Healthcare worker-related MRSA cluster in a German neonatology level III ICU: A true European story

Epidemiology and genomics of a slow outbreak of methicillin-resistant Staphyloccus aureus (MRSA) in a neonatal intensive care unit: Successful chronic decolonization of MRSA-positive healthcare personnel

Objective:

To describe the genomic analysis and epidemiologic response related to a slow and prolonged methicillin-resistant Staphylococcus aureus (MRSA) outbreak.

Design:

Prospective observational study.

Setting:

Neonatal intensive care unit (NICU).

Methods:

We conducted an epidemiologic investigation of a NICU MRSA outbreak involving serial baby and staff screening to identify opportunities for decolonization. Whole-genome sequencing was performed on MRSA isolates.

Results:

A NICU with excellent hand hygiene compliance and longstanding minimal healthcare-associated infections experienced an MRSA outbreak involving 15 babies and 6 healthcare personnel (HCP). In total, 12 cases occurred slowly over a 1-year period (mean, 30.7 days apart) followed by 3 additional cases 7 months later. Multiple progressive infection prevention interventions were implemented, including contact precautions and cohorting of MRSA-positive babies, hand hygiene observers, enhanced environmental cleaning, screening of babies and staff, and decolonization of carriers. Only decolonization of HCP found to be persistent carriers of MRSA was successful in stopping transmission and ending the outbreak. Genomic analyses identified bidirectional transmission between babies and HCP during the outbreak.

Conclusions:

In comparison to fast outbreaks, outbreaks that are “slow and sustained” may be more common to units with strong existing infection prevention practices such that a series of breaches have to align to result in a case. We identified a slow outbreak that persisted among staff and babies and was only stopped by identifying and decolonizing persistent MRSA carriage among staff. A repeated decolonization regimen was successful in allowing previously persistent carriers to safely continue work duties.

Exploring the evolution and epidemiology of European CC1-MRSA-IV: tracking a multidrug-resistant community-associated meticillin-resistant Staphylococcus aureus clone

This study investigated the evolution and epidemiology of the community-associated and multidrug-resistant Staphylococcus aureus clone European CC1-MRSA-IV. Whole-genome sequences were obtained for 194 European CC1-MRSA-IV isolates (189 of human and 5 of animal origin) from 12 countries, and 10 meticillin-susceptible precursors (from North-Eastern Romania; all of human origin) of the clone. Phylogenetic analysis was performed using a maximum-likelihood approach, a time-measured phylogeny was reconstructed using Bayesian analysis, and in silico microarray genotyping was performed to identify resistance, virulence-associated and SCCmec (staphylococcal cassette chromosome mec) genes. Isolates were typically sequence type 1 (190/204) and spa type t127 (183/204). Bayesian analysis indicated that European CC1-MRSA-IV emerged in approximately 1995 before undergoing rapid expansion in the late 1990s and 2000s, while spreading throughout Europe and into the Middle East. Phylogenetic analysis revealed an unstructured meticillin-resistant S. aureus (MRSA) population, lacking significant geographical or temporal clusters. The MRSA were genotypically multidrug-resistant, consistently encoded seh, and intermittently (34/194) encoded an undisrupted hlb gene with concomitant absence of the lysogenic phage-encoded genes sak and scn. All MRSA also harboured a characteristic ~5350 nt insertion in SCCmec adjacent to orfX. Detailed demographic data from Denmark showed that there, the clone is typically (25/35) found in the community, and often (10/35) among individuals with links to South-Eastern Europe. This study elucidated the evolution and epidemiology of European CC1-MRSA-IV, which emerged from a meticillin-susceptible lineage prevalent in North-Eastern Romania before disseminating rapidly throughout Europe.

An epidemic CC1-MRSA-IV clone yields false-negative test results in molecular MRSA identification assays: a note of caution, Austria, Germany, Ireland, 2020

We investigated why a clinical meticillin-resistant Staphylococcus aureus (MRSA) isolate yielded false-negative results with some commercial PCR tests for MRSA detection. We found that an epidemic European CC1-MRSA-IV clone generally exhibits this behaviour. The failure of the assays was attributable to a large insertion in the orfX/SCCmec integration site. To ensure the reliability of molecular MRSA tests, it is vital to monitor emergence of new SCCmec types and junction sites.

Determinants for voluntary participation in staff screening during an methicillin-resistant Staphylococcus aureus (MRSA) outbreak on a neonatal ward

We investigated healthcare worker (HCW) behavior with regard to a voluntary methicillin-resistant Staphylococcus aureus (MRSA) staff screening during a MRSA outbreak in a neonatal ward. Avoiding MRSA transmission from HCWs to patients was the most important reason for participation. Inconvenient screening time was the most frequently cited reason for nonparticipation.

Clonal replacement of meticillin-resistant Staphylococcus aureus during repeated outbreaks in a long-term care facility

Meticillin-resistant Staphylococcus aureus (MRSA) is common among residents of long-term care facilities (LTCFs). Analysing the spa types of 22 isolates, mostly bloodstream infections (BSI), revealed five temporally distinct clonal outbreaks occurring in one ward of our local LTCF between 2012 and 2019. Each clone caused episodes of BSI for several months until replaced by another clone. A high MRSA carriage rate of 32% among healthcare workers in this ward was documented during the investigation of the 2019 outbreak. Clonal replacement of MRSA and the role of healthcare workers in transmission are discussed.

A persistent recurring cluster of meticillin-resistant Staphylococcus aureus (MRSA) colonizations in a special care baby unit: a matched case-control study

BACKGROUND

Between August 2016 and November 2019, a cluster of babies colonized with meticillin-resistant Staphylococcus aureus (MRSA) was reported in a special care baby unit in northern England.

AIM

A case-control study was performed to identify the source and prevent further cases.

METHODS

Cases were admitted neonates colonized or infected with MRSA (spa type t316). A retrospective case-control study was performed with two matched controls per case. Exposures were determined by medical record review. Cases were compared with controls using conditional logistic regression. Environmental investigations and staff screening were undertaken.

FINDINGS

Thirty-one colonized cases were identified across the 3-year period, with no infections reported. Thirteen of the 31 cases were sequenced and were within a cluster of 25 single nucleotide polymorphisms, consistent with exposure to a common source over a prolonged period. Most MRSA cases had a prior negative screen (N=22, 71%). Environmental sampling and staff screening were performed on several occasions. In the analytical study, 31 cases were compared with 62 controls. One ward location and one healthcare worker were identified as significant exposures in the multi-variable analysis.

CONCLUSIONS

Due to the sporadic nature of the colonizations, it was hypothesized that MRSA was being introduced intermittently, likely by a colonized healthcare worker, with possible transmission between infants also occurring within each temporal cluster. It is recommended that transiently colonized healthcare workers should be considered as a source of MRSA during outbreaks. This study highlights the importance of analytic epidemiological studies in persistent outbreaks of MRSA.

A novel multidrug-resistant PVL-negative CC1-MRSA-IV clone emerging in Ireland and Germany likely originated in South-Eastern Europe

This study investigated the recent emergence of multidrug-resistant Panton-Valentine leukocidin (PVL)-negative CC1-MRSA-IV in Ireland and Germany. Ten CC1-MSSA and 139 CC1-MRSA isolates recovered in Ireland between 2004 and 2017 were investigated. These were compared to 21 German CC1-MRSA, 10 Romanian CC1-MSSA, five Romanian CC1-MRSA and two UAE CC1-MRSA, which were selected from an extensive global database, based on similar DNA microarray profiles to the Irish isolates. All isolates subsequently underwent whole-genome sequencing, core-genome single nucleotide polymorphism (cgSNP) analysis and enhanced SCCmec subtyping. Two PVL-negative clades (A and B1) were identified among four main clades. Clade A included 20 German isolates, 119 Irish isolates, and all Romanian MRSA and MSSA isolates, the latter of which differed from clade A MRSA by 47-130 cgSNPs. Eighty-six Irish clade A isolates formed a tight subclade (A1) exhibiting 0-49 pairwise cgSNPs, 80 of which harboured a 46 kb conjugative plasmid carrying both ileS2, encoding high-level mupirocin resistance, and qacA, encoding chlorhexidine resistance. The resistance genes aadE, aphA3 and sat were detected in all clade A MRSA and the majority (8/10) of clade A MSSA isolates. None of the clade A isolates harboured any enterotoxin genes other than seh, which is universally present in CC1. Clade B1 included the remaining German isolate, 17 Irish isolates and the two UAE isolates, all of which corresponded to the Western Australia MRSA-1 (WA MRSA-1) clone based on genotypic characteristics. MRSA within clades A and B1 differed by 188 cgSNPs and clade-specific SCCmec characteristics were identified, indicating independent acquisition of the SCCmec element. This study demonstrated the existence of a European PVL-negative CC1-MRSA-IV clone that is distinctly different from the well-defined PVL-negative CC1-MRSA-IV clone, WA MRSA-1. Furthermore, cgSNP analysis revealed that this newly defined clone may have originated in South-Eastern Europe, before spreading to both Ireland and Germany.

Expanding PVL positive MRSA healthcare-associated infections outbreak in a newborns unit, caused by hospital hygiene shortcomings

A prolonged outbreak of Healthcare-Associated Infections (HCAIs) evolved since December 2013, in a Newborns Unit from Hospital A, sited in the North-Eastern development region, Romania. A first cluster consisted of 19 cases, of which 18 infections in newborns and 1 labour infectious complication in a mother. Except for five cases declared and treated in the Neonatology Unit as hospital-acquired infections, the other cases were discharged and further required rehospitalisation and treatment.

Eight of these innitialy discharged cases were readmitted to the Pediatric Surgery Unit and two others to the Pediatrics Unit of Hospital B, while three others were readmitted to three hospitals: one to the Pediatrics Unit of Hospital C, and other two to Hospital A and Hospital D, respectively. The mother with the labour infectious complication was readmitted to the Gynecology Unit of the Hospital A.

A number of fifteen Staphylococcus aureus (S. aureus) strains isolated from the HCAI first episode and 8 strains from 7 HCWs were received by „Cantacuzino” Institute, Nosocomial Infections and Antibiotic Resistance Laboratory from the County Public Health Directorate, for confirmation and molecular typing.

After a first round of interventions for infection control, a second episode bursted in Hospital A and our laboratory received six other S. aureus isolates from newborns, hospital environment, and HCWs.

Public Health interventions based on epidemiologic data and molecular microbiology results were finally successful. The evolution of all cases was favorable.

An important factor favoring the outbreak was the moving of the Birth Unit of Hospital A to an innapropriate location for an 18-month interval, more than innitially estimated, in relation to rehabilitation of the ward.

We considered to report this episode taking into account the unusual evolution, the risk of multiresistant bacterial strains spreading, and multiple unwanted consequences caused by shortcomings in providing appropriate hygiene conditions.

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.

[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.