Estimating the Burden of Pandemic Infectious Disease: The Case of the Second Wave of Pandemic Influenza H1N1 in Forsyth County, North Carolina.

BACKGROUND: Understanding the burden of influenza A(H1N1)pdm09 virus during the second wave of 2009-2010 is important for future pandemic planning. METHODS: Persons who presented to the emergency department (ED) or were hospitalized with fever and/or acute respiratory symptoms at the academic medical center in Forsyth County, North Carolina were prospectively enrolled and underwent nasal/throat swab testing for influenza A(H1N1)pdm09. Laboratory-confirmed cases of influenza A(H1N1)pdm09 virus identified through active surveillance were compared by capture-recapture analysis to those identified through independent, passive surveillance (physician-ordered influenza testing). This approach estimated the number of total cases, including those not captured by either surveillance method. A second analysis estimated the total number of influenza A(H1N1)pdm09 cases by multiplying weekly influenza percentages determined via active surveillance by weekly counts of influenza-associated discharge diagnoses from administrative data. Market share adjustments were used to estimate influenza A(H1N1)pdm09 virus ED visits or hospitalizations per 1,000 residents. RESULTS: Capture-recapture analysis estimated that 753 residents (95% confidence interval [CI], 424-2,735) with influenza A(H1N1)pdm09 virus were seen in the academic medical center from September 2009 through mid-April 2010; this result yielded an estimated 4.7 (95% CI, 2.6-16.9) influenza A(H1N1)pdm09 virus ED visits or hospitalizations per 1,000 residents. Similarly, 708 visits were estimated using weekly influenza percentages and influenza-associated discharge diagnoses, yielding an estimated 4.4 influenza A(H1N1)pdm09 virus ED visits or hospitalizations per 1,000 residents. CONCLUSION: This study demonstrates that the burden of influenza A(H1N1)pdm09 virus in ED and inpatient settings by capture-recapture analysis was 4-5 per 1,000 residents; this rate was approximately 8-fold higher than that detected by physician-ordered influenza testing.

Intermittent occurrence of health care-onset influenza cases in a tertiary care facility during the 2017-2018 flu season.

Health care-onset influenza (HOI) poses a major risk for hospitalized patients. During the 2017-2018 season, 37 HOI cases out of 382 inpatients (9.7%) with influenza were detected in a tertiary care hospital. HOI and community-onset influenza cases peaked simultaneously, and employee absenteeism was delayed by 1 month. A HOI to community-onset influenza case-comparison revealed associations with placement in rehabilitation, leukocytosis, health care-associated infections, and elevated mortality rates. Interventions should be selected based on the epidemiology of influenza occurrence.

Nosocomial bloodstream infections in US hospitals: analysis of 24,179 cases from a prospective nationwide surveillance study.

BACKGROUND: Nosocomial bloodstream infections (BSIs) are important causes of morbidity and mortality in the United States. METHODS: Data from a nationwide, concurrent surveillance study (Surveillance and Control of Pathogens of Epidemiological Importance [SCOPE]) were used to examine the secular trends in the epidemiology and microbiology of nosocomial BSIs. RESULTS: Our study detected 24,179 cases of nosocomial BSI in 49 US hospitals over a 7-year period from March 1995 through September 2002 (60 cases per 10,000 hospital admissions). Eighty-seven percent of BSIs were monomicrobial. Gram-positive organisms caused 65% of these BSIs, gram-negative organisms caused 25%, and fungi caused 9.5%. The crude mortality rate was 27%. The most-common organisms causing BSIs were coagulase-negative staphylococci (CoNS) (31% of isolates), Staphylococcus aureus (20%), enterococci (9%), and Candida species (9%). The mean interval between admission and infection was 13 days for infection with Escherichia coli, 16 days for S. aureus, 22 days for Candida species and Klebsiella species, 23 days for enterococci, and 26 days for Acinetobacter species. CoNS, Pseudomonas species, Enterobacter species, Serratia species, and Acinetobacter species were more likely to cause infections in patients in intensive care units (P<.001). In neutropenic patients, infections with Candida species, enterococci, and viridans group streptococci were significantly more common. The proportion of S. aureus isolates with methicillin resistance increased from 22% in 1995 to 57% in 2001 (P<.001, trend analysis). Vancomycin resistance was seen in 2% of Enterococcus faecalis isolates and in 60% of Enterococcus faecium isolates. CONCLUSION: In this study, one of the largest multicenter studies performed to date, we found that the proportion of nosocomial BSIs due to antibiotic-resistant organisms is increasing in US hospitals.

Nosocomial bloodstream infections in pediatric patients in United States hospitals: epidemiology, clinical features and susceptibilities.

BACKGROUND: We identified the predominant pathogens and antimicrobial susceptibilities of nosocomial bloodstream isolates in pediatric patients in the US Prospective surveillance for nosocomial bloodstream infections at 49 hospitals during a 6-year period [Surveillance and Control of Pathogens of Epidemiologic Importance (SCOPE)] detected 22 609 bloodstream infections, of which 3432 occurred in patients < or =16 years of age. RESULTS: Gram-positive organisms accounted for 65% of cases, Gram-negative organisms accounted for 24% of cases and 11% were caused by fungi. The overall crude mortality was 14% (475 of 3432) but notably higher for infections caused by Candida spp. and Pseudomonas aeruginosa, 20 and 29%, respectively. The most common organisms were coagulase-negative staphylococci (43%), enterococci, Staphylococcus aureus and Candida spp. (each, 9%). The mean interval between admission and infection averaged 21 days for coagulase-negative staphylococci, 25 days for S. aureus and Candida spp., 32 days for Klebsiella spp. and 34 days for Enterococcus spp. The proportion of methicillin-resistant S. aureus increased from 10% in 1995 to 29% in 2001. Vancomycin-resistance was seen in 1% of Enterococcus faecalis and in 11% of Enterococcus faecium isolates. CONCLUSION: Nosocomial BSI occurred predominantly in very young and/or critically ill children. Gram-positive pathogens predominated across all ages, and increasing antimicrobial resistance was observed in pediatric patients.

Vancomycin susceptibility of oxacillin-resistant Staphylococcus aureus isolates causing nosocomial bloodstream infections.

Nosocomial oxacillin-resistant Staphylococcus aureus (ORSA) bloodstream isolates were tested to determine the prevalence of vancomycin heteroresistance. We screened 619 ORSA nosocomial bloodstream isolates from 36 hospitals between 1997 and 2000. Only one isolate exhibiting heterotypic resistance was detected. Thus, vancomycin heteroresistance in clinical bloodstream isolates remains rare in the United States.