A multi-center outbreak of Candida tropicalis bloodstream infections associated with contaminated hemodialysis machine prime buckets

Genotyping of Candida tropicalis isolates uncovers nosocomial transmission of two lineages in Italian tertiary-care hospital

OBJECTIVES

Candida tropicalis is a medically important yeast with rising antifungal resistance, while nosocomial transmission is rarely reported. Here we genotyped C. tropicalis isolates from Italian hospitals to uncover potential nosocomial transmission and assess resistance.

METHODS

A total of 197 C. tropicalis isolates from 161 patients was collected from five centres from 2013 to 2023. Short tandem repeat (STR) genotyping was conducted on all isolates and a selection of 24 isolates was typed with whole genome sequencing (WGS) and the novel Fourier-transform infrared (FTIR) spectroscopy method. Antifungal resistance was investigated with microbroth dilution and WGS.

RESULTS

STR genotyping revealed seven clusters with isolates from multiple patients. WGS single nucleotide polymorphism (SNP) analysis on five groups of isolates with related STR genotypes also separated these isolates into five groups, of which two groups contained a cluster of isolates from different patients distinguished by 59 or fewer SNPs. In comparison, sequential isolates within three patients were differentiated by 141 SNPs at most. The two C. tropicalis WGS clusters also clustered based on FTIR genotyping, although this method did not separate the isolates into five groups. None of the 24 isolates were resistant to common antifungals.

CONCLUSIONS

WGS SNP analysis indicated nosocomial transmission of two lineages within the same hospital, highlighting the need for enforced infection prevention measures and the need for routine genotyping on this common yeast in clinical settings. While both STR and FTIR genotyping also clustered these lineages, WGS SNP analysis is required to determine whether isolates were clonally transmitted.

Involvement of healthcare staff in hospital hygiene during emergency hemodialysis

BACKGROUND

Healthcare-associated infections are still a worrying health problem that complicates patient care and increases morbidity and mortality. The incidence of infections in hemodialysis patients is still high and they constitute the second cause of hospitalization and death in this category.

AIMS

The study's objective was to evaluate nursing and medical staff's involvement in hospital hygiene.

METHODS

This is an observational study that took place within the hemodialysis unit of a Moroccan university hospital from March 2021 to June 2021. A surface swabbing technique for bacteriological examination was also carried out.

RESULTS

The study revealed some shortcomings regarding hand hygiene which was respected by the nurses in only 17.5% of sessions and in 42.2% by the doctors. Other shortcomings in asepsis measures, were also noted such as the non-change of gloves after skin preparation (1.03%) and before manual compression. The serological status of patients concerning HBV, HVC, and HIV was also not always known (31.1%). The bacteriological samples from the surfaces also showed colonization of the medical devices and the ultrasound scanner used for the ultrasound-guided introduction of the central catheters. The results of the study showed some deviations concerning the recommendations; however, they are comparable to other studies conducted internationally, especially in terms of hand hygiene.

CONCLUSION

Our study results highlight some shortcomings adherence to hygiene measures like inconsistent disinfection of medical devices and dialysis stations, as well as insufficient hand hygiene practices among some staff members. However, we observed an improvement in practices following the implementation of awareness-raising sessions. To maintain improved hygiene practices and prevent infections, it is crucial to provide ongoing training for staff, ensure adequate resources, and regularly monitor compliance with hygiene standards.

Outbreaks of Fungal Infections in Hospitals: Epidemiology, Detection, and Management

Nosocomial clusters of fungal infections, whilst uncommon, cannot be predicted and are associated with significant morbidity and mortality. Here, we review reports of nosocomial outbreaks of invasive fungal disease to glean insight into their epidemiology, risks for infection, methods employed in outbreak detection including genomic testing to confirm the outbreak, and approaches to clinical and infection control management. Both yeasts and filamentous fungi cause outbreaks, with each having general and specific risks. The early detection and confirmation of the outbreak are essential for diagnosis, treatment of affected patients, and termination of the outbreak. Environmental sampling, including the air in mould outbreaks, for the pathogen may be indicated. The genetic analysis of epidemiologically linked isolates is strongly recommended through a sufficiently discriminatory approach such as whole genome sequencing or a method that is acceptably discriminatory for that pathogen. An analysis of both linked isolates and epidemiologically unrelated strains is required to enable genetic similarity comparisons. The management of the outbreak encompasses input from a multi-disciplinary team with epidemiological investigation and infection control measures, including screening for additional cases, patient cohorting, and strict hygiene and cleaning procedures. Automated methods for fungal infection surveillance would greatly aid earlier outbreak detection and should be a focus of research.

Genotyping and susceptibility testing uncovers large azole-resistant Candida tropicalis clade in Alexandria, Egypt

OBJECTIVES

Candida tropicalis is an emerging medically relevant Candida species. The yeast primarily causes opportunistic infections in intensive care units and is highly prevalent in tropical countries. The genetic diversity within this species is high, and nosocomial transmission has been reported. C. tropicalis genotyping of isolates from low- and middle-income countries is underrepresented when compared with that from high-income countries. Also, in Egypt, only limited genotyping has been conducted for C. tropicalis isolates, while antifungal resistance seems to increase, especially against azoles.

METHODS

Antifungal susceptibility testing was performed on 64 C. tropicalis isolates from ICU patients collected from multiple hospitals in Alexandria, Egypt. Genotyping by means of short tandem repeat (STR) and whole genome sequencing (WGS) single nucleotide polymorphism (SNP) analysis was performed.

RESULTS

Using antifungal susceptibility testing, fluconazole resistance was observed in 24 isolates (38%), of which 23 harboured an ERG11 G464S substitution, previously shown to cause resistance in Candida albicans. STR genotyping showed that these 23 isolates were related, forming a distinct resistant clade. WGS SNP analysis subsequently confirmed this genetic relationship, although isolates within this clade differed in at least 429 SNPs, suggesting that these were independently introduced.

CONCLUSION

Overall, STR and WGS SNP analysis of this collection indicates limited C. tropicalis nosocomial transmission in Alexandria, while the presence of this large azole-resistant C. tropicalis clade within this city hampers the treatment of intensive care unit patients.

Development and Application of a Short Tandem Repeat Multiplex Typing Assay for Candida tropicalis

Candida tropicalis is a clinically important yeast that causes candidemia in humans with a high mortality rate. The yeast primarily infects immunocompromised patients, and causes outbreaks in health care facilities. Antifungal resistant isolates have been reported. We developed a short tandem repeat (STR) typing scheme for C. tropicalis to enable fast, cost-effective, and high-resolution genotyping. For the development of the typing scheme, 6 novel STR markers were selected, combined into 2 multiplex PCRs. In total, 117 C. tropicalis isolates were typed, resulting in the identification of 104 different genotypes. Subsequently, the outcome of STR typing of 10 isolates was compared to single nucleotide polymorphism (SNP) calling from whole-genome sequencing (WGS). Isolates with more than 111 SNPs were differentiated by the typing assay. Two isolates, which were identical according to SNP analysis, were separated by STR typing in 1 marker. To test specificity, the STR typing was applied to 15 related yeast species, and we found no amplification of these targets. For reproducibility testing, 2 isolates were independently typed five times, which showed identical results in each experiment. In summary, we developed a reliable and multiplex STR genotyping for C. tropicalis, which was found to correlate well to SNP calling by WGS. WGS analysis from and extensive collection of isolates is required to establish the precise resolution of this STR assay. IMPORTANCE Candida tropicalis frequently causes candidemia in immunocompromised patients. C. tropicalis infections have a high mortality rate, and the yeast is able to cause outbreaks in health care facilities. Further, antifungal resistant isolates are on the rise. Genotyping is necessary to investigate potential outbreaks. Here, we developed and applied a STR genotyping scheme in order to rapidly genotype isolates with a high-resolution. WGS SNP outcomes were highly comparable with STR typing results. Altogether, we developed a rapid, high-resolution, and specific STR genotyping scheme for C. tropicalis.

Systematic Characterization of Epidemiology, Antifungal Susceptibility, Risk Factors and Outcomes of Candidaemia: A Six-Year Chinese Study

Background

Candida bloodstream infection (BSI), the fourth most common nosocomial BSI, is an urgent global health challenge with the tremendous growth in antifungal resistance rate and mortality rate.

Purpose

To establish the epidemiology, species distribution, risk factors, and 30-day mortality of candidaemia among 115 patients in this 6-year surveillance study.

Materials and Methods

We retrospectively analyzed the clinical characteristics, epidemiology, antifungal susceptibility patterns, and risk factors for morbidity and mortality of 115 candidaemia cases diagnosed in one tertiary care hospital from January 2016 through December 2021.

Results

Of the 115 candidaemia cases, the most prevalent species were Candida tropicalis (33.0%), followed by Candida albicans (27.8%), Candida parapsilosis complex (19.1%), and others. The overall incidence was 0.21 cases/1000 admissions. The overall crude resistance rate of Candida spp. against azoles was 20.0% (23/115), while Candida tropicalis showed a significant increase in the resistance rate to azoles (from 1/6, 16.7% in 2017 to 6/10, 60.0% in 2021). Multivariate analyses demonstrated that hematological malignancy and neutropenia were significantly associated with Candida tropicalis BSI than Candida non-tropicalis BSI. Candida albicans BSI had a significantly higher rate of previous surgery than Candida non-albicans BSI. Candida parapsilosis BSI had a significantly higher rate of receiving total parenteral nutrition (TPN). The overall 30-day mortality rate was 27.0% (31/115). The presence of high age-adjusted Charlson comorbidity index (aCCI), neutropenia, and septic shock were factors independently associated with increased 30-day mortality.

Conclusion

Candida tropicalis are emerging as the predominant isolate in candidaemia. Of note, the unexpectedly increased resistance rate to azoles in Candida tropicalis BSI was observed. The aCCI scores, neutropenia, and septic shock were independently associated with 30-day mortality. Prompt, adequate antifungal treatment among high-risk patients may lead to a reduction in mortality.

A Cluster of Gram-Negative Bloodstream Infections in Connecticut Hemodialysis Patients Associated with Contaminated Wall Boxes and Prime Buckets

BACKGROUND

Maintenance hemodialysis (HD) patients are at increased risk of bloodstream infections (BSI). We investigated a cluster of Delftia acidovorans infections among patients undergoing HD at an outpatient unit (Facility A).

METHODS

A case was defined as a Facility A HD patient with ≥1 culture positive for Delftia acidovorans between February 1 - April 30, 2018. An investigation included review of patient records, facility policies, practice observations, and environmental cultures.

RESULTS

The cluster included two patients with confirmed D. acidovorans BSI. Both patients had recently been dialyzed at Station #2, where a wall box culture yielded D. acidovorans. One patient also had a BSI due to Enterobacter asburiae, which was recovered from several other wall boxes and saline prime buckets (SPB). Observations revealed leakage of wastewater from wall boxes onto the floor, and that SPBs were not always disinfected and dried appropriately before reuse. Multiple deficiencies in hand hygiene and station disinfection were observed. No deficiencies in water treatment practices were identified, and water cultures were negative for the observed pathogens.

CONCLUSIONS

The cluster of D. acidovorans infections was most likely due to indirect exposures to contaminated wall boxes and possibly SPBs due to poor hand hygiene and station disinfection.

Waterborne Outbreaks in Hemodialysis Patients and Infection Prevention

Individuals treated with dialysis are at high risk for healthcare-associated infections. We conducted a literature review of outbreaks associated with water in hemodialysis during years 2011–2021 to understand the role of water as a source of infections for patients receiving hemodialysis with a focus on the risks associated with dialysis water and dialysate. For dialysis patients, water and dialysate have been a source of healthcare-associated pathogens, including nontuberculous mycobacteria and gram-negative bacilli as well as systemic reactions due to gram-negative bacilli–associated endotoxin. Lapses in infection prevention practices and dialysis water management were primarily involved in waterborne outbreaks. Dialysis clinics should adhere to recommendations regarding monitoring and levels of bacteria and endotoxin in hemodialysis water and dialysate. Since hemodialysis patients are at increased risk of healthcare-associated infections, it is important for healthcare personnel to adhere to infection prevention guidelines in hemodialysis patient care, especially hand hygiene, aseptic technique, cleaning/disinfection, and water management.

Secondary Immunodeficiency Related to Kidney Disease (SIDKD)-Definition, Unmet Need, and Mechanisms

Kidney disease is a known risk factor for poor outcomes of COVID-19 and many other serious infections. Conversely, infection is the second most common cause of death in patients with kidney disease. However, little is known about the underlying secondary immunodeficiency related to kidney disease (SIDKD). In contrast to cardiovascular disease related to kidney disease, which has triggered countless epidemiologic, clinical, and experimental research activities or interventional trials, investments in tracing, understanding, and therapeutically targeting SIDKD have been sparse. As a call for more awareness of SIDKD as an imminent unmet medical need that requires rigorous research activities at all levels, we review the epidemiology of SIDKD and the numerous aspects of the abnormal immunophenotype of patients with kidney disease. We propose a definition of SIDKD and discuss the pathogenic mechanisms of SIDKD known thus far, including more recent insights into the unexpected immunoregulatory roles of elevated levels of FGF23 and hyperuricemia and shifts in the secretome of the intestinal microbiota in kidney disease. As an ultimate goal, we should aim to develop therapeutics that can reduce mortality due to infections in patients with kidney disease by normalizing host defense to pathogens and immune responses to vaccines.