How many outbreaks of nosocomial infections occur in German neonatal intensive care units annually?

Methicillin-resistant Staphylococcus aureus (MRSA) clusters in neonatal intensive care units (NICUs) and other neonatal units in New York State (NYS), 2001 to 2017

BACKGROUND

New York State (NYS) mandates reporting of all hospital-associated communicable disease outbreaks. We describe trends in NYS surveillance for neonatal unit methicillin-resistant Staphylococcus aureus (MRSA) outbreaks, the evolution of national MRSA infection prevention and control (IPC) recommendations, and IPC measures taken by NYS neonatal units.

METHODS

We evaluated trends of reported neonatal unit MRSA outbreaks by etiology from 2001 to 2017. We reviewed all reports and the use of IPC recommendations over time.

RESULTS

From 2001 to 2017, 124 MRSA outbreaks were reported in 47 hospital neonatal units, with a total of 1,055 laboratory-confirmed infant cases, 18 infant deaths, and 52 laboratory-confirmed staff cases. The number of outbreaks increased with the level of care. During the study period, a higher proportion of hospitals reported implementing IPC measures, including reinforcing hand hygiene compliance (increased from 79.2% to 95.1%) and enhancing environmental cleaning and disinfection (increased from 4.2% to 78.0%) as well as performing active surveillance testing (AST) on exposed neonates (increased from 4.2% to 51.2%) and molecular testing on MRSA-positive isolates (increased from 5.3% to 18.9%).

CONCLUSIONS

From 2001 to 2017, IPC measures in neonatal units increased in parallel with expanded national IPC recommendations. However, MRSA outbreaks in neonatal units continued to be frequent occurrences in NYS.

Antimicrobial resistance and epidemic clustering of late-onset neonatal infections in a Brazilian intensive care unit

Nosocomial infections in the neonatal intensive care unit (NICU) tend to cluster and multidrug-resistant (MDR) pathogens are rising in developing countries. We did a retrospective cohort study of neonates admitted to a NICU in Brazil with late-onset neonatal sepsis (LOS) confirmed by blood culture from October 2012 to December 2016 and from July 2018 to December 2021. We defined a cluster of infection when at least two cases of LOS occurred within two different time intervals: 15 and 30 days with the same pathogen in different patients. A random amplified polymorphic DNA (RAPD) was performed from samples from one of these clusters. A logistic regression model was applied having death as the outcome and the infection with an MDR pathogen as the exposure of interest. There were 987 blood cultures from 754 neonates, 621 (63%) were gram-positive cocci, 264 (30%) were gram-negative rods and 72 (7%) fungi. A third of Enterobacterales were resistant to cefepime and a third of non-fermenting glucose rods were resistant to carbapenems. There were 100 or 104 clusters of infection in the 15- or 30-day interval, respectively. A RAPD analysis from an outbreak of MDR Acinetobacter baumannii showed that all five samples belonged to a single clone. An infection with an MDR pathogen was associated with death (OR 1.82, 95% CI 1.03-3.21). In conclusion, clusters of infections in a Brazilian NICU are a frequent phenomenon as seen elsewhere. They suggest cross-transmission of pathogens with increasing antimicrobial resistance and should prompt intensified surveillance and infection control measures.

Analysis of transmission-related third-generation cephalosporin-resistant Enterobacterales by electronic data mining and core genome multi-locus sequence typing

BACKGROUND

To contain intra-hospital transmission of third-generation cephalosporin-resistant Enterobacterales (3GCR-E), contact isolation precautions are recommended.

AIM

To quantify transmissions of 3GCR Escherichia coli and 3GCR Klebsiella pneumoniae within a hospital.

METHODS

An automated outbreak detection system (AODS) was used to identify clusters (N≥2) of 3GCR Enterobacterales for the years 2016, 2018 and 2020. Clusters were defined by phenotypic agreement of microbiological results and spatial and temporal relationship. Core genome multi-locus sequence typing (cgMLST) was used to confirm whether the cluster isolates were transmitted between patients.

FINDINGS

A total of 4343 3GCR E. coli and 1377 K. pneumoniae isolates were analysed. Among the 3GCR E. coli isolates, the AODS identified 304 isolates as cluster isolates, the median cluster size was two (range: 2-5). The cgMLST analysis revealed that a total of 23 (7.5%) 3GCR E. coli cluster isolates were transmission-associated, of which 20 isolates (87%) were detected in intensive care patients. Among the 3GCR K. pneumoniae isolates, the AODS identified 73 isolates as cluster isolates, the median cluster size was two (range: 2-4). CgMLST revealed that 35 (48%) 3GCR K. pneumoniae cluster isolates were transmission associated, of which 27 isolates (77%) were detected in intensive care patients.

CONCLUSION

For 3GCR K. pneumoniae, cgMLST confirmed the AODS results more frequently than for 3GCR E. coli. Therefore, contact isolation precautions for 3GCR K. pneumoniae may be appropriate on intensive care units, but only in certain circumstances, such as outbreaks, for Enterobacterales with lower transmissibility, such as E. coli.

Surveillance of Enterobacter cloacae complex colonization and comparative analysis of different typing methods on a neonatal intensive care unit in Germany

Background

Enterobacter cloacae complex is a group of common opportunistic pathogens on neonatal intensive care units. Active microbiological screening to guide empirical antimicrobial treatment or to detect transmission events is recommended in high-risk preterm neonates. A rise in colonization with E. cloacae complex was observed in a German perinatal centre. The aim of this study was to evaluate the performance of different typing techniques using whole genome sequencing (WGS) as a reference.

Methods

Enterobacter cloacae complex isolates from clinical and screening specimens with an epidemiological link to the neonatal intensive care units were further assessed. Identification and antibiotic susceptibility testing was performed by a combination of VITEK2 (bioMérieux) and MALDI-TOF (Bruker Daltonics), followed by RAPD/rep-PCR and PFGE (XbaI). Retrospectively, all isolates were analyzed by Fourier-transform infrared (FTIR) spectroscopy (IR Biotyper, Bruker Daltonics). Whole genome sequencing with SNP-based clustering was used as the reference method. Furthermore, resistome analysis, sequence type and species identification were derived from the WGS data. Transmission analysis was based on epidemiological and typing data.

Results

Between September 2017 and March 2018 32 mostly preterm neonates were found to be colonized with E. cloacae complex and 32 isolates from 24 patients were available for further typing. RAPD/rep-PCR and PFGE showed good concordance with WGS whereas FTIR displayed mediocre results [adjusted rand index (ARI) = 0.436]. A polyclonal increase and two dominant and overlapping clonal clusters of two different E. hormaechei subspecies were detected. Overall, four different species were identified. Genotyping confirmed third-generation cephalosporin resistance development in isolates of the same patient. During the six-month period several infection prevention interventions were performed and no E. cloacae complex isolates were observed during the following months.

Conclusions

Interpretation of the microbiological results alone to detect transmission events is often challenging and bacterial typing is of utmost importance to implement targeted infection control measures in an epidemic occurrence of E. cloacae complex. WGS is the most discriminatory method. However, traditional methods such as PFGE or RAPD/rep-PCR can provide reliable and quicker results in many settings. Furthermore, research is needed to quickly identify E. cloacae complex to the species level in the microbiological laboratory.

Invasive Candida Infections in Neonates after Major Surgery: Current Evidence and New Directions

Infections represent a serious health problem in neonates. Invasive Candida infections (ICIs) are still a leading cause of mortality and morbidity in neonatal intensive care units (NICUs). Infants hospitalized in NICUs are at high risk of ICIs, because of several risk factors: broad spectrum antibiotic treatments, central catheters and other invasive devices, fungal colonization, and impaired immune responses. In this review we summarize 19 published studies which provide the prevalence of previous surgery in neonates with invasive Candida infections. We also provide an overview of risk factors for ICIs after major surgery, fungal colonization, and innate defense mechanisms against fungi, as well as the roles of different Candida spp., the epidemiology and costs of ICIs, diagnosis of ICIs, and antifungal prophylaxis and treatment.

Identification and Containment of a Cluster of Two Bacillus cereus Infections in a Neonatal Intensive Care Unit

We report a cluster of invasive Bacillus cereus infections in a neonatal intensive care unit. We describe the clinical course of two infected patients, one of whom died of severe pneumonia after successfully being weaned from ECMO. Environmental analyses failed to yield a common source. Molecular characterization confirmed the homogeneity of both isolates. Rigorous hygiene control and adequate therapy enabled the containment of the cluster.

First reported nosocomial outbreak of Serratia marcescens harboring bla IMP-4 and bla VIM-2 in a neonatal intensive care unit in Cairo, Egypt

Introduction

Serratia marcescens is a significant hospital-acquired pathogen, and many outbreaks of S. marcescens infection have been reported in neonates. We report a sudden breakout of S. marcescens harboring the bla_IMP-4 and bla_VIM-2 metallo-β-lactamase (MBL) genes that occurred from March to August 2015 in the neonatal intensive care unit of Cairo University Hospital, Cairo, Egypt.

Methods

During the study period, 40 nonduplicate clinical isolates of S. marcescens were collected from blood culture samples. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry was used to identify each isolate. Then, minimum inhibitory concentrations of different antibiotics were assessed by the Vitek 2 compact system. Screening of the MBL genes bla_IMP, bla_VIM, bla_SIM-1, bla_SPM-1, and bla_GIM-1 as well as the carbapenemase genes KPC, NDM, OXA-48, SME-1, and SME-2 were evaluated. Pulsed field gel electrophoresis was preformed to detect the genetic relationship of the isolates.

Results

Analysis showed that 37.5% of the S. marcescens clinical isolates were resistant to meropenem (minimum inhibitory concentrations ≥ 2 µg/mL), and bla_IMP-4 and bla_VIM-2 were the most prevalent MBL genes (42.5% and 37.5%, respectively). None of the other investigated genes were observed. Pulsed field gel electrophoresis typing revealed two discrete clones; 33/40 (82.5%) were pulsotype A and 7/40 (17.5%) were pulsotype B.

Conclusion

Here, we report for the first time the detection of MBL-producing S. marcescens isolates, particularly IMP-4 and VIM-2 recovered from inpatients with bacteremias from the intensive care unit at Cairo University Hospital.

Long-Term, Low-Frequency Cluster of a German-Imipenemase-1-Producing Enterobacter hormaechei ssp. steigerwaltii ST89 in a Tertiary Care Hospital in Germany

Enterobacter cloacae complex is a common cause of hospital outbreaks. A retrospective and prospective molecular analysis of carbapenem-resistant clinical isolates in a tertiary care center demonstrated an outbreak of a German-imipenemase-1 (GIM-1) metallo-beta-lactamase-producing Enterobacter hormaechei ssp. steigerwaltii affecting 23 patients between 2009 and 2016. Thirty-three isolates were sequence type 89 by conventional multilocus sequence typing (MLST) and displayed a maximum difference of 49 out of 3,643 targets in the ad-hoc core-genome MLST (cgMLST) scheme (SeqSphere+ software; Ridom, Münster, Germany). The relatedness of all isolates was confirmed by further maximum-likelihood phylogeny. One clonal complex of highly related isolates (≤15 allele difference in cgMLST) contained 17 patients, but epidemiological data only suggested five transmission events. The bla_GIM-1-gene was embedded in a class-1-integron (In770) and the Tn21-subgroup transposon Tn6216 (KC511628) on a 25-kb plasmid. Environmental screening detected one colonized sink trap in a service room. The outbreak was self-limited as no further bla_GIM-1-positive E. hormaechei has been isolated since 2016. Routine molecular screening of carbapenem-nonsusceptible gram-negative isolates detected a long-term, low-frequency outbreak of a GIM-1-producing E. hormaechei ssp. steigerwaltii clone. This highlights the necessity of molecular surveillance.

Management and investigation of a Serratia marcescens outbreak in a neonatal unit in Switzerland - the role of hand hygiene and whole genome sequencing

Background

Many outbreaks due to Serratia marcescens among neonates have been described in the literature but little is known about the role of whole genome sequencing in outbreak analysis and management.

Methods

Between February and March 2013, 2 neonates and 2 infants previously hospitalised in the neonatal unit of a tertiary care centre in Switzerland, were found to be colonised with S. marcescens. An investigation was launched with extensive environmental sampling and neonatal screening in four consecutive point prevalence surveys between April and May 2013. All identified isolates were first investigated by fingerprinting and later by whole genome sequencing. Audits of best practices were performed and a hand hygiene promotion programme was implemented.

Results

Twenty neonates were colonised with S. marcescens. No invasive infection due to S. marcescens occurred. All 231 environmental samples were negative. Hand hygiene compliance improved from 51% in April 2013 to 79% in May 2013 and remained high thereafter. No S. marcescens was identified in point prevalence surveys in June and October 2013. All strains were identical in the fingerprinting analysis and closely related according to whole genome sequencing.

Conclusions

Improving best practices and particularly hand hygiene proved effective in terminating the outbreak. Whole genome sequencing is a helpful tool for genotyping because it allows both sufficient discrimination of strains and comparison to other outbreaks through the use of an emerging international database.

Protracted Regional Dissemination of GIM-1-Producing Serratia marcescens in Western Germany

The metallo-beta-lactamase GIM-1 has been found in various bacterial host species nearly exclusively in western Germany. However, not much is known about the epidemiology of GIM-1-positive Serratia marcescens Here we report on a surprisingly protracted regional dissemination. In-hospital transmission was investigated by using conventional epidemiological tools to identify spatiotemporal links. Strain typing was performed using pulsed-field gel electrophoresis (PFGE) and whole-genome sequencing (WGS). Bayesian phylogeny was used to infer the time axis of the observed occurrence. Thirteen S. marcescens strains from 10 patients from 6 different German hospitals were investigated. Suspected in-hospital transmissions were confirmed by molecular typing at a higher resolution by WGS than by PFGE. A detailed sequence analysis demonstrated the spread of one predominant strain variant but also provided evidence for transfer of the bla_GIM-1 gene cassette between different strains. A Bayesian phylogenetic analysis showed that the most recent common ancestor of the identified clonal cluster could be dated back to April 1993 (95% highest posterior density interval, January 1973 to March 2003) and that this strain might have already harbored the bla_GIM-1 at that time and, therewith, years before the first detection of this resistance gene in clinical specimens. This study shows a long-standing clonal and plasmid-mediated expansion of GIM-1-producing S. marcescens that might have gone unnoticed in the absence of a standardized and effective molecular screening for carbapenemases. The systematic and early detection of resistance is thus highly advisable, especially for the prevention of potentially long-term dissemination that may progress beyond control.

A pore-forming toxin enables Serratia a nonlytic egress from host cells

Several pathogens co-opt host intracellular compartments to survive and replicate, and they thereafter disperse progeny to prosper in a new niche. Little is known about strategies displayed by Serratia marcescens to defeat immune responses and disseminate afterwards. Upon invasion of nonphagocytic cells, Serratia multiplies within autophagosome-like vacuoles. These Serratia-containing vacuoles (SeCV) circumvent progression into acidic/degradative compartments, avoiding elimination. In this work, we show that ShlA pore-forming toxin (PFT) commands Serratia escape from invaded cells. While ShlA-dependent, Ca²⁺ local increase was shown in SeCVs tight proximity, intracellular Ca²⁺ sequestration prevented Serratia exit. Accordingly, a Ca²⁺ surge rescued a ShlA-deficient strain exit capacity, demonstrating that Ca²⁺ mobilization is essential for egress. As opposed to wild-type-SeCV, the mutant strain-vacuole was wrapped by actin filaments, showing that ShlA expression rearranges host actin. Moreover, alteration of actin polymerization hindered wild-type Serratia escape, while increased intracellular Ca²⁺ reorganized the mutant strain-SeCV actin distribution, restoring wild-type-SeCV phenotype. Our results demonstrate that, by ShlA expression, Serratia triggers a Ca²⁺ signal that reshapes cytoskeleton dynamics and ends up pushing the SeCV load out of the cell, in an exocytic-like process. These results disclose that PFTs can be engaged in allowing bacteria to exit without compromising host cell integrity.

Pathogen-Specific Clustering of Nosocomial Blood Stream Infections in Very Preterm Infants

BACKGROUND AND OBJECTIVES

Nosocomial infections in NICUs tend to cluster, sometimes as devastating outbreaks, but pathogen-specific transmission probabilities are unknown. We aimed to quantify the pathogen-specific risk of a blood stream infection (BSI) in preterm infants after an index case with that pathogen in the same department.

METHODS

Data of 44 818 infants below 1500 g birth weight of the German NICU surveillance system (2000-2011) were used to calculate the probability of a BSI in the presence or absence of another infant in the same unit with a same-pathogen BSI.

RESULTS

The relative risk was similar for the more common pathogens, Enterococcus spp (4.3; 95% confidence interval: 2.7-6.9; n = 243), Enterobacter spp (7.9, 5.4-11.4; n = 246), Escherichia coli (7.9; 5.1-12.1; n = 210), Candida albicans (8.7; 5.0-15.4; n = 138), Staphylococcus aureus (9.5; 7.6-12.1; n = 407) and Klebsiella spp (13.1; 9.0-19.1; n = 190) but markedly elevated for Serratia spp (77.5; 41.1-146.1; n = 58) and Pseudomonas aeruginosa (64.5; 25.7-162.1; n = 38). Rates of BSI per 100 exposed infants ranged between 2.21 (Enterococcus) and 8.15 (Serratia). The same pattern emerged after adjustments were made for patients' characteristics or when the analysis was restricted to positive blood cultures during the preceding 30 days.

CONCLUSIONS

Although BSIs with P aeruginosa or Serratia spp in preterm infants are rare, they are associated with a markedly elevated risk of secondary same-pathogen BSI and should prompt intensified active surveillance and infection control measures.

Treatment options for infections caused by carbapenem-resistant Enterobacteriaceae: can we apply "precision medicine" to antimicrobial chemotherapy?

INTRODUCTION

For the past three decades, carbapenems played a central role in our antibiotic armamentarium, trusted to effectively treat infections caused by drug-resistant bacteria. The utility of this class of antibiotics has been compromised by the emergence of resistance especially among Enterobacteriaceae.

AREAS COVERED

We review the current mainstays of pharmacotherapy against infections caused by carbapenem-resistant Enterobacteriaceae (CRE) including tigecycline, aminoglycosides, and rediscovered 'old' antibiotics such as fosfomycin and polymyxins, and discuss their efficacy and potential toxicity. We also summarize the contemporary clinical experience treating CRE infections with antibiotic combination therapy. Finally, we discuss ceftazidime/avibactam and imipenem/relebactam, containing a new generation of beta-lactamase inhibitors, which may offer alternatives to treat CRE infections. We critically evaluate the published literature, identify relevant clinical trials and review documents submitted to the United States Food and Drug Administration.

EXPERT OPINION

Defining the molecular mechanisms of resistance and applying insights about pharmacodynamic and pharmacokinetic properties of antibiotics, in order to maximize the impact of old and new therapeutic approaches should be the new paradigm in treating infections caused by CRE. A concerted effort is needed to carry out high-quality clinical trials that: i) establish the superiority of combination therapy vs. monotherapy; ii) confirm the role of novel beta-lactam/beta-lactamase inhibitor combinations as therapy against KPC- and OXA-48 producing Enterobacteriaceae; and, iii) evaluate new antibiotics active against CRE as they are introduced into the clinic.

[Colonization-outbreak of two clonally different strains of Serratia marcescens in a neonatal intensive care unit]

We describe an outbreak of two clonally different strains of Serratia marcescens in a neonatal intensive care unit. Three colonization cases in the first outbreak phase were related to contact transmission from an index patient during emergency respiratory treatment while eight colonizations in the second phase were caused by contaminated bathing lotion. All transmissions resulted in colonization only and no infections were recorded. Based on our experience and the literature review sufficient staffing levels, basic hygiene and a goal-directed investigation of the environment are the cornerstones of a rapid outbreak termination. The epidemiological search for parallels in cases should be assisted by sophisticated electronic records.

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.

Public health microbiology in Germany: 20 years of national reference centers and consultant laboratories

In 1995, in agreement with the German Federal Ministry of Health, the Robert Koch Institute established a public health microbiology system consisting of national reference centers (NRCs) and consultant laboratories (CLs). The goal was to improve the efficiency of infection protection by advising the authorities on possible measures and to supplement infectious disease surveillance by monitoring selected pathogens that have high public health relevance. Currently, there are 19 NRCs and 40 CLs, each appointed for three years. In 2009, an additional system of national networks of NRCs and CLs was set up in order to enhance effectiveness and cooperation within the national reference laboratory system. The aim of these networks was to advance exchange in diagnostic methods and prevention concepts among reference laboratories and to develop geographic coverage of services. In the last two decades, the German public health laboratory reference system coped with all major infectious disease challenges. The European Union and the European Centre for Disease Prevention and Control (ECDC) are considering implementing a European public health microbiology reference laboratory system. The German reference laboratory system should be well prepared to participate actively in this upcoming endeavor.

[Update on outbreaks reported from neonatal intensive care units: Serratia marcescens, Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa]

In terms of the unique risk profile, the clinical course of nosocomial infections, and the most prevalent bacterial pathogens, literature on outbreaks of potentially pathogenic bacteria on neonatal intensive care units (NICUs) needs to be analyzed separately from reports derived from other intensive care units. With the purpose 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. This review focuses on NICU outbreaks caused by Serratia marcescens, Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa.