Routes of transmission of VIM-positive Pseudomonas aeruginosa in the adult intensive care unit-analysis of 9 years of surveillance at a university hospital using a mathematical model

Assessing the role of environment in Pseudomonas aeruginosa healthcare-associated bloodstream infections: a one-year prospective survey

BACKGROUND

Deciphering precise sources and patterns of healthcare-associated Pseudomonas aeruginosa colonization/infection is crucial in defining strategies of prevention and control.

AIM

To prospectively investigate the role of hospital environment in P. aeruginosa nosocomial bloodstream infections (Pa-BSIs) during one year in a tertiary-care hospital.

METHODS

Clinical records of patients presenting Pa-BSIs after >48 h of hospitalization were investigated to confirm the nosocomial character of BSIs and identify the routes of entry and risk factors. Environmental investigations were performed to track P. aeruginosa source/reservoir along the care pathway. Clinical and environmental strains were compared by whole-genome sequencing to identify the route of contamination from hospital environment to patients.

FINDINGS

Fifty-three BSIs episodes in 49 patients were considered as nosocomial, mostly involving men (73%), with an average age of 62.4 years, immunosuppressed in >40% of cases, and after previous antibiotic therapy in almost 92% of cases. BSIs occurred after 27 days of hospitalization on average. The main routes of entry were urinary (30%, on indwelling catheters for two-thirds of cases) and cutaneous (17%, catheter-related in almost 80% of cases). P. aeruginosa was found in 16 out of 49 investigations, representing 34 positive samples, including 54% of sink traps, 23% of water, and 20% of tap aerators. An epidemiological link was established between environmental and clinical strains only for eight patients, representing 15% of nosocomial BSIs.

CONCLUSION

The hospital environment usually considered as the main source of P. aeruginosa healthcare-associated infections was identified as responsible for nosocomial BSIs in only 15% of patients. Since the implementation of water and hospital environment management, one may hypothesize that P. aeruginosa has become a community-acquired pathogen with a nosocomial expression in infection.

Sources and Transmission Routes of Carbapenem-Resistant Pseudomonas aeruginosa: Study Design and Methodology of the SAMPAN Study

Background/Objectives: The global spread of carbapenem-resistant Pseudomonas aeruginosa (CRPA) warrants collaborative action. Guidance should come from integrated One Health surveillance; however, a surveillance strategy is currently unavailable due to insufficient knowledge on the sources and transmission routes of CRPA. The aim of the SAMPAN study ("A Smart Surveillance Strategy for Carbapenem-resistant Pseudomonas aeruginosa") is to develop a globally applicable surveillance strategy. Methods: First, an international cross-sectional study will be conducted to investigate CRPA in clinical and environmental settings in Rotterdam (The Netherlands), Rome (Italy), and Jakarta (Indonesia). Screening cultures and risk factor questionnaires will be taken from healthy individuals and patients upon hospital admission. Clinical CRPA isolates will also be included. Additionally, samples will be taken twice from wet hospital environments and monthly from the hospitals' (drinking) water system, hospital and municipal wastewater treatment plants, and receiving rivers. Whole-genome sequencing will be performed to characterize CRPA isolates and determine the genetic relatedness among the isolates from different reservoirs. Findings from the cross-sectional study, combined with expert elicitation using a Delphi method, will serve as the input for the surveillance strategy. Conclusions: The SAMPAN study will provide a broader understanding of the sources and transmission routes of CRPA. Therewith, the development of a globally applicable smart surveillance strategy will be made possible, delivering information that is needed to guide actions against the spread of CRPA.

Clinical burden of community-associated infections caused by multidrug-resistant Pseudomonas aeruginosa: a propensity-matched longitudinal cohort study in Southern China

Background

Limited research has been conducted on the burden of community-associated infections caused by multidrug-resistant Pseudomonas aeruginosa (CA-MDRPa). We quantitatively modeled the incidence rate and clinical factors associated with CA-MDRPa among hospitalized patients in Southern China.

Methods

Data were obtained from the local nosocomial surveillance system. Poisson regression was applied to estimate annual incidence rate ratios (IRRs) from 2018 to 2021. After propensity-score 1:2 matching, multivariable conditional logistic regression was used to identify factors for CA-MDRPa upon admission and adverse clinical outcomes during hospitalization.

Results

278 patients were clinically and microbiologically diagnosed with CA-MDRPa and 647 with CA-non-MDRPa. CA-MDRPa rate exhibited a slight, non-significant, increase during the research period (IRR=1.03; 95% confidence interval [CI], 0.93-1.15). Neurological conditions, cardiovascular diseases, respiratory disorders, urinary tract infections, and use of cefoperazone/sulbactam prior to admission were identified as risk factors for CA-MDRPa upon admission. CA-MDRPa upon admission was associated with ESBL-producing P. aeruginosa acquisition during hospitalization (odds ratio [OR], 2.70; 95% CI, 1.53-4.77) and increased in-hospital mortality (OR, 2.24; 95% CI, 1.17-4.28).

Conclusions

The findings emphasize the importance of regular targeted screening for CA-MDRPa upon hospital admission and offer valuable insights for strengthening infection control and antimicrobial stewardship programs.

Risk factors for Pseudomonas aeruginosa VIM colonization or infection in the ICU: Case-control study

BACKGROUND

Carbapenem-resistant strains of Pseudomonas aeruginosa (CRPA) have become a major health care concern in many countries, against which anti-infective strategies are limited and which require adequate infection control interventions. Knowing the different modes of transmission of CRPA in intensive care units (ICUs) would be helpful to adapt the means of prevention.

METHODS

The aim of this retrospective case-control study was conducted between January 1, 2017 and February 28, 2022 to identify the risk factors for the acquisition of CRPA in ICUs.

RESULTS

During the study period, 147 patients were included (49 cases and 98 controls). Among the 49 patients, 31 (63%) acquired CRPA in clusters and 18 (37%) sporadically. A univariate analysis showed that 4 variables were associated with CRPA acquisition, including (1) prior antibiotic prescriptions, (2) admission to rooms 203 and 207, (3) severity of illness at admission, and (4) use of mechanical ventilation. Multivariate analysis identified 3 factors of CRPA acquisition, including admission to room 203 (odds ratio [OR] = 29.5 [3.52-247.09]), previous antibiotic therapy (OR = 3.44 [1.02-11.76]), and severity of condition at admission (OR = 1.02 [1-1.04]).

CONCLUSIONS

Our study suggests the role of a contaminated environment in the acquisition of CRPA in the ICU, along with antibiotic use.

Residual risk of Pseudomonas aeruginosa waterborne contamination in an intensive care unit despite the presence of filters at all water points-of-use

OBJECTIVE

To assess the residual risk of waterborne contamination by Pseudomonas aeruginosa from a water network colonized by a single genotype [sequence type (ST) 299] despite the presence of antimicrobial filters in a medical intensive care unit (ICU).

METHODS

During the first 19-month period since the ICU opened, contamination of the water network was assessed monthly by collecting water upstream of the filters. Downstream water was also sampled to assess the efficiency of the filters. P. aeruginosa isolates from patients were collected and compared with the waterborne ST299 P. aeruginosa by multiplex-rep polymerase chain reaction (PCR), pulsed-field gel electrophoresis (PFGE) and whole-genome sequencing. Cross-transmission events by other genotypes of P. aeruginosa were also assessed.

RESULTS

Overall, 1.3% of 449 samples of filtered water were positive for P. aeruginosa in inoculum, varying between 1 and 104 colony-forming units/100 mL according to the tap. All P. aeruginosa hydric isolates belonged to ST299 and displayed fewer than two single nucleotide polymorphisms (SNPs). Among 278 clinical isolates from 122 patients, 10 isolates in five patients showed identical profiles to the hydric ST299 clone on both multiplex-rep PCR and PFGE, and differed by an average of fewer than five SNPs, confirming the water network reservoir as the source of contamination by P. aeruginosa for 4.09% of patients. Cross-transmission events by other genotypes of P. aeruginosa were responsible for the contamination of 1.75% of patients.

DISCUSSION/CONCLUSION

Antimicrobial filters are not sufficient to protect patients from waterborne pathogens when the water network is highly contaminated. A microbiological survey of filtered water may be needed in units hosting patients at risk of P. aeruginosa infections, even when all water points-of-use are fitted with filters.

In search of the best method to detect carriage of carbapenem-resistant Pseudomonas aeruginosa in humans: a systematic review

BACKGROUND

Detection of carbapenem-resistant Pseudomonas aeruginosa (CR-PA) in humans is important to prevent transmission. However, the most optimal culture method to detect CR-PA is unknown. This systematic review aims to determine which culture method is most sensitive and which culture methods are used to detect CR-PA in humans. Second, to establish the most feasible culture method taking into account the turnaround time (TAT), and third, to provide an overview of the sampling sites used to detect carriage.

METHODS

We systematically searched the electronic databases Embase, Medline Ovid, Cochrane, Scopus, CINAHL, and Web of Science until January 27, 2023. All diagnostic accuracy studies comparing two or more culture methods to detect CR-PA and recent outbreak or surveillance reports on CR-PA carriage or infection in humans, which describe culture methods and their results, were eligible for inclusion. We used QUADAS-2 guideline for diagnostic accuracy studies and the STROBE or ORION guideline for outbreak-surveillance studies to assess the risk of bias.

RESULTS

Six diagnostic accuracy studies were included. An enrichment broth was found to increase the detection of CR-PA. Using an enrichment broth extended the TAT by 18-24 h, yet selective media could reduce the TAT by 24 h compared to routine media. In total, 124 outbreak-surveillance studies were included, of which 17 studies with surveillance samples and 116 studies with clinical samples. In outbreak-surveillance studies with surveillance samples, perianal, rectal swabs or stools were the most common sampling site/specimen (13/17, 76%). A large variety was observed in whether and which kind of enrichment broth and selective media were used.

CONCLUSIONS

We found a benefit of using an enrichment step prior to inoculation of the material onto selective media for the detection of CR-PA. More research is needed to determine the most sensitive sampling site and culture method.

TRAIL REGISTRATION

This study was registered in the PROSPERO International prospective register of systematic reviews (registration number: CRD42020207390, http://www.crd.york.ac.uk/PROSPERO/display_record.asp?ID=CRD42020207390 ).

In vitro activity of cefiderocol against a global collection of carbapenem-resistant Pseudomonas aeruginosa with a high level of carbapenemase diversity

OBJECTIVES

To determine the in vitro activity of cefiderocol in a global collection of carbapenem-resistant Pseudomonas aeruginosa including >200 carbapenemase-producing isolates.

METHODS

Isolates (n = 806) from the ERACE-PA Surveillance Program were assessed. Broth microdilution MICs were determined for cefiderocol (iron-depleted CAMHB) and comparators (CAMHB). Susceptibility was interpreted by CLSI and EUCAST breakpoints and reported as percent of isolates. The MIC distribution of cefiderocol in the entire cohort and by carbapenemase status was assessed.

RESULTS

In the entire cohort, cefiderocol was the most active agent (CLSI 98% susceptible; EUCAST 95% susceptible; MIC50/90, 0.25/2 mg/L). Amikacin (urinary only breakpoint) was the second most active, with 70% of isolates testing as susceptible. The percentage of isolates susceptible to all other agents was low (<50%) including meropenem/vaborbactam, imipenem/relebactam, piperacillin/tazobactam and levofloxacin. Cefiderocol maintained significant activity against the most commonly encountered carbapenemases including VIM- (CLSI 97% susceptible; EUCAST 92% susceptible) and GES (CLSI 100% susceptible; EUCAST 97% susceptible)-harbouring isolates. The cefiderocol MIC distribution was similar regardless of carbapenemase status, with MIC50/90 values of 0.5/4 mg/L, 0.5/2 mg/L and 0.25/1 mg/L for MBL, serine carbapenemase and molecular carbapenemase-negative isolates, respectively.

CONCLUSIONS

Cefiderocol displayed potent in vitro activity in this global cohort of carbapenem-resistant P. aeruginosa including >200 carbapenemase-harbouring isolates. Cefiderocol was highly active against MBL-producing isolates, where treatment options are limited. These data can help guide empirical therapy guidelines based on local prevalence of carbapenemase-producing P. aeruginosa or in response to rapid molecular diagnostics.

Impact of the COVID-19 pandemic on prevalence of highly resistant microorganisms in hospitalised patients in the Netherlands, March 2020 to August 2022

BackgroundThe COVID-19 pandemic resulted in adaptation in infection control measures, increased patient transfer, high occupancy of intensive cares, downscaling of non-urgent medical procedures and decreased travelling.AimTo gain insight in the influence of these changes on antimicrobial resistance (AMR) prevalence in the Netherlands, a country with a low AMR prevalence, we estimated changes in demographics and prevalence of six highly resistant microorganisms (HRMO) in hospitalised patients in the Netherlands during COVID-19 waves (March-June 2020, October 2020-June 2021, October 2021-May 2022 and June-August 2022) and interwaves (July-September 2020 and July-September 2021) compared with pre-COVID-19 (March 2019-February 2020).MethodsWe investigated data on routine bacteriology cultures of hospitalised patients, obtained from 37 clinical microbiological laboratories participating in the national AMR surveillance. Demographic characteristics and HRMO prevalence were calculated as proportions and rates per 10,000 hospital admissions.ResultsAlthough no significant persistent changes in HRMO prevalence were detected, some relevant non-significant patterns were recognised in intensive care units. Compared with pre-COVID-19 we found a tendency towards higher prevalence of meticillin-resistant Staphylococcus aureus during waves and lower prevalence of multidrug-resistant Pseudomonas aeruginosa during interwaves. Additionally, during the first three waves, we observed significantly higher proportions and rates of cultures with Enterococcus faecium (pooled 10% vs 6% and 240 vs 120 per 10,000 admissions) and coagulase-negative Staphylococci (pooled 21% vs 14% and 500 vs 252 per 10,000 admissions) compared with pre-COVID-19.ConclusionWe observed no substantial changes in HRMO prevalence in hospitalised patients during the COVID-19 pandemic.

Nationwide surveillance of bacterial respiratory pathogens conducted by the surveillance committee of the Japanese Society of Chemotherapy, the Japanese Association for Infectious Diseases, and the Japanese Society for Clinical Microbiology in 2019-2020: General view of the pathogens' antibacterial susceptibility

The trends and prevalence of antimicrobial susceptibility of pathogens vary by country, region, and time. Long-term regular surveillance is required to investigate trends in the antimicrobial resistance of various isolated bacterial pathogens. We report the results of a nationwide surveillance on the antimicrobial susceptibility of bacterial respiratory pathogens in Japan conducted by the Japanese Society of Chemotherapy, the Japanese Association for Infectious Diseases, and the Japanese Society for Clinical Microbiology. The isolates were collected from clinical specimens obtained from adult patients who visited a collaborating medical facility between June 2019 and December 2020 and were diagnosed with respiratory tract infections by a physician. Antimicrobial susceptibility testing was performed in a centralized laboratory according to the methods recommended by the Clinical and Laboratory Standards Institute. Susceptibility testing was performed for 932 strains (201 Staphylococcus aureus, 158 Streptococcus pneumoniae, 6 S. pyogenes, 136 Haemophilus influenzae, 127 Moraxella catarrhalis, 141 Klebsiella pneumoniae, and 163 Pseudomonas aeruginosa) collected from 32 facilities in Japan. The proportions of methicillin-resistant S. aureus and penicillin-resistant S. pneumoniae were 35.3% and 0%, respectively. In H. influenzae, 16.2% and 16.9% were β-lactamase-producing ampicillin resistant and β-lactamase-negative ampicillin resistant, respectively. Extended-spectrum β-lactamase-producing K. pneumoniae accounted for 5.0% of all K. pneumoniae infections. Carbapenemase-producing K. pneumoniae and multi-drug-resistant P. aeruginosa with metallo-β-lactamase were not detected in this study. This surveillance will be a useful reference for treating respiratory infections in Japan and will provide evidence to enhance the appropriate use of antimicrobial agents.

Outbreak investigations after identifying carbapenem-resistant Pseudomonas aeruginosa: a systematic review

BACKGROUND

Carbapenem-resistant Pseudomonas aeruginosa (CRPA) are a serious cause of healthcare-associated infections. Part of the infection prevention and control measures are outbreak investigations (OI) of patients, healthcare workers (HCW), and the environment after identifying a CRPA in order to identify carriers and environmental reservoirs, so that targeted actions can be taken to prevent further transmission. However, little is known on when and how to perform such OI. Therefore, this systematic review aims to summarize OI performed after detection of CRPA in the endemic and epidemic hospital setting.

MAIN TEXT

Articles related to our research question were identified through a literature research in multiple databases (Embase, Medline Ovid, Cochrane, Scopus, Cinahl, Web of Science, and Google Scholar) until January 12, 2022 (Prospero registration number CRD42020194165). Hundred-twenty-six studies were included. In both the endemic and the epidemic setting, a median number of two out of seven predefined components of OI were identified. In the endemic setting, the most frequent component of OI was screening of the environment (28 studies, 62.2%). In the epidemic setting, screening of the environment (72 studies, 88.9%), and screening of patients during hospitalization (30 studies, 37%) were most frequently performed. Only 19 out of 126 studies (15.1%) reported screening of contact patients, and 37 studies reported screening of healthcare workers (HCW, 29.4%).

CONCLUSION

Due to probable underreporting of OI in the literature, the available evidence for the usefulness of the individual components of OI is scarce. This could lead to inhomogeneous performance of OI after detection of CRPA in the healthcare setting, and with this, potential under- or overscreening. While we could show evidence for the usefulness for environmental screening in order to identify the mode of transmission, evidence for HCW screening is scarce and might not lead to the identification of modes of transmission. Further studies are needed to better understand CI in different settings and, finally, develop guidance on when and how to best perform OI.

Environmental contamination with highly resistant microorganisms after relocating to a new hospital building with 100% single-occupancy rooms: A prospective observational before-and-after study with a three-year follow-up

INTRODUCTION

Inanimate surfaces within hospitals can be a source of transmission for highly resistant microorganisms (HRMO). While many hospitals are transitioning to single-occupancy rooms, the effect of single-occupancy rooms on environmental contamination is still unknown. We aimed to determine differences in environmental contamination with HRMO between an old hospital building with mainly multiple-occupancy rooms and a new hospital building with 100% single-occupancy rooms, and the environmental contamination in the new hospital building during three years after relocating.

METHODS

Environmental samples were taken twice in the old hospital, and fifteen times over a three-year period in the new hospital. Replicate Organism Direct Agar Contact-plates (RODACs) were used to determine colony forming units (CFU). Cotton swabs premoistened with PBS were used to determine presence of methicillin-resistant Staphylococcus aureus, carbapenemase-producing Pseudomonas aeruginosa, highly resistant Enterobacterales, carbapenem-resistant Acinetobacter baumannii, and vancomycin-resistant Enterococcus faecium. All identified isolates were subjected to whole genome sequencing (WGS) using Illumina technology.

RESULTS

In total, 4993 hospital sites were sampled, 724 in the old and 4269 in the new hospital. CFU counts fluctuated during the follow-up period in the new hospital building, with lower CFU counts observed two- and three years after relocating, which was during the COVID-19 pandemic. The CFU counts in the new building were equal to or surpassed the CFU counts in the old hospital building. In the old hospital building, 24 (3.3%) sample sites were positive for 49 HRMO isolates, compared to five (0.1%) sample sites for seven HRMO isolates in the new building (P < 0.001). In the old hospital, 89.8% of HRMO were identified from the sink plug. In the new hospital, 71.4% of HRMO were identified from the shower drain, and no HRMO were found in sinks.

DISCUSSION

Our results indicate that relocating to a new hospital building with 100% single-occupancy rooms significantly decreases HRMO in the environment. Given that environmental contamination is an important source for healthcare associated infections, this finding should be taken into account when considering hospital designs for renovations or the construction of hospitals.