To describe the distribution of nosocomial infections among surgical patients by site of infection for different types of operations, and to show how the risk of certain adverse outcomes associated with nosocomial infection varied by site, type of operation, and exposure to specific medical devices.

Surveillance of surgical patients during January 1986-June 1992 using standard definitions and protocols for both comprehensive (all sites, all operations) and targeted (all sites, selected operations) infection detection.

Acute care US hospitals participating in the National Nosocomial Infection Surveillance (NNIS) System: 42,509 patients with 52,388 infections from 95 hospitals using comprehensive surveillance protocols and an additional 5,659 patients with 6,963 infections from 11 more hospitals using a targeted protocol.

Surgical site infection was the most common nosocomial infection site (37%) when data were reported by hospitals using the comprehensive protocols. When infections reported from both types of protocols were stratified by type of operation, other sites were most frequent following certain operations (e.g., urinary tract infection after joint prosthesis surgery [52%]). Among the infected surgical patients who died, the probability that an infection was related to the patient's death varied significantly with the site of infection, from 22% for urinary tract infection to 89% for organ/space surgical site infection, but was independent of the type of operation performed. The probability of developing a secondary bloodstream infection also varied significantly with the primary site of infection, from 3.1% for incisional surgical site infection to 9.5% for organ/space surgical site infection (p<.001). For all infections except pneumonia, the risk of developing a secondary bloodstream infection also varied significantly with the type of operation performed (p<.00l) and was generally highest for cardiac surgery and lowest for abdominal hysterectomy. Surgical patients who developed ventilator-associated pneumonia were more than twice as likely to develop a secondary bloodstream infection as nonventilated pneumonia patients (8.1% versus 3.3%, p<.001).

For surgical patients with nosocomial infection, the distribution of nosocomial infections by site varies by type of operation, the frequency with which nosocomial infections contribute to patient mortality varies by site of infection but not by type of operation, and the risk of developing a secondary bloodstream infection varies by type of primary infection and, except for pneumonia, by type of operation.

Healthcare workers experience occupational risk of infection and may transmit infections to patients. Vaccination provides an efficient means of protecting workers and patients, but uptake may be low. We sought to identify factors influencing vaccine acceptance by healthcare workers in order to obtain insights leading to more effective vaccination programs in this population.

Systematic review and meta-analysis.

We searched Medline, Embase, and CINAHL databases to identify studies published up to May 2012. Factors influencing vaccination acceptance were devised a priori. Random-effects meta-analysis was performed to generate summary estimates of effect. Heterogeneity and publication bias were explored using statistical tools.

Thirty-seven studies evaluating a variety of vaccines (against influenza, pertussis, smallpox, anthrax, and hepatitis B) were included. Homogeneous effects on vaccine acceptance were identified with desire for self-protection (odds ratio [OR], 3.42 [95% confidence interval (CI), 2.42–4.82]) and desire to protect family and friends (OR, 3.28 [95% CI, 1.10–9.75]). Concern that vaccine transmits the illness it was meant to prevent decreased acceptance (OR, 0.42 [95% CI, 0.30–0.58]). Differences in physician and nurse acceptance of immunization were seen between Asian and non-Asian studies.

Consideration of self-protection (rather than absolute disease risk or protection of patients) appears the strongest and most consistent driver of healthcare workers’ decisions to accept vaccination, though other factors may also be impactful, and reasons for between-study divergence in effects is an important area for future research. This finding has important implications for the design of programs to enhance healthcare worker vaccine uptake.

Infect Control Hosp Epidemiol 2014;35(6):699–708

Serratia marcescens causes healthcare-associated infections and significant morbidity and mortality in neonatal intensive care units (NICUs). We report the investigation and control of an outbreak of multidrug-resistant (MDR) S. marcescens infection at an NICU.

An outbreak investigation and a case-control study were undertaken at a 36-bed NICU in a tertiary care hospital in Baltimore, Maryland, for the period from October 2004 through February 2005. The outbreak investigation included case identification, review of medical records, environmental cultures, patient surveillance cultures, personnel hand cultures, and pulsed-field gel electrophoresis (PFGE). The case-control study included case identification and review of medical records. Infection control measures were implemented. Eighteen NICU neonates had cultures that grew MDR S. marcescens during the study period. The case-control study included 16 patients with the outbreak strain or an unidentified strain of MDR S. marcescens and 32 control patients not infected and/or colonized with MDR S. marcescens, treated in the NICU for at least 48 hours during the study period.

PFGE analysis identified a single strain of MDR S. marcescens that infected or colonized 15 patients. Two patients had unique strains, and 1 patient's isolate could not be subtyped. An unrelated MDR S. marcescens isolate was recovered from a sink drain. Exposure to inhalational therapy was an independent risk factor for MDR S. marcescens acquisition after adjusting for birth weight. Extensive investigation failed to reveal a point source for the outbreak.

A single epidemic strain of MDR S. marcescens spread rapidly and threatened to become endemic in this NICU. Transient carriage on the hands of healthcare personnel or on respiratory care equipment was the likely mode of transmission. Cohorting patients and staff, at the cost of bed closures and additional personnel, interrupted transmission and halted the outbreak.

To compare 8 severity score indices for Clostridium difficile infection (CDI).

Prospective observational study.

This study was conducted from July through October 2006. All hospitalized patients in 3 university-affiliated hospitals with a positive fecal Clostridium difficile toxin assay result were evaluated. Infection was considered severe if patients had at least 1 of the following clinical events during their hospitalization: (1) death attributed to CDI within 30 days after diagnosis, (2) colectomy necessitated by CDI, or (3) intensive care unit admission for management of complications attributed to CDI. Severity was assessed on the basis of 8 severity score indices, using published criteria for severe CDI as the benchmark. The 8 severity score indices studied were Beth Israel, University of Pittsburgh Medical Center version 1, University of Pittsburgh Medical Center version 2, Hines VA, modified University of Illinois, University of Calgary version 1, University of Calgary version 2, and University of Temple.

Of 184 patients with CDI evaluated, 19 had severe cases and 165 had nonsevere cases, as assessed on the basis of the defined severe CDI criteria. Sensitivities of the 8 severity score indices studied ranged from 63.2% to 84.2%, and specificities ranged from 59.4% to 93.9%. The Hines VA index had the highest kappa score (0.69 [95% confidence interval, 0.54-0.83]), followed by the University of Pittsburgh Medical Center version 1 index. Independent risk factors for severe CDI determined by multivariate analysis were abdominal distention (P = .007), fever (temperature, 38.0°C or above; P = .042), white blood cell count of at least 20,000 cells/mm3 (P = .035), and hypoalbuminemia (serum albumin level less than 3 mg/dL; P = .029).

The Hines VA CDI severity score index appeared to display the strongest correlation for predicting more severe forms of CDI.

To identify the source of an outbreak of acute hepatitis C virus (HCV) infection among 3 patients occurring within 8 weeks of hospitalization in the same ward of a Florida hospital during November 1998.

A retrospective cohort study was conducted among 41 patients hospitalized between November 11 and 19, 1998. Patients' blood was tested for antibodies to HCV, and HCV RNA-positive samples were genotyped and sequenced.

Of the 41 patients, 24 (59%) participated in the study. HCV genotype 1b infections were found in 5 patients. Three of 4 patients who received saline flushes from a multidose saline vial on November 16 had acute HCV infection, whereas none of the 9 patients who did not receive saline flushes had HCV infection (P = .01). No other significant exposures were identified. The HCV sequence was available for 1 case of acute HCV and differed by a single nucleotide (0.3%) from that of the indeterminate case.

This outbreak of HCV probably occurred when a multidose saline vial was contaminated with blood from an HCV-infected patient. Hospitals should emphasize adherence to standard procedures to prevent blood-borne infections. In addition, the use of single-dose vials or prefilled saline syringes might further reduce the risk for nosocomial transmission of blood-borne pathogens.

Pseudomonas aeruginosa is one of the most common gram-negative hospital-acquired pathogens. Resistance of this organism to imipenem complicates treatment.

To elucidate the risk factors for imipenem-resistant P. aeruginosa (IRPA) infection or colonization and to identify the effect of resistance on clinical and economic outcomes.

Longitudinal trends in prevalence of IRPA from 2 centers were characterized during the period from 1989 through 2006. For P. aeruginosa isolates obtained during the period from 2001 through 2006, a case-control study was conducted to investigate the association between prior carbapenem use and IRPA infection or colonization, and a cohort study was performed to identify the effect of IRPA infection or colonization on mortality, length of stay after culture, and hospital cost after culture.

From 1989 through 2006, the proportion of P. aeruginosa isolates demonstrating resistance to imipenem increased from 13% to 20% (P< .001, trend). During the period from 2001 through 2006, there were 2,542 unique patients with P. aeruginosa isolates, and 253 (10.0%) had IRPA isolates. Prior carbapenem use was independently associated with IRPA infection or colonization (adjusted odds ratio [OR], 7.92 [95% confidence interval {CI}, 4.78-13.11]). Patients with an IRPA isolate recovered had higher in-hospital mortality than did patients with an imipenem-susceptible P. aeruginosa isolate (17.4% vs 13.4%; P = .01). IRPA infection or colonization was an independent risk factor for mortality among patients with isolates recovered from blood (adjusted OR, 5.43 [95% CI, 1.72-17.10]; P = .004) but not among patients with isolates recovered from other anatomic sites (adjusted OR, 0.78 [95% CI, 0.51-1.21]; P = .27). Isolation of IRPA was associated with longer hospital stay after culture (P<.001) and greater hospital cost after culture (P<.001) than was isolation of an imipenem-susceptible strain. In multivariable analysis, IRPA infection or colonization remained an independent risk factor for both longer hospital stay after culture (coefficient, 0.20 [95% CI, 0.04-0.36]; P = .02) and greater hospital cost after culture (coefficient, 0.30 [95% CI, 0.06-0.54]; P = .02).

The prevalence of IRPA infection or colonization has increased significantly, with important implications for both clinical and economic outcomes. Interventions to curb this continued increase and strategies to optimize therapy are urgently needed.

To evaluate the efficacy of silicone-based, silver ion–impregnated urinary catheters in the prevention of nosocomial urinary tract infections (NUTIs).

Prospective, crossover study to compare the efficacy of a silicone-based, hydrogel-coated, silver-impregnated Foley catheter with that of a silicone-based, hydrogel-coated catheter in the prevention of NUTIs.

Adult medical and surgical wards of a university teaching hospital.

A total of 3,036 patients with catheters were evaluated; 1,165 (38%) of the catheters were silver impregnated, and 1,871 (62%) were not silver impregnated. Study groups were not identical; there were more men, a shorter duration of catheterization, and fewer urine cultures per 1,000 catheter-days in the silver catheter group. The rate of NUTIs per 1,000 Foley-days was 14.29 in the silver catheter group, compared with 16.15 in the nonsilver catheter group (incidence rate ratio, 0.88; 95% confidence interval, 0.70-1.11; P = .29). The median length of catheterization prior to the onset of a urinary tract infection (ie, exposure time) was 4 days for each group. There were no differences in the recovery of gram-positive, gram-negative, or fungal organisms in NUTIs. In a multivariate survival analysis, no factors, including silver catheters, were protective against NUTI.

Unlike previous trials of latex-based, silver ion–impregnated Foley catheters, we found that silicone-based, silver-impregnated Foley catheters were not effective in preventing NUTIs; however, this study was affected by differences in the study groups. Prospective trials remain important in assessing the efficacy and cost-effectiveness of new silver-coated products.

To report the results of a surveillance study on surgical site infections (SSIs) conducted by the International Nosocomial Infection Control Consortium (INICC).

Cohort prospective multinational multicenter surveillance study.

Eighty-two hospitals of 66 cities in 30 countries (Argentina, Brazil, Colombia, Cuba, Dominican Republic, Egypt, Greece, India, Kosovo, Lebanon, Lithuania, Macedonia, Malaysia, Mexico, Morocco, Pakistan, Panama, Peru, Philippines, Poland, Salvador, Saudi Arabia, Serbia, Singapore, Slovakia, Sudan, Thailand, Turkey, Uruguay, and Vietnam) from 4 continents (America, Asia, Africa, and Europe).

Patients undergoing surgical procedures (SPs) from January 2005 to December 2010.

Data were gathered and recorded from patients hospitalized in INICC member hospitals by using the methods and definitions of the Centers for Disease Control and Prevention National Healthcare Safety Network (CDC-NHSN) for SSI. SPs were classified into 31 types according to International Classification of Diseases, Ninth Revision, criteria.

We gathered data from 7,523 SSIs associated with 260,973 SPs. SSI rates were significantly higher for most SPs in INICC hospitals compared with CDC-NHSN data, including the rates of SSI after hip prosthesis (2.6% vs 1.3%; relative risk [RR], 2.06 [95% confidence interval (CI), 1.8–2.4]; P<.001), coronary bypass with chest and donor incision (4.5% vs 2.9%; RR, 1.52 [95% CI, 1.4–1.6]; P<.001); abdominal hysterectomy (2.7% vs 1.6%; RR, 1.66 [95% CI, 1.4–2.0]; P<.001); exploratory abdominal surgery (4.1 % vs 2.0%; RR, 2.05 [95% CI, 1.6–2.6]; P<.001); ventricular shunt, 12.9% vs 5.6% (RR, 2.3 [95% CI, 1.9–2.6]; P<.001), and others.

SSI rates were higher for most SPs in INICC hospitals compared with CDC-NHSN data.

To characterize the current economic burden of ventilator-associated pneumonia (VAP) and to determine which services increase the cost of VAP in North American hospitals.

We performed a retrospective, matched cohort analysis of mechanically ventilated patients enrolled in the North American Silver-Coated Endotracheal Tube (NASCENT) study, a prospective, randomized study conducted from 2002 to 2006 in 54 medical centers, including 45 teaching institutions (83.3%).

Case patients with microbiologically confirmed VAP (n = 30) were identified from 542 study participants with claims data and were matched by use of a primary diagnostic code, and subsequently by the Acute Physiology and Chronic Health Evaluation II score, to control patients without VAP (n = 90). Costs were estimated by applying hospital-specific cost-to-charge ratios based on all-payer inpatient costs associated with VAP diagnosis-related groups.

Median total charges per patient were $198,200 for case patients and $96,540 for matched control patients (P <.001); corresponding median hospital costs were $76,730 for case patients and $41,250 for control patients (P = .001). After adjusting for diagnosis-related group payments, median losses to hospitals were $32,140 for case patients and $19,360 for control patients (P = .151). The median duration of intubation was longer for case patients than for control patients (10.1 days vs 4.7 days; P < .001), as were the median duration of intensive care unit stay (18.5 days vs 8.0 days; P < .001) and the median duration of hospitalization (26.5 days vs 14.0 days; P < .001). Examples of services likely to be directly related to VAP and having higher median costs for case patients were hospital care (P < .05) and respiratory therapy (P < .05).

VAP was associated with increased hospital costs, longer duration of hospital stay, and a higher number of hospital services being affected, which underscores the need for bundled measures to prevent VAP.

NASCENT study ClinicalTrials.gov Identifier: NCT00148642.

To evaluate risk factors and treatment outcomes of bloodstream infections caused by extended-spectrum beta-lactamase-producing Klebsiella pneumoniae (ESBL-KP).

Retrospective case-control study. Stored blood isolates of K. pneumoniae were tested for ESBL production by NCCLS guidelines, double-disk synergy test, or both.

A 1,500-bed, tertiary-care university hospital and referral center.

Sixty case-patients with bacteremia due to ESBL-KP were compared with 60 matched control-patients with non-ESBL-KP.

There were no significant differences in age, gender, APACHE II score, or underlying diseases between the groups. Independent risk factors for infections caused by ESBL-KP were urinary catheterization, invasive procedure within the previous 72 hours, and an increasing number of antibiotics administered within the previous 30 days. Complete response rate, evaluated 72 hours after initial antimicrobial therapy, was higher among control-patients (13.3% vs 36.7%; P = .003). Treatment failure rate was higher among case-patients (35.0% vs 15%; P = .011). Overall 30-day mortality rate was 30% for case-patients and 28.3% for control-patients (P = .841). Case-patients who received imipenem or ciprofloxacin as a definitive antibiotic had 10.5% mortality. The mortality rate for initially ineffective therapy was no higher than that for initially effective therapy (9.1% vs 11.1%; P = 1.000), but statistical power was low for evaluating mortality in the absence of septic shock.

For K. pneumoniae bacteremia, patients with ESBL-KP had a higher initial treatment failure rate but did not have higher mortality if antimicrobial therapy was appropriately adjusted in this study with limited statistical power.

The Centers for Disease Control and Prevention implemented new surveillance definitions for ventilator-associated events (VAEs) in January 2013. We describe the epidemiology, attributable morbidity, and attributable mortality of VAEs.

Retrospective cohort study.

Academic tertiary care center.

All patients initiated on mechanical ventilation between January 1, 2006, and December 31, 2011.

We calculated and compared VAE hazard ratios, antibiotic exposures, microbiology, attributable morbidity, and attributable mortality for all VAE tiers.

Among 20,356 episodes of mechanical ventilation, there were 1,141 (5.6%) ventilator-associated condition (VAC) events, 431 (2.1%) infection-related ventilator-associated complications (IVACs), 139 (0.7%) possible pneumonias, and 127 (0.6%) probable pneumonias. VAC hazard rates were highest in medical, surgical, and thoracic units and lowest in cardiac and neuroscience units. The median number of days to VAC onset was 6 (interquartile range, 4–11). The proportion of IVACs to VACs ranged from 29% in medical units to 42% in surgical units. Patients with probable pneumonia were more likely to be prescribed nafcillin, ceftazidime, and fluroquinolones compared with patients with possible pneumonia or IVAC-alone. The most frequendy isolated organisms were Staphylococcus aureus (29%), Pseudomonas aeruginosa (14%), and Enterobacter species (7.9%). Compared with matched controls, VAEs were associated with more days to extubation (relative rate, 3.12 [95% confidence interval (CI), 2.96–3.29]), more days to hospital discharge (relative rate, 1.46 [95% CI, 1.37–1.55]), and higher hospital mortality risk (odds ratio, 1.98 [95% CI, 1.60–2.44]).

VAEs are common and morbid. Prevention strategies targeting VAEs are needed.

Potential transmission of organisms from the environment to patients is a concern, especially in enclosed settings, such as operating rooms, in which there are multiple and frequent contacts between patients, provider's hands, and environmental surfaces. Therefore, adequate disinfection of operating rooms is essential. We aimed to determine the change in both the thoroughness of environmental cleaning and the proportion of environmental surfaces within operating rooms from which pathogenic organisms were recovered.

Prospective environmental study using feedback with UV markers and environmental cultures.

A 1,500-bed county teaching hospital.

Environmental service personnel, hospital administration, and medical and nursing leadership

The proportion of UV markers removed (cleaned) increased from 0.47 (284 of 600 markers; 95% confidence interval [CI], 0.42-0.53) at baseline to 0.82 (634 of 777 markers; 95% CI, 0.77-0.85) during the last month of observations (P < .0001). Nevertheless, the percentage of samples from which pathogenic organisms (gram-negative bacilli, Staphylococcus aureus, and Enterococcus species) were recovered did not change throughout our study. Pathogens were identified on 16.6% of surfaces at baseline and 12.5% of surfaces during the follow-up period (P = .998). However, the percentage of surfaces from which gram-negative bacilli were recovered decreased from 10.7% at baseline to 2.3% during the follow-up period (P = .015).

Feedback using Gram staining of environmental cultures and UV markers was successful at improving the degree of cleaning in our operating rooms.

We evaluated the usefulness of topical decolonization therapy for reducing the risk of methicillin-resistant Staphylococcus aureus (MRSA) infection among MRSA-colonized inpatients.

Retrospective cohort study.

Three hospitals with universal surveillance for MRSA; at their physician's discretion, colonized patients could be treated with a 5-day course of nasal mupirocin calcium 2%, twice daily, plus Chlorhexidine gluconate 4% every second day.

MRSA carriers were later retested for colonization (407 subjects; study 1) or followed up for development of MRSA infection (933 subjects; study 2). Multivariable methods were used to determine the impact of decolonization therapy on the risks of sustained colonization (in study 1) and MRSA infection (in study 2).

Independent risk factors for sustained colonization included residence in a long-term care facility (odds ratio [OR], 1.8 [95% confidence interval {CI}, 1.1–3.2]) and a pressure ulcer (OR, 2.3 195% CI, 1.2–4.4]). Mupirocin at any dose decreased this risk, particularly during the 30-60-day period after therapy; mupirocin resistance increased this risk (OR, 4.1 [95% CI, 1.6–10.7]). Over a median follow-up duration of 269 days, 69 (7.4%) of 933 patients developed infection. Independent risk factors for infection were length of stay (hazard ratio [HR], 1.2 per 5 additional days [95% CI, 1.0–1.4]), chronic lung disease (HR, 1.7 [95% CI, 1.0–2.8]), and receipt of non-MRSA-active systemic antimicrobial agents (HR, 1.8 [95% CI, 1.1–3.1]). Receipt of mupirocin did not affect the risk of infection, although there was a trend toward delayed infection among patients receiving mupirocin (median time to infection, 50 vs 15.5 days; P = .06).

Mupirocin-based decolonization therapy temporarily reduced the risk of continued colonization but did not decrease the risk of subsequent infection.

To study multicenter antibiotic practices for suspected early-onset sepsis (EOS) with negative blood cultures (NegBCs) and to identify opportunities for reduction of antimicrobial exposure.

Retrospective study.

Thirty academic hospitals (University HealthSystem Consortium) located in 24 states.

Data were from a survey of 790 extremely low birth weight (ELBW) infants. Total antibiotic exposures (antibiotic-days per patient) were calculated.

On admission to the NICU, 94% of 790 ELBW infants had BCs performed and empiric antibiotics initiated. When PosBC and NegBC infants were compared, 47 patients with PosBCs were similar to 695 with NegBCs in birth weight, gestational age (GA), and mortality. Patients with suspected EOS but NegBCs given ampicillin/aminoglycosides were grouped by length of administration and GA. For GA of 26 weeks or younger, 170 infants given a short (≤ 3 days) and 157 given a long (≥ 7 days) course were similar regarding birth weight, mortality, antepartum history, and CRIB scores, but were different (P < .01) in number receiving a third antimicrobial (3% and 17%) and antibiotic-days (23 and 38). For GA of 27 weeks or older, 113 infants given a short and 77 given a long course differed (P < .01) in number receiving a third antimicrobial (2% and 23%) and antibiotic-days (19 and 30).

Most suspected EOS infants with NegBCs are given antibiotics, but no antepartum historical risk factors or neonatal clinical signs explained prolonged administration. Discontinuing empiric antibiotics when BCs are negative in asymptomatic ELBW infants can reduce antimicrobial exposure without compromising clinical outcome.