The combined application of hand hygiene and non-sterile gloves by nurses in a tertiary hospital: a multi methods study.

BACKGROUND: The application of hand hygiene (HH) and the use of non-sterile gloves (NSG) in daily care is highly intertwined. We aimed (1) to assess the combined application of HH and NSG among nurses and (2) to explore determinants that influence their ability to combine both measures in their care. METHODS: In a multi-methods study, we combined direct observations of care episodes with semi-structured interviews with nurses in two affiliated university hospitals. Topics were based on Flottorp's checklist of determinants of practice. RESULTS: In total, we observed 205 care episodes and interviewed 10 nurses. Observations revealed that the combination of NSG and HH was correctly applied in 19% of care episodes in which a single procedure was executed, and in 2% of care episodes in which multiple procedures were performed. From the interviews, we found determinants that influenced compliance, covered mainly by three out of seven of Flottorp's checklist domains. Nurses indicated that their knowledge of protocols was limited to HH and protocols were hardly ever actively consulted; visual reminders within their workplace were used as sources of information. Nurses' behavior was primarily influenced by their ability to operationalize this information and their ability to integrate both infection prevention measures into their care. The intention to apply and combine HH and NSG use was influenced by their risk assessment of cross-contamination, by the urge to self-protect and gut feeling. The feasibility to execute HH and NSG protocols is influenced by the urgency and the complexity of the care episode. CONCLUSIONS: The combined correct application with HH and NSG measures by nurses is low. Nurses are instructed in a fragmented way while in the day to day care HH and NSG use are highly intertwined. Operationalization and simplification of infection prevention protocols, in which instructions on both infection prevention measures are fused, should be considered. Strategies to improve practice should consider the power of habit and nurses urge to self-protect.

Seroprevalence of SARS-CoV-2 antibodies among healthcare workers in Dutch hospitals after the 2020 first wave: a multicentre cross-sectional study with prospective follow-up.

BACKGROUND: We aimed to estimate the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) seroprevalence and describe its determinants and associated symptoms among unvaccinated healthcare workers (HCWs) after the first wave of the pandemic. METHODS: HCWs from 13 Dutch hospitals were screened for antibodies against the spike protein of SARS-CoV-2 in June-July 2020 and after three months. Participants completed a retrospective questionnaire on determinants for occupational and community exposure to SARS-CoV-2 and symptoms suggestive of COVID-19 experienced since January 2020. The seroprevalence was calculated per baseline characteristic and symptom at baseline and after follow-up. Adjusted odds ratios (aOR) for seropositivity were determined using logistic regression. RESULTS: Among 2328 HCWs, 323 (13.9%) were seropositive at enrolment, 49 of whom (15%) reported no previous symptoms suggestive of COVID-19. During follow-up, only 1% of the tested participants seroconverted. Seroprevalence was higher in younger HCWs compared to the mid-age category (aOR 1.53, 95% CI 1.07-2.18). Nurses (aOR 2.21, 95% CI 1.34-3.64) and administrative staff (aOR 1.87, 95% CI 1.02-3.43) had a higher seroprevalence than physicians. The highest seroprevalence was observed in HCWs in the emergency department (ED) (aOR 1.79, 95% CI 1.10-2.91), the lowest in HCWs in the intensive, high, or medium care units (aOR 0.47, 95% CI 0.31-0.71). Chronic respiratory disease, smoking, and having a dog were independently associated with a lower seroprevalence, while HCWs with diabetes mellitus had a higher seroprevalence. In a multivariable model containing all self-reported symptoms since January 2020, altered smell and taste, fever, general malaise/fatigue, and muscle aches were positively associated with developing antibodies, while sore throat and chills were negatively associated. CONCLUSIONS: The SARS-CoV-2 seroprevalence in unvaccinated HCWs of 13 Dutch hospitals was 14% in June-July 2020 and remained stable after three months. A higher seroprevalence was observed in the ED and among nurses, administrative and young staff, and those with diabetes mellitus, while a lower seroprevalence was found in HCWs in intensive, high, or medium care, and those with self-reported lung disease, smokers, and dog owners. A history of altered smell or taste, fever, muscle aches and fatigue were independently associated with the presence of SARS-CoV-2 antibodies in unvaccinated HCWs.

Evaluation of an infection control link nurse program: an analysis using the RE-AIM framework.

BACKGROUND: Important elements of programs that train and support infection control link nurses (ICLN) are the engagement of stakeholders, support from hospital and ward management and a structure for iterative improvement. The effects of programs, that combine all these elements, are unknown. We evaluated such a comprehensive program to explore its impact on link nurses and infection prevention practices and routines. METHODS: We used the RE-AIM framework, a robust, evidence-based framework within the field of Implementation Science, to evaluate the impact of our ICLN training and support program. We used a mixed methods approach and organized the outcomes along its five dimensions: Reach, Effectiveness, Adoption, Implementation and Maintenance. RESULTS: Between 2014 and 2018, on average 91% of the inpatient wards and 58% of the outpatient clinics participated in the program (Reach) and impacted guideline adherence in inpatient wards. Link nurses felt engaged and empowered, and perceived their contribution to these results as pivotal. Ward managers confirmed the value of ICLN to help with implementing IPC practices (Effectiveness). The program was adopted both at the hospital and at the ward level (Adoption). Based on ongoing evaluations, the program was adapted by refining education, training and support strategies with emphasis on ward specific aspects (Implementation). The ICLN program was described as a key component of the infection prevention policy to sustain its effects (Maintenance). CONCLUSIONS: Our infection control link nurse program helped ICLN to improve infection prevention practices, especially in inpatient wards. The key to these improvements lay within the adaptability of our link nurse program. The adjustments to the program led to a shift of focus from hospital goals to goals tailored to the ward level. It allowed us to tailor activities to align them with the needs specific to each ward.

Comparison of fast Fourier transform infrared spectroscopy biotyping with whole genome sequencing-based genotyping in common nosocomial pathogens.

Early detection of bacterial transmission and outbreaks in hospitals is important because nosocomial infections can result in health complications and longer hospitalization. Current practice to detect outbreaks uses genotyping methods amplified fragment length polymorphism (AFLP) and whole genome sequencing (WGS), which are not suitable methods for real-time transmission screening of both susceptible and resistant bacteria. The aim was to assess the typing technique Fourier transform infrared (FTIR) spectroscopy as real-time screening method to discriminate large amounts of susceptible and resistant bacteria at strain level when there is no evident outbreak in comparison with the WGS reference. Isolates of past hospital outbreak strains of Acinetobacter baumannii/calcoaceticus complex (n = 25), Escherichia coli (n = 31), Enterococcus faecium (n = 22), Staphylococcus aureus (n = 37) and Pseudomonas aeruginosa (n = 30) were used for validation of FTIR. Subsequently, Enterococcus faecalis (n = 106) and Enterococcus faecium (n = 104) isolates from weekly routine screening samples when no potential outbreak was present were analysed. FTIR showed reproducibility and congruence of cluster composition with WGS for A. baumannii/calcoaceticus complex and E. faecium outbreak isolates. The FTIR results of E. faecalis and E. faecium isolates from routine samples showed reproducibility, but the congruence of cluster composition with WGS was low. For A. baumannii/calcoaceticus complex and E. faecium outbreak isolates, FTIR appears to be a discriminatory typing tool. However, our study shows the discriminatory power is too low to screen real-time for transmission of E. faecium and E. faecalis at patient wards based on isolates acquired in routine surveillance cultures when there is no clear suspicion of an ongoing outbreak.

Bacterial Contamination of Ultrasound and Stethoscope Surfaces in Low- and High-Resource Settings.

Point-of-care ultrasound is an accurate diagnostic and monitoring tool. Its increasing affordability, portability, and versatility make it an excellent component of standard clinical evaluation alongside the stethoscope. However, like the stethoscope, ultrasound carries risks of surface contamination and potential cross-infection. In this international observational study, we compared the surface contamination of ultrasound equipment to stethoscopes in two medical centers: a tropical low-resource hospital and academic high-resource hospital. Ultrasound equipment and coupling gel had similar prevalence of microbial surface contamination compared with observed stethoscopes. Most microbes were commensal Gram-positive, but some were opportunistic and pathogenic microbes (such as Escherichia coli and Staphylococcus aureus). In conclusion, it is crucial to appreciate and reduce the risk of ultrasound device contaminations. When ultrasound is used bedside, similar to stethoscopes, conscientious hygiene measures are equally fundamental.

Role perception of infection control link nurses; a multi-centre qualitative study.

Background: Infection control link nurses (ICLN) disseminate knowledge on infection prevention topics to their peers. Little is known about how they succeed and thereby contribute to infection prevention in daily practise. Aim: To explore the experiences of infection control link nurses regarding their role in acute care hospitals and identify perceived facilitators and best practices. Methods: We conducted a qualitative study with semi-structured individual and focus group interviews with ICLN. The effect of COVID-19 on the ICLN role was added as a topic in focus group interviews during the pandemic. Results: Twenty-six ICLN working in acute care hospitals were interviewed. ICLN perceived their role as to identify, monitor, facilitate and inform their colleagues on infection prevention topics related to their ward. Their experiences vary from feeling challenged and wonder how to get started, to feeling confident and taking initiatives that lead to ward-based improvements. When inspired by each other and supported by infection control practitioners or managers, ICLN feel empowered to initiate more activities to improve practice. During the COVID-19 pandemic, ICLN felt their responsibilities were magnified. When transferred to another ward, the focus on the ICLN role seemed dispersed. Discussion: Empowered ICLN adjust and operationalize infection prevention policies to fit the conditions of their specific wards and provide practical instructions and feedback to their peers which enable better compliance to infection prevention policies. Support and inspiration from other ICLN, infection control practitioners and management contribute to this empowerment and consequently to taking impactful initiatives to improve practice.

Rapid reinfection with SARS-CoV-2 variant-of-concern Alpha detected in a nurse during an outbreak at a non-covid inpatient ward: lessons learned.

We describe the lessons learned during a SARS-CoV-2 variant-of-concern Alpha outbreak investigation at a normal care unit in a university hospital in Amsterdam in December 2020. The outbreak consisted of nine nurses and two roomed-in patient family members. (attack rate 18%). One nurse tested positive with a phylogenetically distinct variant, after a documented infection 83 days prior. Three key points were taken from this investigation. First, it was controlled by adherence to existing guidelines, despite increased transmissibility of the variant. Second, viral sequencing can inform transmission cluster inference, but the epidemiological context is essential to draw appropriate conclusions. Third, reinfections with Alpha variants can occur rapidly after primary infection.

Serologic Surveillance and Phylogenetic Analysis of SARS-CoV-2 Infection Among Hospital Health Care Workers.

Importance: It is unclear when, where, and by whom health care workers (HCWs) working in hospitals are infected with SARS-CoV-2. Objective: To determine how often and in what manner nosocomial SARS-CoV-2 infection occurs in HCW groups with varying exposure to patients with COVID-19. Design, Setting, and Participants: This cohort study comprised 4 weekly measurements of SARS-CoV-2-specific antibodies and collection of questionnaires from March 23 to June 25, 2020, combined with phylogenetic and epidemiologic transmission analyses at 2 university hospitals in the Netherlands. Included individuals were HCWs working in patient care for those with COVID-19, HCWs working in patient care for those without COVID-19, and HCWs not working in patient care. Data were analyzed from August through December 2020. Exposures: Varying work-related exposure to patients infected with SARS-CoV-2. Main Outcomes and Measures: The cumulative incidence of and time to SARS-CoV-2 infection, defined as the presence of SARS-CoV-2-specific antibodies in blood samples, were measured. Results: Among 801 HCWs, there were 439 HCWs working in patient care for those with COVID-19, 164 HCWs working in patient care for those without COVID-19, and 198 HCWs not working in patient care. There were 580 (72.4%) women, and the median (interquartile range) age was 36 (29-50) years. The incidence of SARS-CoV-2 was increased among HCWs working in patient care for those with COVID-19 (54 HCWs [13.2%; 95% CI, 9.9%-16.4%]) compared with HCWs working in patient care for those without COVID-19 (11 HCWs [6.7%; 95% CI, 2.8%-10.5%]; hazard ratio [HR], 2.25; 95% CI, 1.17-4.30) and HCWs not working in patient care (7 HCWs [3.6%; 95% CI, 0.9%-6.1%]; HR, 3.92; 95% CI, 1.79-8.62). Among HCWs caring for patients with COVID-19, SARS-CoV-2 cumulative incidence was increased among HCWs working on COVID-19 wards (32 of 134 HCWs [25.7%; 95% CI, 17.6%-33.1%]) compared with HCWs working on intensive care units (13 of 186 HCWs [7.1%; 95% CI, 3.3%-10.7%]; HR, 3.64; 95% CI, 1.91-6.94), and HCWs working in emergency departments (7 of 102 HCWs [8.0%; 95% CI, 2.5%-13.1%]; HR, 3.29; 95% CI, 1.52-7.14). Epidemiologic data combined with phylogenetic analyses on COVID-19 wards identified 3 potential HCW-to-HCW transmission clusters. No patient-to-HCW transmission clusters could be identified in transmission analyses. Conclusions and Relevance: This study found that HCWs working on COVID-19 wards were at increased risk for nosocomial SARS-CoV-2 infection with an important role for HCW-to-HCW transmission. These findings suggest that infection among HCWs deserves more consideration in infection prevention practice.

Simultaneous detection and ribotyping of Clostridioides difficile, and toxin gene detection directly on fecal samples.

BACKGROUND: Clostridioides difficile is the most common cause of nosocomial diarrhea. Ribotyping of cultured strains by a PCR-based test is used to study potential transmission between patients. We aimed to develop a rapid test that can be applied directly on fecal samples for simultaneous detection and ribotyping of C. difficile, as well as detection of toxin genes. METHODS: We developed a highly specific and sensitive primer set for simultaneous detection and ribotyping of C. difficile directly on total fecal DNA. Toxin genes were detected with primers adapted from Persson et al. (Clin Microbiol Infect 14(11):1057-1064). Our study set comprised 130 fecal samples: 65 samples with positive qPCR for C. difficile toxin A/B genes and 65 C. difficile qPCR negative samples. PCR products were analyzed by capillary gel electrophoresis. RESULTS: Ribosomal DNA fragment peak profiles and toxin genes were detected in all 65 C. difficile positive fecal samples and in none of the 65 C. difficile negative samples. The 65 samples were assigned to 27 ribotypes by the Dutch reference laboratory. Our peak profiles corresponded to these ribotypes, except for two samples. During a C. difficile outbreak, patients were correctly allocated to the outbreak-cluster based on the results of direct fecal ribotyping, before C. difficile isolates were cultured and conventionally typed. CONCLUSION: C. difficile ribotyping directly on fecal DNA is feasible, with sensitivity and specificity comparable to that of diagnostic toxin gene qPCR and with ribotype assignment similar to that obtained by conventional typing on DNA from cultured isolates. This supports simultaneous diagnosis and typing to recognize an outbreak.

[Rational use of respiratory protective equipment: advice for health care professionals in time of COVID-19]. / Rationeel gebruik van ademhalingsbeschermingsmaskers.

The current COVID-19 pandemic has led to a worldwide shortage of respiratory protective equipment. In order to offer maximum protection against infection for all healthcare workers, we need to optimise our use of the available equipment. This article provides practical advice on which type of mask is indicated in what specific situation, what requirements the mask should meet and how to optimise the local workflow, including the re-use of masks after decontamination.

Infection control link nurse programs in Dutch acute care hospitals; a mixed-methods study.

BACKGROUND: Infection control link nurse programs show considerable variation. We report how Dutch link nurse programs are organized, how they progress, and how contextual factors may play a role in the execution of these programs. METHODS: This mixed-methods study combined a survey and semi-structured interviews with infection control practitioners, based on items of the Template for Intervention Description and Replication (TIDieR) checklist. RESULTS: The Netherlands has 74 hospitals; 72 infection control practitioners from 72 different hospitals participated in the survey. Four of these infection control practitioners participated in interviews. A link nurse program was present in 67% of the hospitals; responsibility for 76% of these programs lied solely with the infection prevention and control team. The core component of most programs (90%) was education. Programs that included education on infection prevention topics and training in implementation skills were perceived as more effective than programs without such education or programs where education included only infection prevention topics. The interviews illustrated that these programs were initiated by the infection prevention team with the intention to collaborate with other departments to improve practice. Content for these programs was created at the time of their implementation. Infection control practitioners varied in their ability to express program goals and to engage experts and key stakeholders. CONCLUSIONS: Infection control link nurse programs vary in content and in set up. Programs with a clear educational content are viewed as more successful by the infection control practitioners that implement these programs.

Implementing a Clostridium difficile testing algorithm and its effect on isolation duration and treatment initiation: a pre- and post-implementation study.

A proportion of patients suspected of Clostridium difficile infection are unnecessarily placed in contact isolation. By introducing a random-access glutamate dehydrogenase (GDH) test for C. difficile, we aimed to reduce isolation time. In addition, we investigated whether the result of the toxin A&B enzyme immunoassay (EIA) was associated with the decision to initiate antibiotic treatment against C. difficile. This retrospective pre- and post-implementation study was from June 3, 2016, to June 4, 2018. Pre-implementation, only a NAAT was performed. In the post-implementation period, a GDH test was performed; if positive, a toxin A&B EIA followed the same day and subsequently a NAAT. Contact isolation for CDI was discontinued when the GDH test was negative. Median time in isolation was 50.8 h pre-implementation (n = 189) versus 28.0 h post-implementation (n = 119), p < 0.001. The GDH test had a negative predictive value of 98.8% (95% CI 97.9-99.4). In 7/31 (22.6%) patients with a positive NAAT and GDH test and a negative toxin A&B EIA, no antibiotics against C. difficile were initiated versus 4/28 (14.3%) patients who were NAAT, GDH and toxin A&B EIA positive. Introducing a random-access screening test resulted in a significant decrease in patient isolation time. The GDH test had a high negative predictive value making it suitable to determine whether contact isolation can be discontinued. Furthermore, the result of a toxin A&B EIA had limited added value on the percentage of patients in whom antibiotic treatment against C. difficile was initiated.

The First Two Cases of Candida auris in The Netherlands.

Candida auris is a rapidly emerging multidrug-resistant pathogenic yeast. In recent years, an increasing number of C. auris invasive infections and colonized patients have been reported, and C. auris has been associated with hospital outbreaks worldwide, mainly in intensive care units (ICUs). Here, we describe the first two cases of C. auris in The Netherlands. Both cases were treated in a healthcare facility in India prior to admission. The patients were routinely placed in contact precautions in a single room after admission, which is common practice in The Netherlands for patients with hospitalization outside The Netherlands. No transmission of C. auris was noticed in both hospitals. Routine admission screening both for multidrug-resistant (MDR) bacteria and MDR yeasts should be considered for patients admitted from foreign hospitals or countries with reported C. auris transmission.

Infection control link nurses in acute care hospitals: a scoping review.

Background: Involving link nurses in infection prevention and control is a strategy to improve clinical practice that has been implemented in hospitals worldwide. However, little is known about the use, the range and benefits of this strategy. We aimed to identify key concepts of infection control link nurses (ICLN) and ICLN programs, to evaluate the effect of such programs, and to identify gaps in the evidence base. Methods: In a scoping review, we searched PubMed, CINAHL, Google and Google Scholar for manuscripts on ICLN in acute care hospitals. We included research- and opinion-based papers, abstracts, reports and guidelines. Results: We included 29 publications and identified three key concepts: the profile of ICLN, strategies to support ICLN, and the implementation of ICLN programs. The majority of included studies delineates the ICLN profile with accompanying roles, tasks and strategies to support ICLN, without a thorough evaluation of the implementation process or effects. Few studies report on the effect of ICLN programs in terms of patient outcomes or guideline adherence, with positive short term effects. Conclusion: This scoping review reveals a lack of robust evidence on the effectiveness of ICLN programs. Current best practice for an ICLN program includes a clear description of the ICLN profile, education on infection prevention topics as well as training in implementation skills, and support from the management at the ward and hospital level. Future research is needed to evaluate the effects of ICLN on clinical practice and to further develop ICLN programs for maximal impact.

Colonization sites in carriers of ESBL-producing Gram-negative bacteria.

Objective: The distribution of Extended-Spectrum Beta-Lactamase-producing Gram-negative bacteria (ESBL-GNB) colonization sites is relevant for infection control guidelines on detection and follow-up of colonization. We questioned whether it is possible to rely solely on rectal swab culture for follow-up of ESBL-GNB colonization. Methods: We retrospectively assessed ESBL-GNB colonization sites in patients in a tertiary hospital in the Netherlands. The Laboratory Information Management System was queried for all bacterial cultures obtained between January 2012 and August 2016. All patients with one or more cultures positive for ESBL-GNB were identified and the distribution of ESBL-GNB positive sample sites was assessed. A subgroup analysis was performed on patients for whom at least one rectal swab specimen was available. Results: We identified 1011 ESBL-GNB carriers with 16,578 specimens for analysis. ESBL-GNB were most frequently isolated from the rectum (506/1011), followed by the urogenital (414/1011) and respiratory tract (142/1011), and pus (136/1011). For 588 patients at least one rectal swab specimen was available. In this subgroup, ESBL-GNB colonization was detected only in the rectum in 55.4% (326/588) of patients, in 30.6% (180/588) in the rectum and a different culture site, and in 13.9% (82/588) no rectal colonization was detected. Conclusions: Rectal colonization with ESBL-GNB was detected in 86% of ESBL-GNB carriers. However, in 14% of ESBL-GNB carriers we did not detect rectal colonization. Therefore, samples taken for follow-up of colonization with multi-drug resistant Gram-negative bacteria (MDR-GNB) should ideally also include samples from the site where the MDR-GNB was initially found.

Effectiveness of a Behavioral Approach to Improve Healthcare Worker Compliance With Hospital Dress Code.

BACKGROUND The VU University Medical Center, a tertiary-care hospital in the Netherlands, has adopted a dress code based on national guidelines. It includes uniforms provided by the hospital and a 'bare-below-the-elbow' policy for all healthcare workers (HCWs) in direct patient care. Because compliance was poor, we sought to improve adherence by interventions targeted at the main causes of noncompliance. OBJECTIVE To measure compliance with the dress code, to assess causes of noncompliance and to assess whether a behavioral approach (combing a nominal group technique with participatory action) is effective in improving compliance METHODS Between March 2014 and June 2016, a total of 1,920 HCWs were observed in hospital hallways for adherence to the policy, at baseline, and at follow-up measurements. Based on the outcome of the baseline measurement, a nominal group technique was applied to assess causes of noncompliance. The causes revealed served as input for interventions that were developed, prioritized, and tailored to specific groups of HCWs and specific departments through participatory action. RESULTS We identified lack of knowledge, lack of facilities, and negative attitudes as the main causes of noncompliance. The importance of each cause varied for different groups of HCWs. Tailored interventions targeted at these causes increased overall compliance by 39.6% (95% CI, 31.7-47.5). CONCLUSION The combination of a nominal group technique and participatory action approach is an effective method to increase and sustain compliance with hospital dress code. This combined approach may also be useful to improve adherence to other guidelines. Infect Control Hosp Epidemiol 2017;38:1435-1440.

The Effect of Strict Segregation on Pseudomonas aeruginosa in Cystic Fibrosis Patients.

INTRODUCTION: Segregation of patients with cystic fibrosis (CF) was implemented to prevent chronic infection with epidemic Pseudomonas aeruginosa strains with presumed detrimental clinical effects, but its effectiveness has not been carefully evaluated. METHODS: The effect of strict segregation on the incidence of P. aeruginosa infection in CF patients was investigated through longitudinal protocolized follow-up of respiratory tract infection before and after segregation. In two nested cross-sectional studies in 2007 and 2011 the P. aeruginosa population structure was investigated and clinical parameters were determined in patients with and without infection with the Dutch epidemic P. aeruginosa clone (ST406). RESULTS: Of 784 included patients 315 and 382 were at risk for acquiring chronic P. aeruginosa infection before and after segregation. Acquisition rates were, respectively, 0.14 and 0.05 per 1,000 days at risk (HR: 0.66, 95% CI [0.2548-1.541]; p = 0.28). An exploratory subgroup analysis indicated lower acquisition after segregation in children < 15 years of age (HR: 0.43, 95% CI[0.21-0.95]; p = 0.04). P. aeruginosa population structure did not change after segregation and ST406 was not associated with lung function decline, death or lung transplantation. CONCLUSIONS: Strict segregation was not associated with a statistically significant lower acquisition of chronic P. aeruginosa infection and ST406 was not associated with adverse clinical outcome. After segregation there were no new acquisitions of ST406. In an unplanned exploratory analysis chronic acquisition of P. aeruginosa was lower after implementation of segregation in patients under 15 years of age.

Within-Host Evolution of the Dutch High-Prevalent Pseudomonas aeruginosa Clone ST406 during Chronic Colonization of a Patient with Cystic Fibrosis.

This study investigates adaptation of ST406, a prevalent P. aeruginosa clone, present in 15% of chronically infected cystic fibrosis (CF) patients in the Netherlands, in a newly infected CF patient during three years using whole genome sequencing (WGS), transcriptomics, and phenotypic assays, including biofilm formation. WGS-based phylogeny demonstrates that ST406 is genetically distinct from other reported CF related strains or epidemic clones. Comparative genomic analysis of the early (S1) and late (S2) isolate yielded 42 single nucleotide polymorphisms (SNPs) and 10 indels and a single 7 kb genomic fragment only found in S2. Most SNPs and differentially expressed genes encoded proteins involved in metabolism, secretion and signal transduction or transcription. SNPs were identified in regulator genes mexT and exsA and coincided with differential gene expression of mexE and mexF, encoding the MexE/F efflux pump, genes encoding the type six secretion system (T6SS) and type three secretion system (T3SS), which have also been previously implicated in adaptation of other P. aeruginosa strains during chronic infection of CF lungs. The observation that genetically different strains from different patients have accumulated similar genetic adaptations supports the concept of adaptive parallel evolution of P. aeruginosa in chronically infected CF patients. Phenotypically, there was loss of biofilm maturation coinciding with a significant lower level of transcription of both bfmR and bfmS during chronic colonization. These data suggest that the high-prevalent Dutch CF clone ST406 displays adaptation to the CF lung niche, which involves a limited number of mutations affecting regulators controlling biofilm formation and secretion and genes involved in metabolism. These genes could provide good targets for anti-pseudomonal therapy.

Wide dispersion of ST175 clone despite high genetic diversity of carbapenem-nonsusceptible Pseudomonas aeruginosa clinical strains in 16 Spanish hospitals.

During the COMParative Activity of Carbapenems Testing (COMPACT) surveillance study, 448 Pseudomonas aeruginosa clinical isolates were obtained from 16 Spanish hospitals. Nonsusceptibility (EUCAST breakpoints) to imipenem (35%), meropenem (33%), and/or doripenem (33%) was observed with 175 isolates (39%). Simultaneous resistance to these three drugs was observed with 126 of the 175 isolates (72%). Except for colistin, high resistance rates were observed among noncarbapenem antibiotics. Clonal relatedness was investigated by pulsed-field gel electrophoresis (PFGE) with SpeI, discriminating 68 patterns. Multilocus sequence typing (MLST) was performed on 84 isolates representing different PFGE types and all participating hospitals. Thirty-nine sequence types (STs) could be distinguished, and of these, ST175 (48 isolates, 10 hospitals), ST646 (16 isolates, 4 hospitals), ST532 (13 isolates, 3 hospitals), and ST111 (13 isolates, 7 hospitals) were the most frequently encountered. Minimum-spanning tree analysis confirmed a wide dissemination of different clones among participant hospitals, particularly ST175. PFGE pattern comparison within the four most frequent STs revealed that ST175 isolates were relatively uniform, while ST646, ST532, and ST111 isolates were highly diverse, with almost every isolate belonging to a unique pulsotype, even when originating from the same center. The population of carbapenem-nonsusceptible P. aeruginosa isolates from 16 hospitals is highly diverse, with one ST (ST175) representing a highly conserved clone disseminated in 10 of the 16 participant hospitals. This ST175 clone should be added to the list of P. aeruginosa clones at high risk for epidemic spread, such as the Liverpool, Manchester, and Melbourne clones previously found in cystic fibrosis patients and ST235 in the nosocomial setting.