What Infection Control Interventions Should Be Undertaken to Control Multidrug-Resistant Gram-Negative Bacteria?

Integrated Analysis of Patient Networks and Plasmid Genomes to Investigate a Regional, Multispecies Outbreak of Carbapenemase-Producing Enterobacterales Carrying Both blaIMP and mcr-9 Genes

BACKGROUND

Carbapenemase-producing Enterobacterales (CPE) are challenging in healthcare, with resistance to multiple classes of antibiotics. This study describes the emergence of imipenemase (IMP)-encoding CPE among diverse Enterobacterales species between 2016 and 2019 across a London regional network.

METHODS

We performed a network analysis of patient pathways, using electronic health records, to identify contacts between IMP-encoding CPE-positive patients. Genomes of IMP-encoding CPE isolates were overlaid with patient contacts to imply potential transmission events.

RESULTS

Genomic analysis of 84 Enterobacterales isolates revealed diverse species (predominantly Klebsiella spp, Enterobacter spp, and Escherichia coli); 86% (72 of 84) harbored an IncHI2 plasmid carrying blaIMP and colistin resistance gene mcr-9 (68 of 72). Phylogenetic analysis of IncHI2 plasmids identified 3 lineages showing significant association with patient contacts and movements between 4 hospital sites and across medical specialties, which was missed in initial investigations.

CONCLUSIONS

Combined, our patient network and plasmid analyses demonstrate an interspecies, plasmid-mediated outbreak of blaIMPCPE, which remained unidentified during standard investigations. With DNA sequencing and multimodal data incorporation, the outbreak investigation approach proposed here provides a framework for real-time identification of key factors causing pathogen spread. Plasmid-level outbreak analysis reveals that resistance spread may be wider than suspected, allowing more interventions to stop transmission within hospital networks.SummaryThis was an investigation, using integrated pathway networks and genomics methods, of the emergence of imipenemase-encoding carbapenemase-producing Enterobacterales among diverse Enterobacterales species between 2016 and 2019 in patients across a London regional hospital network, which was missed on routine investigations.

Prevalence of metallo-β-lactamases as a correlate of multidrug resistance among clinical Pseudomonas aeruginosa isolates in Nepal

Pseudomonas aeruginosa is an opportunistic human pathogen that has developed antibiotic resistance (AR) and causes a range of illnesses, including respiratory pneumonia, gastrointestinal infections, keratitis, otitis media and bacteremia in patients with compromised immune system. The production of metallo-β-lactamases (MBLs) is one of the major mechanisms of AR in this bacterium with ensuing infections difficult to treat. The main goal of this study was to provide a quantitative estimate of MBLs producing clinical P. aeruginosa isolates among the Nepalese patients and determine if MBL correlates with multi-drug resistance (MDR). Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guideline was followed for meta-analysis of relevant literature using PubMed, Research4Life, and Google Scholar. The prevalence of MBLs in P. aeruginosa from clinical samples was determined using R 4.1.2 for data pooled from studies published until 2021. The meta-analysis of a total of 19 studies selected (of 6038 studies for which titles and abstracts were reviewed) revealed the prevalence of MBLs producing P. aeruginosa (MBL-PA) was 14 % (95 % CI: 0.10-0.19) while MDR isolates among P. aeruginosa was 42 % (95 % CI: 0.30-0.55) in Nepal. Combined Disc Test was predominantly used phenotypic method for confirming MBLs phenotypes among the studies. Sputum was the most common specimen from which MBL-PA was recovered. A significant positive correlation was observed between MDR and MBL production in P. aeruginosa. We conclude that MBL producing strains are widespread among the clinical isolates of P. aeruginosa in Nepal and responsible for emerging MDR strains. It is paramount that antibiotics prescription against the bacterium should be monitored closely and alternative therapeutic modalities against MBL-PA explored.

Discovery of the Lead Molecules Targeting the First Step of the Histidine Biosynthesis Pathway of Acinetobacter baumannii

Acinetobacter baumannii is a multidrug-resistant, opportunistic, nosocomial pathogen for which a new line of treatments is desperately needed. We have targeted the enzyme of the first step of the histidine biosynthesis pathway, viz., ATP-phosphoribosyltransferase (ATP-PRT). The three-dimensional structure of ATP-PRT was predicted on the template of the known three-dimensional structure of ATP-PRT from Psychrobacter arcticus (PaATPPRT) using a homology modeling approach. High-throughput virtual screening (HTVS) of the antibacterial library of Life Chemicals Inc., Ontario, Canada was carried out followed by molecular dynamics simulations of the top hit compounds. In silico results were then biochemically validated using surface plasmon resonance spectroscopy. We found that two compounds, namely, F0843-0019 and F0608-0626, were binding with micromolar affinities to the ATP-phosphoribosyltransferase from Acinetobacter baumannii (AbATPPRT). Both of these compounds were binding in the same way as AMP in PaATPPRT, and the important residues of the active site, viz., Val4, Ser72, Thr76, Tyr77, Glu95, Lys134, Val136, and Tyr156, were also interacting via hydrogen bonds. The calculated binding energies of these compounds were -10.5 kcal/mol and -11.1 kcal/mol, respectively. These two compounds can be used as the potential lead molecules for designing antibacterial compounds in the future, and this information will help in drug discovery programs against Acinetobacter worldwide.

Impact of single room design on the spread of multi-drug resistant bacteria in an intensive care unit

Background

Cross-transmission of nosocomial pathogens occurs frequently in intensive care units (ICU). The aim of this study was to investigate whether the introduction of a single room policy resulted in a decrease in transmission of multidrug-resistant (MDR) bacteria in an ICU.

Methods

We performed a retrospective study covering two periods: between January 2002 and April 2009 (old-ICU) and between May 2009 and March 2013 (new-ICU, single-room). These periods were compared with respect to the occurrence of representative MDR Gram-negative bacteria. Routine microbiological screening, was performed on all patients on admission to the ICU and then twice a week. Multi-drug resistance was defined according to a national guideline. The first isolates per patient that met the MDR-criteria, detected during the ICU admission were included in the analysis. To investigate the clonality, isolates were genotyped by DiversiLab (bioMérieux, France) or Amplified Fragment Length Polymorphism (AFLP). To guarantee the comparability of the two periods, the ‘before’ and ‘after’ periods were chosen such that they were approximately identical with respect to the following factors: number of admissions, number of beds, bed occupancy rate, per year and month.

Results

Despite infection prevention efforts, high prevalence of MRD bacteria continue to occur in the original facility. A marked and sustained decrease in the prevalence of MDR-GN bacteria was observed after the migration to the new ICU, while there appear to be no significant changes in the other variables including bed occupancy and numbers of patient admissions.

Conclusion

Single room ICU design contributes significantly to the reduction of cross transmission of MRD-bacteria.

Extended-spectrum beta-lactamase--producing enterobacteriaceae in the intensive care unit: acquisition does not mean cross-transmission

Background

In intensive care unit (ICU), infection and colonization by resistant Gram-negative bacteria increase costs, length of stay and mortality. Extended-spectrum beta-lactamase − producing Enterobacteriaceae (ESBL-E) is a group of pathogens increasingly encountered in ICU setting. Conditions that promote ESBL-E acquisition are not completely understood. The increasing incidence of infections related to ESBL-E and the unsolved issues related to ESBL-E cross-transmission, prompted us to assess the rates of referred and acquired cases of ESBL-E in ICU and to assess patient-to-patient cross-transmission of ESBL-E using a multimodal microbiological analysis.

Methods

During a 5-month period, all patients admitted to a medical ICU were tested for ESBL-E carriage. A rectal swab was performed at admission and then twice a week until discharge or death. ESBL-E strains were analyzed according to antibiotic susceptibility pattern, rep-PCR (repetitive-element Polymerase chain reaction) chromosomal analysis, and plasmid PCR (Polymerase chain reaction) analysis of ESBL genes. Patient-to-patient transmission was deemed likely when 2 identical strains were found in 2 patients hospitalized simultaneously in the ICU.

Results

Among the 309 patients assessed for ESBL-E carriage on admission, 25 were found to carry ESBL-E (importation rate: 8 %). During follow-up, acquisition was observed among 19 of them (acquisition rate: 6.5 %). Using the multimodal microbiological approach, we found only one case of likely patient-to-patient ESBL-E transmission.

Conclusions

In unselected ICU patients, we found rather low rates of ESBL-E referred and acquired cases. Only 5 % of acquisitions appeared to be related to patient-to-patient transmission. These data highlight the importance of jointly analyzing phenotypic profile and molecular data to discriminate strains of ESBL-E.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-016-1489-z) contains supplementary material, which is available to authorized users.

Casualties of war: the infection control assessment of civilians transferred from conflict zones to specialist units overseas for treatment

The casualties of global conflict attract media attention and sympathy in public, governmental, and non-governmental circles. Hospitals in developed countries offering specialist reconstructive or tertiary services are not infrequently asked to accept civilian patients from overseas conflict for complex surgical procedures or rehabilitation. Concern about the infection prevention and control risks posed by these patients, and the lack of a good evidence base on which to base measured precautions, means that the precautionary principle of accepting zero risk is usually followed. The aim of this article is to highlight infection control considerations that may be required when treating casualties from overseas conflict, based partly on our own experience. Currently there is a lack of published evidence and national consensus on how to manage these patients. The precautionary principle requires that there is an ongoing search for evidence and knowledge that can be used to move towards more traditional risk management. We propose that only by gathering the experiences of the many individual hospitals that have each cared for small numbers of such patients can such evidence and knowledge be assimilated.

[Update on outbreaks reported from neonatal intensive care units: Serratia marcescens, Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa]

In terms of the unique risk profile, the clinical course of nosocomial infections, and the most prevalent bacterial pathogens, literature on outbreaks of potentially pathogenic bacteria on neonatal intensive care units (NICUs) needs to be analyzed separately from reports derived from other intensive care units. With the purpose of updating important information for those involved in outbreak management and fostering preventive efforts, this article summarizes the results of a systematic literature analysis, referring to an earlier publication by Gastmeier et al. This review focuses on NICU outbreaks caused by Serratia marcescens, Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa.

Targeted screening for third-generation cephalosporin-resistant Enterobacteriaceae carriage among patients admitted to intensive care units: a quasi-experimental study

Introduction

Identification of third-generation, cephalosporin-resistant Enterobacteriaceae (3GC-RE) carriers by rectal screening at admission seems to be an important step in the prevention of transmission and outbreaks; however, little is known about its effectiveness. The aim of this study was to evaluate the impact of ‘targeted screening’ at patient admission to intensive care units (ICUs) on the incidence of 3GC-RE hospital-acquired infections (HAIs) and compare it to ‘universal screening’.

Methods

We undertook a quasi-experimental study of two ICUs (unit A: intervention group; unit B: control group) at a university-affiliated hospital between 1 January 2008 and 31 December 2011. In unit A, patients were screened universally for 3GC-RE at admission during period 1 (1 January 2008 through 30 September 2010). During period 2 (2011 calendar year), the intervention was implemented in unit A; patients transferred from another unit or hospital were screened selectively. In unit B, all patients were screened throughout periods 1 and 2. 3GC-RE-related HAI incidence rates were expressed per 1,000 patient-days. Incidence rate ratios (IRRs) were examined by multivariate Poisson regression modelling.

Results

In unit A, 3GC-RE-related HAI incidence rates decreased from 5.4 (95% confidence interval (CI), 4.1 to 7.0) during period 1 to 1.3 (95% CI, 0.5 to 2.9) during period 2 (P < 0.001). No changes were observed in unit B between periods 1 and 2 (P = 0.5). In unit A, the adjusted incidence of 3GC-RE-related HAIs decreased in period 2 compared with period 1 (adjusted IRR, 0.3; 95% CI, 0.1 to 0.9; P = 0.03) independently of temporal trend, trauma and age. No changes were seen in unit B (P = 0.4). The total number of rectal swabs taken showed an 85% decrease in unit A between period 1 and 2 (P < 0.001).

Conclusions

Targeted screening of 3GC-RE carriers at ICU admission was not associated with an increase in 3GC-RE-related HAI incidence compared with universal screening. Total number of rectal swabs decreased significantly. These findings suggest that targeted screening may be worth assessing as an alternative to universal screening.

Natural History of Colonization with Gram-Negative Multidrug-Resistant Organisms among Hospitalized Patients

Objective.

To determine the anatomic sites and natural history of colonization with gram-negative multidrug-resistant organisms (MDROs).

Design.

Prospective, longitudinal cohort study.

Setting.

Walter Reed Army Medical Center, a 236-bed tertiary care center in Washington, DC.

Patients.

Deployed subjects (ie, inpatients medically evacuated from Iraq or Afghanistan) or nondeployed subjects admitted to the same hospital.

Methods.

Consenting patients had 6 anatomic sites cultured every 3 days for 2 weeks and then weekly. Gram-negative organisms resistant to 3 or more classes of antibiotics were considered MDROs. Isolates were genotyped using pulsed-field gel electrophoresis. Clinical data, data on antibiotic use, and clinical culture results were collected.

Results.

Of 60 deployed subjects, 14 (23%) were colonized with an MDRO at admission, and 13 (22%) had incident colonization during hospitalization. The groin was the most sensitive anatomic site for detecting MDRO colonization, and all but one subject remained colonized for the duration of their hospitalization. Sixty percent of subjects with incident Acinetobacter colonization and 25% of subjects with incident Klebsiella colonization had strains that were related to those isolated from other subjects. Of 60 nondeployed subjects, 5 (8%) were colonized with an MDRO at admission; all had recent healthcare contact, and 1 nondeployed subject had an isolate related to a strain recovered from a deployed subject.

Conclusions.

Colonization with gram-negative MDROs is common among patients with war-related trauma admitted to a military hospital and also occurs among nondeployed patients with recent healthcare contact. The groin is the most sensitive anatomic site for active surveillance, and spontaneous decolonization is rare.

Epidemiology of Multidrug-Resistant Bacteria in Patients With Long Hospital Stays

Objective.

To determine rates of colonization with multidrug-resistant (MDR) bacteria (ie, methicillin-resistantStaphylococcus aureus[MRSA], vancomycin-resistantEnterococcus[VRE], extended-spectrum β-lactamase [ESBL]-producing Enterobacteriaceae, andAcinetobacter baumannii) after prolonged hospitalization and to assess the yield of surveillance cultures and variables associated with colonization with MDR bacteria.

Design.

Prospective observational cohort study conducted from February 6 to May 26, 2006.

Methods.

All patients who spent more than 30 days in our university hospital (Paris, France) were included. Rectal and nasal swab samples obtained during day 30 screening were examined for MRSA, VRE, ESBL-producing Enterobacteriaceae, andA. baumannii.

Results.

Of 470 eligible patients, 439 had surveillance culture samples available for analysis, including 51 patients (11.6%) with a history of colonization or infection due to 1 or more types of MDR bacteria (MRSA, recovered from 35 patients; ESBL-producing Enterobacteriaceae, from 16 patients;A. baumannii, from 6 patients; and VRE, from 0 patients) and 37 patients (9.5% of the 388 patients not known to have any of the 4 MDR bacteria before day 30 screening) newly identified as colonized by 1 or more MDR bacteria (MRSA, recovered from 20 patients; ESBL-producing Enterobacteriaceae, from 16 patients;A. baumannii, from 1 patient; and VRE, from 0 patients). A total of 87 (19.8%) of 439 patients were identified as colonized or infected with MDR bacteria at day 30. Factors that differed between patients with and without MRSA colonization included age, McCabe score, comorbidity score, receipt of surgery, and receipt of fluoroquinolone treatment. Patients with ESBL-producing Enterobacteriaceae colonization were younger than patients with MRSA colonization.

Conclusions.

Differences in the variables associated with MRSA colonization and ESBL-producing Enterobacteriaceae colonization suggest differences in the epidemiology of these 2 organisms. Day 30 screening resulted in a 72.5% increase in the number of patients identified as colonized with at least 1 type of MDR bacteria.

Recommendations For Metrics For Multidrug-Resistant Organisms In Healthcare Settings: SHEA/HICPAC Position Paper

Monitoring multidrug-resistant organisms (MDROs) and the infections they cause in a healthcare setting is important to detect newly emerging antimicrobial resistance profiles, to identify vulnerable patient populations, and to assess the need for and effectiveness of interventions; however, it is unclear which metrics are the best, because most of the metrics are not standardized. This document describes useful and practical metrics and surveillance considerations for measuring MDROs and the infections they cause in the practice of infection prevention and control in healthcare settings. These metrics are designed to aid healthcare workers in documenting trends over time within their facility and should not be used for interfacility comparison.

Antimicrobial Stewardship—the State of the Art in 2011 Focus on Outcome and Methods

Antimicrobial stewardship programs attempt to optimize prescribing of these drugs to benefit both current and future patients. Recent regulatory and other incentives have led to widespread adoption of such programs. Measurements of the success of these programs have focused primarily on process measures. However, evaluation of outcome measures will be needed to ensure sustainability of these efforts. Outcome efforts to date provide some evidence for improved care of individual patients, some evidence for minimizing emergence of resistance, and ample evidence for cost reduction. Attention to evaluation methods must be increased to provide convincing evidence for the continuation of such programs.

Sensitivity of surveillance testing for multidrug-resistant Gram-negative bacteria in the intensive care unit

We tested intensive care unit patients for colonization with multidrug-resistant Gram-negative bacilli (MDR GNB) and compared the results with those of concurrent clinical cultures. The sensitivity of the surveillance test for detecting MDR GNB was 58.8% (95% confidence interval, 48.6 to 68.5%). Among 133 patients with positive surveillance tests, 61% had no prior clinical culture with MDR GNB.

Are strict isolation policies based on susceptibility testing actually effective in the prevention of the nosocomial spread of multi-drug-resistant gram-negative rods?

BACKGROUND

The emergence of multi-drug-resistant gram-negative rods (MDR-GNRs) has become a worldwide problem. To limit the emergence of MDR-GNRs, a tertiary care cancer center in Japan implemented a policy that requires the pre-emptive isolation of patients with organisms that have the potential to be MDR-GNRs.

METHODS

A retrospective analysis was performed. Any gram-negative bacillus isolates categorized as intermediate or resistant to at least 2 classes of antimicrobials were subjected to contact precautions. The incidence of patients with MDR-GNRs was analyzed.

RESULTS

There was no difference between the preintervention and intervention time periods in the detection rate of nonfermenting MDR-GNR species (0.15 per 10,000 vs 0.35 per 10,000 patient-days, P = .08). There was an increase in the detection rate of multi-drug-resistant Enterobacteriaceae (0.19 per 10,000 vs 0.56 per 10,000 patient-days, P = .007), which was prominent for extended-spectrum β-lactamase (ESBL)-producing organisms (0.19 per 10,000 vs 0.50 per 10,000 patient-days, P = .02).

CONCLUSIONS

Our intervention kept the emergence of multi-drug-resistant non-glucose-fermenting gram-negative bacilli to a small number, but it failed to prevent an increase in ESBL producers. Policies, such as active detection and isolation, are warranted to decrease the incidence of these bacilli.

Control of a two-decade endemic situation with carbapenem-resistant Acinetobacter baumannii: electronic dissemination of a bundle of interventions

BACKGROUND

Our institution continued to experience a hyperendemic situation with carbapenem-resistant Acinetobacter baumannii despite a bundle of interventions. We aim to describe the effect of the subsequent implementation of electronic dissemination of the weekly findings of a bundle of interventions.

METHODS

This was a quasiexperimental study performed at a 1,500-bed, public, teaching hospital. From January 2011 to March 2012, weekly electronic communications were sent to the hospital leadership and intensive care units (ICUs). These communications aimed to describe, interpret, and package the findings of the previous week's active surveillance cultures, environmental cultures, environmental disinfection, and hand cultures. Additionally, action plans based on these findings were shared with recipients.

RESULTS

During 42 months and 1,103,900 patient-days, we detected 438 new acquisitions of carbapenem-resistant A baumannii. Hospital wide, the rate of acquisition decreased from 5.13 ± 0.39 to 1.93 ± 0.23 per 10,000 patient-days, during the baseline and postintervention periods, respectively (P < .0001). This effect was also observed in the medical and trauma ICUs, with decreased rates from 67.15 ± 10.56 to 17.4 ± 4.6 (P < .0001) and from 55.9 ± 8.95 to 14.71 ± 4.45 (P = .0004), respectively.

CONCLUSION

Weekly and systematic dissemination of the findings of a bundle of interventions was successful in decreasing the rates of carbapenem-resistant A baumannii across a large public hospital.

Effectiveness and cost of implementing an active surveillance screening policy for Acinetobacter baumannii: a Monte Carlo simulation model

BACKGROUND

Acinetobacter baumannii infections are common and associated with high mortality and costs. Early identification of asymptomatic carriers can reduce patient-to-patient transmission, but the sensitivity of A baumannii surveillance tools is poor, and thus active surveillance is not routine practice. This study examined whether an active surveillance screening policy can reduce the transmission, mortality, and costs associated with A baumannii.

METHODS

A simulation model was developed to determine the impact of active screening on patient outcomes. Model parameters included A baumannii prevalence, screening sensitivity and specificity, probability of transmission, progression from colonization to infection, mortality, and cost of screening, contact precautions, and infection. A scenario analysis was performed to evaluate the robustness of the results when varying the sensitivity of the screening test and the prevalence rate of A baumannii.

RESULTS

Assuming a screening sensitivity of 55%, active screening reduced A baumannii transmissions, infections, and deaths by 48%. As the screening sensitivity approached 90%, the reduction in transmissions, infections, and deaths reached 78%. For all scenarios tested, active surveillance was cost saving (19%-53% reduction in mean hospital cost per patient) except at a carrier prevalence of ≤2% and screening test sensitivity of ≤55%.

CONCLUSIONS

In institutions where A baumannii is endemic or during epidemics, implementing a surveillance program is cost-saving and can greatly reduce transmissions and deaths. Methodologies to improve the sensitivity of surveillance testing will help optimize the clinical impact of active screening programs on preventing the spread of A baumannii in health care facilities.

Multidrug-resistant organisms in a routine ward environment: differential propensity for environmental dissemination and implications for infection control

Multidrug-resistant organisms (MDROs) pose significant infection-control challenges in settings with high prevalence and limited isolation facilities. This observational study in an 800-bed hospital determined the prevalence, bacterial density and genetic relatedness of MDROs isolated from ward surfaces, medical devices and the hands of healthcare professionals. The targeted MDROs were meticillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), Escherichia coli and Klebsiella pneumoniae resistant to extended-spectrum cephalosporins, and carbapenem-resistant (CR) Acinetobacter baumannii. During a 2-month period, microbiological sampling and molecular typing were performed on environment isolates, clinical isolates and isolates recovered from the hands of healthcare professionals. The target MDROs were recovered from 79 % of sampled surfaces, predominantly MRSA (74 % of all tested surfaces) and CR A. baumannii (29 %) but also VRE (2 %) and K. pneumoniae (1 %). MRSA was recovered from most tested surfaces throughout the ward, whilst CR A. baumannii was significantly more likely to be recovered from near-patient surfaces. Hand sampling demonstrated infrequent recovery of MRSA (5 %), CR A. baumannii (1 %) and VRE (1 %). Molecular typing of the study isolates identified seven MRSA and five Acinetobacter clonal clusters, respectively, and typing identified similar strains from the environment, patients and hands. Thus, in a healthcare setting with endemic circulation of MDROs, MRSA and CR A. baumannii were the predominant organisms recovered from ward surfaces, with MRSA in particular demonstrating widespread environmental dissemination. Molecular typing demonstrated the presence of related strains in patients, in the environment and on the hands of healthcare workers.

Practices to prevent multidrug-resistant Acinetobacter baumannii and methicillin-resistant Staphylococcus aureus in Thailand: a national survey

BACKGROUND

Multidrug-resistant organisms (MDRO) are increasing challenges for health care institutions worldwide, and there are many factors associated with their distribution.

OBJECTIVES

We conducted a national survey of Thai hospitals with 1 or more intensive care units and ≥250 hospital beds to evaluate hospital characteristics and current practices to minimize the endemic burden of multidrug-resistant (MDR) Acinetobacter baumannii (AB) and methicillin-resistant Staphylococcus aureus (MRSA).

METHODS

Research nurses collected survey data from participating hospitals between January 1 and April 30, 2011. Data collection focused on hospital characteristics and practices to prevent endemic MDR-AB and MRSA; logistic regression analyses were used to assess associations between hospital characteristics and infection prevention control (IPC) interventions.

RESULTS

There was an 80% survey response (N = 204) from 256 eligible hospitals. Endemic MDR-AB and MRSA were reported in 184 (90%) and 100 (40%) hospitals, respectively. The most frequently reported IPC interventions were contact isolation, hand hygiene campaigns, and antimicrobial stewardship; active surveillance, chlorhexidine gluconate bathing, and multifaceted interventions were uncommon. By multivariate analysis, having a physician as the lead infection control professional and participation in a collaborative effort to prevent MDR organisms were associated with multifaceted interventions to reduce MDR-AB, and medical school affiliation and participating in a collaborative effort to prevent MDR organisms were associated with multifaceted interventions to reduce MRSA.

CONCLUSION

Multifaceted interventions to reduce, if not prevent, MDR-AB and MRSA were infrequently reported from Thai hospitals. Our survey findings provide baseline data for IPC interventions for MDR-AB and MRSA. Future efforts that correlate IPC interventions and MDRO trends will help develop evidence-based practices in these resource-limited settings.

Limits of patient isolation measures to control extended-spectrum beta-lactamase-producing Enterobacteriaceae: model-based analysis of clinical data in a pediatric ward

Background

Extended-spectrum beta-lactamase–producing Enterobacteriaceae (ESBL-E) are a growing concern in hospitals and the community. How to control the nosocomial ESBL-E transmission is a matter of debate. Contact isolation of patients has been recommended but evidence supporting it in non-outbreak settings has been inconclusive.

Methods

We used stochastic transmission models to analyze retrospective observational data from a two-phase intervention in a pediatric ward, successively implementing single-room isolation and patient cohorting in an isolation ward, combined with active ESBL-E screening.

Results

For both periods, model estimates suggested reduced transmission from isolated/cohorted patients. However, most of the incidence originated from sporadic sources (i.e. independent of cross-transmission), unaffected by the isolation measures. When sporadic sources are high, our model predicted that even substantial efforts to prevent transmission from carriers would have limited impact on ESBL-E rates.

Conclusions

Our results provide evidence that, considering the importance of sporadic acquisition, e.g. endogenous selection of resistant strains following antibiotic treatment, contact-isolation measures alone might not suffice to control ESBL-E. They also support the view that estimating cross-transmission extent is key to predicting the relative success of contact-isolation measures. Mathematical models could prove useful for those estimations and guide decisions concerning the most effective control strategy.

Disparity in infection control practices for multidrug-resistant Enterobacteriaceae

BACKGROUND

There is a lack of empiric evidence regarding the optimal approach to controlling the transmission of extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-E) and carbapenem-resistant Enterobacteriaceae (CRE). In this context, we expect that infection control practices for these organisms vary widely between hospitals.

METHODS

A survey examining infection control practices for ESBL-E and CRE was distributed to 6 academic and 9 community hospitals in Toronto, Canada.

RESULTS

All hospitals responded to the survey. Among 15 hospitals in 1 geographic area, 8 different approaches to the management of ESBL-E were utilized. There was wide variation in the use infection control practices including admission screening (53% and 53%), contact precautions (53% and 100%), and isolation (60% and 100%) for ESBL-E and CRE, respectively. Of hospitals performing admission screening, 75% used risk factor-based screening for ESBL-E and CRE.

CONCLUSION

Even within a single geographic area, there is wide variation in infection control strategies to contain or control ESBL-E and CRE. These results are concerning given evidence that a coordinated approach may be required to prevent or limit the emergence of CRE.

Comparison of PCR/electron spray ionization-time-of-flight-mass spectrometry versus traditional clinical microbiology for active surveillance of organisms contaminating high-use surfaces in a burn intensive care unit, an orthopedic ward and healthcare workers

Background

Understanding nosocomial pathogen transmission is restricted by culture limitations. Novel platforms, such as PCR-based electron spray ionization-time-of-flight-mass spectrometry (ESI-TOF-MS), may be useful as investigational tools.

Methods

Traditional clinical microbiology (TCM) and PCR/ESI-TOF-MS were used to recover and detect microorganisms from the hands and personal protective equipment of 10 burn intensive care unit (ICU) healthcare workers providing clinical care at a tertiary care military referral hospital. High-use environmental surfaces were assessed in 9 burn ICU and 10 orthopedic patient rooms. Clinical cultures during the study period were reviewed for pathogen comparison with investigational molecular diagnostic methods.

Results

From 158 samples, 142 organisms were identified by TCM and 718 by PCR/ESI-TOF-MS. The molecular diagnostic method detected more organisms (4.5 ± 2.1 vs. 0.9 ± 0.8, p < 0.01) from 99% vs. 67% of samples (p < 0.01). TCM detected S. aureus in 13 samples vs. 21 by PCR/ESI-TOF-MS. Gram-negative organisms were less commonly identified than gram-positive by both methods; especially by TCM. Among all detected bacterial species, similar percentages were typical nosocomial pathogens (18-19%) for TCM vs. PCR/ESI-TOF-MS. PCR/ESI-TOF-MS also detected mecA in 112 samples, vanA in 13, and KPC-3 in 2. MecA was associated (p < 0.01) with codetection of coagulase negative staphylococci but not S. aureus. No vanA was codetected with enterococci; one KPC-3 was detected without Klebsiella spp.

Conclusions

In this pilot study, PCR/ESI-TOF-MS detected more organisms, especially gram-negatives, compared to TCM, but the current assay format is limited by the number of antibiotic resistance determinants it covers. Further large-scale assessments of PCR/ESI-TOF-MS for hospital surveillance are warranted.

Preventing the spread of multidrug-resistant gram-negative pathogens: recommendations of an expert panel of the German Society For Hygiene and Microbiology

BACKGROUND

Infections with multidrug-resistant gram-negative bacteria are hard to treat and cause high morbidity and mortality. The direct transmission of such pathogens is well documented, and measures to protect other patients would seem indicated. Nonetheless, evidence-based recommendations are not yet available because of insufficient data from clinical trials.

METHODS

An expert panel was convened by two sections of the German Society for Hygiene and Microbiology (the permanent committee on general and hospital hygiene and the special committee on infection prevention and antibiotic resistance in hospitals) to review existing data on the epidemiology and diagnostic evaluation of multidrug-resistant gram-negative pathogens. The panel carried out a selective review of the relevant literature, with special attention to national guidelines.

RESULTS AND CONCLUSION

In this paper, the expert panel presents a definition of multidrug-resistant gram-negative pathogens and recommends measures for presenting the spread of infection from colonized and infected patients in non-outbreak situations. These measures depend on the risk profile of the clinical setting. They are mostly to be considered "expert opinion," rather than "evidence-based."

A multifaceted intervention strategy for eradication of a hospital-wide outbreak caused by carbapenem-resistant Klebsiella pneumoniae in Southern Israel

OBJECTIVE

To devise a local strategy for eradication of a hospital-wide outbreak caused by carbapenem-resistant Klebsiella pneumoniae (CRKP).

DESIGN

Quasi-experimental, before-and-after, interrupted time-series study.

SETTING

A 1,000-bed tertiary-care university teaching hospital.

METHODS

Retrospectively, all relevant data were collected from the medical records of patients with CRKP infections from May 2006 through April 2007, the preintervention period. From May 1, 2007, through May 1, 2010, the postintervention period, the intervention was applied and prospectively followed. The 5 key elements of this strategy were an emergency department flagging system, the building of a cohort ward, the eradication of clusters, environmental and personnel hand cultures, and a carbapenem-restriction policy. The demographic and clinical parameters of patients colonized by and/or infected with CRKP were collected from medical records.

RESULTS

A total of 10,680 rectal cultures were performed for 8,376 patients; 433 (5.16%) and 370 (4.4%) were CRKP-colonized and CRKP-infected patients, respectively, and 789 (98%) of 803 patients were admitted to the CRKP cohort ward. The CRKP infection density was reduced from 5.26 to 0.18 per 10,000 patient-days (P ≤ .001), and no nosocomial CRKP infections were diagnosed. Twenty-three percent of environmental cultures were found to be positive. Meropenem use was reduced from 283 ± 70.92 to 118 ± 74.32 defined daily doses per 1,000 patient-days (P ≤ .001).

CONCLUSION

This intervention produced an enormous impact on patient location, surveillance cultures, and antibiotic policies and a massive investment in infection control resources.

Patterns of ciprofloxacin-resistant gram-negative bacteria colonization in nursing home residents

We evaluated the prevalence of colonization with all gram-negative bacilli (GNB) and with ciprofloxacin-resistant GNB among nursing home residents with and without indwelling devices. We found that device presence increases the risk of colonization with all GNB and with ciprofloxacin-resistant GNB. Colonization with ciprofloxacin-resistant GNB increases with decreasing functional status.

[A national multicentre study on nosocomial infections in PICU]

INTRODUCTION

Nosocomial infection (NI) is a common complication in paediatric critical care units (PICU), with an associated mortality up to 11%.

OBJECTIVE

To describe NI epidemiology in the national PICU. To initiate an standard NI control measures to obtain paediatric incidence rates.

PATIENTS AND METHOD

Multicentre prospective study from 1 to 31 march 2007. Centre Disease Control diagnosis and methodological criteria were used. It was specially analyzed NI related to invasive devices: central venous catheter (CVC), mechanical ventilation (MV), urinary catheter (UC).

RESULTS

There were recruited 300 patients from 6 PICU, with 17 NI episodes in 16 patients (5,3% from admitted). NI rates resulted in 13,8 infections/1000 patients-day. Middle age from infected patients was 2,31 years (± 3,43), 9 males. Risk factors were found in 7 cases. NI location was: catheter-related bloodstream infection in 7 patients (6,7/1000 days CVC), ventilator associated pneumonia in 4 (9,4/1000 MV days), urinary-tract infection associated with UC in 4 (5,5/1000 UC days), one case of primary bloodstream infection and one surgical site infection. Isolated microorganisms were: 9 gram negatives bacillus, 4 Candida, 2 plasmocoagulase negative staphylococcus, 1 Haemophilus and 1 Staphylococcus aureus. Seven isolations were resistant microorganisms. There weren't any died related to NI.

CONCLUSIONS

NI epidemiology was similar to published data in our near countries. NI surveillance, with a standardized method of analysis is essential to the NI correct manage.

Hospital epidemiology and infection control in acute-care settings

Health care-associated infections (HAIs) have become more common as medical care has grown more complex and patients have become more complicated. HAIs are associated with significant morbidity, mortality, and cost. Growing rates of HAIs alongside evidence suggesting that active surveillance and infection control practices can prevent HAIs led to the development of hospital epidemiology and infection control programs. The role for infection control programs has grown and continues to grow as rates of antimicrobial resistance rise and HAIs lead to increasing risks to patients and expanding health care costs. In this review, we summarize the history of the development of hospital epidemiology and infection control, common HAIs and the pathogens causing them, and the structure and role of a hospital epidemiology and infection control program.

Risk of acquiring multidrug-resistant Gram-negative bacilli from prior room occupants in the intensive care unit

The objective of this prospective cohort study was to determine whether admission to an intensive care unit (ICU) room previously occupied by a patient with multidrug-resistant (MDR) Gram-negative bacilli (GNB) increases the risk of acquiring these bacteria by subsequent patients. All patients hospitalized for >48 h were eligible. Patients with MDR GNB at ICU admission were excluded. The MDR GNB were defined as MDR Pseudomonas aeruginosa, Acinetobacter baumannii and extended spectrum β-lactamase (ESBL) -producing GNB. All patients were hospitalized in single rooms. Cleaning of ICU rooms between two patients was performed using quaternary ammonium disinfectant. Risk factors for MDR P. aeruginosa, A. baumannii and ESBL-producing GNB were determined using univariate and multivariate analysis. Five hundred and eleven consecutive patients were included; ICU-acquired MDR P. aeruginosa was diagnosed in 82 (16%) patients, A. baumannii in 57 (11%) patients, and ESBL-producing GNB in 50 (9%) patients. Independent risk factors for ICU-acquired MDR P. aeruginosa were prior occupant with MDR P. aeruginosa (OR 2.3, 95% CI 1.2-4.3, p 0.012), surgery (OR 1.9, 95% CI 1.1-3.6, p 0.024), and prior piperacillin/tazobactam use (OR 1.2, 95% CI 1.1-1.3, p 0.040). Independent risk factors for ICU-acquired A. baumannii were prior occupant with A. baumannii (OR 4.2, 95% CI 2-8.8, p <0.001), and mechanical ventilation (OR 9.3, 95% CI 1.1-83, p 0.045). Independent risk factors for ICU-acquired ESBL-producing GNB were tracheostomy (OR 2.6, 95% CI 1.1-6.5, p 0.049), and sedation (OR 6.6, 95% CI 1.1-40, p 0.041). We conclude that admission to an ICU room previously occupied by a patient with MDR P. aeruginosa or A. baumannii is an independent risk factor for acquisition of these bacteria by subsequent room occupants. This relationship was not identified for ESBL-producing GNB.

Potential role of active surveillance in the control of a hospital-wide outbreak of carbapenem-resistant Klebsiella pneumoniae infection

BACKGROUND

The recent emergence of carbapenem resistance among Enterobacteriaceae is a major threat for hospitalized patients, and effective strategies are needed.

OBJECTIVE

To assess the effect of an intensified intervention, which included active surveillance, on the incidence of infection with carbapenem-resistant Klebsiella pneumoniae.

SETTING

Sheba Medical Center, a 1,600-bed tertiary care teaching hospital in Tel Hashomer, Israel.

DESIGN

Quasi-experimental study.

METHODS

The medical records of all the patients who acquired a carbapenem-resistant K. pneumoniae infection during 2006 were reviewed. An intensified intervention was initiated in May 2007. In addition to contact precautions, active surveillance was initiated in high-risk units. The incidence of clinical carbapenem-resistant K. pneumoniae infection over time was measured, and interrupted time-series analysis was performed.

RESULTS

The incidence of clinical carbapenem-resistant K. pneumoniae infection increased 6.42-fold from the first quarter of 2006 up to the initiation of the intervention. In 2006, of the 120 patients whose clinical microbiologic culture results were positive for carbapenem-resistant K. pneumoniae, 67 (56%) developed a nosocomial infection. During the intervention period, the rate of carbapenem-resistant K. pneumoniae rectal colonization was 9%. Of the 390 patients with carbapenem-resistant K. pneumoniae colonization or infection, 204 (52%) were identified by screening cultures. There were a total of 12,391 days of contact precautions, and of these, 4,713 (38%) were added as a result of active surveillance. After initiation of infection control measures, we observed a significant decrease in the incidence of carbapenem-resistant K. pneumoniae infection.

CONCLUSIONS

The use of active surveillance and contact precautions, as part of a multifactorial intervention, may be an effective strategy to decrease rates of nosocomial transmission of carbapenem-resistant K. pneumoniae colonization or infection.

Screening and isolation for infection control

Control measures aimed to reduce the prevalence of healthcare-associated infections include active surveillance cultures (ASCs), contact isolation of patients colonised with epidemiologically significant pathogens, and pre-emptive isolation of high risk patients. However, the benefits of these measures are questionable. A systematic review of isolation policies demonstrated that intensive concerted interventions including isolation can substantially reduce nosocomial meticillin-resistant Staphylococcus aureus (MRSA) infection. Monitoring of interventions is fundamental. Surveillance data should be presented and fed back appropriately. International guidelines suggest that only intensive care units should apply extensive ASCs. However, legislation for mandatory screening at hospital admission has been advocated in many countries. Targeted screening could be used to limit the potential for dissemination of antibiotic-resistant pathogens from otherwise unsuspected carriers from the start of patients' hospitalisation, as opposed to other strategies, in which screening programmes target patients already hospitalised. Although the influx of antibiotic-resistant pathogens into the hospital would not change, early detection would reduce the time colonised patients might have to disseminate pathogens. Recently, rapid methods for molecular detection of MRSA have been developed. Data on the impact of these tests on the MRSA acquisition rate are extremely heterogeneous. Published studies differ according to the settings in which they have been evaluated, the choice of patient population to be screened, other infection control measures employed and, most importantly, study design and baseline prevalence of MRSA. Based on these studies, definitive recommendations cannot be made.

The role of interventional molecular epidemiology in controlling clonal clusters of multidrug resistant Pseudomonas aeruginosa in critically ill cancer patients

BACKGROUND

Pseudomonas aeruginosa is one of the leading causes of hospital-acquired infections in intensive care units (ICUs). The objective was to evaluate the impact of molecular identification of clonal multidrug-resistant (MDR) P aeruginosa strains and the implementation of infection control measures.

METHODS

One hundred seventy-seven strains from ICU patients infected or colonized with MDR P aeruginosa from May 2001 to April 2006 were collected. In vitro susceptibility to 16 antibiotics was done. Pulsed-field gel electrophoresis was performed to identify clonal strains. Nosocomial outbreak was defined as the presence of > or =3 MDR P aeruginosa over < or =3 consecutive months.

RESULTS

During the 5 years of the study, 25 infected and 14 colonized patients with a clonal strain of MDR P aeruginosa were distributed among 5 episodic clusters. These strains were only susceptible to ceftazidime and colistin. Molecular biology identification, diligent monitoring, and multidisciplinary infection control interventions were implemented to suppress this clonal strain after each cluster. Even more, after the last outbreak (June-August 2005), the infection control measures were able to reduce the MDR P aeruginosa to zero during the last 8 months of this study.

CONCLUSION

Interventional molecular epidemiology combined with early identification, monitoring, and implementation of multidisciplinary infection control measures can control temporarily the transmission of MDR P aeruginosa infection in ICUs.

The emerging threat of multidrug-resistant gram-negative organisms in long-term care facilities

BACKGROUND

Infections caused by antimicrobial-resistant bacteria are associated with substantial morbidity and mortality. Residents of long-term care facilities (LTCF) are among the main reservoirs of antimicrobial-resistant bacteria, including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE). Multidrug-resistant gram-negative organisms (MDRGN) are emerging as important pathogens among LTCF residents. Data on the clinical epidemiology of MDRGN, especially in comparison to VRE and MRSA, are limited.

METHODS

All clinical cultures collected from residents of a 750-bed LTCF for a period of 2 years were analyzed for the presence of MDRGN, VRE, and MRSA. Multidrug resistance among gram-negative bacteria was defined as resistance to three or more antimicrobials or antimicrobial groups including extended-spectrum penicillins (ampicillin/sulbactam or piperacillin/tazobactam), cephalosporins (cefazolin or ceftriaxone), gentamicin, ciprofloxacin, and trimethoprim-sulfamethoxazole (TMP/SMX).

RESULTS

A total of 1,661 clinical cultures were included in the analysis. MDRGN were recovered from 180 (10.8%) cultures, MRSA from 104 (6.3%), and VRE from 11 (0.6%). MDRGN were isolated more frequently than MRSA or VRE throughout the study period. The prevalence of MDRGN increased significantly from 7% in 2003 to 13% in 2005 (p = .001). More than 80% of MDRGN isolates were resistant to ciprofloxacin, TMP/SMX, and ampicillin/sulbactam. Resistance to three, four, and five or more antimicrobials were identified among 122 (67.8%), 47 (26.1%), and 11 (6.1%) MDRGN isolates, respectively.

CONCLUSIONS

Rates of MDRGN exceeded those of MRSA and VRE and increased throughout the study period. Resistance to multiple, commonly prescribed antimicrobials among MDRGN raises concerns about therapeutic options available to treat MDRGN infections among LTCF residents.