Spread of methicillin-resistant Staphylococcus aureus in a large tertiary NICU: network analysis

Impact of active surveillance and decolonization strategies for methicillin-resistant Staphylococcus aureus in a neonatal intensive care unit

OBJECTIVE

To assess the impact of active surveillance and decolonization strategies on methicillin-resistant Staphylococcus aureus (MRSA) infection rates in a NICU.

STUDY DESIGN

MRSA infection rates were compared before (2014-2016) and during (2017-2022) an active surveillance program. Eligible infants were decolonized with chlorohexidine gluconate (CHG) bathing and/or topical mupirocin. Successful decolonization and rates of recolonization were assessed.

RESULTS

Fifty-two (0.57%) of 9 100 hospitalized infants had invasive MRSA infections from 2014 to 2022; infection rates declined non-significantly. During the 6-year surveillance program, the risk of infection was 16.9-times [CI95 8.4, 34.1] higher in colonized infants than uncolonized infants. Those colonized with mupirocin-susceptible MRSA were more likely successfully decolonized (aOR 9.7 [CI95 4.2, 22.5]). Of 57 infants successfully decolonized who remained hospitalized, 34 (60%) became recolonized.

CONCLUSIONS

MRSA infection rates did not significantly decline in association with an active surveillance and decolonization program. Alternatives to mupirocin and CHG are needed to facilitate decolonization.

Methicillin-Resistant Staphylococcus aureus Carriage among Neonate Mothers, Healthcare Workers, and Environmental Samples in Neonatal Intensive Care Units: A Systematic Review

Background

Methicillin-resistant Staphylococcus aureus (MRSA) is a significant cause of morbidity and mortality among neonates admitted to neonatal intensive care units (NICUs). The MRSA colonization of neonates, attributed to various sources, including mothers, healthcare workers, and environmental surfaces, can lead to severe infection, prolonged hospital stays, and even death, imposing substantial economic burdens. Given the pressing need to mitigate MRSA spread in these vulnerable environments, further examination of the subject is warranted. This systematic review is aimed at synthesizing available evidence on MRSA carriage proportions among mothers of newborns, healthcare workers, and environmental surfaces in NICUs. Methodology. We included observational studies published in English or French from database inception to March 21, 2023. These studies focused on MRSA in nonoutbreak NICU settings, encompassing healthy neonate mothers and healthcare workers, and environmental surfaces. Literature search involved systematic scanning of databases, including Medline, Embase, Web of Science, Global Health, and Global Index Medicus. The quality of the selected studies was assessed using the Hoy et al. critical appraisal scale. The extracted data were summarized to calculate the pooled proportion of MRSA positives, with a 95% confidence interval (CI) based on the DerSimonian and Laird random-effects model.

Results

A total of 1891 articles were retrieved from which 16 studies were selected for inclusion. Most of the studies were from high-income countries. The pooled proportion of MRSA carriage among 821 neonate mothers across four countries was found to be 2.1% (95% CI: 0.3-5.1; I2 = 76.6%, 95% CI: 36.1-91.5). The proportion of MRSA carriage among 909 HCWs in eight countries was determined to be 9.5% (95% CI: 3.1-18.4; I2 = 91.7%, 95% CI: 87.1-94.6). The proportion of MRSA carriage among HCWs was highest in the Western Pacific Region, at 50.00% (95% CI: 23.71-76.29). In environmental specimens from five countries, a pooled proportion of 16.6% (95% CI: 3.5-36.0; I2 = 97.7%, 95% CI: 96.6-98.4) was found to be MRSA-positive.

Conclusion

With a significant heterogeneity, our systematic review found high MRSA carriage rates in neonate mothers, healthcare workers, and across various environmental surfaces in NICUs, posing a potential risk of nosocomial infections. Urgent interventions, including regular screening and decolonization of MRSA carriers, reinforcing infection control measures, and enhancing cleaning and disinfection procedures within NICUs, are crucial. This trial is registered with CRD42023407114.

Healthcare worker perceptions surrounding Staphylococcus aureus transmission and prevention practices in the neonatal intensive care unit

OBJECTIVE

To understand healthcare worker (HCW) perceptions surrounding Staphylococcus aureus transmission and prevention in the neonatal intensive care unit (NICU).

DESIGN

Qualitative case study with focus groups.

SETTING

A level IV, 150-bed NICU at a Midwestern academic medical center that conducts active surveillance and decolonization of S. aureus-positive patients.

PARTICIPANTS

NICU HCWs, including bedside nurses, nurse managers, therapy services personnel, pediatric nurse practitioners, clinical fellows, and attending neonatologists.

METHODS

Semistructured focus group interviews, assembled by occupation, were conducted by 2 study team members. Interviews were video recorded and transcribed. Deductive coding and thematic analyses were performed using NVivo software.

RESULTS

In total, 38 HCWs participated in 10 focus groups (1-12 participants each), lasting 40-90 minutes. Four main themes emerged: (1) Methicillin-resistant S. aureus (MRSA) and methicillin-susceptible S. aureus (MSSA) are inconsistently described as high risk. (2) Infection prevention interventions are burdensome. (3) Multiple sources of transmission are recognized. (4) opportunities exist to advance infection prevention. HCWs perceived MSSA to be less clinically relevant than MRSA. Participants expressed a desire to see published data supporting infection prevention interventions, including contact precautions, environmental cleaning, and patient decolonization. These practices were identified to be considerable burdens. HCWs perceived families to be the main source of S. aureus in the NICU, and they suggested opportunities for families to play a larger role in infection prevention.

CONCLUSIONS

These data highlight opportunities for HCW and parental education, research, and reevaluating interventions aimed at improving infection prevention efforts to reduce the burden of S. aureus in NICU settings.

Methicillin-resistant Staphylococcus aureus nasal colonization in children with cerebral palsy

A retrospective cohort of children admitted to the pediatric intensive care unit (PICU) with cerebral palsy was matched 1:3 by age and admission year to determine odds of methicillin-resistant Staphylococcus aureus (MRSA) nasal colonization. Adjusted odds of MRSA nasal colonization at PICU admission were 2.6-fold higher among children with cerebral palsy.

Next Steps for Health Care-Associated Infections in the Neonatal Intensive Care Unit

We discuss the burden of health care-associated infections (HAIs) in the neonatal ICU and the role of quality improvement (QI) in infection prevention and control. We examine specific QI opportunities and approaches to prevent HAIs caused by Staphylococcus aureus , multidrug-resistant gram-negative pathogens, Candida species, and respiratory viruses, and to prevent central line-associated bloodstream infections (CLABSIs) and surgical site infections. We explore the emerging recognition that many hospital-onset bacteremia episodes are not CLABSIs. Finally, we describe the core tenets of QI, including engagement with multidisciplinary teams and families, data transparency, accountability, and the impact of larger collaborative efforts to reduce HAIs.

MRSA outbreak in a Neonatal Intensive Care Unit in a developed country: importance of rapid detection of reservoirs and implementation of intervention measures

We described a MRSA bloodstream infection outbreak that was rapidly identified and controlled in a Neonatal Intensive Care Unit after implementation of a bundle of measures, including PCR-screening and HCW decolonization. We found 35% of healthcare workers(HCW) colonized with S. aureus by PCR, one of them that presented skin lesion positive for MSSA (same clone and spa type than two patients). Our findings raise the hypothesis that the outbreak could be related to HCW colonization.

Risk factors for nosocomial methicillin resistant Staphylococcus aureus (MRSA) colonization in a neonatal intensive care unit: A Case-control study

AIM

To determine risk factors for MRSA colonization in a Level IV Neonatal Intensive Care Unit (NICU) independent of length of stay and gestational age in the context of a persistently circulating MRSA clone.

DESIGN

Retrospective matched case-control study.

SETTING

Level IV NICU PATIENTS: Infants admitted between April 4,2017- March 31,2018.

METHODS

Based on weekly surveillance cultures, infants who acquired MRSA were matched 1:1 with MRSA-negative control infants by duration of exposure (length of stay) and gestational age to determine risk factors for acquisition.

RESULTS

Fifty case infants were matched with controls. Isolates from 45 of the 50 cases were mupirocin-resistant and related by pulse-field gel electrophoresis. On matched univariable analysis, the following were significantly associated with a risk for MRSA acquisition: 1.Bed location in the acute area(P = 0.03), 2.Requirement of any level of respiratory support during the week prior to MRSA detection(P = 0.04), 3.Higher ATP pass rate (a measure of effectiveness of cleaning) during the week of and week prior(P = 0.01), 4.Higher MRSA colonization pressure during the week of and week prior(P< 0.0001), 5.Not having a hearing test during the time between the previous negative culture and MRSA acquisition(P = 0.01). A multivariable conditional logistic regression model (that excluded ATP pass rate) found that only colonization pressure was associated with acquisition of MRSA colonization.

CONCLUSIONS

In an outbreak setting, MRSA colonization pressure is significantly associated with MRSA acquisition in the NICU independent of length of stay and gestational age.

Randomized Placebo-Controlled Trial of Topical Mupirocin to Reduce Staphylococcus aureus Colonization in Infants in the Neonatal Intensive Care Unit

OBJECTIVE

To evaluate the efficacy of topical mupirocin in reducing Staphylococcus aureus colonization in infants in the neonatal intensive care unit (NICU).

STUDY DESIGN

A prospective double-blind randomized controlled trial of mupirocin vs placebo in S aureus-colonized infants was conducted in a tertiary care NICU between October 2016 and December 2019. Weekly universal active surveillance with polymerase chain reaction screening identified colonized infants. Colonized infants received a 5-day course of mupirocin (mupirocin group) or petroleum jelly (control group). Repeat courses were given for additional positive screens.

RESULTS

A total of 216 infants were enrolled; 205 were included in data analyses. Primary decolonization was more successful for mupirocin-treated infants (86 of 104 [83%]) than for controls (20 of 101; 20%) (P < .001). Although recurrent S aureus colonization occurred frequently (59 of 81 [73%] mupirocin-treated and 26 of 33 [79%] controls), subsequent decolonization remained more successful for mupirocin-treated infants than for controls (38 of 49 [78%] vs 2 of 21 [10%]; P < .001). Subgroup analyses of infants of ≤30 weeks' gestational age yielded similar results; decolonization occurred more often in mupirocin-treated infants compared with control infants (63 of 76 [83%] vs 13 of 74 [18%]; P < .001). Bacterial sterile site infections tended to be less frequent in mupirocin-treated infants compared with controls (2 of 104 [2%] vs 8 of 101 [8%]; P = .057). No invasive S aureus infections occurred in mupirocin-treated infants, but 50% of infections in controls were from S aureus, and 1 resulted in death.

CONCLUSIONS

Universal active surveillance and targeted treatment with topical mupirocin is a successful decolonization strategy for NICU infants and may prevent S aureus infection. However, S aureus colonization frequently recurs, necessitating repeat treatment.

TRIAL REGISTRATION

Clinicaltrials.gov: NCT02967432.

Prevalence of MRSA nasal carriage among pregnant women in Copenhagen

Background

Methicillin resistant Staphylococcus aureus (MRSA) frequently causes outbreaks in neonatal intensive care units (NICUs). It is believed that MRSA predominantly enters the NICU with MRSA colonized parents. In Denmark, 27 MRSA NICU outbreaks have been registered between 2008 and 2019.

Aim

The aim of this study was to determine the prevalence of MRSA nasal carriage in pregnant women in Copenhagen and to clarify if MRSA screening during pregnancy could add to the prevention of NICU outbreaks.

Methods

All pregnant women 18 years or older were offered MRSA nasal screening at their first midwife visit between 13 and 20 weeks of gestation.

Results

1778 pregnant women were included, two (0.11%) carried MRSA in the nose.

Conclusion

Infants of the two MRSA positive women were not admitted to a NICU and therefore the screening had no impact on NICU outbreaks. The low prevalence of MRSA found in this study does not justify MRSA screening of all pregnant women in Denmark.

Evaluation of nosocomial infections through contact patterns in a small animal hospital using social network analysis and genotyping techniques

Nosocomial infections or hospital-acquired infections (HAIs) are common health problems affecting patients in human and animal hospitals. Herein, we hypothesised that HAIs could be spread through human and animal movement, contact with veterinary medical supplies, equipment, or instruments. We used a combination of social network analysis and genotyping techniques to find key players (or key nodes) and spread patterns using Escherichia coli as a marker. This study was implemented in the critical care unit, outpatient department, operation room, and ward of a small animal hospital. We conducted an observational study used for key player determination (or key node identification), then observed the selected key nodes twice with a one-month interval. Next, surface swabs of key nodes and their connecting nodes were analysed using bacterial identification, matrix-assisted laser desorption/ionisation-time of flight mass spectrometry, and pulsed-field gel electrophoresis. Altogether, our results showed that veterinarians were key players in this contact network in all departments. We found two predominant similarity clusters; dendrogram results suggested E. coli isolates from different time points and places to be closely related, providing evidence of HAI circulation within and across hospital departments. This study could aid in limiting the spread of HAIs in veterinary and human hospitals.

Borderline oxacillin-resistant Staphylococcus aureus carriage among healthcare workers at neonatal intensive care unit and paediatric ward

BACKGROUND

During a meticillin-resistant Staphylococcus aureus contact tracing and screening investigation, two borderline oxacillin-resistant Staphylococcus aureus (BORSA)-positive screening cultures were encountered among neonatal intensive care unit (NICU) healthcare workers (HCWs). This finding led to further investigations.

AIM

To assess the likelihood of an outbreak with direct transmission among HCWs.

METHODS

An infection control team was initiated after the discovery. The team initiated additional infection control measures and evaluated new findings. All NICUs and paediatric ward HCWs were screened for BORSA carriage, and a prospective BORSA seven-week monitoring period for patients was observed. To assess the likelihood of an outbreak with direct transmission among HCWs, the BORSA isolates were analysed using augmented fragment length polymorphism and whole-genome sequencing (WGS).

FINDINGS

Positive HCWs were prohibited from clinical work while awaiting the results from the screening programme. In all, 127 NICU and 77 general paediatric ward HCWs were screened for BORSA carriage; five HCWs were BORSA positive. Seventy-two patients were screened during the seven-week period yielding a total of 138 cultures, ranging from one to nine cultures per patient. No spread from HCWs to patients occurred, and the BORSA screening programme was discontinued. WGS analysis with core genome multi-locus sequence typing of all five BORSA strains showed relatedness between two NICU strains.

CONCLUSION

During a seven-week period, no transmission from BORSA-positive HCWs to neonates was observed in either screening or clinical cultures. More vigilance and experience is needed to design adequate evidence-based interventions in the future for this vulnerable population.

Effect of Contact Precautions on Staphylococcus aureus and Clinical Outcomes of Colonized Patients in the Neonatal Intensive Care Unit

BACKGROUND

Staphylococcus aureus is a common pathogen in neonatal intensive care units (NICUs), yet little is known about the effect of contact precautions and clinical outcomes of colonized patients.

METHODS

Retrospective cohort study of all neonates from August 2014 to November 2018 colonized with either methicillin-resistant S. aureus (MRSA) or methicillin-susceptible S. aureus (MSSA) and select noncolonized patients at two neonatal intensive care units at the University of California, Los Angeles. Outcomes during two time periods (during and after the use of contact precautions) were assessed.

RESULTS

A total of 234 patients were included in the study: 83 colonized and 151 noncolonized patients. There was a fourfold higher incidence of MSSA colonization versus MRSA (P < 0.001). There was a higher incidence of positive surveillance cultures after contact precautions were discontinued (P = 0.01), but this did not correlate with a higher incidence of invasive cultures (P = 0.475). There were twice as many MSSA invasive cultures than MRSA, but a higher rate of invasion with MRSA (P < 0.05). Colonized patients were more likely to develop an invasive infection than noncolonized (P = 0.003 MRSA; P = 0.004 MSSA). When controlling for gestational age and surgical interventions, colonization was more likely to be associated with skin and soft tissue infections (P < 0.001) and a longer length of stay by a mean of 27.8 days (P < 0.0001).

CONCLUSIONS

Contact precautions resulted in a lower incidence of colonization without a difference in invasive cultures in our NICUs. Those colonized with S. aureus had a higher incidence of skin and soft tissue infections and a longer NICU length of stay.

The Role of Healthcare Worker-Mediated Contact Networks in the Transmission of Vancomycin-Resistant Enterococci

BACKGROUND

User- and time-stamped data from hospital electronic health records (EHRs) present opportunities to evaluate how healthcare worker (HCW)-mediated contact networks impact transmission of multidrug-resistant pathogens, such as vancomycin-resistant enterococci (VRE).

METHODS

This is a retrospective analysis of incident acquisitions of VRE between July 1, 2016 and June 30, 2018. Clinical and demographic patient data were extracted from the hospital EHR system, including all recorded HCW contacts with patients. Contacts by an HCW with 2 different patients within 1 hour was considered a "connection". Incident VRE acquisition was determined by positive clinical or surveillance cultures collected ≥72 hours after a negative surveillance culture.

RESULTS

There were 2952 hospitalizations by 2364 patients who had ≥2 VRE surveillance swabs, 112 (4.7%) patients of which had incident nosocomial acquisitions. Patients had a median of 24 (interquartile range [IQR], 18-33) recorded HCW contacts per day, 9 (IQR, 5-16) of which, or approximately 40%, were connections that occurred <1 hour after another patient contact. Patients that acquired VRE had a higher average number of daily connections to VRE-positive patients (3.1 [standard deviation {SD}, 2.4] versus 2.0 [SD, 2.1]). Controlling for other risk factors, connection to a VRE-positive patient was associated with increased odds of acquiring VRE (odds ratio, 1.64; 95% confidence interval, 1.39-1.92).

CONCLUSIONS

We demonstrated that EHR data can be used to quantify the impact of HCW-mediated patient connections on transmission of VRE in the hospital. Defining incident acquisition risk of multidrug-resistant organisms through HCWs connections from EHR data in real-time may aid implementation and evaluation of interventions to contain their spread.

Effect of Treating Parents Colonized With Staphylococcus aureus on Transmission to Neonates in the Intensive Care Unit: A Randomized Clinical Trial

IMPORTANCE

Staphylococcus aureus is a leading cause of health care-associated infections in the neonatal intensive care unit (NICU). Parents may expose neonates to S aureus colonization, a well-established predisposing factor to invasive S aureus disease.

OBJECTIVE

To test whether treating parents with intranasal mupirocin and topical chlorhexidine compared with placebo would reduce transmission of S aureus from parents to neonates.

DESIGN, SETTING, AND PARTICIPANTS

Double-blinded randomized clinical trial in 2 tertiary NICUs in Baltimore, Maryland. Neonates (n = 236) with S aureus-colonized parent(s) were enrolled. The study period was November 7, 2014, through December 13, 2018.

INTERVENTIONS

Parents were assigned to intranasal mupirocin and 2% chlorhexidine-impregnated cloths (active treatment, n = 117) or petrolatum intranasal ointment and nonmedicated soap cloths (placebo, n = 119) for 5 days.

MAIN OUTCOMES AND MEASURES

The primary end point was concordant S aureus colonization by 90 days, defined as neonatal acquisition of an S aureus strain that was the same strain as a parental strain at time of screening. Secondary outcomes included neonatal acquisition of any S aureus strain and neonatal S aureus infections.

RESULTS

Among 236 randomized neonates, 208 were included in the analytic sample (55% male; 76% singleton births; mean birth weight, 1985 g [SD, 958 g]; 76% vaginal birth; mean parent age, 31 [SD, 7] years), of whom 18 were lost to follow-up. Among 190 neonates included in the analysis, 74 (38.9%) acquired S aureus colonization by 90 days, of which 42 (56.8%) had a strain concordant with a parental baseline strain. In the intervention and placebo groups, 13 of 89 neonates (14.6%) and 29 of 101 neonates (28.7%), respectively, acquired concordant S aureus colonization (risk difference, -14.1% [95% CI, -30.8% to -3.9%]; hazard ratio [HR], 0.43 [95.2% CI, 0.16 to 0.79]). A total of 28 of 89 neonates (31.4%) in the intervention group and 46 of 101 (45.5%) in the control group acquired any S aureus strain (HR, 0.57 [95% CI, 0.31 to 0.88]), and 1 neonate (1.1%) in the intervention group and 1 neonate (1.0%) in the control group developed an S aureus infection before colonization. Skin reactions in parents were common (4.8% intervention, 6.2% placebo).

CONCLUSIONS AND RELEVANCE

In this preliminary trial of parents colonized with S aureus, treatment with intranasal mupirocin and chlorhexidine-impregnated cloths compared with placebo significantly reduced neonatal colonization with an S aureus strain concordant with a parental baseline strain. However, further research is needed to replicate these findings and to assess their generalizability.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02223520.

Network analysis of cases with methicillin-resistant Staphylococcus aureus and controls in a large tertiary care facility

BACKGROUND

Despite increased awareness of infection control precautions, methicillin-resistant Staphylococcus aureus (MRSA) still spreads through patients and contaminated objects, causing a substantial burden of illness and cost. Our objective was to define risk factors for contracting MRSA in a tertiary health care facility using a historic case-control study and to validate health care network changes during pre-outbreak and outbreak periods.

METHODS

We conducted a case-control study using secondary data on hospitalizations where infected or colonized cases were compared with matched controls who tested negative by age, sex, and campus over 1 year. Social networks of all cases and controls were built from links joining patients to rooms, roommates, and health care providers over time.

RESULTS

Matched controls were similar to cases in comorbidity, lengths of stay, mortality, and number of roommates, rooms, and health care providers. As expected, the number of rooms and roommates increased in the outbreak by more than 50%. A timed animation of the network at one campus identified potential source patients linked to 2 rooms and many roommates, after which cases connected to those same rooms proliferated.

CONCLUSIONS

Only the network animation over time revealed possible transmission of MRSA through the network, rather than attributes measured in the traditional case control study.

Prevalence and clinical impact of methicillin-resistant Staphylococcus aureus colonization among infants at a level III neonatal intensive care unit

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) is a well-known nosocomial pathogen in neonatal intensive care unit (NICU) patients. Studies on the impact of MRSA colonization on neonatal morbidities are scarce.

METHODS

We conducted a 1:3 matched cohort study among infants with and without MRSA colonization, born between January 2010 and June 2014, in a tertiary NICU to review their demographic characteristics and outcomes.

RESULTS

During the study period, rates of MRSA colonization and bacteremia were found to be 0.68% and 0.10%, respectively. No differences in demographic characteristics, mortality, and major morbidities were identified among infants with and without MRSA colonization.

CONCLUSIONS

We reported a low rate of MRSA colonization in infants admitted to our NICU, without impact on mortality and inhospital morbidity. Further large-scale studies are needed to understand the implications and cost-effectiveness of active MRSA surveillance.

A survey of the implementation status of selected infection control strategies in neonatal intensive care units in Japan

BACKGROUND

Infection control strategies are implemented in all neonatal intensive care units (NICUs); however, the details of the strategies seem to differ among institutions. The purpose of this survey was to investigate the current implementation status of infection control strategies in NICUs in Japan and to identify and recommend appropriate strategies for the prevention of outbreaks in neonatal units.

METHODS

This survey documented the current implementation status and methods of selected infection prevention and control measures (active surveillance cultures and standard precaution) in 453 Japanese NICUs/neonatal units registered with the Japan Society of Perinatal and Neonatal Medicine, using questionnaires, in May 2018.

FINDINGS

The response rate was 48.1% (level I institutions, 25.5%; level II, 55.9%; level III, 64.2%). Surveillance cultures were performed every week and targeted all bacteria in most units. The proportion of level III institutions that experienced outbreaks over the previous five years was significantly higher than that of level II institutions (55% vs 27%, P=0.0003). However, wearing a mask was less frequently recommended in level III institutions (55.7%) than in level II institutions (67.9%). Meticillin-resistant Staphylococcus aureus (MRSA) was the most frequently reported bacterial pathogen responsible for NICU outbreaks.

CONCLUSION

Infection prevention and control practices regarding active pathogen surveillance cultures and the use of barrier precautions varied widely in Japanese neonatal units. National guidelines and evidence-based recommendations are needed to rationalize and standardize current infection prevention and control practices in neonatal units in Japan.

Intra-Hospital, Inter-Hospital and Intercontinental Spread of ST78 MRSA From Two Neonatal Intensive Care Unit Outbreaks Established Using Whole-Genome Sequencing

From 2009 to 2011 [transmission period (TP) 1] and 2014 to 2017 (TP2), two outbreaks involving community-associated clonal complex (CC) 88-MRSA spa types t186 and t786, respectively, occurred in the Neonatal Intensive Care Unit (NICU) of an Irish hospital (H1). This study investigated the relatedness of these isolates, their relationship to other CC88 MRSA from Ireland and their likely geographic origin, using whole-genome sequencing (WGS). All 28 CC88-MRSA isolates identified at the Irish National MRSA Reference Laboratory between 2009 and 2017 were investigated including 20 H1 patient isolates, two H1 isolates recovered from a single healthcare worker (HCW) 2 years apart, three patient isolates from a second hospital (H2) and one patient isolate from each of three different hospitals (H3, H4, and H5). All isolates underwent DNA microarray profiling. Thirteen international isolates with similar microarray profiles to at least one Irish isolate were selected from an extensive global database. All isolates underwent Illumina MiSeq WGS. The majority of Irish isolates (25/28; all H1 isolates, two H2 isolates and the H3 isolate) were identified as ST78-MRSA-IVa and formed a large cluster, exhibiting 1–71 pairwise allelic differences, in a whole-genome MLST-based minimum spanning tree (MST) involving all Irish isolates. A H1/H2, H1/H3, and H1 HCW/patient isolate pair each exhibited one allelic difference. The TP2 isolates were characterised by a different spa type and the loss of hsdS. The three remaining Irish isolates (from H2, H4, and H5) were identified as ST88-MRSA-IVa and dispersed at the opposite end of the MST, exhibiting 81–211 pairwise allelic differences. Core-genome MLST and sequence-based plasmid analysis revealed the recent shared ancestry of Irish and Australian ST78-MRSA-IVa, and of Irish and French/Egyptian ST88-MRSA-IVa. This study revealed the homogeneity of isolates recovered during two NICU outbreaks (despite spa type and hsdS carriage variances), HCW involvement in the outbreak transmission chain and the strain's spread to two other Irish hospitals. The outbreak strain, CC88/ST78-MRSA-IVa, was likely imported from Australia, where it is prevalent. CC88/ST88-MRSA-IVa was also identified in Irish hospitals and was likely imported from Africa, where it is predominant, and/or a country with a large population of African descent.

Applications of network analysis to routinely collected health care data: a systematic review

Objective

To survey network analyses of datasets collected in the course of routine operations in health care settings and identify driving questions, methods, needs, and potential for future research.

Materials and Methods

A search strategy was designed to find studies that applied network analysis to routinely collected health care datasets and was adapted to 3 bibliographic databases. The results were grouped according to a thematic analysis of their settings, objectives, data, and methods. Each group received a methodological synthesis.

Results

The search found 189 distinct studies reported before August 2016. We manually partitioned the sample into 4 groups, which investigated institutional exchange, physician collaboration, clinical co-occurrence, and workplace interaction networks. Several robust and ongoing research programs were discerned within (and sometimes across) the groups. Little interaction was observed between these programs, despite conceptual and methodological similarities.

Discussion

We use the literature sample to inform a discussion of good practice at this methodological interface, including the concordance of motivations, study design, data, and tools and the validation and standardization of techniques. We then highlight instances of positive feedback between methodological development and knowledge domains and assess the overall cohesion of the sample.

Risk factors for methicillin-resistant Staphylococcus aureus colonization in the neonatal intensive care unit: A systematic review and meta-analysis

CONTEXT

Methicillin-resistant Staphylococcus aureus (MRSA) causes a significant burden of illness in neonatal intensive care units (NICUs) worldwide. Identifying infants colonized with MRSA has become an important infection control strategy to interrupt nosocomial transmission.

OBJECTIVE

Assess risk factors for MRSA colonization in NICUs via a systematic review and meta-analysis.

DATA SOURCES

MEDLINE, Embase, Web of Science, and The Cochrane Library databases were searched from inception through September 2015.

STUDY SELECTION

Studies reporting risk factors for MRSA colonization using noncolonized controls in subspecialty level III or IV NICUs were included.

DATA EXTRACTION

Two authors independently extracted data on MRSA colonization risk factors, study design, and MRSA screening methodology.

RESULTS

Eleven articles were included in the systematic review, with 10 articles analyzed via meta-analysis. MRSA colonization was associated with gestational age <32 weeks (odds ratio [OR], 2.67; 95% confidence interval [CI], 1.35-5.27; P = .01) and birth weight <1,500 g (OR, 2.63; 95% CI, 1.25-5.55; P = .01). Infant sex (P = .21), race (P = .06), inborn status (P = .09), and delivery type (P = .24) were not significantly associated with colonization.

CONCLUSIONS

Very preterm and very-low birth weight infants were identified as having an increased risk for MRSA colonization on meta-analysis. Multifaceted infection prevention strategies should target these high-risk infants to reduce MRSA colonization rates in NICUs.

Risk Factors for Staphylococcus aureus Acquisition in the Neonatal Intensive Care Unit: A Matched Case-Case-Control Study

OBJECTIVE To determine risk factors independent of length of stay (LOS) for Staphylococcus aureus acquisition in infants admitted to the neonatal intensive care unit (NICU). DESIGN Retrospective matched case-case-control study. SETTING Quaternary-care referral NICU at a large academic children's hospital. METHODS Infants admitted between January 2014 and March 2016 at a level IV NICU who acquired methicillin resistant (MRSA) or susceptible (MSSA) S. aureus were matched with controls by duration of exposure to determine risk factors for acquisition. A secondary post hoc analysis was performed on the entire cohort of at-risk infants for risk factors identified in the primary analysis to further quantify risk. RESULTS In total, 1,751 infants were admitted during the study period with 199 infants identified as having S. aureus prevalent on admission. There were 246 incident S. aureus acquisitions in the remaining at-risk infant cohort. On matched analysis, infants housed in a single-bed unit were associated with a significantly decreased risk of both MRSA (P=.03) and MSSA (P=.01) acquisition compared with infants housed in multibed pods. Across the entire cohort, pooled S. aureus acquisition was significantly lower in infants housed in single-bed units (hazard ratio,=0.46; confidence interval, 0.34-0.62). CONCLUSIONS NICU bed design is significantly associated with S. aureus acquisition in hospitalized infants independent of LOS. Infect Control Hosp Epidemiol 2018;39:46-52.

Infant Colonization With Methicillin-Resistant Staphylococcus aureus or Vancomycin-Resistant Enterococci Preceding Neonatal Intensive Care Unit Discharge

Rates of colonization with methicillin-resistant Staphylococcus aureus (MRSA) and/or vancomycin-resistant enterococci (VRE) were determined for 1320 infants within 7 days of neonatal intensive care unit discharge. Overall, 4% and 1% of the infants were colonized with MRSA or VRE, respectively. Predictors identified in fixed-effects models were surgery during hospitalization (for MRSA colonization) and prolonged antimicrobial treatment (for VRE colonization).

Provider Connectedness to Other Providers Reduces Risk of Readmission After Hospitalization for Heart Failure

Provider interactions other than explicit care coordination, which is challenging to measure, may influence practice and outcomes. We performed a network analysis using claims data from a commercial payor. Networks were identified based on provider pairs billing outpatient care for the same patient. We compared network variables among patients who had and did not have a 30-day readmission after hospitalization for heart failure. After adjusting for comorbidities, high median provider connectedness-normalized degree, which for each provider is the number of connections to other providers normalized to the number of providers in the region-was the network variable associated with reduced odds of readmission after heart failure hospitalization (odds ratio = 0.55; 95% confidence interval [0.35, 0.86]). We conclude that heart failure patients with high provider connectedness are less likely to require readmission. The structure and importance of provider relationships using claims data merits further study.

A Network Model of Hand Hygiene: How Good Is Good Enough to Stop the Spread of MRSA?

BACKGROUND Simulation models have been used to investigate the impact of hand hygiene on methicillin-resistant Staphylococcus aureus (MRSA) transmission within the healthcare setting, but they have been limited by their ability to accurately model complex patient-provider interactions. METHODS Using a network-based modeling approach, we created a simulated neonatal intensive care unit (NICU) representing the potential for per-hour infant-infant MRSA transmission via the healthcare worker resulting in subsequent colonization. The starting prevalence of MRSA colonized infants varied from 2% to 8%. Hand hygiene ranged from 0% (none) to 100% (theoretical maximum), with an expected effectiveness of 88% inferred from literature. RESULTS Based on empiric care provided within a 1-hour period, the mean number of infant-infant MRSA transmissible opportunities per hour was 1.3. Compared to no hand hygiene and averaged across all initial colonization states, colonization was reduced by approximately 29%, 51%, 67%, 80%, and 86% for the respective levels of hygiene: 24%, 48%, 68%, 88%, and 100%. Preterm infants had a 61% increase in MRSA colonization, and mechanically ventilated infants had a 27% increase. CONCLUSIONS Even under optimal hygiene conditions, horizontal transmission of MRSA is possible. Additional prevention paradigms should focus on the most acute patients because they are at greatest risk. Infect Control Hosp Epidemiol 2017;38:945-952.

Genomic Epidemiology of Methicillin-Resistant Staphylococcus aureus in a Neonatal Intensive Care Unit

Despite infection prevention efforts, neonatal intensive care unit (NICU) patients remain at risk of Methicillin-resistant Staphylococcus aureus (MRSA) infection. Modes of transmission for healthcare-associated (HA) and community-associated (CA) MRSA remain poorly understood and may vary by genotype, hindering the development of effective prevention and control strategies. From 2008–2010, all patients admitted to a level III NICU were screened for MRSA colonization, and all available isolates were spa-typed. Spa-type t008, the most prevalent CA- genotype in the United States, spa-type t045, a HA- related genotype, and a convenience sample of strains isolated from 2003–2011, underwent whole-genome sequencing and phylodynamic analysis. Patient risk factors were compared between colonized and noncolonized infants, and virulence and resistance genes compared between spa-type t008 and non-t008 strains. Epidemiological and genomic data were used to estimate MRSA importations and acquisitions through transmission reconstruction. MRSA colonization was identified in 9.1% (177/1940) of hospitalized infants and associated with low gestational age and birth weight. Among colonized infants, low gestational age was more common among those colonized with t008 strains. Our data suggest that approximately 70% of colonizations were the result of transmission events within the NICU, with the remainder likely to reflect importations of “outside” strains. While risk of transmission within the NICU was not affected by spa-type, patterns of acquisition and importation differed between t008 and t045 strains. Phylodynamic analysis showed the effective population size of spa-type t008 has been exponentially increasing in both community and hospital, with spa-type t008 strains possessed virulence genes not found among t045 strains; t045 strains, in contrast, appeared to be of more recent origin, with a possible hospital source. Our data highlight the importance of both intra-NICU transmission and recurrent introductions in maintenance of MRSA colonization within the NICU environment, as well as spa-type-specific differences in epidemiology.

Molecular typing of toxic shock syndrome toxin-1- and Enterotoxin A-producing methicillin-sensitive Staphylococcus aureus isolates from an outbreak in a neonatal intensive care unit

Outbreaks of Staphylococcus aureus are common in neonatal intensive care units (NICUs). Usually they are documented for methicillin-resistant strains, while reports involving methicillin-susceptible S. aureus (MSSA) strains are rare. In this study we report the epidemiological and molecular investigation of an MSSA outbreak in a NICU among preterm neonates. Infection control measures and interventions were commissioned by the Local Public Health Authority and supported by the Robert Koch Institute. To support epidemiological investigations molecular typing was done by spa-typing and Multilocus sequence typing; the relatedness of collected isolates was further elucidated by DNA SmaI-macrorestriction, microarray analysis and bacterial whole genome sequencing. A total of 213 neonates, 123 healthcare workers and 205 neonate parents were analyzed in the period November 2011 to November 2012. The outbreak strain was characterized as a MSSA spa-type t021, able to produce toxic shock syndrome toxin-1 and Enterotoxin A. We identified seventeen neonates (of which two died from toxic shock syndrome), four healthcare workers and three parents putatively involved in the outbreak. Whole-genome sequencing permitted to exclude unrelated cases from the outbreak and to discuss the role of healthcare workers as a reservoir of S. aureus on the NICU. Genome comparisons also indicated the presence of the respective clone on the ward months before the first colonized/infected neonates were detected.

Whole-genome sequencing for outbreak investigations of methicillin-resistant Staphylococcus aureus in the neonatal intensive care unit: time for routine practice?

BACKGROUND Infants in the neonatal intensive care unit (NICU) are at increased risk for methicillin-resistant Staphylococcus aureus (MRSA) acquisition. Outbreaks may be difficult to identify due in part to limitations in current molecular genotyping available in clinical practice. Comparison of genome-wide single nucleotide polymorphisms (SNPs) may identify epidemiologically distinct isolates among a population sample that appears homogenous when evaluated using conventional typing methods. OBJECTIVE To investigate a putative MRSA outbreak in a NICU utilizing whole-genome sequencing and phylogenetic analysis to identify recent transmission events. DESIGN Clinical and surveillance specimens collected during clinical care and outbreak investigation. PATIENTS A total of 17 neonates hospitalized in a 43-bed level III NICU in northeastern Florida from December 2010 to October 2011 were included in this study. METHODS We assessed epidemiological data in conjunction with 4 typing methods: antibiograms, PFGE, spa types, and phylogenetic analysis of genome-wide SNPs. RESULTS Among the 17 type USA300 isolates, 4 different spa types were identified using pulsed-field gel electrophoresis. Phylogenetic analysis identified 5 infants as belonging to 2 clusters of epidemiologically linked cases and excluded 10 unlinked cases from putative transmission events. The availability of these results during the initial investigation would have improved infection control interventions. CONCLUSION Whole-genome sequencing and phylogenetic analysis are invaluable tools for epidemic investigation; they identify transmission events and exclude cases mistakenly implicated by traditional typing methods. When routinely applied to surveillance and investigation in the clinical setting, this approach may provide actionable intelligence for measured, appropriate, and effective interventions.

[Update on outbreaks reported from neonatal intensive care units (2010-203): Staphylococcus aureus]

In terms of the unique risk profile of the patients and the morbidity associated with S. aureus infections in this vulnerable patient population, the literature on outbreaks of S. aureus (including MRSA) in neonatal intensive care units (NICUs) needs to be analyzed separately from reports derived from other intensive care units. With the objective of updating important information for those involved in outbreak management and fostering preventive efforts, this article summarizes the results of a systematic literature analysis, referring to an earlier publication by Gastmeier et al. It focuses on NICU outbreaks caused by S. aureus (including MRSA) and on controlling them.

Reuse of clinical data

OBJECTIVES

To provide an overview of the benefits of clinical data collected as a by-product of the care process, the potential problems with large aggregations of these data, the policy frameworks that have been formulated, and the major challenges in the coming years.

METHODS

This report summarizes some of the major observations from AMIA and IMIA conferences held on this admittedly broad topic from 2006 through 2013. This report also includes many unsupported opinions of the author.

RESULTS

The benefits of aggregating larger and larger sets of routinely collected clinical data are well documented and of great societal benefit. These large data sets will probably never answer all possible clinical questions for methodological reasons. Non-traditional sources of health data that are patient-sources will pose new data science challenges.

CONCLUSIONS

If we ever hope to have tools that can rapidly provide evidence for daily practice of medicine we need a science of health data perhaps modeled after the science of astronomy.

Staphylococcus aureus in a neonatal care center: methicillin-susceptible strains should be a main concern

BACKGROUND

In the context of a methicillin-susceptible Staphylococcus aureus (MSSA) outbreak, we aimed to improve our knowledge of S. aureus (SA) epidemiology in the neonatal care center (NCC) of a tertiary care teaching hospital.

METHODS

We performed a complete one-year review of SA carrier, colonized or infected patients. Monthly prevalence and incidence of SA intestinal carriage, colonization and infection were calculated and the types of infection analysed. During the MSSA outbreak, strains were studied for antimicrobial resistance, content of virulence genes and comparative fingerprint in Pulsed-Field Gel Electrophoresis. Hand hygiene and catheter-related practices were assessed by direct observational audits. Environmental investigation was performed in search of a SA reservoir.

RESULTS

Epidemiological analyses showed 2 or 3 prevalence peaks on a background of SA endemicity. In the NCC, during 2009, overall MSSA prevalence did not decrease below 5.5%, while mean MRSA prevalence was about 1.53%. Analysis of infection cases revealed that the outbreak corresponded to the emergence of catheter-related infections and was probably related to the relaxation in infection control practices in a context of high colonization pressure. Health care workers' white coats appeared as a potential environmental reservoir that could perpetuate SA circulation in the ward.

CONCLUSION

This report emphasizes the importance of integrating MSSA along with methicillin-resistant SA in a program of epidemiological surveillance in the NCC.

MRSA colonization and risk of infection in the neonatal and pediatric ICU: a meta-analysis

BACKGROUND AND OBJECTIVE

Methicillin-resistant Staphylococcus aureus (MRSA) is a significant cause of morbidity and mortality in NICUs and PICUs. Our objective was to assess the burden of MRSA colonization on admission, study the time trends, and examine the significance of MRSA colonization in this population.

METHODS

PubMed and Embase databases were consulted. Studies that reported prevalence of MRSA colonization on ICU admission were selected. Two authors independently extracted data on MRSA colonization and infection.

RESULTS

We identified 18 suitable articles and found an overall prevalence of MRSA colonization of 1.9% (95% confidence interval [CI] 1.3%-2.6%) on admission to the NICU or PICU, with a stable trend over the past 12 years. Interestingly, 5.8% (95% CI 1.9%-11.4%) of outborn neonates were colonized with MRSA on admission to NICU, compared with just 0.2% (95% CI 0.0%-0.9%) of inborn neonates (P = .01). The pooled acquisition rate of MRSA colonization was 4.1% (95% CI 1.2%-8.6%) during the NICU and PICU stay and was as high as 6.1% (95% CI 2.8%-10.6%) when the NICU population was studied alone. There was a relative risk of 24.2 (95% CI 8.9-66.0) for colonized patients to develop a MRSA infection during hospitalization.

CONCLUSIONS

In the NICU and PICU, there are carriers of MRSA on admission, and MRSA colonization in the NICU is almost exclusively associated with outborn neonates. Importantly, despite infection control measures, the acquisition rate is high, and patients colonized with MRSA on admission are more likely to suffer a MRSA infection during hospitalization.

MRSA transmission on a neonatal intensive care unit: epidemiological and genome-based phylogenetic analyses

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) may cause prolonged outbreaks of infections in neonatal intensive care units (NICUs). While the specific factors favouring MRSA spread on neonatal wards are not well understood, colonized infants, their relatives, or health-care workers may all be sources for MRSA transmission. Whole-genome sequencing may provide a new tool for elucidating transmission pathways of MRSA at a local scale.

METHODS AND FINDINGS

We applied whole-genome sequencing to trace MRSA spread in a NICU and performed a case-control study to identify risk factors for MRSA transmission. MRSA genomes had accumulated sequence variation sufficiently fast to reflect epidemiological linkage among individual patients, between infants and their mothers, and between infants and staff members, such that the relevance of individual nurses' nasal MRSA colonization for prolonged transmission could be evaluated. In addition to confirming previously reported risk factors, we identified an increased risk of transmission from infants with as yet unknown MRSA colonisation, in contrast to known MRSA-positive infants.

CONCLUSIONS

The integration of epidemiological (temporal, spatial) and genomic data enabled the phylogenetic testing of several hypotheses on specific MRSA transmission routes within a neonatal intensive-care unit. The pronounced risk of transmission emanating from undetected MRSA carriers suggested that increasing the frequency or speed of microbiological diagnostics could help to reduce transmission of MRSA.

Methicillin-resistant Staphylococcus aureus in the neonatal intensive care unit

Methicillin-resistant Staphylococcus aureus (MRSA) is a frequent source of infections affecting premature and critically ill infants in neonatal intensive care units (NICUs). Neonates are particularly vulnerable to colonization and infection with MRSA, and many studies have attempted to identify risk factors that predispose certain infants to its acquisition to discover potential areas for clinical intervention. In addition, epidemiologic assessment of transmission patterns and molecular analysis of changes in the characteristics of MRSA strains over time have helped clarify additional factors affecting MRSA infections in the NICU. Numerous strategies for prevention and eradication have been used with variable rates of success. Despite these interventions, MRSA remains a significant source of morbidity in the NICU population.

Changing epidemiology of methicillin-resistant Staphylococcus aureus colonization in paediatric intensive-care units

Community-associated methicillin-resistant S. aureus (CA-MRSA) accounts for a growing proportion of hospital-onset infections, and colonization is a risk factor. This study aimed to determine changes in the prevalence of CA-MRSA colonization in paediatric intensive-care units (ICUs). A total of 495 paediatric patients colonized with MRSA from neonatal, medical, surgical, and cardiac ICUs between 2001 and 2009 were identified. Isolates were characterized by spa type, staphylococcal cassette chromosome (SCC) mec type and the presence of the genes encoding Panton–Valentine leukocidin (PVL). The proportion of patients colonized with MRSA remained stable (average 3·2%). The proportion of isolates with spa type 1, SCCmec type IV and PVL increased over time to maximums in 2009 of 36·1% (P < 0·001), 54·2% (P = 0·03) and 28·9% (P = 0·003), respectively. Antibiotic susceptibility patterns showed increasing proportions susceptible to clindamycin, gentamicin, tetracycline and trimethoprim-sulfamethoxazole (P values <0·001). In conclusion, the proportion of MRSA-colonized children in ICUs with CA-MRSA increased significantly over time.