Don't overlook the little guy: An evaluation of the frequency of small plasmids co-conjugating with larger carbapenemase gene containing plasmids

As the spread of antimicrobial resistance (AMR) genes becomes an increasing global threat, improved understanding of mobile genetic elements which contribute to the spread of antimicrobial resistance genes, becomes more critical. We created transconjugants from the mating of three chromosomally isogenic Klebsiella pneumoniae carbapenemase (bla_KPC) positive Citrobacter freundii isolates with a laboratory strain of Escherichia coli and evaluated the movement of small cryptic plasmids (SCPs), p3223 and p1916, when larger bla_KPC-plasmids were transferred. In all of the 143 transconjugants, multiple plasmids, both large and small, transferred with each mating. When two bla_KPC-plasmids were present in the host, frequently (87%; 98/113) both would be transferred during mating. p3223 is found in a wide range of bacterial hosts that harbor AMR genes; p1916 has been identified in only a limited number of publicly available sequences to date. From our evaluation, there is still much to learn about SCPs, and the high rate of co-transfer of multiple plasmids from real-world carbapenemase-producing Enterobacteriales.

Risk Assessment After a Severe Hospital-Acquired Infection Associated With Carbapenemase-Producing Pseudomonas aeruginosa

IMPORTANCE

Resistance of gram-negative bacilli to carbapenems is rapidly emerging worldwide. In 2016, the World Health Organization defined the hospital-built environment as a core component of infection prevention and control programs. The hospital-built environment has recently been reported as a source for outbreaks and sporadic transmission events of carbapenemase-producing gram-negative bacilli from the environment to patients.

OBJECTIVE

To assess risk after the identification of an unexpected, severe, and lethal hospital-acquired infection caused by carbapenemase-producing Pseudomonas aeruginosa in a carbapenemase-low endemic setting.

DESIGN, SETTINGS, AND PARTICIPANTS

A case series study in which a risk assessment was performed on all 11 patients admitted to the combined cardiothoracic surgery and pulmonary diseases ward and the hospital-built environment in the Radboud University Medical Center, the Netherlands, in February 2018.

EXPOSURES

Water and aerosols containing carbapenemase-producing (Verona integron-mediated metallo-β-lactamase [VIM]) P aeruginosa.

MAIN OUTCOMES AND MEASURES

Colonization and/or infection of patients and/or contamination of the environment after the detection of 1 patient infected with carbapenemase-producing (VIM) P aeruginosa.

RESULTS

A total of 5 men (age range, 60-84 years) and 6 women (age range, 55-74 years) were admitted to the combined cardiothoracic surgery and pulmonary diseases ward. The risk assessment was performed after carbapenemase-producing (VIM) P aeruginosa was unexpectedly detected in a man in his early 60s, who had undergone a left-sided pneumonectomy and adjuvant radiotherapy. No additional cases (colonization or infection) of carbapenemase-producing (VIM) P aeruginosa were detected. Plausible transmission of carbapenemase-producing P aeruginosa from the hospital environment to the patient via the air was confirmed by whole-genome sequencing, which proved the relation of Pseudomonas strains from the patient, the shower drains in 8 patient rooms, 1 sink, and an air sample.

CONCLUSIONS AND RELEVANCE

This study suggests that rethinking the hospital-built environment, including shower drains and the sewage system, will be crucial for the prevention of severe and potential lethal hospital-acquired infections.

Carbapenem-resistant Enterobacteriaceae dispersal from sinks is linked to drain position and drainage rates in a laboratory model system

BACKGROUND

Hospital sinks, waste traps and drains can harbour carbapenem-resistant Enterobacteriaceae (CRE).

AIM

To investigate the dispersal of CRE from sinks in which water delivered from the tap flows directly into the drain and from clinical handwash basins with the drain at the rear. The effect of fast and slow drainage rates was also assessed.

METHODS

Waste traps, known to be colonized with CRE, were taken from a hospital and installed within a model laboratory system. New waste traps were also installed and artificially inoculated with CRE. The potential for bacteria to be dispersed from sinks was assessed using cyclone air samplers and/or settle plates.

FINDINGS

When the waste traps were artificially contaminated and CRE colonization was confined to the waste trap water, significantly fewer bacteria were dispersed from sinks that drained quickly (P = 0.004) and/or from rear-draining sinks (P = 0.002). When the waste traps were naturally contaminated and CRE colonized the trap, pipework and drain, there was significant interaction between sink drainage and position of the drain (P < 0.001). When drainage was slow, dispersal from rear-draining sinks was almost 30-fold less than from sinks with the drain underneath the tap (P < 0.001). When drainage was fast, rear-draining sinks again released comparatively fewer CRE, although, in this case, the difference was not statistically significant (P = 0.7). Contaminated splashes travelled up to 1 m from the sink.

CONCLUSION

Slow drainage rates and sink designs with the drain directly underneath the tap increase the risk of CRE present in waste traps and drains contaminating the ward environment.

Sink traps as the source of transmission of OXA-48-producing Serratia marcescens in an intensive care unit

BACKGROUND

Carbapenemase-producing Enterobacteriaceae (CPE) outbreaks are mostly attributed to patient-to-patient transmission via healthcare workers.

OBJECTIVE

We describe successful containment of a prolonged OXA-48-producing S. marcescens outbreak after recognizing the sink traps as the source of transmission.

METHODS

The Sheba Medical Center intensive care unit (ICU), contains 16 single-bed, semi-closed rooms. Active CPE surveillance includes twice-weekly rectal screening of all patients. A case was defined as a patient detected with OXA-48 CPE >72 hours after admission. A root-cause analysis was used to investigate the outbreak. All samples were inoculated on chrom-agar CRE, and carbapenemase genes were detected using commercial molecular Xpert-Carba-R. Environmental and patient S. marcescens isolates were characterized using PFGE.

RESULTS

From January 2016 to May 2017, 32 OXA-48 CPE cases were detected, and 81% of these were S. marcescens. A single clone was the cause of all but the first 2 cases. The common factor in all cases was the use of relatively large amounts of tap water. The outbreak clone was detected in 2 sink outlets and 16 sink traps. In addition to routine strict infection control measures, measures taken to contain the outbreak included (1) various sink decontamination efforts, which eliminated the bacteria from the sink drains only temporarily and (2) educational intervention that engaged the ICU team and lead to high adherence to 'sink-contamination prevention guidelines.' No additional cases were detected for 12 months.

CONCLUSIONS

Despite persistence of the outbreak clones in the environmental reservoir for 1 year, the outbreak was rapidly and successfully contained. Addressing sink traps as hidden reservoirs played a major role in the intervention.

How to: molecular investigation of a hospital outbreak

BACKGROUND

Studying hospital outbreaks by using molecular tools, i.e. synthesizing the molecular epidemiology data to its appropriate clinical-epidemiologic context, is crucial in order to identify infection source, infer transmission dynamics, appropriately allocate prevention resources and implement control measures. Whole-genome sequencing (WGS) of pathogens has become the reference standard, as it is becoming more accessible and affordable. Consequently, sequencing of the full pathogen genome via WGS and major progress in fit-for-purpose genomic data analysis tools and interpretation is revolutionizing the field of outbreak investigations in hospitals. Metagenomics is an additional evolving field that might become commonly used in the future for outbreak investigations. Nevertheless, practitioners are frequently limited in terms of WGS or metagenomics, especially for local outbreak analyses, as a result of costs or logistical considerations, reduced or lack of locally available resources and/or expertise. As a result, traditional approaches, including pulsed-field gel electrophoresis, repetitive-element palindromic PCR and multilocus sequence typing, along with other typing methods, are still widely used.

AIMS

To provide practitioners with evidenced-based action plans for usage of the various typing techniques in order to investigate the molecular epidemiology of nosocomial outbreaks, of clinically significant pathogens in acute-care hospitals.

SOURCES

PubMed search with relevant keywords along with personal collection of relevant publications.

CONTENT

Representative case scenarios and critical review of the relevant scientific literature.

IMPLICATIONS

The review provides practical action plans to manage molecular epidemiologic investigations of outbreaks caused by clinically significant nosocomial pathogens, while prioritizing the use and timely integration of the various methodologies.

Effect of copper-impregnated linens on multidrug-resistant organism acquisition and Clostridium difficile infection at a long-term acute-care hospital

Copper-impregnated surfaces and linens have been shown to reduce infections and multidrug-resistant organism (MDRO) acquisition in healthcare settings. However, retrospective analyses of copper linen deployment at a 40-bed long-term acute-care hospital demonstrated no significant reduction in incidences of healthcare facility-onset Clostridium difficile infection or MDRO acquisition.

A novel sink drain cover prevents dispersal of microorganisms from contaminated sink drains

In hospital sinks, a novel plastic drain cover was effective in preventing dispersal of gram-negative bacilli and fluorescent gel associated with splattering of flowing water. Our findings suggest that the sink drain covers could provide a simple means to reduce dissemination of pathogens from contaminated sinks.

Sink-Related Outbreaks and Mitigation Strategies in Healthcare Facilities

PURPOSE OF REVIEW

In this review, we summarize recent outbreaks attributed to hospital sinks and examine design features and behaviors that contributed to these outbreaks. The effectiveness of various risk mitigation strategies is presented. Finally, we examine investigational strategies targeted at reducing the risk of sink-related infections.

RECENT FINDINGS

Outbreaks of hospital sink-related infections involve a diverse spectrum of microorganisms. They can be attributed to defects in sink design and hospital wastewater systems that promote the formation and dispersion of biofilm, as well as healthcare practitioner and patient behaviors. Risk mitigation strategies are often bundled; while they may reduce clinical cases, sink colonization may persist. Novel approaches targeting biofilms show promise but require more investigation. Emphasis should be placed on optimizing best practices in sink design and placement to prevent infections. Hospitals should consider developing a rational surveillance and prevention strategy based on the current design and state of their sinks.

Characterizations of handwashing sink activities in a single hospital medical intensive care unit

BACKGROUND

Handwashing sink drains are increasingly implicated as a potential reservoir of antibiotic-resistant bacteria in hospital outbreaks; however, usage patterns that may promote this source remain unknown.

AIM

To understand behaviours in the intensive care unit (ICU) that may facilitate establishment and nosocomial transmission of multidrug-resistant Gram negatives from a sink-trap reservoir to a patient.

METHODS

Motion-sensitive cameras captured anonymized activity paired with periodic in-person observations during a quality investigation from four ICU sinks (two patient rooms and two patient bathrooms) in a university hospital.

FINDINGS

We analysed 4810 sink videos from 60 days in patient rooms (3625) and adjoining bathrooms (1185). There was a false-positive rate of 38% (1837 out of 4810) in which the camera triggered but no sink interaction occurred. Of the 2973 videos with analysed behaviours there were 5614 observed behaviours which were assessed as: 37.4% medical care, 29.2% additional behaviours, 17.0% hand hygiene, 7.2% patient nutrition, 5.0% environmental care, 4.2% non-medical care. Handwashing was only 4% (224 out of 5614) of total behaviours. Sub-analysis of 2748 of the later videos further categorized 56 activities where a variety of nutrients, which could promote microbial growth, were disposed of in the sink.

CONCLUSION

Several non-hand hygiene activities took place regularly in ICU handwashing sinks; these may provide a mechanism for nosocomial transmission and promotion of bacterial growth in the drain. Redesigning hospital workflow and sink usage may be necessary as it becomes apparent that sink drains may be a reservoir for transmission of multidrug-resistant bacteria.