Carbapenem-resistant Klebsiella pneumoniae is an emerging healthcare-associated pathogen.

To describe the epidemiology of and clinical outcomes associated with carbapenem-resistant K. pneumoniae infection and to identify risk factors associated with mortality among patients with this type of infection.

Mount Sinai Hospital, a 1,171-bed tertiary care teaching hospital in New York City.

Two matched case-control studies.

In the first matched case-control study, case patients with carbapenem-resistant K. pneumoniae infection were compared with control patients with carbapenem-susceptible K. pneumoniae infection. In the second case-control study, patients who survived carbapenem-resistant K. pneumoniae infection were compared with those who did not survive, to identify risk factors associated with mortality among patients with carbapenem-resistant K. pneumoniae infection.

There were 99 case patients and 99 control patients identified. Carbapenem-resistant K. pneumoniae infection was independently associated with recent organ or stem-cell transplantation (P = .008), receipt of mechanical ventilation (P = .04), longer length of stay before infection (P = .01), and exposure to cephalosporins (P = .02) and carbapenems (P < .001). Case patients were more likely than control patients to die during hospitalization (48% vs 20%; P < .001) and to die from infection (38% vs 12%; P < .001). Removal of the focus of infection (ie, debridement) was independently associated with patient survival (P = .002). The timely administration of antibiotics with in vitro activity against carbapenem-resistant K. pneumoniae was not associated with patient survival.

Carbapenem-resistant K. pneumoniae infection is associated with numerous healthcare-related risk factors and with high mortality. The mortality rate associated with carbapenem-resistant K. pneumoniae infection and the limited antimicrobial options for treatment of carbapenem-resistant K. pneumoniae infection highlight the need for improved detection of carbapenem-resistant K. pneumoniae infection, identification of effective preventive measures, and development of novel agents with reliable clinical efficacy against carbapenem-resistant K. pneumoniae.

To determine the incidence density of highly resistant organisms (HROs) and the relative contribution of horizontal spread in a setting of endemicity.

Prospective surveillance was performed among hospitalized patients during an 18-month period. Enterobacteriaceae, non-fermentative gram-negative bacilli, Staphylococcus aureus, Streptococcus pneumoniae, and Enterococcus faecium—all considered highly resistant, according to Dutch guidelines—were included. Epidemiological linkage and nosocomial transmission were determined on the basis of molecular typing and hospital admission data.

From 119 patients, we recovered a total of 170 unique HRO isolates, as follows: Escherichia coli, 96 isolates; Klebsiella species, 11 isolates; Enterobacter species, 8 isolates; Proteus species, 9 isolates; Citrobacter species, 5 isolates; Pseudomonas species, 5 isolates; Aci-netobacter species, 3 isolates; Morganella species, 2 isolates; Salmonella species, 1 isolate; Serratia species, 1 isolate; S. pneumoniae, 20 isolates; and S. aureus, 9 isolates. No vancomycin-resistant E. faecium was found. The incidence density was 4.3 HRO isolates per 10,000 patient-days. The majority of HRO isolates were unique, and nosocomial transmission was observed 4 times for highly resistant gram-negative bacilli (case reproduction rate, 0.05) and 4 times for penicillin-nonsusceptible S. pneumoniae (case reproduction rate, 0.29). A stay on the intensive care unit was the main determinant for the recovery of an HRO.

Nosocomial transmission of HROs was observed 8 times during the 18-month period. The intensive care unit was identified as the main reservoir of horizontal spread of HROs. This study shows that nosocomial transmission of HROs is largely preventable using transmission precautions.

To assess the impact of isolation precautions on the incidence of patients colonized or infected with Acinetobacter baumannii (case patients) in a university hospital during the period from 1999 to 2006.

Ecological study.

The Besançon University Hospital in France, a 1,200-bed acute care hospital with approximately 50,000 admissions per year.

Using Poisson regression analysis, we evaluated a total of 350,000 patient-days to determine the annual incidence of case patients. This annual incidence was used as the outcome variable, and infection control practices, antibiotic use, and other aggregated data regarding patients' age, sex, McCabe score, and immune status were used as covariates.

The implementation of isolation precautions was independently and negatively associated with the incidence of patients colonized or infected with A. baumannii (relative risk, 0.50 [95% confidence interval, 0.40–0.64]; P < .001).

Our study suggests that the implementation of isolation precautions, in addition to standard precautions, effectively prevents the spread of A. baumannii in a hospital setting.

Recognition of seasonal trends in hospital infections may improve diagnosis, use of empirical therapy, and infection prevention interventions. There are very few data available regarding the seasonal variability of these infections. We quantified the seasonal variation in the incidences of hospital infection caused by common bacterial pathogens and estimated the association between temperature changes and infection rates.

A cohort of all adult patients admitted to the University of Maryland Medical Center during the period from 1998 through 2005 was analyzed. Time-series analyses were used to estimate the association of the number of infections per month caused by Pseudomonas aeruginosa, Acinetobacter baumannii, Enterobacter cloacae, Escherichia coli, Staphylococcus aureus, and enterococci with season and temperature, while controlling for long-term trends.

There were 218,594 admissions to the index hospital, and analysis of 26,624 unique clinical cultures that grew the organisms of interest identified increases in the mean monthly rates of infection caused by P. aeruginosa (28% of isolates recovered; P < .01), E. cloacae (46%; P < .01), E. coli (12%; P < .01), and A. baumannii (21%; P = .06). For each 10°F increase, we observed a 17% increase in the monthly rates of infection caused by P. aeruginosa (P = .01) and A. baumanii (P = .05).

Significantly higher rates of gram-negative infection were observed during the summer months, compared with other seasons. For some pathogens, higher temperatures were associated with higher infection rates, independent of seasonality. These findings have important implications for infection prevention, such as enhanced surveillance during the warmer months, and for choice of empirical antimicrobial therapy among hospitalized adults. Future, quasi-experimental investigations of gram-negative infection prevention initiatives should control for seasonal variation.

To evaluate the time trend in the surgical site infection (SSI) rate in relation to the duration of surveillance in The Netherlands.

Forty-two hospitals that participated in the the Dutch national nosocomial surveillance network, which is known as PREZIES (Preventie van Ziekenhuisinfecties door Surveillance), and that registered at least 1 of the following 5 frequently performed surgical procedures for at least 3 years during the period from 1996 through 2006: mastectomy, colectomy, replacement of the head of the femur, total hip arthroplasty, or knee arthroplasty.

Analyses were performed for each surgical procedure. The surveillance time to operation was stratified in consecutive 1-year periods, with the first year as reference. Multivariate logistic regression analysis was performed using a random coefficient model to adjust for random variation among hospitals. All models were adjusted for method of postdischarge surveillance.

The number of procedures varied from 3,031 for colectomy to 31,407 for total hip arthroplasty, and the SSI rate varied from 1.6% for knee arthroplasty to 12.2% for colectomy. For total hip arthroplasty, the SSI rate decreased significantly by 6% per year of surveillance (odds ratio [OR], 0.94 [95% confidence interval {CI}, 0.90–0.98]), indicating a 60% decrease after 10 years. Nonsignificant but substantial decreasing trends in the rate of SSI were found for replacement of the head of the femur (OR, 0.94 [95% CI, 0.88–1.00]) and for colectomy (OR, 0.92 [95% CI, 0.83–1.02]).

Even though most decreasing trends in the SSI rate were not statistically significant, they were encouraging. To use limited resources as efficiently as possible, we would suggest switching the surveillance to another surgical procedure when the SSI rate for that particular procedure has decreased below the target rate.

The risk of percutaneous blood and body fluid (BBF) exposures in operating rooms was analyzed with regard to various properties of surgical procedures.

Retrospective cohort study.

A single university hospital.

All surgical procedures performed during the period 2001–2002 (n = 60,583) were included in the analysis. Administrative data were linked to allow examination of 389 BBF exposures. Stratified exposure rates were calculated; Poisson regression was used to analyze risk factors. Risk of percutaneous BBF exposure was examined separately for events involving suture needles and events involving other device types.

Operating room personnel reported 6.4 BBF exposures per 1,000 surgical procedures (2.6 exposures per 1,000 surgical hours). Exposure rates increased with an increase in estimated blood loss (17.5 exposures per 1,000 procedures with 501–1,000 cc blood loss and 22.5 exposures per 1,000 procedures with >1,000 cc blood loss), increased number of personnel ever working in the surgical field (20.5 exposures per 1,000 procedures with 15 or more personnel ever in the field), and increased surgical procedure duration (13.7 exposures per 1,000 procedures that lasted 4–6 hours, 24.0 exposures per 1,000 procedures that lasted 6 hours or more). Associations were generally stronger for suture needle–related exposures.

Our results support the need for prevention programs that are targeted to mitigate the risks for BBF exposure posed by high blood loss during surgery (eg, use of blunt suture needles and a neutral zone for passing surgical equipment) and prolonged duration of surgery (eg, double gloving to defend against the risk of glove perforation associated with long surgery). Further investigation is needed to understand the risks posed by lengthy surgical procedures.

Respiratory protection programs, including fit testing of respirators, have been inconsistently implemented; evidence of their long-term efficacy is lacking. We undertook a study to determine the short- and long-term efficacy of training for fit testing of N95 respirators in both untrained and trained healthcare workers (HCWs).

Prospective observational cohort study.

A group of at-risk, consenting HCWs not previously fit-tested for a respirator were provided with a standard fit-test protocol. Participants were evaluated after each of 3 phases, and 3 and 14 months afterward. A second group of previously fit-tested nurses was studied to assess the impact of regular respirator use on performance.

Of 43 untrained fit-tested HCWs followed for 14 months, 19 (44.2%) passed the initial fit test without having any specific instruction on respirator donning technique. After the initial test, subsequent instruction led to a pass for another 13 (30.2%) of the 43 HCWs, using their original respirators. The remainder required trying other types of respirators to acheive a proper fit. At 3 and 14 months' follow-up, failure rates of 53.5% (23 of 43 HCWs) and 34.9% (15 of 43 HCWs), respectively, were observed. Pass rates of 87.5%-100.0% were observed among regular users.

Without any instruction, nearly 50% of the HCWs achieved an adequate facial seal with the most commonly used N95 respirator. Formal fit testing does not predict future adequacy of fit, unless frequent, routine use is made of the respirator. The utility of fit testing among infrequent users of N95 respirators is questionable.

With childhood varicella vaccination in the United States have come concerns that the incidence of herpes zoster may increase, because of diminishing natural exposure to varicella and consequent reactivation of latent varicella zoster virus. We wanted to estimate the rate of herpes zoster-related hospitalizations and the associated hospital charges before and during the promotion of varicella vaccination in the United States.

A retrospective study of patients from the Nationwide Inpatient Sample for the years 1993–2004 who were hospitalized due to herpes zoster infection.

We searched for diagnoses of herpes zoster (using the International Classification of Diseases, Ninth Revison, Clinical Modification codes starting with 053) in all 15 diagnostic-code fields included for hospital discharges in the Nationwide Inpatient Sample during 1993–2004. We designed our analysis to examine the rates of severe illness due to herpes zoster that resulted in hospitalization, as measured by the rates of herpes zoster-related hospital discharges (HZHDs). The annual population-adjusted rate of HZHDs (per 10,000 US population) and the annual inflation-adjusted total charges for HZHDs were the primary outcomes. Secondary outcomes included mean charges for HZHDs and the distribution of total charges for HZHDs by expected primary payer. Varicella-related hospital discharges (VRHDs) were identified by use of similar diagnosis-based methods, which were described in our previous study.

Population-adjusted rates of HZHDs did not change significantiy from the prevaccination years (1993–1995) through the initial 5 years of the varicella vaccination period. Beginning in 2001, however, the rate of HZHDs overall began to increase, and by 2004 the overall rate was 2.5 HZHDs (95% confidence interval, 2.38–2.62) per 10,000 US population, significantly higher than any of the rates calculated during the years prior to 2002. Hospital charges for HZHDs overall increased by more than $700 million annually by 2004; in particular, we found that the herpes zoster vaccine–eligible population (ie, persons aged 60 years or older) accounted for 74% of the total annual hospital charges in 2004. The annual rate of VRHDs and the associated hospital charges decreased significantly from 1993 through 2004, but the decrease in hospitalizations and charges for VRHDs was less than the increase in hospitalizations and charges for HZHDs.

AS the rates of VRHDs and the associated charges have decreased, there has been a significant increase in HZHDs and associated charges, disproportionately among older adults. Herpes zoster vaccine may mitigate these trends for HZHDs.