Recurrent outbreaks of Serratia marcescens among neonates and infants at a pediatric department: an outbreak analysis

Prevalence and risk factors associated with drug resistant bacteria in neonatal and pediatric intensive care units: A retrospective study in Saudi Arabia

Successful empirical antibiotic therapy for infected patients with multi drug resistant bacteria (MDR) can be challenging task in various healthcare settings, including neonatal and pediatric intensive care units (NICU and PICU, respectively), unless an up-to-date comprehensive local antibiogram data is available. Thus, this project aimed to investigate the prevalence of MDR among PICU and NICU patients as well as the identification of risk factors associated with recovered MDR bacteria. This was a retrospective study of PICU and NICU patients admitted with bacterial infection of MDR organisms between October 2020 and May 2021. Frequency distribution, Chi-square test were applied to verify the significance differences among subgroups and to identify risk factor associated with each group. About 36.4% of recruited patients were neonates, while the remaining percentage (63.6%) were pediatric. The most predominant site of infection among these patients were revealed as urinary tract (35%), followed by bloodstream (20.0%), wound/skin (12.9%) and respiratory system (11.4%). Methicillin-resistant Staphylococcus aureus (MRSA) was identified as the most common microbe across these sites of infections (30.7%), followed by Escherichia coli (25.0%), Klebsiella pneumoniae (22.9%) and Serratia (10.0%). High mortality rate was significantly associated with patients who were on mechanical ventilators (28.9%, OR 5.5; 95% CI), followed by patients had invasive operation (27.5%, OR, 8.04; 95% CI) and those who required a total parental nutrition (TPN) since almost one-half of these cases have (46.2%) died. In addition, mortality rate was relatively higher among patients infected with species of Serratia (28.6%) and Enterobacter (20.0%). These data highlighted that MRSA was the main MDR bacteria isolated from PICU and NICU followed by gram-negative bacteria, which were associated with high mortality rate. Therefore, infection control measures and continuous monitoring of emerging MDR bacteria should be applied to limit the bacterial infections in NICU and PICU patients.

A fatal outbreak of neonatal sepsis caused by mcr-10 carrying Enterobacter kobei in a tertiary care hospital in Nepal

BACKGROUND

Enterobacter kobei is an emerging cause of outbreak of nosocomial infections in neonatal intensive care units (NICUs). Between July and September of 2016, an NICU in a tertiary care hospital of Nepal observed an abrupt increase in the number of neonatal sepsis cases caused by Enterobacter spp. infecting 11 of 23 admitted neonates, 5 of whom died of an exacerbated sepsis.

AIM

Main aims of this study were to confirm the suspected outbreak, identify environmental source of infection, and characterize genetic determinants of antimicrobial resistance (AMR) and virulence of the pathogen.

METHODS

We performed whole genome sequencing of all Enterobacter spp. isolated from blood cultures of septic neonates admitted to NICU between May 2016 and December 2017. Also, an environmental sampling was intensified from fortnightly to weekly during the outbreak.

FINDINGS

The genomic analysis revealed that 10 of 11 non-duplicated E. kobei isolated from neonatal blood cultures between July and September 2016 were clonal, confirming the outbreak. The isolates carried AMR genes including bla_AmpC and mcr-10 conferring reduced susceptibility to carbapenem and colistin respectively. The environmental sampling however failed to isolate any Enterobacter spp. Reinforcement of aseptic protocols in invasive procedures, hand hygiene, environmental decontamination, fumigation, and secluded care of culture positive cases successfully terminated the outbreak.

CONCLUSION

Our study underscored the need to implement stringent infection control measures to prevent infection outbreaks. Further, for the first time, we report the emergence of carbapenem and colistin non-susceptible E. kobei carrying mcr-10 gene as an important cause of nosocomial neonatal sepsis in an NICU.

Exploring the antibacterial, antibiofilm, and antivirulence activities of tea tree oil-containing nanoemulsion against carbapenem-resistant Serratia marcescens associated infections

Carbapenem-resistant Serratia marcescens (CRE-S. marcescens) has recently emerged as an opportunistic human pathogen that causes various nosocomial and respiratory tract infections. The prognosis for CRE-S. marcescens-related infections is very poor and these infections are difficult to treat. This study investigated the synthesis of tea tree oil nanoemulsion (TTO-NE) and its impact on CRE-S. marcescens both in vitro and in vivo. TTO-NE was characterized by dynamic light scattering (DLS) and effectively eradicated bacterial planktonic and sessile forms, reduced bacterial virulence factors, and generated reactive oxygen species (ROS) in the bacterial cell. Notably, TTO-NE was efficient in reducing the colonization of CRE-S. marcescens in a C. elegans in vivo model. The data suggest that TTO-NE might be an excellent tool to combat infections associated with CRE-S. marcescens.

Mechanisms of recurrent outbreak of COVID-19: a model-based study

Recurrent outbreaks of the coronavirus disease 2019 (COVID-19) have occurred in many countries around the world. We developed a twofold framework in this study, which is composed by one novel descriptive model to depict the recurrent global outbreaks of COVID-19 and one dynamic model to understand the intrinsic mechanisms of recurrent outbreaks. We used publicly available data of cumulative infected cases from 1 January 2020 to 2 January 2021 in 30 provinces in China and 43 other countries around the world for model validation and further analyses. These time series data could be well fitted by the new descriptive model. Through this quantitative approach, we discovered two main mechanisms that strongly correlate with the extent of the recurrent outbreak: the sudden increase in cases imported from overseas and the relaxation of local government epidemic prevention policies. The compartmental dynamical model (Susceptible, Exposed, Infectious, Dead and Recovered (SEIDR) Model) could reproduce the obvious recurrent outbreak of the epidemics and showed that both imported infected cases and the relaxation of government policies have a causal effect on the emergence of a new wave of outbreak, along with variations in the temperature index. Meanwhile, recurrent outbreaks affect consumer confidence and have a significant influence on GDP. These results support the necessity of policies such as travel bans, testing of people upon entry, and consistency of government prevention and control policies in avoiding future waves of epidemics and protecting economy.

Towards accurate exclusion of neonatal bacterial meningitis: a feasibility study of a novel 16S rDNA PCR assay

Background

PCRctic is an innovative assay based on 16S rDNA PCR technology that has been designed to detect a single intact bacterium in a specimen of cerebro-spinal fluid (CSF). The assay’s potential for accurate, fast and inexpensive discrimination of bacteria-free CSF makes it an ideal adjunct for confident exclusion of bacterial meningitis in newborn babies where the negative predictive value of bacterial culture is poor. This study aimed to stress-test and optimize PCRctic in the “field conditions” to attain a clinically useful level of specificity.

Methods

The specificity of PCRctic was evaluated in CSF obtained from newborn babies investigated for meningitis on a tertiary neonatal unit. Following an interim analysis, the method of skin antisepsis was changed to increase bactericidal effect, and snap-top tubes (Eppendorf™) replaced standard universal containers for collection of CSF to reduce environmental contamination.

Results

The assay’s specificity was 90.5% in CSF collected into the snap-top tubes – up from 60% in CSF in the universal containers. The method of skin antisepsis had no effect on the specificity. All CSF cultures were negative and no clinical cases of neonatal bacterial meningitis occurred during the study.

Conclusions

A simple and inexpensive optimization of CSF collection resulted in a high specificity output. The low prevalence of neonatal bacterial meningitis means that a large multi-centre study will be required to validate the assay’s sensitivity and its negative predictive value.

Genetic Diversity of Pediculus humanus capitis (Phthiraptera: Pediculidae) in Peninsular Malaysia and Molecular Detection of Its Potential Associated Pathogens

Pediculosis capitis caused by Pediculus humanus capitis (De Geer) is endemic all over the world, and children are mostly affected, particularly those living in overcrowded institutions. Several studies have shown that P. h. capitis carried human pathogenic bacteria, suggesting the potential role of head lice in the transmission of pathogens to humans. In this study, we determined the genetic diversity of head lice collected from welfare homes sheltering underprivileged children by using DNA barcoding and demonstrated the presence of Acinetobacter spp., Serratia marcescens, and Staphylococcus aureus in head lice, which have never been investigated before in Malaysia. Cox1 DNA barcoding identified the head lice, P. h. capitis collected from welfare homes across two geographical areas of Peninsular Malaysia as belonging to clades A, B, and D. Acinetobacter bacteria: Acinetobacter guillouiae, Acinetobacter junii, Acinetobacter baumannii, and Acinetobacter nosocomialis were detected in head lice belonging to clades A and also D. In addition, DNA from S. marcescens and S. aureus were also detected in both clades A and D. To our knowledge, this is the first report on the genetic diversity of head lice in Malaysia through DNA barcoding, as well as the first to provide molecular evidence on the type of bacteria occurring in head lice in Malaysia. It is anticipated that the DNA barcoding technique used in this study will be able to provide rapid and accurate identification of arthropods, in particular, medically important ectoparasites.

Serratia marcescens colonization in preterm neonates during their neonatal intensive care unit stay

Background

Nosocomial sepsis is the main problem that preterms have to face during their stay at neonatal intensive care units (NICU). Serratia marcescens is an emerging cause of preterm sepsis but its epidemiology is still largely unknown. Consequently, the aims of this study were to know the rate of preterms colonized by S. marcescens during their stay at the NICU and the characteristics and evolution of the S. marcescens population, including the susceptibility to clinically relevant antibiotics.

Methods

Twenty-six preterm infants born with a gestational age ≤ 32 weeks and/or weigh ≤1500 g were included in the study. Samples of meconium and feces (n = 92) were collected during their first month of life of the infants, together with feeding samples after their pass through enteral feeding tubes (n = 37). Samples were inoculated on MacConkey agar plates. The isolates identified as S. marcescens were genotyped using RAPD and PFGE; and antibiotics susceptibility was performed in a Vitek 2 system.

Results

A total of 179 S. marcescens isolates were obtained from the samples. PFGE profiling and cluster analysis allowed the classification of the isolates into 7 different S. marcescens clones. PFGE patterns 1 and 3 were the dominant strains in the fecal samples colonizing 31 and 35% of the infants, respectively. Those isolates causing bacteremia in two infants clustered in PFGE pattern 3.

Conclusion

S. marcescens is a bacterial species closely associated to the NICU environment. It can be frequently isolated from preterm’s feces although only some genetic lineages seem to be associated to sepsis. Enteral feeding tubes act as important reservoirs to keep the S. marcescens population in the NICU.

Trial registration

The local ethic committee approved this trial with the reference 09/157.

Use of MALDI-TOF mass spectrometry to detect nosocomial outbreaks of Serratia marcescens and Citrobacter freundii

MALDI-TOF mass spectrometry (MS) may be used as a rapid typing method for nosocomial pathogens. Here, we evaluated MALDI-TOF MS for discrimination of hospital outbreak-related clusters of Serratia marcescens and carbapenemase-producing Citrobacter freundii. Thirty-three S. marcescens isolates collected from neonatal intensive care unit (NICU) patients, and 23 C. freundii isolates including VIM-positive isolates from a hospital colonization outbreak were measured by Vitek MS. Consensus spectra of each isolate were clustered using SARAMIS software. Genotyping was performed by whole-genome sequencing (WGS). First, a set of 21 S. marcescens isolates from 2014 with seven genotypes including three monoclonal clusters was used for the evaluation of MALDI-TOF typing. MS clustering was largely in agreement with genotyping results when the similarity cut-off for clonal identity was set on 90%. MALDI-TOF cluster analysis was then investigated for the surveillance of S. marcescens in the NICU in 2017 and demonstrated the introduction of new strains into the hospital and nosocomial transmissions. MS analysis of the C. freundii outbreak in 2016 revealed a monoclonal cluster of VIM-positive isolates and the separation of epidemiologically non-related VIM-positive and negative isolates. Two additional VIM-positive Citrobacter isolates from food samples were closely related to the large monoclonal cluster. WGS confirmed the MS results. MALDI-TOF MS may be used as a first-line typing tool for S. marcescens and C. freundii to detect transmission events in the hospital because isolates of an identical WGS type were grouped into the same MS cluster.

Sink traps as the source of transmission of OXA-48-producing Serratia marcescens in an intensive care unit

BACKGROUND

Carbapenemase-producing Enterobacteriaceae (CPE) outbreaks are mostly attributed to patient-to-patient transmission via healthcare workers.

OBJECTIVE

We describe successful containment of a prolonged OXA-48-producing S. marcescens outbreak after recognizing the sink traps as the source of transmission.

METHODS

The Sheba Medical Center intensive care unit (ICU), contains 16 single-bed, semi-closed rooms. Active CPE surveillance includes twice-weekly rectal screening of all patients. A case was defined as a patient detected with OXA-48 CPE >72 hours after admission. A root-cause analysis was used to investigate the outbreak. All samples were inoculated on chrom-agar CRE, and carbapenemase genes were detected using commercial molecular Xpert-Carba-R. Environmental and patient S. marcescens isolates were characterized using PFGE.

RESULTS

From January 2016 to May 2017, 32 OXA-48 CPE cases were detected, and 81% of these were S. marcescens. A single clone was the cause of all but the first 2 cases. The common factor in all cases was the use of relatively large amounts of tap water. The outbreak clone was detected in 2 sink outlets and 16 sink traps. In addition to routine strict infection control measures, measures taken to contain the outbreak included (1) various sink decontamination efforts, which eliminated the bacteria from the sink drains only temporarily and (2) educational intervention that engaged the ICU team and lead to high adherence to 'sink-contamination prevention guidelines.' No additional cases were detected for 12 months.

CONCLUSIONS

Despite persistence of the outbreak clones in the environmental reservoir for 1 year, the outbreak was rapidly and successfully contained. Addressing sink traps as hidden reservoirs played a major role in the intervention.

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.

Necrotizing fasciitis due to Serratia marcescens: case report and review of the literature

BACKGROUND

Necrotizing fasciitis is a severe, life-threatening infection.  Serratia marcescens, a Gram-negative bacterium, is an extremely rare cause of necrotizing fasciitis.

METHODS

A case of S. marcescens necrotizing fasciitis is described, and a comprehensive review of the literature (1966-2015) of monomicrobial cases due to this organism performed.

RESULTS

We report the first case of S. marcescens necrotizing fasciitis in the setting of calciphylaxis associated with end-stage renal disease.  A comprehensive review of the literature of S. marcescens necrotizing fasciitis is provided to enhance the awareness of this increasingly recognized infection, and to provide a concise summary of risk factors, treatment, and outcome.

CONCLUSIONS

Our case and review highlight the potential risk factors for S. marcescens necrotizing fasciitis, including underlying renal disease and open wounds, and demonstrate the emergence of this organism as a cause of severe, life-threatening soft tissue infections.

Phenol, 2,4-bis(1,1-dimethylethyl) of marine bacterial origin inhibits quorum sensing mediated biofilm formation in the uropathogen Serratia marcescens

Intercellular communication in bacteria (quorum sensing, QS) is an important phenomenon in disease dissemination and pathogenesis, which controls biofilm formation also. This study reports the anti-QS and anti-biofilm efficacy of seaweed Gracilaria gracilis associated Vibrio alginolyticus G16 against Serratia marcescens. Purification and mass spectrometric analysis revealed the active principle as phenol, 2,4-bis(1,1-dimethylethyl) [PD]. PD affected the QS regulated virulence factor production in S. marcescens and resulted in a significant (p < 0.05) reduction in biofilm (85%), protease (41.9%), haemolysin (69.9%), lipase (84.3%), prodigiosin (84.5%) and extracellular polysaccharide (84.62%) secretion without hampering growth, as evidenced by XTT [2,3-bis (2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide] assay. qPCR analysis confirmed the down-regulation of the fimA, fimC, flhD and bsmA genes involved in biofilm formation. Apart from biofilm inhibition and disruption, PD increased the susceptibility of S. marcescens to gentamicin when administered synergistically, which opens another avenue for combinatorial therapy where PD can be used to enhance the efficacy of conventional antibiotics.