Active bacterial core surveillance of the emerging infections program network

Active Bacterial Core surveillance (ABCs) is a collaboration between the Centers for Disease Control and Prevention and several state health departments and universities participating in the Emerging Infections Program Network. ABCs conducts population-based active surveillance, collects isolates, and performs studies of invasive disease caused by Streptococcus pneumoniae, group A and group B Streptococcus, Neisseria meningitidis, and Haemophilus influenzae for a population of 17 to 30 million. These pathogens caused an estimated 97,000 invasive cases, resulting in 10,000 deaths in the United States in 1998. Incidence rates of these pathogens are described. During 1998, 25% of invasive pneumococcal infections in ABCs areas were not susceptible to penicillin, and 13.3% were not susceptible to three classes of antibiotics. In 1998, early-onset group B streptococcal disease had declined by 65% over the previous 6 years. More information on ABCs is available at www.cdc.gov/ncidod/dbmd/abcs. ABCs specimens will soon be available to researchers through an archive.

Increasing prevalence of multidrug-resistant Streptococcus pneumoniae in the United States

BACKGROUND

The emergence of drug-resistant strains of bacteria has complicated treatment decisions and may lead to treatment failures.

METHODS

We examined data on invasive pneumococcal disease in patients identified from 1995 to 1998 in the Active Bacterial Core Surveillance program of the Centers for Disease Control and Prevention. Pneumococci that had a high level of resistance or had intermediate resistance according to the definitions of the National Committee for Clinical Laboratory Standards were defined as "resistant" for this analysis.

RESULTS

During 1998, 4013 cases of invasive Streptococcus pneumoniae disease were reported (23 cases per 100,000 population); isolates were available for 3475 (87 percent). Overall, 24 percent of isolates from 1998 were resistant to penicillin. The proportion of isolates that were resistant to penicillin was highest in Georgia (33 percent) and Tennessee (35 percent), in children under five years of age (32 percent, vs. 21 percent for persons five or more years of age), and in whites (26 percent, vs. 22 percent for blacks). Penicillin-resistant isolates were more likely than susceptible isolates to have a high level of resistance to other antimicrobial agents. Serotypes included in the 7-valent conjugate and 23-valent pneumococcal polysaccharide vaccines accounted for 78 percent and 88 percent of penicillin-resistant strains, respectively. Between 1995 and 1998 (during which period 12,045 isolates were collected), the proportion of isolates that were resistant to three or more classes of drugs increased from 9 percent to 14 percent; there also were increases in the proportions of isolates that were resistant to penicillin (from 21 percent to 25 percent), cefotaxime (from 10 percent to 15 percent), meropenem (from 10 percent to 16 percent), erythromycin (from 11 percent to 16 percent), and trimethoprim-sulfamethoxazole (from 25 percent to 29 percent). The increases in the frequency of resistance to other antimicrobial agents occurred exclusively among penicillin-resistant isolates.

CONCLUSIONS

Multidrug-resistant pneumococci are common and are increasing. Because a limited number of serotypes account for most infections with drug-resistant strains, the new conjugate vaccines offer protection against most drug-resistant strains of S. pneumoniae.

Mortality from invasive pneumococcal pneumonia in the era of antibiotic resistance, 1995-1997

OBJECTIVES

This study examined epidemiologic factors affecting mortality from pneumococcal pneumonia in 1995 through 1997.

METHODS

Persons residing in a surveillance area who had community-acquired pneumonia requiring hospitalization and Streptococcus pneumoniae isolated from a sterile site were included in the analysis. Factors affecting mortality were evaluated in univariate and multivariate analyses. The number of deaths from pneumococcal pneumonia requiring hospitalization in the United States in 1996 was estimated.

RESULTS

Of 5837 cases, 12% were fatal. Increased mortality was associated with older age, underlying disease. Asian race, and residence in Toronto/Peel, Ontario. When these factors were controlled for, increased mortality was not associated with resistance to penicillin or cefotaxime. However, when deaths during the first 4 hospital days were excluded, mortality was significantly associated with penicillin minimum inhibitory concentrations of 4.0 or higher and cefotaxime minimum inhibitory concentrations of 2.0 or higher. In 1996, about 7000 to 12,500 deaths occurred in the United States from pneumococcal pneumonia requiring hospitalization.

CONCLUSIONS

Older age and underlying disease remain the most important factors influencing death from pneumococcal pneumonia. Mortality was not elevated in most infections with beta-lactam-resistant pneumococci.

The changing epidemiology of meningococcal disease in the United States, 1992-1996

New meningococcal vaccines are undergoing clinical trials, and changes in the epidemiologic features of meningococcal disease will affect their use. Active laboratory-based, population-based US surveillance for meningococcal disease during 1992-1996 was used to project that 2400 cases of meningococcal disease occurred annually. Incidence was highest in infants; however, 32% of cases occurred in persons >/=30 years of age. Serogroup C caused 35% of cases; serogroup B, 32%; and serogroup Y, 26%. Increasing age (relative risk [RR], 1.01 per year), having an isolate obtained from blood (RR, 4.5), and serogroup C (RR, 1.6) were associated with increased case fatality. Among serogroup B isolates, the most commonly expressed serosubtype was P1.15; 68% of isolates expressed 1 of the 6 most common serosubtypes. Compared with cases occurring in previous years, recent cases are more likely to be caused by serogroup Y and to occur among older age groups. Ongoing surveillance is necessary to determine the stability of serogroup and serosubtype distribution.

Risk factors for invasive pneumococcal disease in children: a population-based case-control study in North America

OBJECTIVE

To identify risk factors for invasive pneumococcal disease, including penicillin-resistant infections, among children 2 to 59 months of age.

DESIGN

Case-control study.

PARTICIPANTS

Patients with invasive pneumococcal infections identified by population-based surveillance (n = 187) and controls identified through random-digit telephone dialing (n = 280).

OUTCOME MEASURES

Invasive pneumococcal disease was defined as isolation of Streptococcus pneumoniae from a normally sterile site. Patients 2 to 59 months of age who were residents of one of four active surveillance areas were included. S pneumoniae isolates were tested by broth microdilution. Isolates with a minimum inhibitory concentration to penicillin >/=2 microg/mL were considered resistant.

RESULTS

Invasive pneumococcal disease was strongly associated with underlying disease and with day care attendance in the previous 3 months. Among 2- to 11-month-olds, current breastfeeding was associated with a decreased likelihood of invasive pneumococcal disease (odds ratio, 0.27; 95% confidence interval: 0.08, 0.90). Penicillin-resistant infections were independently associated with day care attendance, at least one course of antibiotics, and at least one ear infection in the previous 3 months.

CONCLUSIONS

This study shows the association of underlying illnesses, day care attendance, and lack of breastfeeding with risk of invasive pneumococcal disease in children. The association of recent antibiotic use and infection with penicillin-resistant S pneumoniae highlights the need to avoid unnecessary antibiotic use in children.

Bacterial meningitis in the United States in 1995. Active Surveillance Team

BACKGROUND

Before the introduction of the conjugate vaccines, Haemophilus influenzae type b was the major cause of bacterial meningitis in the United States, and meningitis was primarily a disease of infants and young children. We describe the epidemiologic features of bacterial meningitis five years after the H. influenzae type b conjugate vaccines were licensed for routine immunization of infants.

METHODS

Data were collected from active, population-based surveillance for culture-confirmed meningitis and other invasive bacterial disease during 1995 in laboratories serving all the acute care hospitals in 22 counties of four states (total population, more than 10 million). The rates were compared with those for 1986 obtained by similar surveillance.

RESULTS

On the basis of 248 cases of bacterial meningitis in the surveillance areas, the rates of meningitis (per 100,000) for the major pathogens in 1995 were Streptococcus pneumoniae, 1.1; Neisseria meningitidis, 0.6; group B streptococcus, 0.3; Listeria monocytogenes, 0.2; and H. influenzae, 0.2. Group B streptococcus was the predominant pathogen among newborns, N. meningitidis among children 2 to 18 years old, and S. pneumoniae among adults. Pneumococcal meningitis had the highest case fatality rate (21 percent) and in 36 percent of cases was caused by organisms that were not susceptible to penicillin. From these data, we estimate that 5755 cases of bacterial meningitis were caused by these five pathogens in the United States in 1995, as compared with 12,920 cases in 1986, a reduction of 55 percent. The median age of persons with bacterial meningitis increased greatly, from 15 months in 1986 to 25 years in 1995, largely as a result of a 94 percent reduction in the number of cases of H. influenzae meningitis.

CONCLUSIONS

Because of the vaccine-related decline in meningitis due to H. influenzae type b, bacterial meningitis in the United States is now a disease predominantly of adults rather than of infants and young children.

Long-term efficacy and safety of dronabinol for acquired immunodeficiency syndrome-associated anorexia

We studied the effects of long-term (12 months) dronabinol in 94 late-stage acquired immunodeficiency syndrome (AIDS) patients (mean CD4 count of 45/mm3) who previously participated in a 6-week study (placebo versus dronabinol). All patients received dronabinol orally-2.5 mg twice daily (90%) or 2.5 mg once daily (10%). Appetite was measured using a visual analogue scale for hunger (VASH). Dronabinol was associated with consistent improvement in mean appetite. Patients previously treated with dronabinol continued to show improvement in VASH (percent change from baseline of 6-week trial: 48.6-76.1% at each month), whereas those previously treated with placebo exhibited substantial improvement in mean appetite, particularly during the initial 4 months of treatment (48.5-69.9%). Thereafter, dronabinol was associated with a VASH change at least twice baseline. Patients tended toward stable body weight for at least 7 months. Adverse events were primarily related to known central nervous system effects of dronabinol. These data support long-term, safe use of dronabinol for anorexia associated with weight loss in patients with AIDS.

Virologic and immunologic benefits of initial combination therapy with zidovudine and zalcitabine or didanosine compared with zidovudine monotherapy. Wellcome Resistance Study Collaborative Group

A randomized controlled study was done to determine whether initial combination therapy with zidovudine and zalcitabine or zidovudine and didanosine would delay the emergence of zidovudine-resistant virus. Human immunodeficiency virus (HIV)-1-infected patients with <300 CD4 cells/mm3 and <4 weeks of prior zidovudine therapy were randomized to zidovudine, zidovudine plus zalcitabine, or zidovudine plus didanosine. Combination therapy did not delay the emergence of zidovudine-resistant virus isolates. However, combination therapy resulted in a significant increase in CD4 cells through 72 weeks compared with zidovudine monotherapy and a greater and more sustained decline in serum HIV-1 RNA. Although this trial was not designed as a clinical end-point study, patients assigned to zidovudine plus didanosine combination therapy experienced a significant delay in time to first AIDS-defining event or death compared with those assigned to zidovudine monotherapy.

Dronabinol as a treatment for anorexia associated with weight loss in patients with AIDS

The effects of dronabinol on appetite and weight were evaluated in 139 patients with AIDS-related anorexia and > or = 2.3 kg weight loss in a multi-institutional study. Patients were randomized to receive 2.5 mg dronabinol twice daily or placebo. Patients rated appetite, mood, and nausea by using a 100-mm visual analogue scale 3 days weekly. Efficacy was evaluable in 88 patients. Dronabinol was associated with increased appetite above baseline (38% vs 8% for placebo, P = 0.015), improvement in mood (10% vs -2%, P = 0.06), and decreased nausea (20% vs 7%; P = 0.05). Weight was stable in dronabinol patients, while placebo recipients had a mean loss of 0.4 kg (P = 0.14). Of the dronabinol patients, 22% gained > or = 2 kg, compared with 10.5% of placebo recipients (P = 0.11). Side effects were mostly mild to moderate in severity (euphoria, dizziness, thinking abnormalities); there was no difference in discontinued therapy between dronabinol (8.3%) and placebo (4.5%) recipients. Dronabinol was found to be safe and effective for anorexia associated with weight loss in patients with AIDS.