Surveillance and Isolation of Methicillin-Resistant Staphylococcus aureus Colonization in the Neonatal Intensive Care Unit

Antibiotic Stewardship in the Neonatal Intensive Care Unit

Antibiotic stewardship is a multidisciplinary, evidence-based approach to optimize antibiotic use and mitigate development of antibiotic resistance. Neonates have high rates of antibiotic exposure, particularly those born preterm and admitted to the NICU, and mounting evidence describes the adverse consequences of such exposures in the absence of infection. Here, we review the general principles of antibiotic stewardship and how they can be applied in NICUs. The unique characteristics of NICUs and patients cared for in this setting, which warrant unique implementation strategies and special considerations are discussed. We summarize current antibiotic use metrics for assessment of responses to stewardship interventions and changes over time, and review evidence-based infection prevention practices in the NICU. Current recommendations for empiric antibiotic use in the NICU and the utility of infection biomarkers are summarized. Lastly, given the growing global threat of increasing antibiotic resistance, specific threats in the NICU are highlighted.

Effects of Discontinuation of Weekly Surveillance Testing on Methicillin-Resistant Staphylococcus aureus in the NICU

OBJECTIVE

Methicillin-resistant Staphylococcus aureus (MRSA) infection is a major cause of serious morbidity and mortality in the neonatal intensive care unit (NICU). There is no clear consensus on infection control measures. Some approaches to MRSA colonization management may be burdensome with unclear benefits. The objective of this study was to determine if stopping weekly MRSA surveillance with active detection and contact isolation (ADI) was associated with a change in infection rate.

STUDY DESIGN

This is a retrospective cohort study of infants admitted to two affiliated NICUs. The ADI cohort infants received weekly nasal MRSA cultures and were placed in contact isolation if MRSA colonized for the duration of their hospitalization. The No Surveillance cohort infants were only placed in isolation if there was active MRSA infection or if MRSA colonization was identified incidentally. The rates of infection were determined between the cohorts.

RESULTS

There were 8,406 neonates representing 193,684 NICU days in the comparison period. In the ADI cohort, MRSA colonization occurred in 3.4% of infants and infection occurred in 29 infants (0.4%). There were no differences between cohorts in the percent of infants with a MRSA infection at any site (0.5 vs. 0.5%, p = 0.89), rate of MRSA infections per 1,000 patient-days (0.197 vs. 0.201, p = 0.92), rate of bloodstream infections (0.12 vs. 0.26%, p = 0.18), or in the overall mortality rate (3.7 vs. 3.0% p = 0.13). ADI represented an annual cost of $590,000.

CONCLUSION

The rates of MRSA infection did not change when weekly ADI was discontinued and was associated with a decrease in cost and resource utilization.

KEY POINTS

· Placing MRSA-colonized infants in contact isolation is a common practice.. · Data are limited with respect to efficacy in the NICU.. · This study provides evidence that active detection and contact isolation for MRSA colonization may not be beneficial..

A cost analysis of active surveillance culture in a neonatal intensive care unit

Active surveillance culture (ASC) in neonatal intensive care units (NICUs) has been implemented to monitor horizontal transmission and choose appropriate antimicrobials when neonates experience late-onset infections (LOIs). To perform a cost analysis of ASC in the NICU, we evaluated data from a NICU ward in a Japanese community hospital. This was a retrospective study of neonates admitted to the NICU of Nara Prefecture General Medical Center, Nara City, Japan, from April 2012 to May 2017. We implemented biweekly ASC (nasal, stool and umbilical cultures) during this period. We assessed the detection rate for methicillin-sensitive and -resistant S. aureus (MSSA and MRSA) in each culture and reviewed the cases of LOI. Among the 785 cases, MSSA and MRSA were detected in 158 and 75 cases, respectively. Nasal culture was the most sensitive method for detecting MSSA and MRSA. Three cases benefitted from changing the empiric treatment based on previous ASC results, with an annual cost of ¥808,331 (£5773.80 or $7282.30) for ASC. The total cost per one benefited case during the study period was calculated as ¥1,392,126 (£9943.80 or $12,541.70). The total cost per benefited case in risk factor targeted ASC, nasal culture targeted ASC and MRSA-targeted ASC was ¥1,332,264 (£9516.20 or $12,002.30), ¥692,222 (£4944.40 or $6236.20) and ¥858,547 (£6132.50 or $7734.70), respectively. Considering the frequency of S. aureus detection and the cost of each culture, our ASC was modified to use only nasal cultures. This study suggests that the cost performance of ASC should be evaluated with consideration of the characteristics of each NICU.

Evaluating a neonatal intensive care unit MRSA surveillance programme using agent-based network modelling

BACKGROUND

Surveillance for meticillin-resistant Staphylococcus aureus (MRSA) in neonatal intensive care units (NICUs) is a commonplace infection prevention strategy, yet the optimal frequency with which to monitor the unit is unknown.

AIM

To compare various surveillance frequencies using simulation modelling.

METHODS

One hundred NICU networks of 52 infants were simulated over a six-month period to assess MRSA transmission. Unit-wide surveillance occurred every N weeks where N={1,2,3,4}, and was compared with the current NICU policy of dynamic surveillance (i.e. weekly when at least one positive screen, otherwise every three weeks). For each surveillance period, colonized infants received a decolonization regimen (56% effective) and were moved to isolation rooms, if available.

FINDINGS

As the surveillance frequency increased, the mean number of MRSA-colonized infants decreased, from a high of 2.9 (four-weekly monitoring) to a low of 0.6 (weekly monitoring) detected per episode. The mean duration of colonization decreased from 307 h (four-weekly monitoring) to 61 h (weekly monitoring). Meanwhile, the availability of isolation rooms followed an inverse relationship: as surveillance frequency increased, the availability of isolation rooms decreased (61% isolation success rate for four-weekly monitoring vs 49% success rate for weekly monitoring). The dynamic policy performed similar to a biweekly programme.

CONCLUSIONS

An effective MRSA surveillance programme needs to balance resource availability with potential for harm due to longer colonization periods and opportunity for development of invasive disease. While more frequent monitoring led to greater use of a decolonization regimen, it also reduced the likelihood of isolation rooms being available.

New Threats from an Old Foe: Methicillin-Resistant Staphylococcus aureus Infections in Neonates

Methicillin-resistant Staphylococcus aureus (MRSA) is a ubiquitous human inhabitant and one of the important pathogens of neonatal infections. MRSA is associated with significant mortality and morbidity, especially in very immature preterm neonates. Moreover, MRSA may be implicated in adverse long-term neonatal outcomes, posing a substantial disease burden. Recent advances in molecular microbiology have shed light on the evolution of MRSA population structure and virulence factors, which may contribute to MRSA epidemic waves worldwide. Equipped with remarkable genetic flexibility, MRSA has successfully developed resistance to an extensive range of antibiotics including vancomycin, as well as antiseptics. In the face of these new challenges from MRSA, our armamentarium of anti-infective strategies is very limited and largely dependent on prevention measures. Active surveillance cultures followed by decolonization may be a promising approach to control MRSA infections, with its efficacy and safety in the specific population of neonates yet to be addressed by large multicenter studies.

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.