Spread of clonal linezolid-resistant Staphylococcus epidermidis in an intensive care unit associated with linezolid exposure

Outbreak of multidrug-resistant Staphylococcus haemolyticus ST29 in a French neonatal unit

BACKGROUND

Staphylococcus haemolyticus is a clinically relevant coagulase-negative staphylococcus frequently responsible for hospital-acquired infections, especially in premature newborns.

AIM

To describe an outbreak of multidrug-resistant S. haemolyticus in a neonatal department.

METHODS

The outbreak was investigated using classical methods, including screening of the patients, genotyping of the isolates and environmental survey. Numerous infection control measures were implemented.

FINDINGS

In 2022 and 2023, a clonal outbreak of multidrug-resistant S. haemolyticus ST29 (40 infections and 71 carriages) occurred in the neonatology department of a University Hospital in France. The infection control measures implemented only partially controlled the outbreak. Although our investigation did not clearly identify the source and mode of transmission, a reservoir constituted by patients and transmission by healthcare workers are the most likely. This episode occurred in a context of countrywide outbreaks of S. haemolyticus ST29 in several French neonatology departments.

CONCLUSION

This prolonged outbreak of S. haemolyticus ST29 accounted for the increase in the incidence of S. haemolyticus-related infections in French neonatology departments. Implementation of proactive measures is crucial to limit the spread of such pathogens in neonatal ICUs.

Investigation of a linezolid-resistant Staphylococcus epidermidis outbreak in a French hospital: phenotypic, genotypic, and clinical characterization

Purpose

We aimed to retrospectively investigate an outbreak of linezolid-resistant Staphylococcus epidermidis (LRSE), at Tours University Hospital between 2017 and 2021.

Methods

Twenty of the 34 LRSE isolates were included in the study. Antimicrobial susceptibility testing was performed using the disk diffusion method and MICs of last-resort antibiotics were determined using broth microdilution or Etest®. Seventeen of the 20 resistant strains were sent to the French National Reference Centre for Staphylococci to determine the mechanism of resistance to linezolid. The clonal relationship between LRSE strains was assessed by PFGE and the sequence type determined by MLST. We retrospectively evaluated a new typing tool, IR-Biotyper®, and compared its results to PFGE to evaluate its relevance for S. epidermidis typing. Medical records were reviewed, and antibiotic consumption was determined. Search for a cross transmission was performed.

Results

All LRSE strains showed high levels of resistance to linezolid (MICs ≥ 256 mg/L) and were multi-drug resistant. Linezolid resistance was associated with the 23S rRNA G2576T mutation and none of the 17 strains analyzed carried the cfr gene. Ninety-five percent of the 20 LRSE studied strains were genetically related and belonged to sequence-type ST2. The dendrogram obtained from IR-Biotyper® showed 87% congruence with the PFGE analysis. Prior to isolation of the LRSE strain, 70% of patients received linezolid. No patients stayed successively in the same room.

Conclusion

Linezolid exposure may promote the survival and spread of LRSE strains. At Tours University Hospital, acquisition of the resistant clone may also have been triggered by hand-to-hand transmission by healthcare workers. In addition, IR-Biotyper® is a promising typing tool for the study of clonal outbreaks due to its low cost and short turnaround time, although further studies are needed to assess the optimal analytical parameters for routine use.

Characterization of linezolid- and methicillin-resistant coagulase-negative staphylococci in a tertiary hospital in China

BACKGROUND

Recently, linezolid-resistant staphylococci have become an emerging problem worldwide. Understanding the mechanisms of resistance, molecular epidemiology and transmission of linezolid-resistant CoNS in hospitals is very important.

METHODS

The antimicrobial susceptibilities of all isolates were determined by the microdilution method. The resistance mechanisms and molecular characteristics of the strains were determined using whole-genome sequencing and PCR.

RESULTS

All the strains were resistant to oxacillin and carried the mecA gene; 13 patients (36.1%) had prior linezolid exposure. Most S. epidermidis and S. hominis isolates were ST22 and ST1, respectively. MLST typing and evolutionary analysis indicated most linezolid-resistant CoNS strains were genetically related. In this study, we revealed that distinct CoNS strains have different mechanisms of linezolid resistance. Among ST22-type S. epidermidis, acquisition of the T2504A and C2534T mutations in the V domain of the 23 S rRNA gene, as well as mutations in the ribosomal proteins L3 (L101V, G152D, and D159Y) and L4 (N158S), were linked to the development of linezolid resistance. In S. cohnii isolates, cfr, S158Y and D159Y mutations in the ribosomal protein L3 were detected. Additionally, emergence of the G2576T mutation and the cfr gene were major causes of linezolid resistance in S. hominis isolates. The cfr gene, G2576T and C2104T mutations, M156T change in L3 protein, and I188S change in L4 protein were found in S. capitis isolates.

CONCLUSION

The emergence of linezolid-resistant CoNS in the environment is concerning because it involves clonal dissemination and frequently coexists with various drug resistance mechanisms.

Staphylococcus epidermidis bloodstream infections are a cause of septic shock in intensive care unit patients

OBJECTIVES

Staphylococcus epidermidis (SE) is a supposedly low-virulence agent, which may cause proven bloodstream infections (BSIs), with little-known consequences on intensive care unit (ICU) patients. We aimed at studying ICU patients diagnosed with BSIs caused by SE (SE-BSIs).

METHODS

We constituted a retrospective cohort in two medical ICUs. SE-BSIs were defined by two or more independent SE-positive blood cultures of the same strain, within 48 hours, without concurrent infection.

RESULTS

We included 59 patients; 58% were men (n = 34), with median age of 67 (interquartile range 60-74) years and a simplified acute physiology score II of 59 (36-74) points, and 56% were immunocompromised (n = 33). Among the 37 (63%) patients requiring norepinephrine initiation or increase at the onset of SE-BSI versus patients not requiring vasopressors (37%; n = 22), concomitant arterial lactate levels reached 2.8 (1.9-5.8) versus 1.5 (1.3-2.2) mmol/l (P <0.01), whereas the mean blood pressure was 49 (42-54) versus 61 (56-65) mm Hg (P = 0.01) and the mortality was 46% (n = 17) vs 14% (n = 3) at day 28 (P = 0.01), respectively. Regarding antibiotics, the susceptibility rates toward linezolid and vancomycin were 71% (n = 41/58) and 100% (n = 54/54), respectively. At the time of SE-BSI, all but one patient had a central venous access device.

CONCLUSION

This work highlights SE-BSIs as a cause of septic shock, mostly in immunocompromised ICU patients, with increasing concerns about resistance to antibiotics and central line management.

Molecular Characterization of Clinical Linezolid-Resistant Staphylococcus epidermidis in a Tertiary Care Hospital

Staphylococcus epidermidis (S. epidermidis) is part of the human skin flora but can also cause nosocomial infections, such as device-associated infections, especially in vulnerable patient groups. Here, we investigated clinical isolates of linezolid-resistant S. epidermidis (LRSE) collected from blood cultures at the University Hospital Münster (UHM) during the period 2020-2022. All detected isolates were subjected to whole genome sequencing (WGS) and the relatedness of the isolates was determined using core genome multilocus sequence typing (cgMLST). The 15 LRSE isolates detected were classified as multilocus sequence type (ST) 2 carrying the staphylococcal cassette chromosome mec (SCCmec) type III. All isolates showed high-level resistance for linezolid by gradient tests. However, no isolate carried the cfr gene that is often associated with linezolid resistance. Analysis of cgMLST data sets revealed a cluster of six closely related LRSE isolates, suggesting a transmission event on a hematological/oncological ward at our hospital. Among the included patients, the majority of patients affected by LRSE infections had underlying hematological malignancies. This confirms previous observations that this patient group is particularly vulnerable to LRSE infection. Our data emphasize that the surveillance of LRSE in the hospital setting is a necessary step to prevent the spread of multidrug-resistant S. epidermidis among vulnerable patient groups, such as patients with hematological malignancies, immunosuppression or patients in intensive care units.

The Effects of Antiperspirant Aluminum Chlorohydrate on the Development of Antibiotic Resistance in Staphylococcus epidermidis

This study investigates the effects of the antiperspirant aluminum chlorohydrate on the development of antibiotic resistance in commensal Staphylococcus epidermidis isolates. The isolates were exposed to aluminum chlorohydrate for 30 days. The bacteria that developed resistance to oxacillin and ciprofloxacin were isolated, and the expression levels of some antibiotic resistance genes were determined using quantitative reverse transcriptase PCR. Before and after exposure, the minimum inhibitory concentration (MIC) values of the bacteria were determined using the microdilution method. A time-dependent increase was observed in the number of bacteria that developed resistance and increased MIC values. Consistent with the ciprofloxacin resistance observed after exposure, an increase in norA, norB/C, gyrA, gyrB, parC, and parE gene expression was observed. In addition to aluminum chlorohydrate exposure, oxacillin resistance was observed in all test bacteria in the group only subcultured in the medium, suggesting that phenotypic resistance cannot be correlated with chemical exposure in light of these data. The increase in mecA gene expression in selected test bacteria that acquired resistance to oxacillin after exposure compared with control groups suggests that the observed resistance may have been related to aluminum chlorohydrate exposure. To our knowledge, this is the first time in the literature that the effects of aluminum chlorohydrate as an antiperspirant on the development of antibiotic resistance in Staphylococcus epidermidis have been reported.

Trends of Antimicrobial Susceptibility in Clinically Significant Coagulase-Negative Staphylococci Isolated from Cerebrospinal Fluid Cultures in Neurosurgical Adults: a Nine-Year Analysis

Coagulase-negative staphylococci (CoNS) are the main pathogens in health care-associated ventriculitis and meningitis (HCAVM). This study aimed to assess antimicrobial susceptibility. Moreover, the treatment and clinical outcome were described. All neurosurgical adults admitted to one of the largest neurosurgical centers in China with clinically significant CoNS isolated from cerebrospinal fluid cultures in 2012 to 2020 were recruited. One episode was defined as one patient with one bacterial strain. Interpretive categories were applied according to the MICs. The clinical outcomes were dichotomized into poor (Glasgow Outcome Scale 1 to 3) and acceptable (Glasgow Outcome Scale 4 to 5). In total, 534 episodes involving 519 patients and 16 bacteria were analyzed. Over the 9 years, eight antimicrobial agents were used in antimicrobial susceptibility tests, including six in over 80% of CoNS. The range of resistance rates was 0.8% to 84.6%. The vancomycin resistance rate was the lowest, whereas the penicillin resistance rate was the highest. The linezolid (a vancomycin replacement) resistance rate was 3.1%. The rate of oxacillin resistance, representing methicillin-resistant staphylococci, was 70.2%. There were no significant trends of antimicrobial susceptibility over the 9 years for any agents analyzed. However, there were some apparent changes. Notably, vancomycin-resistant CoNS appeared in recent years, while linezolid-resistant CoNS appeared early and disappeared in recent years. Vancomycin (or norvancomycin), the most common treatment agent, was used in 528 (98.9%) episodes. Finally, 527 (98.7%) episodes had acceptable outcomes. It will be safe to use vancomycin to treat CoNS-related HCAVM in the immediate future, although continuous monitoring will be needed. IMPORTANCE Coagulase-negative staphylococci are the main pathogens in health care-associated ventriculitis and meningitis. There are three conclusions from the results of this study. First, according to antimicrobial susceptibility, the rates of resistance to primary antimicrobial agents are high and those to high-level agents, including vancomycin, are low. Second, the trends of resistance rates are acceptable, especially for high-level agents, although long-term and continuous monitoring is necessary. Finally, the clinical outcomes of neurosurgical adults with coagulase-negative staphylococci-related health care-associated ventriculitis and meningitis are acceptable after treatment with vancomycin. Therefore, according to the antimicrobial susceptibility and clinical practice, vancomycin will be safe to treat coagulase-negative staphylococci-related health care-associated ventriculitis and meningitis.

Molecular Diagnosis, Antimicrobial Resistance Profiles and Disease Patterns of Gram-Positive Pathogens Recovered from Clinical Infections in Major Ha’il Hospitals

Nosocomial resistance in staphylococci and enterococci is challenging. The aim of this work was to conduct a multipoint study using molecular detections, antimicrobial resistances profiles, patient demographics and disease patterns for objective assessments of Staphilococcus aureus and other Gram-positive pathogens recovered from clinical infections in the Ha’il region. We have surveyed 188 non-duplicate Gram-positives against 22 antimicrobials for molecular-differentiation, resistance, patient demographics, and disease patterns from January–April 2021. According to definitions for acquired resistance, Staphylococcus aureus was the most frequent with multidrug resistant (65.4%), where MRSA was 60% (n = 72 out of 121). In age-identified patients, 43% were seniors ≥50 years, 38% 21–49 years, and 19% 0–20 years. In gender-identified patients, 63% were males, and 37% were females. While 25% of specimens were from the ICU, the majority (60%) of specimens were from surgical infection in other wards. Staphylococcus epidermidis was the second (15.4%) species of infection identified with 81% from bloodstream infections at the ICU and other wards. The majority of S. epidermidis patients (69%) were seniors ≥50 years, while other age groups 0–20 and 21–49 each had 14% isolates. Although S. epidermidis was multidrug-resistant, it was susceptible to many drugs. Enterococcus faecalis (13%) ranked third with two major infections; bloodstream (64%) and urinary-tract infections (36%) in mainly seniors (86%). Its isolates were fully resistant to oxacillin, penicillin, cefoxitin, and cefotaxime but nearly 100% susceptible to seven others. Other Gram-positive bacteria (6%) were susceptible to many antibiotics. The use of combinations of objective criteria is a well thought out approach in infection control. While the low-frequency of Gram-positives is an impressive achievement, future large-scale investigations should include all private hospitals, clinics and other cities over a longer sampling time to gain more insights. Although geriatric susceptibility can be justified by age and comorbidities, the staphylococcal infections in young adults and children is a global concern and warrants more vertical studies.

Combined antibiotic stewardship and infection control measures to contain the spread of linezolid-resistant Staphylococcus epidermidis in an intensive care unit

Background

The unrestricted use of linezolid has been linked to the emergence of linezolid-resistant Staphylococcus epidermidis (LRSE). We report the effects of combined antibiotic stewardship and infection control measures on the spread of LRSE in an intensive care unit (ICU).

Methods

Microbiological data were reviewed to identify all LRSE detected in clinical samples at an ICU in southwest Germany. Quantitative data on the use of antibiotics with Gram-positive coverage were obtained in defined daily doses (DDD) per 100 patient-days (PD). In addition to infection control measures, an antibiotic stewardship intervention was started in May 2019, focusing on linezolid restriction and promoting vancomycin, wherever needed. We compared data from the pre-intervention period (May 2018–April 2019) to the post-intervention period (May 2019–April 2020). Whole-genome sequencing (WGS) was performed to determine the genetic relatedness of LRSE isolates.

Results

In the pre-intervention period, LRSE were isolated from 31 patients (17 in blood cultures). The average consumption of linezolid and daptomycin decreased from 7.5 DDD/100 PD and 12.3 DDD/100 PD per month in the pre-intervention period to 2.5 DDD/100 PD and 5.7 DDD/100 PD per month in the post-intervention period (p = 0.0022 and 0.0205), respectively. Conversely, vancomycin consumption increased from 0.2 DDD/100 PD per month to 4.7 DDD/100 PD per month (p < 0.0001). In the post-intervention period, LRSE were detected in 6 patients (4 in blood cultures) (p = 0.0065). WGS revealed the predominance of one single clone.

Conclusions

Complementing infection control measures by targeted antibiotic stewardship interventions was beneficial in containing the spread of LRSE in an ICU.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13756-021-00970-3.

Genomic and Phenotypic Analysis of Linezolid-Resistant Staphylococcus epidermidis in a Tertiary Hospital in Innsbruck, Austria

Whole genome sequencing is a useful tool to monitor the spread of resistance mechanisms in bacteria. In this retrospective study, we investigated genetic resistance mechanisms, sequence types (ST) and respective phenotypes of linezolid-resistant Staphylococcus epidermidis (LRSE, n = 129) recovered from a cohort of patients receiving or not receiving linezolid within a tertiary hospital in Innsbruck, Austria. Hereby, the point mutation G2603U in the 23S rRNA (n = 91) was the major resistance mechanism followed by the presence of plasmid-derived cfr (n = 30). The majority of LRSE isolates were ST2 strains, followed by ST5. LRSE isolates expressed a high resistance level to linezolid with a minimal inhibitory concentration of ≥256 mg/L (n = 83) in most isolates, particularly in strains carrying the cfr gene (p < 0.001). Linezolid usage was the most prominent (but not the only) trigger for the development of linezolid resistance. However, administration of linezolid was not associated with a specific resistance mechanism. Restriction of linezolid usage and the monitoring of plasmid-derived cfr in LRSE are potential key steps to reduce linezolid resistance and its transmission to more pathogenic Gram-positive bacteria.

Update on Coagulase-Negative Staphylococci-What the Clinician Should Know

Coagulase-negative staphylococci (CoNS) are among the most frequently recovered bacteria in routine clinical care. Their incidence has steadily increased over the past decades in parallel to the advancement in medicine, especially in regard to the utilization of foreign body devices. Many new species have been described within the past years, while clinical information to most of those species is still sparse. In addition, interspecies differences that render some species more virulent than others have to be taken into account. The distinct populations in which CoNS infections play a prominent role are preterm neonates, patients with implanted medical devices, immunodeficient patients, and those with other relevant comorbidities. Due to the property of CoNS to colonize the human skin, contamination of blood cultures or other samples occurs frequently. Hence, the main diagnostic hurdle is to correctly identify the cases in which CoNS are causative agents rather than contaminants. However, neither phenotypic nor genetic tools have been able to provide a satisfying solution to this problem. Another dilemma of CoNS in clinical practice pertains to their extensive antimicrobial resistance profile, especially in healthcare settings. Therefore, true infections caused by CoNS most often necessitate the use of second-line antimicrobial drugs.

Guidelines for Robotic Flexible Endoscopy at the Time of COVID-19

Flexible endoscopy involves the insertion of a long narrow flexible tube into the body for diagnostic and therapeutic procedures. In the gastrointestinal (GI) tract, flexible endoscopy plays a major role in cancer screening, surveillance, and treatment programs. As a result of gas insufflation during the procedure, both upper and lower GI endoscopy procedures have been classified as aerosol generating by the guidelines issued by the respective societies during the COVID-19 pandemic-although no quantifiable data on aerosol generation currently exists. Due to the risk of COVID-19 transmission to healthcare workers, most societies halted non-emergency and diagnostic procedures during the lockdown. The long-term implications of stoppage in cancer diagnoses and treatment is predicted to lead to a large increase in preventable deaths. Robotics may play a major role in this field by allowing healthcare operators to control the flexible endoscope from a safe distance and pave a path for protecting healthcare workers through minimizing the risk of virus transmission without reducing diagnostic and therapeutic capacities. This review focuses on the needs and challenges associated with the design of robotic flexible endoscopes for use during a pandemic. The authors propose that a few minor changes to existing platforms or considerations for platforms in development could lead to significant benefits for use during infection control scenarios.