Staphylococcus capitis isolated from bloodstream infections: a nationwide 3-month survey in 38 neonatal intensive care units

Emergence and establishment of Staphylococcus haemolyticus ST29 in two neonatal intensive care units in Western France

PURPOSE

Since 2021, several reports of Staphylococcus haemolyticus outbreaks in neonatal intensive care units (NICUs) have been reported in France. The aim of this study was to understand how S. haemolyticus became established in the NICUs of two facilities which share the care of newborns.

METHODS

All positive S. haemolyticus clinical samples isolated between 2020 and 2023 and medical records were analysed. Phenotypic analyses consisted of typing using the quantitative antibiogram method and microbiological investigations using whole genome sequencing. Environmental samples and samples from the hands of healthcare workers (HCWs) were collected, with the same analyses undertaken if S. haemolyticus was identified. Observational studies of the hygiene practices of HCWs were also performed.

RESULTS

One hundred and sixteen neonates were positive for S. haemolyticus, of whom 44 (38%) were infected. The ST29 strain was highly predominant, and distinct clonal populations were identified. Transfers of newborns between the two centres, followed by cross-transmissions, could explain the dissemination of one population. Twenty-one environmental samples revealed the presence of the clones involved in neonates. One clonal population was also found on the hands of 15% of the HCWs sampled. Misconceptions about alcohol-based hand rub were observed, and daily disinfection of NICU equipment was not optimal.

CONCLUSION

Preliminary reports point to cross-transmission within and between the NICUs, either directly via the hands of HCWs or indirectly via contaminated environments, especially incubators. The ST29 lineage is identified in most NICUs, with the capacity to adapt locally and cause outbreaks.

Fatal Superior Vena Cava Obstruction With High-Output Chylothorax in a Preterm Infant: A Complication of Central Venous Catheterization

Chylothorax in the perinatal period may have congenital or acquired aetiologies. In premature infants, invasive procedures with thrombosis risk are common practice. We present a case of a 29-week gestation neonate, diagnosed on the 27th postnatal day with vegetation on the tip of the central venous catheter (CVC) and right auricle thrombosis, along with superior vena cava (SVC) syndrome, leading to significant bilateral chylothorax. Despite antithrombotic therapy, extensive intramural SVC obstruction persisted. Surgical intervention was considered high risk in such a preterm infant. Lung function declined progressively, and the neonate died from cardiorespiratory failure at the age of 2 months and 26 days. A post-mortem examination revealed minimal SVC lumen obstruction, emphasizing the potential lethality of secondary complications, regardless of successful thrombolysis. This case highlights both the life-threatening risk of neonatal SVC thrombosis associated with CVC and the need to assess the causes of chylothorax for coexisting aetiologies.

Staphylococcus capitis: insights into epidemiology, virulence, and antimicrobial resistance of a clinically relevant bacterial species

SUMMARYStaphylococcus capitis is divided into two subspecies, S. capitis subsp. ureolyticus (renamed urealyticus in 1992; ATCC 49326) and S. capitis subsp. capitis (ATCC 27840), and fits with the archetype of clinically relevant coagulase-negative staphylococci (CoNS). S. capitis is a commensal bacterium of the skin in humans, which must be considered an opportunistic pathogen of interest particularly as soon as it is identified in a clinically relevant specimen from an immunocompromised patient. Several studies have highlighted the potential determinants underlying S. capitis pathogenicity, resistance profiles, and virulence factors. In addition, mobile genetic element acquisitions and mutations contribute to S. capitis genome adaptation to its environment. Over the past decades, antibiotic resistance has been identified for S. capitis in almost all the families of the currently available antibiotics and is related to the emergence of multidrug-resistant clones of high clinical significance. The present review summarizes the current knowledge concerning the taxonomic position of S. capitis among staphylococci, the involvement of this species in human colonization and diseases, the virulence factors supporting its pathogenicity, and the phenotypic and genomic antimicrobial resistance profiles of this species.

Staphylococcus capitis Central-Line-Associated Bloodstream Infections in the Neonatal Intensive Care Unit: A Single-Center, Four-Year Experience in Central-Line Management during Sepsis Treatment

Coagulase-negative staphylococci (CoNS) are reportedly responsible for 50-60% of bloodstream infections in very preterm (<1500 g) infants in neonatal intensive care units (NICUs). Staphylococcus capitis is an increasingly prevalent pathogen in the neonatal setting, frequently causing central-line-associated bloodstream infections (CLABSIs) that can be difficult to eradicate. Central venous catheter (CVC) removal versus in situ treatment with CoNS CLABSIs is a controversial treatment strategy with no clear consensus. We reviewed all S. capitis CLABSIs in our NICU between 2019 and 2022, focusing on the role of catheter removal in eradication. Among the 25 patients, 17 CVCs were removed after diagnosis, leading to a 76.5% eradication rate in this group. Three infants had a persistently positive blood culture after CVC substitution. A new catheter was then inserted after a 48 h washout period, resulting in resolution of the infection. Only two of the eight patients (25%) who retained their catheter after diagnosis achieved infection eradication with antibiotic therapy alone. When feasible, catheter removal seems to be the most effective strategy for eradicating S. capitis CLABSIs, sometimes even requiring a 48 h washout period before reinsertion. Further studies on this topic are needed to better standardize the management of this type of infection.

Identification of staphyloxanthin and derivates in yellow-pigmented Staphylococcus capitis subsp. capitis

Introduction

Staphylococcus capitis naturally colonizes the human skin but as an opportunistic pathogen, it can also cause biofilm-associated infections and bloodstream infections in newborns. Previously, we found that two strains from the subspecies S. capitis subsp. capitis produce yellow carotenoids despite the initial species description, reporting this subspecies as non-pigmented. In Staphylococcus aureus, the golden pigment staphyloxanthin is an important virulence factor, protecting cells against reactive oxygen species and modulating membrane fluidity.

Methods

In this study, we used two pigmented (DSM 111179 and DSM 113836) and two non-pigmented S. capitis subsp. capitis strains (DSM 20326T and DSM 31028) to identify the pigment, determine conditions under which pigment-production occurs and investigate whether pigmented strains show increased resistance to ROS and temperature stress.

Results

We found that the non-pigmented strains remained colorless regardless of the type of medium, whereas intensity of pigmentation in the two pigmented strains increased under low nutrient conditions and with longer incubation times. We were able to detect and identify staphyloxanthin and its derivates in the two pigmented strains but found that methanol cell extracts from all four strains showed ROS scavenging activity regardless of staphyloxanthin production. Increased survival to cold temperatures (-20°C) was detected in the two pigmented strains only after long-term storage compared to the non-pigmented strains.

Conclusion

The identification of staphyloxanthin in S. capitis is of clinical relevance and could be used, in the same way as in S. aureus, as a possible target for anti-virulence drug design.

Whole-genome sequencing reveals widespread presence of Staphylococcus capitis NRCS-A clone in neonatal units across the United Kingdom

OBJECTIVE

Increased incidence of neonatal Staphylococcus capitis bacteraemia in summer 2020, London, raised suspicion of widespread multidrug-resistant clone NRCS-A. We set out to investigate the molecular epidemiology of this clone in neonatal units (NNUs) across the UK.

METHODS

We conducted whole-genome sequencing (WGS) on presumptive S. capitis NRCS-A isolates collected from infants admitted to nationwide NNUs and from environmental sampling in two distinct NNUs in 2021. Previously published S. capitis genomes were added for comparison. Genetic clusters of NRCS-A isolates were defined based on core-genome single-nucleotide polymorphisms.

RESULTS

We analysed WGS data of 838 S. capitis isolates and identified 750 NRCS-A isolates. We discovered a possible UK-specific NRCS-A lineage consisting of 611 isolates collected between 2005 and 2021. We determined 28 genetic clusters of NRCS-A isolates, which covered all geographical regions in the UK, and isolates of 19 genetic clusters were found in ≥2 regions, suggesting inter-regional spread. Within the NRCS-A clone, strong genetic relatedness was identified between contemporary clinical and incubator-associated fomite isolates and between clinical isolates associated with inter-hospital infant transfer.

CONCLUSIONS

This WGS-based study confirms the dispersion of S. capitis NRCS-A clone amongst NNUs across the UK and urges research on improving clinical management of neonatal S. capitis infection.

Molecular epidemiology and antibiotic resistance of staphylococci other than Staphylococcus aureus in children in Cape Town, South Africa

Introduction

Staphylococci other than Staphylococcus aureus (SOSA) have emerged as significant pathogens in healthcare settings, particularly among patients with indwelling devices and immunocompromised individuals. Staphylococcus epidermidis, Staphylococcus haemolyticus and Staphylococcus hominis are the most common commensal SOSA species and are implicated in infections such as endocarditis and bacteremia. SOSA infections in neonates and children have been reported globally. Recent increases in antibiotic resistance and virulence among SOSA strains in clinical settings have highlighted the need to describe the reservoirs of SOSA to enable monitoring of these emerging pathogens.

Methods

Stool samples were collected from 150 healthy children from Cape Town communities between 2017 and 2020. Staphylococci were isolated, identified using mass-spectrometry, and antimicrobial susceptibility testing and Illumina whole genome sequencing were performed.

Results

Among the participants, 50 (33.3%) were colonized by SOSA, with S. haemolyticus (n = 38; 25.3%) being the most common, followed by S. hominis (n = 5; 3.3%) and Mammalicoccus sciuri (n = 5; 3.3%). Out of the 77 initially isolated S. haemolyticus strains, 23 were identified as Staphylococcus borealis through whole genome sequencing. All S. haemolyticus isolates (n = 49) were methicillin resistant, with 65.3% (n = 32) harbouring mecA. In S. haemolyticus, SCCmec type VIII(4A) was detected in 42.0% of ST9 isolates while non-mecA methicillin resistant S. haemolyticus isolates were mostly ST49 (41.1%). Additionally, 16 (50.0%) S. haemolyticus strains contained non-typeable SCCmec elements.

Discussion

High rates of methicillin resistance were identified among colonizing SOSA in Cape Town, increasing the risk of transmission to clinical settings. This study also identified a new species, S. borealis, for the first time in Africa.

Staphylococcus aureus and Coagulase-Negative Staphylococci from Bloodstream Infections: Frequency of Occurrence and Antimicrobial Resistance, 2018-2021

BACKGROUND

The abuse of antibiotics during the SARS-CoV-2 pandemic might have disrupted efforts to curb the further development and spread of the antimicrobial resistance of Staphylococcus aureus infection and Staphylococcus spp. coagulase-negative (CoNS) agents of nosocomial bloodstream infections (NBSIs). The purpose of our work was to study the resistance patterns of Staphylococcus aureus and CoNS through the analysis of blood cultures in hospitalized SARS-CoV-2-positive and SARS-CoV-2-negative patients (pts.).

MATERIALS AND METHODS

During the period January 2018-June 2021, a retrospective case-control study was performed on blood cultures positive for Staphylococcus spp. detected in 177 adult pts. (≥18 years old) hospitalized for >48 hours at Sant'Elia Hospital, Caltanissetta.

RESULTS

Staphylococcus aureus was isolated in 33.9% of blood culture samples, and among CoNS, the most frequent strains were Staphylococcus capitis (18.6%) and Staphylococcus hominis (18.1%). Patients aged ≥ 65 years, with a greater number of males, comprised the SARS-CoV-2-negative pts. (71.8% vs. 52.2%, p = 0.0154). Among the SARS-CoV-2-positive patients, the significant resistance of Staphylococcus aureus was only observed for erythromycin (57.1%). The oxacillin resistance of Staphylococcus capitis was higher in SARS-CoV-2-positive than in negative pts. (90% and 78.3%, respectively). Comparing the two groups, we found an increase in resistance in SARS-CoV-2-negative patients for the following antibiotics: gentamicin for Staphylococcus aureus (p = 0.007), clindamycin and erythromycin (p = 0.012) for Staphylococcus hominis and oxacillin and rifampicin for Staphylococcus haemoliticus (p = 0.012).

CONCLUSIONS

Our study confirms the relevance of oxacillin-resistant Staphylococcus aureus in being responsible for bloodstream infection and draws attention to highly oxacillin-resistant CoNS such as Staphylococcus capitis. The presence of resistant strains of CoNS in hospitals can be worrying, as it limits treatment options and worsens outcomes. The Infection Control Committee (ICC) recommends new treatment strategies to decrease colonization and infections. As part of the implementation of a bloodstream infection prevention program, the authors encourage the introduction of a report on the antimicrobial resistance of hospital bacteremia due to CoNS.

Prevalence, biofilm formation, and mass spectrometric characterization of linezolid-resistant Staphylococcus capitis isolated from a tertiary hospital in China

OBJECTIVES

Linezolid-resistant Staphylococcus capitis (LRSC) has become a new challenge for clinical anti-infective therapy. The present study aimed to investigate the trends of LRSC prevalence in a tertiary hospital of China 2017-2020. The resistance mechanisms, virulence genes, biofilm formation, and mass spectrometric characteristics of LRSC isolates were also analysed.

METHODS

This study retrospectively analysed the antibiotic resistance trends of coagulase negative staphylococci (CoNS) isolated from clinical samples collected between 2017-2020. Antimicrobial resistance profiles were tested by micro-broth dilution and the E-test method. Antimicrobial resistance genes and virulence genes were detected by polymerase chain reaction, and dru-typing sequences were obtained by Sanger sequencing. Crystal violet staining in 96-well plates was used to detect biofilm formation ability. Mass spectrometric characterization of LRSC was analysed by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) coupled with ClinProTools.

RESULTS

The linezolid resistance rate in 3575 CoNS clinical strains was 1.6%, wherein the great majority of was LRSC (91.1%, n = 51/56), with a resistant rate of 15.5% (n = 51/328) in all S. capitis isolates. In this study, 48 out of the 51 LRSC strains and 54 of 277 linezolid-susceptible S. capitis (LSSC) strains were enrolled. G2576T, C2104T, T2130A, C2163T, and T2319C mutations in the 23S rRNA V region and acquisition of cfr were the main linezolid resistant mechanisms in LRSC. The biofilm-forming ability of LRSC was more potent than LSSC, with a higher detection rate of bap (P < 0.05). Eleven mass spectrometric peaks of interest were identified by using MALDI-TOF MS and ClinProTools, which were differently distributed between LRSC and LSSC strains, with the area under the receiver operating characteristic curve of more than 0.8, especially for 5465.37 m/z.

CONCLUSIONS

Linezolid resistance was mediated by mutations in the 23S rRNA V region and presence of the cfr gene in LRSC strains. LRSC strains have stronger biofilm-forming ability than LSSC strains, which maybe associated with the adhesion-related gene of bap. Further, linezolid-resistant and linezolid-susceptible S. capitis could be rapidly identified with mass spectrometric characterization. To the best of our knowledge, this study is the first to document the biofilm formation ability of LRSC and the potential usefulness of MALDI-TOF MS for the discrimination of LRSC and LSSC.

Determinants of morbidity and mortality related to health care-associated primary bloodstream infections in neonatal intensive care units: a prospective cohort study from the SEPREVEN trial

Background

Health care-associated primary bloodstream infections (BSIs), defined as not secondary to an infection at another body site, including central line-associated BSI, are a leading cause of morbidity and mortality in patients in neonatal intensive care units (NICUs). Our objective was to identify factors associated with severe morbidity and mortality after these infections in neonates in NICUs.

Methods

This ancillary study of the SEPREVEN trial included neonates hospitalized ≥2 days in one of 12 French NICUs and with ≥ 1 BSI during the 20-month study period. BSIs (all primary and health care-associated) were diagnosed in infants with symptoms suggestive of infection and classified prospectively as possible (one coagulase-negative staphylococci (CoNS)-growing blood culture) or proven (two same CoNS, or ≥1 recognized pathogen-growing blood culture). BSI consequences were collected prospectively as moderate morbidity (antibiotic treatment alone) or severe morbidity/mortality (life-saving procedure, permanent damage, prolonged hospitalization, and/or death).

Results

Of 557 BSIs identified in 494 patients, CoNS accounted for 378/557 (67.8%) and recognized bacterial or fungal pathogens for 179/557 (32.1%). Severe morbidity/mortality was reported in 148/557 (26.6%) BSIs. Independent factors associated with severe morbidity/mortality were corrected gestational age <28 weeks (CGA) at infection (P < .01), fetal growth restriction (FGR) (P = .04), and proven pathogen-related BSI vs. CoNS-related BSI (P < .01). There were no differences in severe morbidity and mortality between proven and possible CoNS BSIs. In possible BSI, S. epidermidis was associated with a lower risk of severe morbidity than other CoNS (P < .01), notably S. capitis and S. haemolyticus.

Conclusions

In BSIs in the NICU, severe morbidity/mortality was associated with low CGA at infection, FGR, and proven pathogen-related BSIs. When only one blood culture was positive, severe morbidity/mortality were less frequent if it grew with S. epidermidis compared to other CoNS. Further studies to help distinguish real CoNS BSIs from contaminations are needed.

Study registration

ClinicalTrials.gov (NCT02598609).

Staphylococcus capitis: Review of Its Role in Infections and Outbreaks

In June 2021, a national incident team was formed due to an increased detection of Staphylococcus capitis in samples from hospitalised infants. Staphylococcus capitis has been known to cause outbreaks in neonatal units across the globe, but the extent of the UK spread was unclear. A literature review was undertaken to support case identification, clinical management and environmental infection control. A literature search was undertaken on multiple databases from inception to 24 May 2021, using keywords such as “Staphylococcus capitis”, “NRCS-A”, “S. capitis”, “neonate”, “newborn” and “neonatal intensive care unit” (NICU). After screening, 223 articles of relevance were included. Results show incidences of S. capitis outbreaks have frequently been associated with the outbreak clone (NRCS-A) and environmental sources. The NRCS-A harbours a multidrug resistance profile that includes resistance to beta-lactam antibiotics and aminoglycosides, with several papers noting resistance or heteroresistance to vancomycin. The NRCS-A clone also harbours a novel SCCmec-SCCcad/ars/cop composite island and increased vancomycin resistance. The S. capitis NRCS-A clone has been detected for decades, but the reasons for the potentially increased frequency are unclear, as are the most effective interventions to manage outbreaks associated with this clone. This supports the need for improvements in environmental control and decontamination strategies to prevent transmission.

Bacterial exposure risk to the endoscopist's face while performing endoscopy

Objectives

Gastrointestinal endoscopy increases the risk of bacterial exposure to endoscopists. However, before 2019, most endoscopists did not pay attention to microorganism transmission from patients. This study aimed to investigate the incidence of bacterial exposure to endoscopists' faces during gastrointestinal endoscopic procedures using the bacterial culture method.

Methods

This was a single-centered, retrospective study including endoscopists who performed various gastrointestinal endoscopy procedures at the Division of Endoscopy, Hirosaki University Hospital between August 31 and October 6, 2020. Endoscopists wore surgical masks and affixed pre-sterilized films over them. Following the gastrointestinal endoscopic procedures, attached microbes were collected from the endoscopists' surface films using sterilized swabs. Collected microorganisms were cultured on tryptic soy agar and 5% sheep blood agar, and the incidence of bacterial exposure was determined by bacterial culture positivity. Cultured bacteria were identified by gram staining and 16S rRNA gene sequencing.

Results

Bacterial culture positivity was 12.6%, and it was significantly higher in therapeutic than in diagnostic endoscopy. Notably, therapeutic endoscopy increased bacterial culture positivity in colonoscopy, but not in esophagogastroduodenoscopy. Staphylococci, including Staphylococcus epidermidis and Staphylococcus capitis, were the most commonly found bacteria in samples identified through 16S rRNA gene sequencing.

Conclusions

The risk of bacterial exposure to the endoscopist's face was increased in colonoscopy treatment procedures. Therefore, endoscopists should be aware of the significant risk of microbial infection from scattering fluid that comes from the endoscopy's working channel.

Neonatal bloodstream infections

PURPOSE OF REVIEW

Neonatal bloodstream infections (BSI) are a major contributor to morbidity and mortality within neonatal intensive care units. BSI, including central line-associated BSI, have decreased over the past 15 years but remain common in extremely preterm infants. The purpose of this review is to highlight recent advances in the causes, diagnosis, management, and prevention of neonatal BSI.

RECENT FINDINGS

Continued quality improvement efforts and bundles have reduced BSI incidence, and novel approaches are highlighted. An update of emerging pathogens as well as traditional pathogens with novel antimicrobial resistance, which are an increasingly common cause of neonatal BSI, is included. Finally, current and future investigations into serum or noninvasive biomarkers for neonatal BSI are reviewed.

SUMMARY

Neonatal BSIs continue to decrease due to enhanced infection control and prevention techniques. However, many challenges remain, including emerging bacterial and fungal resistance and the continued need for novel diagnostics that hasten time to pathogen identification and effective treatment. This review of the past 18 months highlights the rapid changes in this area. Ongoing efforts to reduce the morbidity and mortality caused by neonatal BSI must remain a priority.