bordetella parapertussis. Erythromycin, azithromycin, ciprofloxacin and gemifloxacin were consistently active against both species. An azithromycin- and erythromycin-resistant B. pertussis isolate was not resistant to any of the other agents tested (gemifloxacin MIC < or =0.008 mg/L; ciprofloxacin, 0.015 mg/L; ampicillin, 2.0 mg/L; trimethoprim-sulphamethoxazole, 4.0 mg/L). The potency of ampicillin, azithromycin, erythromycin, ciprofloxacin and trimethoprim-sulphamethoxazole recorded against B. pertussis and B. parapertussis in this study was comparable to that noted in previous studies. However, MICs were generally higher than those noted in other trials; this may reflect the different methods used. Although in vitro data on the potency of gemifloxacin against B. pertussis and B. parapertussis have not previously been reported, these results are comparable to the potency of other quinolones against these pathogens. Should gemifloxacin achieve similar concentrations within the respiratory tract as other quinolones, this, coupled with its high in vitro potency, suggests that gemifloxacin has potential clinical efficacy in pertussis.

In vitro activity of oral antimicrobial agents against clinical isolates of Pasteurella multocida.

Pasteurella multocida causes a wide variety of infections and is the most common localized soft tissue infection after animal bite injuries. Penicillin or amoxicillin has been considered agent of choice for therapy. Reported beta-lactamase production by some isolates, the therapeutic dilemma of the penicillin allergic patient, and the polymicrobial nature of some infections led to this study of alternate antimicrobial agents. The in vitro activity of ampicillin, amoxicillin/clavulanate, cefprozil, cefuroxime, erythromycin, clarithromycin, trimethoprim/sulfamethoxazole, ciprofloxacin, and tetracycline were compared to penicillin against 73 geographically diverse isolates of P. multocida from human infections collected since 1991. MIC90 (microgram/mL) were as follows: penicillin < or = 0.06; ampicillin < or = 0.5; amoxicillin/clavulanate < or = 0.5; cefaclor 1.0; cefprozil 1.0; cefpodoxime 0.06; cephalothin 2.5; cefuroxime < or = 0.25; erythromycin 2.0; azithromycin 1.0; clarithromycin 4.0; trimethoprim/sulfamethoxazole < or = 0.5/9.5; ciprofloxacin < or 0.25; tetracycline < or = 2.0. No beta-lactamase producing isolates were found in this study. This in vitro study has identified alternate oral agents to penicillins that may be appropriate for therapy of P. multocida infections.

In vitro susceptibility testing of topical antimicrobial agents used in pediatric burn patients: comparison of two methods.

One hundred and seventy-seven bacterial isolates obtained from pediatric burn victims were tested for in vitro susceptibility against bacitracin, silver sulfadiazine, mafenide acetate, nitrofurazone, and mupirocin by two methods: standard microbroth dilution and Nathan's agar well diffusion (NAWD). Nitrofurazone had the broadest spectrum of activity. Mupirocin was the most potent agent against methicillin-susceptible Staphylococcus aureus. Silver sulfadiazine showed activity against gram-positive organisms and higher minimum inhibitory concentration (MIC) values, and smaller zone sizes were seen for methicillin-resistant S. aureus and gram-negative bacilli. Bacitracin showed activity against S. aureus and Streptococcus pyogenes by the microbroth method; activity could not be assessed by NAWD. Mafenide acetate had the highest MICs for all isolates tested. Correlation between methods for all isolates tested was best for mupirocin and nitrofurazone. NAWD was labor intensive and difficult to interpret; MIC method was easy to perform and reproducible. Clinical correlation is necessary to establish breakpoints for interpretation of test results.

Study of antibiotic prophylaxis during burn wound debridement in children.

Twenty-three children completed a randomized, prospective, partially blinded study performed to assess the need and effectiveness of antibiotic prophylaxis at the time of burn wound debridement and grafting. Patients with a total body surface area (TBSA) burn less than 35% were randomized to receive cefazolin or placebo. Patients with burns of 35% or more TBSA were randomized to receive cefazolin or targeted antibiotics based on surveillance cultures. Blood cultures were obtained at commencement, immediately after, and 24 hours after surgical debridement. Quantitative cultures and histologic examination of biopsied burn wounds were performed. Burn wound infection occurred in three patients with burns of less than 35% TBSA, two in the cefazolin group and one in the placebo group. Quantitative tissue cultures and histologic examination did not predict either infection. During the four procedures in three patients with 35% or more TBSA, three were randomized to receive cefazolin, and one targeted antibiotics. All receiving cefazolin developed burn wound infection. Quantitative tissue culture was more than 10(5) colony-forming units per gram in all, whereas histologic examination was positive in one. In our patients with less than 35% burn, cefazolin was not necessary, and in those with 35% or more burn, it was not effective.

An 'epidemic' model of adolescent sexual intercourse: applications to national survey data.

This paper applies models of the onset of adolescent sexual intercourse using national data from Denmark and the USA. The model gave excellent fits to data on Danish Whites and a good fit to American Whites, but the model-fits for American Blacks and Hispanics were not as good. The weakness of the latter model fits may reflect either real processes that the model does not capture or problems in the reliability of adolescent sexuality data.