Concurrent transmission of multiple carbapenemases in a long-term acute-care hospital

OBJECTIVE

We investigated concurrent outbreaks of Pseudomonas aeruginosa carrying blaVIM (VIM-CRPA) and Enterobacterales carrying blaKPC (KPC-CRE) at a long-term acute-care hospital (LTACH A).

METHODS

We defined an incident case as the first detection of blaKPC or blaVIM from a patient's clinical cultures or colonization screening test. We reviewed medical records and performed infection control assessments, colonization screening, environmental sampling, and molecular characterization of carbapenemase-producing organisms from clinical and environmental sources by pulsed-field gel electrophoresis (PFGE) and whole-genome sequencing.

RESULTS

From July 2017 to December 2018, 76 incident cases were identified from 69 case patients: 51 had blaKPC, 11 had blaVIM, and 7 had blaVIM and blaKPC. Also, blaKPC were identified from 7 Enterobacterales, and all blaVIM were P. aeruginosa. We observed gaps in hand hygiene, and we recovered KPC-CRE and VIM-CRPA from drains and toilets. We identified 4 KPC alleles and 2 VIM alleles; 2 KPC alleles were located on plasmids that were identified across multiple Enterobacterales and in both clinical and environmental isolates.

CONCLUSIONS

Our response to a single patient colonized with VIM-CRPA and KPC-CRE identified concurrent CPO outbreaks at LTACH A. Epidemiologic and genomic investigations indicated that the observed diversity was due to a combination of multiple introductions of VIM-CRPA and KPC-CRE and to the transfer of carbapenemase genes across different bacteria species and strains. Improved infection control, including interventions that minimized potential spread from wastewater premise plumbing, stopped transmission.

Gut microbiome perturbation, antibiotic resistance, and Escherichia coli strain dynamics associated with international travel: a metagenomic analysis

BACKGROUND

Culture-based studies have shown that acquisition of extended-spectrum β-lactamase-producing Enterobacterales is common during international travel; however, little is known about the role of the gut microbiome before and during travel, nor about acquisition of other antimicrobial-resistant organisms. We aimed to identify (1) whether the gut microbiome provided colonisation resistance against antimicrobial-resistant organism acquisition, (2) the effect of travel and travel behaviours on the gut microbiome, and (3) the scale and global heterogeneity of antimicrobial-resistant organism acquisition.

METHODS

In this metagenomic analysis, participants were recruited at three US travel clinics (Boston, MA; New York, NY; and Salt Lake City, UT) before international travel. Participants had to travel internationally between Dec 8, 2017, and April 30, 2019, and have DNA extractions for stool samples both before and after travel for inclusion. Participants were excluded if they had at least one low coverage sample (<1 million read pairs). Stool samples were collected at home before and after travel, sent to a clinical microbiology laboratory to be screened for three target antimicrobial-resistant organisms (extended-spectrum β-lactamase-producing Enterobacterales, carbapenem-resistant Enterobacterales, and mcr-mediated colistin-resistant Enterobacterales), and underwent DNA extraction and shotgun metagenomic sequencing. We profiled metagenomes for taxonomic composition, antibiotic-resistant gene content, and characterised the Escherichia coli population at the strain level. We analysed pre-travel samples to identify the gut microbiome risk factors associated with acquisition of the three targeted antimicrobial resistant organisms. Pre-travel and post-travel samples were compared to identify microbiome and resistome perturbation and E coli strain acquisition associated with travel.

FINDINGS

A total of 368 individuals travelled between the required dates, and 296 had DNA extractions available for both before and after travel. 29 travellers were excluded as they had at least one low coverage sample, leaving a final group of 267 participants. We observed a perturbation of the gut microbiota, characterised by a significant depletion of microbial diversity and enrichment of the Enterobacteriaceae family. Metagenomic strain tracking confirmed that 67% of travellers acquired new strains of E coli during travel that were phylogenetically distinct from their pre-travel strains. We observed widespread enrichment of antibiotic-resistant genes in the gut, with a median 15% (95% CI 10-20, p<1 × 10-10) increase in burden (reads per kilobase per million reads). This increase included antibiotic-resistant genes previously classified as threats to public health, which were 56% (95% CI 36-91, p=2 × 10-11) higher in abundance after travel than before. Fluoroquinolone antibiotic-resistant genes were aquired by 97 (54%) of 181 travellers with no detected pre-travel carriage. Although we found that visiting friends or relatives, travel to south Asia, and eating uncooked vegetables were risk factors for acquisition of the three targeted antimicrobial resistant organisms, we did not observe an association between the pre-travel microbiome structure and travel-related antimicrobial-resistant organism acquisition.

INTERPRETATION

This work highlights a scale of E coli and antimicrobial-resistant organism acquisition by US travellers not apparent from previous culture-based studies, and suggests that strategies to control antimicrobial-resistant organisms addressing international traveller behaviour, rather than modulating the gut microbiome, could be worthwhile.

FUNDING

US Centers for Disease Control and Prevention and National Institute of Allergy and Infectious Diseases.

Containment of a Verona Integron-Encoded Metallo-Beta-Lactamase-Producing Pseudomonas aeruginosa Outbreak Associated With an Acute Care Hospital Sink-Tennessee, 2018-2020

Background

Contaminated healthcare facility wastewater plumbing is recognized as a source of carbapenemase-producing organism transmission. In August 2019, the Tennessee Department of Health (TDH) identified a patient colonized with Verona integron-encoded metallo-beta-lactamase-producing carbapenem-resistant Pseudomonas aeruginosa (VIM-CRPA). A record review revealed that 33% (4 of 12) of all reported patients in Tennessee with VIM had history of prior admission to acute care hospital (ACH) A intensive care unit (ICU) Room X, prompting further investigation.

Methods

A case was defined as polymerase chain reaction detection of bla_VIM in a patient with prior admission to ACH A from November 2017 to November 2020. The TDH performed point prevalence surveys, discharge screening, onsite observations, and environmental testing at ACH A. The VIM-CRPA isolates underwent whole-genome sequencing (WGS).

Results

In a screening of 44% (n = 11) of 25 patients admitted to Room X between January and June 2020, we identified 36% (n = 4) colonized with VIM-CRPA, resulting in 8 cases associated with Room X from March 2018 to June 2020. No additional cases were identified in 2 point-prevalence surveys of the ACH A ICU. Samples from the bathroom and handwashing sink drains in Room X grew VIM-CRPA; all available case and environmental isolates were found to be ST253 harboring bla_VIM-1 and to be closely related by WGS. Transmission ended after implementation of intensive water management and infection control interventions.

Conclusions

A single ICU room's contaminated drains were associated with 8 VIM-CRPA cases over a 2-year period. This outbreak highlights the need to include wastewater plumbing in hospital water management plans to mitigate the risk of transmission of antibiotic-resistant organisms to patients.

Trimethoprim-sulfamethoxazole resistance patterns among Staphylococcus aureus in the United States, 2012-2018

We reviewed trimethoprim-sulfamethoxazole antibiotic susceptibility testing data among Staphylococcus aureus using 3 national inpatient databases. In all 3 databases, we observed an increases in the percentage of methicillin-resistant Staphylococcus aureus that were not susceptible to trimethoprim-sulfamethoxazole. Providers should select antibiotic regimens based on local resistance patterns and should report changes to the public health department.

Carbapenem-Resistant enterobacterales in individuals with and without health care risk factors -Emerging infections program, United States, 2012-2015

BACKGROUND

Carbapenem-resistant Enterobacterales (CRE) are usually healthcare-associated but are also emerging in the community.

METHODS

Active, population-based surveillance was conducted to identify case-patients with cultures positive for Enterobacterales not susceptible to a carbapenem (excluding ertapenem) and resistant to all third-generation cephalosporins tested at 8 US sites from January 2012 to December 2015. Medical records were used to classify cases as health care-associated, or as community-associated (CA) if a patient had no known health care risk factors and a culture was collected <3 days after hospital admission. Enterobacterales isolates from selected cases were submitted to CDC for whole genome sequencing.

RESULTS

We identified 1499 CRE cases in 1194 case-patients; 149 cases (10%) in 139 case-patients were CA. The incidence of CRE cases per 100,000 population was 2.96 (95% CI: 2.81, 3.11) overall and 0.29 (95% CI: 0.25, 0.35) for CA-CRE. Most CA-CRE cases were in White persons (73%), females (84%) and identified from urine cultures (98%). Among the 12 sequenced CA-CRE isolates, 5 (42%) harbored a carbapenemase gene.

CONCLUSIONS

Ten percent of CRE cases were CA; some isolates from CA-CRE cases harbored carbapenemase genes. Continued CRE surveillance in the community is critical to monitor emergence outside of traditional health care settings.

Dialysis Water Supply Faucet as Reservoir for Carbapenemase-Producing Pseudomonas aeruginosa

During June 2017-November 2019, a total 36 patients with carbapenem-resistant Pseudomonas aeruginosa harboring Verona-integron-encoded metallo-β-lactamase were identified in a city in western Texas, USA. A faucet contaminated with the organism, identified through environmental sampling, in a specialty care room was the likely source for infection in a subset of patients.

Remote Infection Control Assessments of U.S. Nursing Homes During the COVID-19 Pandemic, April to June 2020

Background

Nursing homes (NHs) provide care in a congregate setting for residents at high risk of severe outcomes from SARS-CoV-2 infection. In spring 2020, NHs were implementing new guidance to minimize SARS-CoV-2 spread among residents and staff.

Objective

To assess whether telephone and video-based infection control assessment and response (TeleICAR) strategies could efficiently assess NH preparedness and help resolve gaps.

Design

We incorporated Centers for Disease Control and Prevention COVID-19 guidance for NH into an assessment tool covering 6 domains: visitor restrictions; health care personnel COVID-19 training; resident education, monitoring, screening, and cohorting; personal protective equipment supply; core infection prevention and control (IPC); and communication to public health. We performed TeleICAR consultations on behalf of health departments. Adherence to each element was documented and recommendations provided to the facility.

Setting and Participants

Health department–referred NHs that agreed to TeleICAR consultation.

Methods

We assessed overall numbers and proportions of NH that had not implemented each infection control element (gap) and proportion of NH that reported making ≥1 change in practice following the assessment.

Results

During April 13 to June 12, 2020, we completed TeleICAR consultations in 629 NHs across 19 states. Overall, 524 (83%) had ≥1 implementation gap identified; the median number of gaps was 2 (interquartile range: 1-4). The domains with the greatest number of facilities with gaps were core IPC practices (428/625; 68%) and COVID-19 education, monitoring, screening, and cohorting of residents (291/620; 47%).

Conclusions and Implications

TeleICAR was an alternative to onsite infection control assessments that enabled public health to efficiently reach NHs across the United States early in the COVID-19 pandemic. Assessments identified widespread gaps in core IPC practices that put residents and staff at risk of infection. TeleICAR is an important strategy that leverages infection control expertise and can be useful in future efforts to improve NH IPC.

Molecular Characterization of Carbapenem-Resistant Enterobacterales Collected in the United States

Carbapenem-resistant Enterobacterales (CRE) are a growing public health concern due to resistance to multiple antibiotics and potential to cause health care-associated infections with high mortality. Carbapenemase-producing CRE are of particular concern given that carbapenemase-encoding genes often are located on mobile genetic elements that may spread between different organisms and species. In this study, we performed phenotypic and genotypic characterization of CRE collected at eight U.S. sites participating in active population- and laboratory-based surveillance of carbapenem-resistant organisms. Among 421 CRE tested, the majority were isolated from urine (n = 349, 83%). Klebsiella pneumoniae was the most common organism (n = 265, 63%), followed by Enterobacter cloacae complex (n = 77, 18%) and Escherichia coli (n = 50, 12%). Of 419 isolates analyzed by whole genome sequencing, 307 (73%) harbored a carbapenemase gene; variants of bla_KPC predominated (n = 299, 97%). The occurrence of carbapenemase-producing K. pneumoniae, E. cloacae complex, and E. coli varied by region; the predominant sequence type within each genus was ST258, ST171, and ST131, respectively. None of the carbapenemase-producing CRE isolates displayed resistance to all antimicrobials tested; susceptibility to amikacin and tigecycline was generally retained.

Prevalence of carbapenemase-producing organisms among hospitalized solid organ transplant recipients, five U.S. hospitals, 2019-2020

BACKGROUND

Passive reporting to the Centers for Disease Control and Prevention has identified carbapenemase-producing organisms (CPOs) among solid organ transplant (SOT) recipients, potentially representing an emerging source of spread. We analyzed CPO prevalence in wards where SOT recipients receive inpatient care to inform public health action to prevent transmission.

METHODS

From September 2019 to June 2020, five U.S. hospitals conducted consecutive point prevalence surveys (PPS) of all consenting patients admitted to transplant units, regardless of transplant status. We used the Cepheid Xpert® Carba-R assay to identify carbapenemase genes (bla_KPC , bla_NDM , bla_VIM , bla_IMP , bla_OXA-48 ) from rectal swabs. Laboratory-developed molecular tests were used to retrospectively test for a wider range of bla_IMP and bla_OXA variants.

RESULTS

In total, 154 patients were screened and 92 (60%) were SOT recipients. CPOs were detected among 7 (8%) SOT recipients, from two of five screened hospitals: 4 bla_KPC , 1 bla_NDM , 2 blaOXA_-23 . CPOs were detected in 2 (3%) of 62 non-transplant patients. In three of five participating hospitals, CPOs were not identified among any patients admitted to transplant units.

CONCLUSIONS

Longitudinal surveillance in transplant units, as well as PPS in areas with diverse CPO epidemiology, may inform the utility of routine screening in SOT units to prevent the spread of CPOs. This article is protected by copyright. All rights reserved.

Extensively Drug-Resistant Carbapenemase-Producing Pseudomonas aeruginosa and Medical Tourism from the United States to Mexico, 2018-2019

Carbapenem-resistant Pseudomonas aeruginosa (CRPA) producing the Verona integron‒encoded metallo-β-lactamase (VIM) are highly antimicrobial drug-resistant pathogens that are uncommon in the United States. We investigated the source of VIM-CRPA among US medical tourists who underwent bariatric surgery in Tijuana, Mexico. Cases were defined as isolation of VIM-CRPA or CRPA from a patient who had an elective invasive medical procedure in Mexico during January 2018‒December 2019 and within 45 days before specimen collection. Whole-genome sequencing of isolates was performed. Thirty-eight case-patients were identified in 18 states; 31 were operated on by surgeon 1, most frequently at facility A (27/31 patients). Whole-genome sequencing identified isolates linked to surgeon 1 were closely related and distinct from isolates linked to other surgeons in Tijuana. Facility A closed in March 2019. US patients and providers should acknowledge the risk for colonization or infection after medical tourism with highly drug-resistant pathogens uncommon in the United States.

Carbapenemase production among less-common Enterobacterales genera: 10 US sites, 2018

Background

Historically, United States’ carbapenem-resistant Enterobacterales (CRE) surveillance and mechanism testing focused on three genera: Escherichia, Klebsiella, and Enterobacter (EsKE); however, other genera can harbour mobile carbapenemases associated with CRE spread.

Objectives

From January through May 2018, we conducted a 10 state evaluation to assess the contribution of less common genera (LCG) to carbapenemase-producing (CP) CRE.

Methods

State public health laboratories (SPHLs) requested participating clinical laboratories submit all Enterobacterales from all specimen sources during the surveillance period that were resistant to any carbapenem (Morganellaceae required resistance to doripenem, ertapenem, or meropenem) or were CP based on phenotypic or genotypic testing at the clinical laboratory. SPHLs performed species identification, phenotypic carbapenemase production testing, and molecular testing for carbapenemases to identify CP-CRE. Isolates were categorized as CP if they demonstrated phenotypic carbapenemase production and ≥1 carbapenemase gene (bla_KPC, bla_NDM, bla_VIM, bla_IMP, or bla_OXA-48-like) was detected.

Results

SPHLs tested 868 CRE isolates, 127 (14.6%) were from eight LCG. Overall, 195 (26.3%) EsKE isolates were CP-CRE, compared with 24 (18.9%) LCG isolates. LCG accounted for 24 (11.0%) of 219 CP-CRE identified. Citrobacter spp. was the most common CP-LCG; the proportion of Citrobacter that were CP (11/42, 26.2%) was similar to the proportion of EsKE that were CP (195/741, 26.3%). Five of 24 (20.8%) CP-LCG had a carbapenemase gene other than bla_KPC.

Conclusions

Participating sites would have missed approximately 1 in 10 CP-CRE if isolate submission had been limited to EsKE genera. Expanding mechanism testing to additional genera could improve detection and prevention efforts.

Using Wastewater Surveillance Data to Support the COVID-19 Response - United States, 2020-2021

Wastewater surveillance, the measurement of pathogen levels in wastewater, is used to evaluate community-level infection trends, augment traditional surveillance that leverages clinical tests and services (e.g., case reporting), and monitor public health interventions (1). Approximately 40% of persons infected with SARS-CoV-2, the virus that causes COVID-19, shed virus RNA in their stool (2); therefore, community-level trends in SARS-CoV-2 infections, both symptomatic and asymptomatic (2) can be tracked through wastewater testing (3-6). CDC launched the National Wastewater Surveillance System (NWSS) in September 2020 to coordinate wastewater surveillance programs implemented by state, tribal, local, and territorial health departments to support the COVID-19 pandemic response. In the United States, wastewater surveillance was not previously implemented at the national level. As of August 2021, NWSS includes 37 states, four cities, and two territories. This report summarizes NWSS activities and describes innovative applications of wastewater surveillance data by two states, which have included generating alerts to local jurisdictions, allocating mobile testing resources, evaluating irregularities in traditional surveillance, refining health messaging, and forecasting clinical resource needs. NWSS complements traditional surveillance and enables health departments to intervene earlier with focused support in communities experiencing increasing concentrations of SARS-CoV-2 in wastewater. The ability to conduct wastewater surveillance is not affected by access to health care or the clinical testing capacity in the community. Robust, sustainable implementation of wastewater surveillance requires public health capacity for wastewater testing, analysis, and interpretation. Partnerships between wastewater utilities and public health departments are needed to leverage wastewater surveillance data for the COVID-19 response for rapid assessment of emerging threats and preparedness for future pandemics.

Gram-Negative Bacteria Harboring Multiple Carbapenemase Genes, United States, 2012-2019

Reports of organisms harboring multiple carbapenemase genes have increased since 2010. During October 2012–April 2019, the Centers for Disease Control and Prevention documented 151 of these isolates from 100 patients in the United States. Possible risk factors included recent history of international travel, international inpatient healthcare, and solid organ or bone marrow transplantation.

Multispecies Outbreak of Verona Integron-Encoded Metallo-ß-Lactamase-Producing Multidrug Resistant Bacteria Driven by a Promiscuous Incompatibility Group A/C2 Plasmid

BACKGROUND

Antibiotic resistance is often spread through bacterial populations via conjugative plasmids. However, plasmid transfer is not well recognized in clinical settings because of technical limitations, and health care-associated infections are usually caused by clonal transmission of a single pathogen. In 2015, multiple species of carbapenem-resistant Enterobacteriaceae (CRE), all producing a rare carbapenemase, were identified among patients in an intensive care unit. This observation suggested a large, previously unrecognized plasmid transmission chain and prompted our investigation.

METHODS

Electronic medical record reviews, infection control observations, and environmental sampling completed the epidemiologic outbreak investigation. A laboratory analysis, conducted on patient and environmental isolates, included long-read whole-genome sequencing to fully elucidate plasmid DNA structures. Bioinformatics analyses were applied to infer plasmid transmission chains and results were subsequently confirmed using plasmid conjugation experiments.

RESULTS

We identified 14 Verona integron-encoded metallo-ß-lactamase (VIM)-producing CRE in 12 patients, and 1 additional isolate was obtained from a patient room sink drain. Whole-genome sequencing identified the horizontal transfer of blaVIM-1, a rare carbapenem resistance mechanism in the United States, via a promiscuous incompatibility group A/C2 plasmid that spread among 5 bacterial species isolated from patients and the environment.

CONCLUSIONS

This investigation represents the largest known outbreak of VIM-producing CRE in the United States to date, which comprises numerous bacterial species and strains. We present evidence of in-hospital plasmid transmission, as well as environmental contamination. Our findings demonstrate the potential for 2 types of hospital-acquired infection outbreaks: those due to clonal expansion and those due to the spread of conjugative plasmids encoding antibiotic resistance across species.

Regional Emergence of Candida auris in Chicago and Lessons Learned From Intensive Follow-up at 1 Ventilator-Capable Skilled Nursing Facility

BACKGROUND

Since the identification of the first 2 Candida auris cases in Chicago, Illinois, in 2016, ongoing spread has been documented in the Chicago area. We describe C. auris emergence in high-acuity, long-term healthcare facilities and present a case study of public health response to C. auris and carbapenemase-producing organisms (CPOs) at one ventilator-capable skilled nursing facility (vSNF-A).

METHODS

We performed point prevalence surveys (PPSs) to identify patients colonized with C. auris and infection-control (IC) assessments and provided ongoing support for IC improvements in Illinois acute- and long-term care facilities during August 2016-December 2018. During 2018, we initiated a focused effort at vSNF-A and conducted 7 C. auris PPSs; during 4 PPSs, we also performed CPO screening and environmental sampling.

RESULTS

During August 2016-December 2018 in Illinois, 490 individuals were found to be colonized or infected with C. auris. PPSs identified the highest prevalence of C. auris colonization in vSNF settings (prevalence, 23-71%). IC assessments in multiple vSNFs identified common challenges in core IC practices. Repeat PPSs at vSNF-A in 2018 identified increasing C. auris prevalence from 43% to 71%. Most residents screened during multiple PPSs remained persistently colonized with C. auris. Among 191 environmental samples collected, 39% were positive for C. auris, including samples from bedrails, windowsills, and shared patient-care items.

CONCLUSIONS

High burden in vSNFs along with persistent colonization of residents and environmental contamination point to the need for prioritizing IC interventions to control the spread of C. auris and CPOs.

918. Pilot Surveillance for Carbapenemase Gene-positive Organisms Among Hospitalized Solid Organ Transplant Recipients

Background

Carbapenemase gene-positive organisms (CPOs) are associated with infections with high mortality rates and have the potential to facilitate epidemic spread of carbapenem resistance. Passive reporting to CDC identified CPOs among organ transplant recipients, potentially representing an emerging reservoir for spread. We aimed to determine the prevalence of CPOs in hospital units where solid organ transplant (SOT) recipients receive care in order to inform public health action to prevent transmission.

Methods

All healthcare facilities identified one medical unit where SOT recipients received inpatient care and conducted point prevalence surveys (PPS) of all consenting patients on 1-2 designated calendar days. We used the Cepheid Xpert^® Carba-R assay to identify carbapenemase genes (bla_KPC, bla_NDM, bla_VIM, bla_IMP, bla_OXA-48) from rectal swabs; carbapenemase-positive swabs were cultured for organisms. All laboratory testing was conducted at the Wadsworth Center, part of CDC’s Antibiotic Resistance Laboratory Network.

Results

Five participating hospitals performed nine PPS from September 2019 through June 2020. In total, 154 patients were screened and 92 (60%) were SOT recipients (Table). The most common transplanted organs were kidney (44, 48%) and liver (39, 42%). Carbapenemase genes were detected among 5 (5%) SOT recipients, all from a single healthcare facility; 4 (80%) were bla_KPC and 1 (20%) was bla_NDM. Of the positive specimens cultured, bla_KPC was carried by Enterobacter cloacae complex (ECC), Klebsiella pneumoniae, and Klebsiella oxytoca and bla_NDM was carried by K. oxytoca; bla_KPC was carried by both ECC and K. pneumoniae in a single individual. For SOT patients with CPOs, the median interval from transplantation to swab collection was 108 days (range: 12 to 323). CPOs were only detected in 1 (2%) of 62 non-transplant patients.

TABLE Characteristics of Carbapenemase Gene-positive Organism (CPO) Pilot Surveillance Participants

Conclusion

Among participating facilities, most did not identify CPOs among patients admitted to transplant units. These findings represent a small number of patients and facilities; additional PPS in areas with varied CPO epidemiology are needed to understand whether SOT recipients should be routinely screened for CPOs.

Disclosures

All Authors: No reported disclosures

868. Investigations of Healthcare-Associated Elizabethkingia Infections – United States, 2013-2019

Background

Elizabethkingia (EK) are non-motile gram-negative rods found in soil and water and are an emerging cause of healthcare-associated infections (HAIs). We describe Centers for Disease Control and Prevention (CDC) consultations for healthcare-associated EK infections and outbreaks.

Methods

CDC maintains records of consultations with state or local health departments related to HAI outbreaks and infection control breaches. We reviewed consultations involving EK species as the primary pathogen of concern January 1, 2013 to December 31, 2019 and summarized data on healthcare settings, infection types, laboratory analysis, and control measures.

Results

We identified 9 consultations among 8 states involving 73 patient infections. Long-term acute-care hospitals (LTACHs) accounted for 4 consultations and 32 (43%) infections, and skilled nursing facilities with ventilated patients (VSNFs) accounted for 2 consultations and 31 (42%) infections. Other settings included an acute care hospital, an assisted living facility, and an outpatient ear, nose, and throat clinic.

Culture sites included the respiratory tract (n=7 consultations), blood (n=4), and sinus tract (n=1), and E. anophelis was the most commonly identified species. Six consultations utilized whole genome sequencing (WGS); 4 identified closely related isolates from different patients and 2 also identified closely related environmental and patient isolates.

Mitigation measures included efforts to reduce EK in facility water systems, such as the development of water management plans, consulting water management specialists, flushing water outlets, and monitoring water quality, as well as efforts to minimize patient exposure such as cleaning of shower facilities and equipment, storage of respiratory therapy supplies away from water sources, and use of splash guards on sinks.

Conclusion

EK is an important emerging pathogen that causes HAI outbreaks, particularly among chronically ventilated patients. LTACHs and VSNFs accounted for the majority of EK consultations and patient infections. Robust water management plans and infection control practices to minimize patient exposure to contaminated water in these settings are important measures to reduce infection risk among vulnerable patients.

Disclosures

All Authors: No reported disclosures

Investigation of Hospital-Onset Methicillin-Resistant Staphylococcus aureus Bloodstream Infections at Eight High Burden Acute Care Facilities in the United States, 2016

BACKGROUND

Despite large reductions from 2005-2012, hospital-onset methicillin-resistant Staphylococcus aureus bloodstream infections (HO MRSA BSIs) continue be a major source of morbidity and mortality.

AIM

To describe risk factors for and underlying sources of HO MRSA BSIs.

METHODS

We investigated HO MRSA BSIs at eight high-burden short-stay acute care hospitals. A case was defined as first isolation of MRSA from a blood specimen collected in 2016 on hospital day ≥4 from a patient without an MRSA-positive blood culture in the 14 days prior. We reviewed case-patient demographics and risk factors by medical record abstraction. The potential clinical source(s) of infection were determined by consensus by a clinician panel.

FINDINGS

Of the 195 eligible cases, 186 were investigated. Case-patients were predominantly male (63%); median age was 57 years (range 0-92). In the two weeks prior to the BSI, 88% of case-patients had indwelling devices, 31% underwent a surgical procedure, and 18% underwent dialysis. The most common locations of attribution were intensive care units (ICUs) (46%) and step-down units (19%). The most commonly identified non-mutually exclusive clinical sources were CVCs (46%), non-surgical wounds (17%), surgical site infections (16%), non-ventilator healthcare-associated pneumonia (13%), and ventilator-associated pneumonia (11%).

CONCLUSIONS

Device-and procedure-related infections were common sources of HO MRSA BSIs. Prevention strategies focused on improving adherence to existing prevention bundles for device-and procedure-associated infections and on source control for ICU patients, patients with certain indwelling devices, and patients undergoing certain high-risk surgeries are being pursued to decrease HO MRSA BSI burden at these facilities.

Carbapenem-Resistant Pseudomonas aeruginosa at US Emerging Infections Program Sites, 2015

Pseudomonas aeruginosa is intrinsically resistant to many antimicrobial drugs, making carbapenems crucial in clinical management. During July–October 2015 in the United States, we piloted laboratory-based surveillance for carbapenem-resistant P. aeruginosa (CRPA) at sentinel facilities in Georgia, New Mexico, Oregon, and Tennessee, and population-based surveillance in Monroe County, NY. An incident case was the first P. aeruginosa isolate resistant to antipseudomonal carbapenems from a patient in a 30-day period from any source except the nares, rectum or perirectal area, or feces. We found 294 incident cases among 274 patients. Cases were most commonly identified from respiratory sites (120/294; 40.8%) and urine (111/294; 37.8%); most (223/280; 79.6%) occurred in patients with healthcare facility inpatient stays in the prior year. Genes encoding carbapenemases were identified in 3 (2.3%) of 129 isolates tested. The burden of CRPA was high at facilities under surveillance, but carbapenemase-producing CRPA were rare.

Transmission of Mobile Colistin Resistance (mcr-1) by Duodenoscope

BACKGROUND

Clinicians increasingly utilize polymyxins for treatment of serious infections caused by multidrug-resistant gram-negative bacteria. Emergence of plasmid-mediated, mobile colistin resistance genes creates potential for rapid spread of polymyxin resistance. We investigated the possible transmission of Klebsiella pneumoniae carrying mcr-1 via duodenoscope and report the first documented healthcare transmission of mcr-1-harboring bacteria in the United States.

METHODS

A field investigation, including screening targeted high-risk groups, evaluation of the duodenoscope, and genome sequencing of isolated organisms, was conducted. The study site included a tertiary care academic health center in Boston, Massachusetts, and extended to community locations in New England.

RESULTS

Two patients had highly related mcr-1-positive K. pneumoniae isolated from clinical cultures; a duodenoscope was the only identified epidemiological link. Screening tests for mcr-1 in 20 healthcare contacts and 2 household contacts were negative. Klebsiella pneumoniae and Escherichia coli were recovered from the duodenoscope; neither carried mcr-1. Evaluation of the duodenoscope identified intrusion of biomaterial under the sealed distal cap; devices were recalled to repair this defect.

CONCLUSIONS

We identified transmission of mcr-1 in a United States acute care hospital that likely occurred via duodenoscope despite no identifiable breaches in reprocessing or infection control practices. Duodenoscope design flaws leading to transmission of multidrug-resistant organsisms persist despite recent initiatives to improve device safety. Reliable detection of colistin resistance is currently challenging for clinical laboratories, particularly given the absence of a US Food and Drug Administration-cleared test; improved clinical laboratory capacity for colistin susceptibility testing is needed to prevent the spread of mcr-carrying bacteria in healthcare settings.

923. Rapid Emergence of Candida auris in the Chicago Region

Background

Methods

Results

Conclusion

Disclosures

1254. Outbreak of Mycobacterium chelonae Skin Infections Associated With Human Chorionic Gonadotropin Injections at Weight Loss Clinics

Background

In December 2016, a dermatologist notified the Minnesota Department of Health (MDH) of three patients with skin lesions after self-administration of human chorionic gonadotropin (HCG) injections supplied by same weight loss clinic chain (Chain X); one lesion had been diagnosed as a nontuberculous mycobacteria (NTM) infection. We investigated to identify the etiology, determine contributing transmission factors, and to prevent additional cases.

Methods

We defined a case as a skin or soft tissue lesion with a suspected infectious etiology in a Minnesota resident occurring within three months after HCG injection at or near an injection site. To find cases we sent health alerts to clinicians and clinical laboratories throughout Minnesota with diagnostic guidance, and we requested Chain X to notify all exposed patients. We visited two Chain X clinics to assess infection control practices, to collect invoices for product traceback, and to collect products for microbiological testing. All NTM isolates were identified by line probe assay and subtyped by pulsed-field gel electrophoresis (PFGE) at MDH.

Results

We identified six cases with illness onset dates ranging from April to November 2016. All patients were adult women who did not share HCG vials. Four patients had clinical specimens that grew NTM; all isolates were identified as Mycobacterium chelonae that were indistinguishable by PFGE. Three patients with confirmed M. chelonae infection obtained HCG at Clinic A, and one from Clinic B, but sharing of reconstituted HCG by the two clinics could not be excluded. We identified several infection control breaches at both clinics including improper reconstitution of HCG and incorrect use of single use vials. The most likely source of the HCG was an unregistered out-of-state compounding pharmacy.

Conclusion

This common source outbreak was likely due to contamination introduced either at a weight loss clinic or a compounding pharmacy. HCG injections are not US FDA-approved for weight loss, and their use may involve compounded products dispensed by alternative care settings that lack infection control expertise and regulatory oversight. This outbreak highlights the important role physician reporting of disease clusters plays in uncovering unsafe practices.

Disclosures

All authors: No reported disclosures.

1162. Epidemiology of Carbapenem-Resistant Pseudomonas aeruginosa Identified Through the Emerging Infections Program (EIP), United States, 2016–2017

Background

Pseudomonas aeruginosa is intrinsically resistant to many commonly used antimicrobials and carbapenems are often required to treat infections. We describe the epidemiology and crude incidence of carbapenem-resistant P. aeruginosa(CRPA) in the EIP catchment area.

Methods

From August 1, 2016 through July 31, 2017, we conducted laboratory- and population-based surveillance for CRPA in selected metropolitan areas in Colorado, Georgia, Maryland, Minnesota, New Mexico, New York, Oregon, and Tennessee. We defined an incident case as the first isolate of P. aeruginosa-resistant to imipenem, meropenem, or doripenem from the lower respiratory tract, urine, wounds, or normally sterile sites identified from a resident of the EIP catchment area in a 30-day period. Patient charts were reviewed. A random sample of isolates was screened at CDC for carbapenemases using the modified carbapenem inactivation method (mCIM) and real-time PCR.

Results

During the 12-month period, we identified 3,042 incident cases among 2,154 patients. The crude incidence rate was 21.2 (95% CI, 20.4–21.9) per 100,000 persons and varied by site (range: 7.7 in Oregon to 31.1 in Maryland). The median age of patients was 64 years (range: <1–101) and 41.2% were female. Nearly all (97.1%) had at least one underlying condition and 10.2% had cystic fibrosis (CF); 17.8% of cases were from CF patients. For most cases, isolates were from the lower respiratory tract (49.2%) or urine (35.3%) and occurred in patients with recent hospitalization (87.2%) or indwelling devices (70.3%); 8.7% died. At the clinical laboratory, 84.7% of isolates were susceptible to an aminoglycoside and 66.4% to ceftazidime or cefepime. Among the 391 isolates tested, nine (2.3%) were mCIM-positive; one had a carbapenemase detected by PCR (bla_VIM-4).

Conclusion

The burden of CRPA varied by EIP site. Most cases occurred in persons with healthcare exposures and underlying conditions. The majority of isolates were susceptible to at least one first-line antimicrobial. Carbapenemase producers were rare; a more specific phenotypic definition would greatly facilitate surveillance for these isolates.

Disclosures

All authors: No reported disclosures.

Circumcision status at HIV infection is not associated with plasma viral load in men: analysis of specimens from a randomized controlled trial

BACKGROUND

Male circumcision provides men with approximately 60% protection from acquiring HIV infection via heterosexual sex, and has become a key component of HIV prevention efforts in sub-Saharan Africa. Possible mechanisms for this protection include removal of the inflammatory anaerobic sub-preputial environment and the high concentration of Langerhans cells on the inside of the foreskin, both believed to promote local vulnerability to HIV infection. In people who do acquire HIV, viral load is partially determined by infecting partner viral load, potentially mediated by size of infecting inoculum. By removing a portal for virion entry, prior male circumcision could decrease infecting inoculum and thus viral load in men who become HIV-infected, conferring the known associated benefits of slower progression to disease and decreased infectiousness.

METHODS

We performed an as-treated analysis of plasma samples collected under a randomized controlled trial of male circumcision for HIV prevention, comparing men based on their circumcision status at the time of HIV acquisition, to determine whether circumcision is associated with lower viral load. Eligible men were seroconverters who had at least one plasma sample available drawn at least 6 months after infection, reported no potential exposures other than vaginal sex and, for those who were circumcised, were infected more than 6 weeks after circumcision, to eliminate the open wound as a confounder. Initial viral load testing indicated that quality of pre-2007 samples might have been compromised during storage and they were excluded, as were those with undetectable or unquantifiable results. Log viral loads were compared between groups using univariable and multivariable linear regression, adjusting for sample age and sexually transmitted infection diagnosis with 3.5 months of seroconversion, with a random effect for intra-individual clustering for samples from the same man. A per-protocol analysis was also performed.

RESULTS

There were no viral load differences between men who were circumcised and uncircumcised at the time of HIV infection (means 4.00 and 4.03 log₁₀ copies/mL respectively, p = .88) in any analysis.

CONCLUSION

Circumcision status at the time of HIV infection does not affect viral load in men.

TRIAL REGISTRATION

The original RCT which provided the samples was ClinicalTrials.gov trial NCT00059371 .

Vital Signs: Containment of Novel Multidrug-Resistant Organisms and Resistance Mechanisms - United States, 2006-2017

BACKGROUND

Approaches to controlling emerging antibiotic resistance in health care settings have evolved over time. When resistance to broad-spectrum antimicrobials mediated by extended-spectrum β-lactamases (ESBLs) arose in the 1980s, targeted interventions to slow spread were not widely promoted. However, when Enterobacteriaceae with carbapenemases that confer resistance to carbapenem antibiotics emerged, directed control efforts were recommended. These distinct approaches could have resulted in differences in spread of these two pathogens. CDC evaluated these possible changes along with initial findings of an enhanced antibiotic resistance detection and control strategy that builds on interventions developed to control carbapenem resistance.

METHODS

Infection data from the National Healthcare Safety Network from 2006-2015 were analyzed to calculate changes in the annual proportion of selected pathogens that were nonsusceptible to extended-spectrum cephalosporins (ESBL phenotype) or resistant to carbapenems (carbapenem-resistant Enterobacteriaceae [CRE]). Testing results for CRE and carbapenem-resistant Pseudomonas aeruginosa (CRPA) are also reported.

RESULTS

The percentage of ESBL phenotype Enterobacteriaceae decreased by 2% per year (risk ratio [RR] = 0.98, p<0.001); by comparison, the CRE percentage decreased by 15% per year (RR = 0.85, p<0.01). From January to September 2017, carbapenemase testing was performed for 4,442 CRE and 1,334 CRPA isolates; 32% and 1.9%, respectively, were carbapenemase producers. In response, 1,489 screening tests were performed to identify asymptomatic carriers; 171 (11%) were positive.

CONCLUSIONS

The proportion of Enterobacteriaceae infections that were CRE remained lower and decreased more over time than the proportion that were ESBL phenotype. This difference might be explained by the more directed control efforts implemented to slow transmission of CRE than those applied for ESBL-producing strains. Increased detection and aggressive early response to emerging antibiotic resistance threats have the potential to slow further spread.

Investigation of a Contaminated, Nationally Distributed, Organ Transplant Preservation Solution — United States, 2016–2017

Background

In December 2016, bacterial contamination of an organ preservation solution (OPS) was reported by Transplant Center A in Iowa. Annually, >20,000 abdominal organs are transplanted in the United States; OPS is used for organ storage. We investigated the scope of OPS contamination and its association with adverse events in patients.

Methods

We assessed infection control practices related to OPS at Transplant Centers A and B in Iowa and the local organ procurement organization (OPO). We issued national notifications about OPS contamination and requested transplant centers to report product-related concerns or potential patient harm. Among transplant recipients at Center A, we compared adverse events (fever, bacteremia, surgical site infection, peritonitis, or pyelonephritis within 14 days of transplantation) during October–December 2015 with October–December 2016, the presumed window of exposure to contaminated OPS. Isolates from OPS were characterized.

Results

No infection control deficiencies were identified at Transplant Centers A, B, or the OPO. In January 2017, contaminated OPS from the same manufacturer was reported by Transplant Center C in Texas. Nationally, there were no reports of patient harm definitively linked to OPS. Post-transplant adverse events at Center A did not increase between fourth quarter 2015 (5/12 [42%]) and 2016 (2/15 [13%]). Organisms recovered from OPS included Pantoea agglomerans and Enterococcus gallinarum (Center A) and Pseudomonas koreensis (Center C). Five Pantoea isolates from ≥3 opened OPS bags were indistinguishable by pulsed-field gel electrophoresis. The OPS distributor issued recalls and suspended production. The US Food and Drug Administration identified deficiencies in current good manufacturing practices at manufacturing and distribution facilities, including inadequate validation of OPS sterility.

Conclusion

Bacterial contamination of a nationally distributed product was identified by astute clinicians. The investigation found no illnesses were directly linked to the product. Prompt reporting of concerns about potentially contaminated healthcare products, which might put patients at risk, is critical for swift public health action.

Disclosures

All authors: No reported disclosures.

Investigation of Escherichia coli Harboring the mcr-1 Resistance Gene - Connecticut, 2016

The mcr-1 gene confers resistance to the polymyxins, including the antibiotic colistin, a medication of last resort for multidrug-resistant infections. The mcr-1 gene was first reported in 2015 in food, animal, and patient isolates from China (1) and is notable for being the first plasmid-mediated colistin resistance mechanism to be identified. Plasmids can be transferred between bacteria, potentially spreading the resistance gene to other bacterial species. Since its discovery, the mcr-1 gene has been reported from Africa, Asia, Europe, South America, and North America (2,3), including the United States, where it has been identified in Escherichia coli isolated from three patients and from two intestinal samples from pigs (2,4-6). In July 2016, the Pathogen Detection System at the National Center for Biotechnology Information (Bethesda, Maryland) identified mcr-1 in the whole genome sequence of an E. coli isolate from a Connecticut patient (7); this is the fourth isolate from a U.S. patient to contain the mcr-1 gene.

Outbreaks of Salmonellosis From Small Turtles

OBJECTIVE

Turtle-associated salmonellosis (TAS), especially in children, is a reemerging public health issue. In 1975, small pet turtles (shell length <4 inches) sales were banned by federal law; reductions in pediatric TAS followed. Since 2006, the number of multistate TAS outbreaks has increased. We describe 8 multistate outbreaks with illness-onset dates occurring in 2011-2013.

METHODS

We conducted epidemiologic, environmental, and traceback investigations. Cases were defined as infection with ≥ 1 of 10 molecular subtypes of Salmonella Sandiego, Pomona, Poona, Typhimurium, and I 4,[5],12:i:-. Water samples from turtle habitats linked to human illnesses were cultured for Salmonella.

RESULTS

We identified 8 outbreaks totaling 473 cases from 41 states, Washington DC, and Puerto Rico with illness onsets during May 2011-September 2013. The median patient age was 4 years (range: 1 month-94 years); 45% percent were Hispanic; and 28% were hospitalized. In the week preceding illness, 68% (187 of 273) of case-patients reported turtle exposure; among these, 88% (124 of 141) described small turtles. Outbreak strains were isolated from turtle habitats linked to human illnesses in seven outbreaks. Traceback investigations identified 2 Louisiana turtle farms as the source of small turtles linked to 1 outbreak; 1 outbreak strain was isolated from turtle pond water from 1 turtle farm.

CONCLUSIONS

Eight multistate outbreaks associated with small turtles were investigated during 2011-2013. Children <5 years and Hispanics were disproportionately affected. Prevention efforts should focus on patient education targeting families with young children and Hispanics and enactment of state and local regulations to complement federal sales restrictions.

Vancomycin-Resistant Staphylococcus aureus - Delaware, 2015

Vancomycin-resistant Staphylococcus aureus (VRSA) is a rare, multidrug-resistant bacterium of public health concern that emerged in the United States in 2002. VRSA (S. aureus with vancomycin minimum inhibitory concentration [MIC] ≥16 μg/mL) arises when vancomycin resistance genes (e.g., the vanA operon, which codes for enzymes that result in modification or elimination of the vancomycin binding site) from vancomycin-resistant enterococci (VRE) are transferred to S. aureus (1). To date, all VRSA strains have arisen from methicillin-resistant S. aureus (MRSA). The fourteenth VRSA isolate (VRSA 14) identified in the United States was reported to CDC in February 2015.

A Qualitative Inquiry About Pruno, an Illicit Alcoholic Beverage Linked to Botulism Outbreaks in United States Prisons

OBJECTIVES

Since 2011, 3 outbreaks of botulism in US prisons have been attributed to pruno, which is an alcoholic beverage made by inmates. Following 1 outbreak, we conducted a qualitative inquiry to understand pruno brewing and its social context to inform outbreak prevention measures.

METHODS

We interviewed staff, inmates, and parolees from 1 prison about pruno production methods, the social aspects of pruno, and strategies for communicating the association between botulism and pruno.

RESULTS

Twenty-seven inmates and parolees and 13 staff completed interviews. Pruno is fermented from water, fruit, sugar, and miscellaneous ingredients. Knowledge of pruno making was widespread among inmates; staff were familiar with only the most common ingredients and supplies inmates described. Staff and inmates described inconsistent consequences for pruno possession and suggested using graphic health messages from organizations external to the prison to communicate the risk of botulism from pruno.

CONCLUSIONS

Pruno making was frequent in this prison. Improved staff recognition of pruno ingredients and supplies might improve detection of brewing activities in this and other prisons. Consistent consequences and clear messages about the association between pruno and botulism might prevent outbreaks.

Shifts in geographic distribution and antimicrobial resistance during a prolonged typhoid fever outbreak--Bundibugyo and Kasese Districts, Uganda, 2009-2011

Background

Salmonella enterica serovar Typhi is transmitted by fecally contaminated food and water and causes approximately 22 million typhoid fever infections worldwide each year. Most cases occur in developing countries, where approximately 4% of patients develop intestinal perforation (IP). In Kasese District, Uganda, a typhoid fever outbreak notable for a high IP rate began in 2008. We report that this outbreak continued through 2011, when it spread to the neighboring district of Bundibugyo.

Methodology/Principal Findings

A suspected typhoid fever case was defined as IP or symptoms of fever, abdominal pain, and ≥1 of the following: gastrointestinal disruptions, body weakness, joint pain, headache, clinically suspected IP, or non-responsiveness to antimalarial medications. Cases were identified retrospectively via medical record reviews and prospectively through laboratory-enhanced case finding. Among Kasese residents, 709 cases were identified from August 1, 2009–December 31, 2011; of these, 149 were identified during the prospective period beginning November 1, 2011. Among Bundibugyo residents, 333 cases were identified from January 1–December 31, 2011, including 128 cases identified during the prospective period beginning October 28, 2011. IP was reported for 507 (82%) and 59 (20%) of Kasese and Bundibugyo cases, respectively. Blood and stool cultures performed for 154 patients during the prospective period yielded isolates from 24 (16%) patients. Three pulsed-field gel electrophoresis pattern combinations, including one observed in a Kasese isolate in 2009, were shared among Kasese and Bundibugyo isolates. Antimicrobial susceptibility was assessed for 18 isolates; among these 15 (83%) were multidrug-resistant (MDR), compared to 5% of 2009 isolates.

Conclusions/Significance

Molecular and epidemiological evidence suggest that during a prolonged outbreak, typhoid spread from Kasese to Bundibugyo. MDR strains became prevalent. Lasting interventions, such as typhoid vaccination and improvements in drinking water infrastructure, should be considered to minimize the risk of prolonged outbreaks in the future.

Typhoid fever is an acute febrile illness caused by the bacteria Salmonella Typhi and transmitted through food and water contaminated with the feces of typhoid fever patients or carriers. We investigated typhoid fever outbreaks in two neighboring Ugandan districts, Kasese and Bundibugyo, where typhoid fever outbreaks began in 2008 and 2011, respectively. In Kasese from August 2009–December 2011, we documented 709 cases of typhoid fever. In Bundibugyo from January–December 2011, we documented 333 cases. Salmonella Typhi from Bundibugyo and Kasese had indistinguishable molecular fingerprints; laboratory and epidemiological evidence indicate that the outbreak spread from Kasese to Bundibugyo. Salmonella Typhi isolated during our investigation were resistant to more antibiotics than isolates obtained from Kasese in 2009. Drinking water in both districts was fecally contaminated and the likely vehicle for the outbreaks. Our investigation highlights that in unchecked typhoid fever outbreaks, illness can become geographically dispersed and outbreak strains can become increasingly resistant to antibiotics. Lasting interventions, including investments in drinking water infrastructure and typhoid vaccination, are needed to control these outbreaks and prevent future outbreaks.

Herpesvirus saimiri open reading frame 50 (Rta) protein reactivates the lytic replication cycle in a persistently infected A549 cell line

Herpesviruses occur in two distinct forms of infection, lytic replication and latent persistence. In this study, we investigated the molecular mechanisms that govern the latent-lytic switch in the prototype gamma-2 herpesvirus, herpesvirus saimiri (HVS). We utilized a persistently HVS-infected A549 cell line, in which HVS DNA is stably maintained as nonintegrated circular episomes, to assess the role of the open reading frame 50 (ORF 50) (Rta) proteins in the latent-lytic switch. Northern blot analysis and virus recovery assays determined that the ORF 50a gene product, when expressed under the control of a constitutively active promoter, was sufficient to reactivate the entire lytic replication cycle, producing infectious virus particles. Furthermore, although the ORF 50 proteins of HVS strains A11 and C488 are structurally divergent, they were both capable of inducing the lytic replication cycle in this model of HVS latency.

Meiosis readiness in Lilium

It was observed in five cultivars and two hybrids of Lilium that premeiotic prophase is retarded in anthers approaching meiosis. The occurrence of premeiotic despiralization was related to the degree of retardation of premeiotic prophase. It is proposed that meiosis is initiated by stimuli arising outside the premeiotic cells. It is suggested that an accumulation of meiosis-inducing substances in the cytoplasm of the premeiotic cells causes prophase to slow down; when a critical level ("meiosis readiness") is reached, mitotic division is no longer possible and cells in premeiotic prophase despiralize to interphase.