Emergence of coagulase-negative staphylococci

Staphylococcus aureus and methicillin-resistant staphylococci and mammaliicocci in the bulk tank milk of dairy cows from a livestock-dense area in northern Italy

Staphylococcus aureus is the main etiologic agent of contagious dairy cow mastitis, while non-aureus staphylococci and mammaliicocci (NASM) are the bacteria most frequently isolated from milk. Beyond their impact on animal health, NASM can harbor antimicrobial resistance (AMR) genes with potential for bidirectional transfer with S. aureus, and methicillin-resistant (MR) staphylococci (MRS) can raise significant One Health concerns. In our study, we evaluated the prevalence and characteristics of MRS in the bulk tank milk (BTM) of 88 dairy farms in the livestock-dense province of Lodi, Lombardy, northern Italy. S. aureus was isolated from 32.95 % of BTM samples, with the Ribosomal Spacer PCR (RS-PCR) genotype B being the most prevalent, identified in 37.93 % of S. aureus positive farms. All isolates carried the ica genes (icaA, icaB, icaC, icaD) indicating the potential to produce biofilm. MRS were isolated in 56.81 % of farms. According to MALDI-TOF MS analysis, the most prevalent MR species included S. epidermidis (MRSE, 35.59 %) followed by S. aureus (MRSA, 18.64 %), M. sciuri (15.25 %), S. saprophyticus (11.86 %), S. borealis (6.78 %), S. haemolyticus (5.08 %), M. fleurettii, (3.39 %), S. cohnii, and S. pettenkoferi (1.70 % each). Most MR isolates carried the mecA gene, while none carried mecC. The staphylococcal cassette chromosome mec (SCCmec) was predominantly type V in MRSA (45.45 %) and type IV in MRSE (61.90 %). Given their relevance to One Health, monitoring AMR in all staphylococci and mammaliicocci isolated from milk is essential for understanding the prevalence, characteristics, and transmission dynamics of MR gene pools within dairy herds.

Deciphering pathogenicity and virulence of the first Staphylococcus debuckii isolate from diabetic foot osteomyelitis

Introduction

This study identifies Staphylococcus debuckii as a new coagulase-negative staphylococcal species isolated from diabetic foot osteomyelitis (DFOM) and provides an in-depth analysis of its pathogenic and virulence profile, as well as demonstrating its potential to cause infection.

Methods

The S. debuckii NSD001 strain was examined for its planktonic growth, biofilm production, and phagocytosis rates in murine macrophages compared to S. aureus NSA739. Additionally, persistence and replication within human osteoblasts were investigated, while the zebrafish embryo model was employed to assess virulence. Genomic sequencing and bioinformatic analysis were also conducted to identify genes associated with virulent potential.

Results and Discussion

S. debuckii NSD001 exhibited robust planktonic growth and significant biofilm production, highlighting its capacity to initiate and maintain an infection, and demonstrated similar rates of phagocytosis as S. aureus NSA739 in murine macrophages, suggesting a mechanism for evading initial host defenses. The strain persisted and replicated within human osteoblasts, indicative of a strategy for intracellular survival and facilitation of chronic osteomyelitis. The zebrafish embryo model revealed a slower, yet fatal, virulence profile for S. debuckii NSD001 compared to the rapid lethality induced by S. aureus NSA739. Genomic sequencing and bioinformatic analysis uncovered various genes corroborating its virulence. S. debuckii NSD001 poses a significant concern in DFOM due to its ability to form biofilms and survive within host cells, presenting challenges for current treatment strategies. This underscores the need for updated clinical protocols and increased awareness among healthcare professionals to effectively manage infections caused by this emerging pathogen.

Emergence of multidrug-resistant Staphylococcus haemolyticus in neonatal intensive care unit in Southern France, a genomic study

An emergence of multidrug-resistant (MDR) Staphylococcus haemolyticus has been observed in the neonatal intensive care unit (NICU) of Nîmes University Hospital in southern France. A case-control analysis was conducted on 96 neonates, to identify risk factors associated with S. haemolyticus infection, focusing on clinical outcomes. Forty-eight MDR S. haemolyticus strains, isolated from neonates between October 2019 and July 2022, were investigated using routine in vitro procedures and whole-genome sequencing. Additionally, five S. haemolyticus isolates from adult patients were sequenced to identify clusters circulating within the hospital environment. The incidence of neonatal S. haemolyticus was significantly associated with low birth weight, lower gestational age, and central catheter use (p < 0.001). Sepsis was the most frequent clinical manifestation in this series (20/46, 43.5%) and was associated with five deaths. Based on whole-genome analysis, three S. haemolyticus genotypes were predicted: ST1 (6/53, 11%), ST25 (3/53, 5.7%), and ST29 (44/53, 83%), which included the subcluster II-A, predominantly emerging in the neonatal department. All strains were profiled in silico to be resistant to methicillin, erythromycin, aminoglycosides, and fluoroquinolones, consistent with in vitro antibiotic susceptibility tests. Moreover, in silico prediction of biofilm formation and virulence-encoding genes supported the association of ST29 with severe clinical outcomes, while the persistence in the NICU could be explained by the presence of antiseptic and heavy metal resistance-encoding genes. The clonality of S. haemolyticus ST29 subcluster II-A isolates confirms healthcare transmission causing severe infections. Based on these results, reinforced hygiene measures are necessary to eradicate the nosocomial transmission of MDR strains.

Staphylococcus epidermidis alters macrophage polarization and phagocytic uptake by extracellular DNA release in vitro

Biofilm formation shields Staphylococcus epidermidis from host defense mechanisms, contributing to chronic implant infections. Using wild-type S. epidermidis 1457, a PIA-negative mutant (1457-M10), and an eDNA-negative mutant (1457ΔatlE), this study examined the influence of biofilm matrix components on human monocyte-derived macrophage (hMDM) interactions. The wild-type strain was resistant to phagocytosis and induced an anti-inflammatory response in hMDMs, while both mutants were more susceptible to phagocytosis and triggered a pro-inflammatory response. Removing eDNA from the 1457 biofilm matrix increased hMDM uptake and a pro-inflammatory reaction, whereas adding eDNA to the 1457ΔatlE mutant reduced phagocytosis and promoted an anti-inflammatory response. Inhibiting TLR9 enhanced bacterial uptake and induced a pro-inflammatory response in hMDMs exposed to wild-type S. epidermidis. This study highlights the critical role of eDNA in immune evasion and the central role of TLR9 in modulating macrophage responses, advancing the understanding of implant infections.

Phage-Derived Endolysins Against Resistant Staphylococcus spp.: A Review of Features, Antibacterial Activities, and Recent Applications

Antimicrobial resistance is a significant global public health issue, and the dissemination of antibiotic resistance in Gram-positive bacterial pathogens has significantly increased morbidity, mortality rates, and healthcare costs. Among them, Staphylococcus, especially methicillin-resistant Staphylococcus aureus (MRSA), causes a wide range of diseases due to its diverse pathogenic factors and infection strategies. These bacteria also present significant issues in veterinary medicine and food safety. Effectively managing staphylococci-related problems necessitates a concerted effort to implement preventive measures, rapidly detect the pathogen, and develop new and safe antimicrobial therapies. In recent years, there has been growing interest in using endolysins to combat bacterial infections. These enzymes, which are also referred to as lysins, are a unique class of hydrolytic enzymes synthesized by double-stranded DNA bacteriophages. They possess glycosidase, lytic transglycosylase, amidase, and endopeptidase activities, effectively destroying the peptidoglycan layer and resulting in bacterial lysis. This unique property makes endolysins powerful antimicrobial agents, particularly against Gram-positive organisms with more accessible peptidoglycan layers. Therefore, considering the potential benefits of endolysins compared to conventional antibiotics, we have endeavored to gather and review the characteristics and uses of endolysins derived from staphylococcal bacteriophages, as well as their antibacterial effectiveness against Staphylococcus spp. based on conducted experiments and trials.

Nasal Carriage of Antimicrobial-Resistant Staphylococci by Fallow Deer (Dama dama) Taken in a Natural Park of Tuscany, Central Italy

Wild animals are recognized as significant reservoirs for various zoonotic pathogens, including antibiotic-resistant bacteria. This study aimed to investigate the presence of Staphylococcus spp. strains in fallow deer (Dama dama) inhabiting a natural preserve in Central Italy and to examine the phenotypic and genotypic antimicrobial resistance and the presence of some virulence genes among the isolates. During July and December 2022, nasal swabs were collected from 175 fallow deer, which were then analyzed through bacteriological cultures. In total, 176 Staphylococcus spp. strains were isolated and subsequently identified using MALDI-TOF mass spectrometry. S. aureus was the most abundant species with 66 (37.5%) strains, followed by S. hyicus, 34 (19.31%) strains, S. sciuri, 32 (18.18%) strains, S. chromogenes, 27 (15.34%) strains, S. xylosus, 11 (6.25%) strains, S. warneri, 5 (2.84%) strains, and S. devriesei, 1 (0.56%) strain. Antimicrobial susceptibility was assessed for each isolate via the agar disk diffusion method, testing a panel of 13 molecules belonging to 9 antimicrobial classes. The highest resistance rates were detected for penicillin (29.55%), rifampicin (22.73%), and amikacin (20.45%). Notably, intermediate susceptibility was observed for erythromycin (61.93%), enrofloxacin (28.41%), and ceftiofur (21.02%). Conversely, the strains exhibited particularly high susceptibility to amoxicillin/clavulanic acid (99.43%), cefoxitin (97.73%), and vancomycin (96.02%). Based on the results, 32 (18.18%) isolates were classified as multidrug-resistant (MDR). Two strains of S. chromogenes and one strain of S. xylosus, both resistant to penicillin, tested positive for the blaZ gene. No methicillin-resistant strains were found, and none of the isolates harbored genes associated with enterotoxin and toxic shock syndrome toxin production. This study highlights the potential role of wildlife, particularly fallow deer, as reservoirs of antibiotic-resistant Staphylococcus spp. strains. Such findings underscore the importance of monitoring wildlife for antimicrobial resistance, which could have implications for public health and veterinary medicine.

Current types of staphylococcal cassette chromosome mec (SCCmec) in clinically relevant coagulase-negative staphylococcal (CoNS) species

Coagulase-negative staphylococci (CoNS) colonize human skin and mucosal membranes, which is why they are considered harmless commensal bacteria. Two species, Staphylococcus epidermidis and Staphylococcus haemolyticus belong to the group of CoNS species and are most frequently isolated from nosocomial infections, including device-associated healthcare-associated infections (DA-HAIs) and local or systemic body-related infections (FBRIs). Methicillin resistance, initially described in Staphylococcus aureus, has also been reported in CoNS species. It is mediated by the mecA gene within the staphylococcal cassette chromosome (SCCmec). SCCmec typing, primarily using PCR-based methods, has been employed as a molecular epidemiological tool. However, the introduction of whole genome sequencing (WGS) and next-generation sequencing (NGS) has enabled the identification and verification of new SCCmec types. This review describes the current distribution of SCCmec types, subtypes, and variants among CoNS species, including S. epidermidis, S. haemolyticus, and S. capitis. The literature review focuses on recent research articles from the past decade that discuss new combinations of SCCmec in coagulase-negative Staphylococcus. The high genetic diversity and gaps in CoNS SCCmec annotation rules underscore the need for an efficient typing system. Typing SCCmec cassettes in CoNS strains is crucial to continuously updating databases and developing a unified classification system.

Characterization of virulence factors and antimicrobial resistance in Staphylococcus spp. isolated from clinical samples

The virulence factors, antibiotic resistance patterns, and the associated genetic elements have been investigated in Staphylococcus species. A total of 100 strains has been isolated from clinical samples in the Microbiology Laboratory of Hesperia Hospital, Modena, Italy, and identified as Staphylococcus aureus (65), Staphylococcus epidermidis (24), Staphylococcus hominis (3), Staphylococcus saprophyticus (3), and Staphylococcus warneri (5). All the strains were analyzed to determine phenotypic and genotypic characters, notably the virulence factors, the antibiotics susceptibility, and the genetic determinants. The highest percentage of resistance in Staphylococcus spp. was found for erythromycin and benzylpenicillin (87% and 85%, respectively). All S. aureus, two S. epidermidis (8.3%), and one S. saprophyticus (33.3%) strains were resistant to oxacillin. The methicillin resistance gene (mecA) was detected by polymerase chain reaction (PCR) amplification in 65 S. aureus strains and in 3 coagulase-negative staphylococci (CoNS) (8.6%). With regard to the virulence characteristics, all the S. aureus were positive to all virulence tests, except for slime test. Among the CoNS isolates, 19 (79.1%) S. epidermidis and one (33.3%) S. saprophyticus strains resulted positive for the slime test only. The results obtained are useful for a more in-depth understanding of the function and contribution of S. aureus and CoNS antibiotic resistance and virulence factors to staphylococcal infections. In particular, the production of slime is very important for CoNS, a virulence factor frequently found in infections caused by these strains. Further investigations on the genetic relatedness among strains of different sources will be useful for epidemiological and monitoring purposes and will enable us to develop new strategies to counteract the diffusion of methicillin-resistant S. aureus (MRSA) and CoNS strains not only in clinical field, but also in other related environments.

Biofilm Eradication and Inhibition of Methicillin-Resistant Staphylococcus Clinical Isolates by Curcumin-Chitosan Magnetic Nanoparticles

Biofilm-producing methicillin-resistant Staphylococcus aureus (MRSA) and coagulase-negative staphylococci (MR-CoNS) pose clinical challenges in treating healthcare-associated infections. As alternative antimicrobial options are needed, in this study, we aimed to determine the effect of curcumin-chitosan magnetic nanoparticles (Cur-Chi-MNP) on the biofilms of staphylococcal clinical isolates. MRSA and CoNS clinical isolates were identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Antimicrobial susceptibility testing was performed using the broth microdilutions. Nanoparticles were synthesized by the co-precipitation of magnetic nanoparticles (MNP) and encapsulated by the ionotropic gelation of curcumin (Cur) and chitosan (Chi). Biofilm inhibition and eradication by nanoparticles, with and without the addition of oxacillin (OXA), were assessed in Staphylococcus strains. Cur-Chi-MNP showed antimicrobial activity against planktonic cells of MRSA and MR-CoNS strains and inhibited MRSA biofilm. The addition of OXA to Cur-Chi-MNP increased the biofilm inhibition and eradication activity against all staphylococcal strains (P = 0.0007), and higher biofilm activity was observed in the early biofilm stages. Cur-Chi-MNP showed antimicrobial and biofilm inhibitory activities against S. aureus. Addition of OXA increased biofilm inhibition and eradication activity against all staphylococcal strains. A combination treatment of Cur-Chi-MNP and OXA could potentially be used to treat staphylococcal biofilm-associated infections in the early stages before the establishment of biofilm bacterial cells.

Prevalence and risk factors associated with nasal carriage of methicillin-resistant staphylococci in horses and their caregivers

Antimicrobial resistance is a global threat, and pet-associated strains may pose a risk to human health. Equine veterinarians are at high risk of carrying methicillin-resistant staphylococci (MRS), but specific risk factors remain elusive, and few data are available for other personnel involved in the horse industry. The prevalence, characteristics, and risk factors for nasal carriage of MRS in horses and their caregivers were studied in northwestern Italy. Nasal swabs from 110 asymptomatic horses housed at 21 barns and 34 human caregivers were collected. Data on barns, horses, and personnel were acquired through questionnaires. The samples were incubated in selective media, and the bacterial isolates were identified by mass spectrometry. Risk factors were investigated by Poisson regression. MRS were isolated from 33 horses (30%), 11 humans (32.4%) and 3 environmental samples (14.2%). Most isolates were multidrug resistant (MDRS). The prevalence of MRS and MDRS was greater in racehorses and their personnel than in pleasurable and jumping/dressing horses. MRS carriage in caregivers was associated with an increased prevalence of MRS carriage in horses. The frequency of antimicrobial treatments administered in the barn during the last 12 months was a risk factor for MRS carriage in horses [prevalence ratio (PR) 3.97, 95% CI 1.11, 14.13] and caregivers (PR 2.00, 95% CI 1.05, 3.82), whereas a good ventilation index of the horse tabling environment was a protective factor (PR 0.43, 95% CI 0.20, 0.92). Our data reveal relevant interactions occurring between bacterial communities of horses and humans that share the same environment, suggesting that One Health surveillance programs should be implemented.

The Etiology of Bloodstream Infections at an Italian Pediatric Tertiary Care Hospital: A 17-Year-Long Series

Knowledge of epidemiology is essential for guiding correct antibiotic prescription, reducing bacteremia-associated mortality, and implementing targeted infection control programs. However, only a few studies have reported on the epidemiology of bloodstream infections (BSIs) in pediatrics. We performed a retrospective analysis of all BSIs (excluding those caused by common skin contaminants) diagnosed from 2006 to 2022 in patients younger than 18 years who were treated at an Italian pediatric tertiary care hospital. Overall, 2395 BSIs were recorded, including 2207 (92.15%) due to bacteria and 188 (7.85%) due to fungi. The incidence rate (BSIs/10,000 hospital discharges, IR) of bacterial BSIs significantly increased during the study period. In particular, BSIs caused by S. aureus (including MRSA), Enterobacterales (including ESBL and AmpC producers), Enterococcus spp., and P. aeruginosa became more common. The frequency of carbapenem-resistant strains was <1% and stable over time. Conversely, there was a significant reduction in the incidence of BSIs due to S. pneumoniae. The BSIs were stratified by patient age, and S. aureus was the most frequent cause of BSIs in all age groups, while E. coli was the most frequent in the Enterobacterales family. S. agalactiae was the third most frequent cause of neonatal early-onset BSIs. The prevalence of Enterococcus spp. increased in the subgroups from 8 days to 5 years of age, while P. aeruginosa became more prevalent in children over 5 years of age. S. aureus was also the most frequent isolate in both community- and hospital-onset BSIs, followed by E. coli. The prevalence of multidrug-resistant (MDR) pathogens was very low. It was <5% for both Gram-positive (i.e., MRSA and VRE) and Gram-negative (ESBL, AmpC, and carbapenem-resistant) pathogens, and MDR pathogens were almost exclusively detected in hospital-onset BSIs. Fungi accounted for just under 8% of BSIs. C. albicans was the most frequently isolated strain, followed by C. parapsilosis. Notably, the IR of fungemia did not change significantly during the study period, in spite of an increase in the absolute number of events. The continuous monitoring of local epidemiology is essential to identify changes in the IRs of pathogens and antibiotic susceptibility and to guide antibiotic treatments, especially in the phase when antibiograms are not yet available.

Increase in methicillin-resistant Staphylococcus spp. colonization among pregnant individuals during COVID-19 pandemic

Methicillin-resistant Staphylococcus (MRS) has been associated with neonatal infections, with colonization of the anovaginal tract being the main source of vertical transmission. The COVID-19 pandemic has altered the frequency of antibiotic usage, potentially contributing to changes in the dynamics of bacterial agents colonizing humans. Here we determined MRS colonization rates among pregnant individuals attending a single maternity in Rio de Janeiro, Brazil before (January 2019-March 2020) and during (May 2020-March 2021) the COVID-19 pandemic. Anovaginal samples (n = 806 [521 samples before and 285 during the pandemic]) were streaked onto chromogenic media. Colonies were identified by MALDI-TOF MS. Detection of mecA gene and SCCmec typing were assessed by PCR and antimicrobial susceptibility testing was done according to CLSI guidelines. After the onset of the pandemic, MRS colonization rates increased significantly (p < 0.05) from 8.6% (45) to 54.7% (156). Overall, 215 (26.6%) MRS isolates were detected, of which S. haemolyticus was the most prevalent species (MRSH, 84.2%; 181 isolates). SCCmec type V was the most frequent among MRS (63.3%; 136), and 31.6% (68) of MRS strains had a non-typeable SCCmec, due to new combinations of ccr and mecA complexes. Among MRS strains, 41.9% (90) were resistant to at least 3 different classes of antimicrobial agents, and 60% (54) of them were S. haemolyticus harboring SCCmec V. MRS colonization rates and the emergence of multidrug-resistant variants detected in this study indicate the need for continuing surveillance of this important pathogen within maternal and child populations.

Association of coagulase-negative staphylococci with orthopedic infections detected by in-house multiplex real-time PCR

Introduction

Clinical significance of coagulase-negative staphylococci (CoNS) has been gradually acknowledged in both healthcare and clinical research, but approaches for their precise discrimination at the species level remain scarce. The current study aimed to evaluate the association of CoNS with orthopedic infections, where accurate and prompt identification of etiology is crucial for appropriate diagnosis and treatment decision-making.

Methods

A 16S rRNA-based quantitative PCR (qPCR) assay was developed for the detection of Staphylococcus genus and two panels of 3-plex qPCR assays for further differentiation of six CoNS species with remarkable clinical significance, including S. epidermidis, S. haemolyticus, S. simulans, S. hominis, S. capitis, and S. caprae. All the assays exhibited excellent analytical performance. ΔCq (quantification cycle) between 16S rRNA and CoNS species-specific targets was established to determine the primary CoNS. These methods were applied to detect CoNS in wound samples from orthopedic patients with and without infection.

Results and discussion

Overall, CoNS were detected in 17.8% (21/118) of patients with clinically suspected infection and in 9.8% (12/123) of patients without any infection symptom (p < 0.05). Moreover, the association with infection was found to be bacterial quantity dependent. S. epidermidis was identified as the predominant species, followed by S. simulans, S. haemolyticus, and S. hominis. Male sex, open injury, trauma, and lower extremity were determined as risk factors for CoNS infections. CoNS-positive patients had significantly longer hospitalization duration (20 days (15, 33) versus 13 days (7, 22) for Staphylococcus-negative patients, p = 0.003), which could be a considerable burden for healthcare and individual patients. Considering the complex characteristics and devastating consequences of orthopedic infections, further expanding the detection scope for CoNS may be pursued to better understand the etiology of orthopedic infections and to improve therapeutic strategies.

Incidence, Common Pathogens, and Risk Factors for Infection after Primary Anterior Cruciate Ligament Reconstruction: A Systematic Review

We sought to assess the current literature to present a comprehensive summary of the incidence, common pathogens, and risk factors for infection after anterior cruciate ligament (ACL) reconstruction. PubMed, CINAHL, EMBASE, and Scopus databases were searched for relevant studies reporting on infection after ACL reconstruction. Two reviewers independently screened the extracted studies for adherence to inclusion and exclusion criteria. Studies were selected if they reported on the incidence of infection, pathogens cultured from infected knees, or risk factors for infection after primary ACL reconstruction. Exclusion criteria consisted of studies with fewer than 100 patients or studies that included revision ACL reconstruction. Fifty studies met the inclusion and exclusion criteria, reporting on a total of 316,214 ACL reconstructions. Included studies evaluated between 123 and 104,255 patients. The overall incidence of infection was 0.60% (0.15-2.44%). The most common pathogens were Staphylococcus aureus, S. epidermidis, and coagulase-negative Staphylococci. Five studies reported that the use of hamstring autograft was a statistically significant risk factor for infection after ACL reconstruction, thus making hamstring autograft the most commonly reported risk factor. Other reported risk factors included male sex, use of immuno-suppressive medications or intraarticular steroid injections, prior knee surgery, and diabetes. Systematic review of the literature revealed that infection after ACL reconstruction remains an infrequent event with an incidence of 0.60% (0.15-2.44%). Furthermore, the most common pathogens are from the Staphylococcus genus of bacteria, comprising 84% of all culture-positive infections. Multiple risk factors have been reported for ACL reconstruction; however, statistical significance varied across studies. Together, these findings may help guide physicians in the prevention and treatment of infection after ACL reconstruction.

Staphylococcus haemolyticus: An updated review on nosocomial infections, antimicrobial resistance, virulence, genetic traits, and strategies for combating this emerging opportunistic pathogen

Staphylococcus haemolyticus, a key species of the Staphylococcus genus, holds significant importance in healthcare-associated infections, due to its notable resistance to antimicrobials, like methicillin, and proficient biofilms-forming capabilities. This coagulase-negative bacterium poses a substantial challenge in the battle against nosocomial infections. Recent research has shed light on Staph. haemolyticus genomic plasticity, unveiling genetic elements responsible for antibiotic resistance and their widespread dissemination within the genus. This review presents an updated and comprehensive overview of the clinical significance and prevalence of Staph. haemolyticus, underscores its zoonotic potential and relevance in the one health framework, explores crucial virulence factors, and examines genetics features contributing to its success in causing emergent and challenging infections. Additionally, we scrutinize ongoing studies aimed at controlling spread and alternative approaches for combating it.

Evaluation of visible light and natural photosensitizers against Staphylococcus epidermidis and Staphylococcus saprophyticus planktonic cells and biofilm

Antimicrobial photoinactivation (API) has shown some promise in potentially treating different nosocomial bacterial infections, however, its application on staphylococci, especially other than Staphylococcus aureus or methicillin-resistant S. aureus (MRSA) species is still limited. Although S. aureus is a well-known and important nosocomial pathogen, several other species of the genus, particularly coagulase-negative Staphylococcus (CNS) species such as Staphylococcus epidermidis and Staphylococcus saprophyticus, can also cause healthcare-associated infections and foodborne intoxications. CNS are often involved in resilient biofilm formation on medical devices and can cause infections in patients with compromised immune systems or those undergoing invasive procedures. In this study, the effects of chlorophyllin and riboflavin-mediated API on S. epidermidis and S. saprophyticus planktonic cells and biofilm are demonstrated for the first time. Based on the residual growth determination and metabolic reduction ability changes, higher inactivating efficiency of chlorophyllin-mediated API was determined against the planktonic cells of both tested species of bacteria and against S. saprophyticus biofilm. Some insights on whether aqueous solutions of riboflavin and chlorophyllin, when illuminated with optimal exciting wavelength (440 nm and 402 nm, respectively) generate O2-•, are also provided in this work.

Addressing Challenges in Wildlife Rehabilitation: Antimicrobial-Resistant Bacteria from Wounds and Fractures in Wild Birds

Injuries and bone fractures are the most frequent causes of admission at wildlife rescue centers. Wild birds are more susceptible to open fractures due to their anatomical structure, which can lead to osteomyelitis and necrosis. Antibiotic therapy in these cases is indispensable, but the increase of antimicrobial-resistant isolates in wildlife has become a significant concern in recent years. In this context, the likelihood of antibiotic failure and death of animals with infectious issues is high. This study aimed to isolate, identify, and assess the antimicrobial resistance pattern of bacteria in wounds and open fractures in wild birds. To this end, injured birds admitted to a wildlife rescue center were sampled, and bacterial isolation and identification were performed. Then, antimicrobial susceptibility testing was assessed according to the disk diffusion method. In total, 36 isolates were obtained from 26 different birds. The genera detected were Staphylococcus spp. (63.8%), Escherichia (13.9%), Bacillus (11.1%), Streptococcus (8.3%), and Micrococcus (2.8%). Among Staphylococcus isolates, S. lentus and S. aureus were the most frequent species. Antimicrobial resistance was detected in 82.6% of the isolates, among which clindamycin resistance stood out, and 31.6% of resistant isolates were considered multidrug-resistant. Results from this study highlight the escalating scope of antimicrobial resistance in wildlife. This level of resistance poses a dual concern for wildlife: firstly, the risk of therapeutic failure in species of significant environmental value, and, secondly, the circulation of resistant bacteria in ecosystems.

The MIC distribution of dalbavancin differs between different coagulase-negative staphylococci

Background

CoNS constitute a significant part of the human microbiota of skin and mucous membranes. They can cause nosocomial infections, and have shown decreased susceptibility to several antibiotics. The few remaining treatment options include (lipo)glycopeptides such as dalbavancin. However, there is a lack of knowledge concerning whether susceptibility to lipoglycopeptides varies between different species of CoNS.

Objectives

To determine the susceptibility to dalbavancin in different species of CoNS.

Methods

We investigated 480 bacterial isolates from 10 CoNS species: Staphylococcus epidermidis, Staphylococcus capitis, Staphylococcus caprae, Staphylococcus haemolyticus, Staphylococcus lugdunensis, Staphylococcus warneri, Staphylococcus pettenkoferi, Staphylococcus hominis, Staphylococcus sciuri and Staphylococcus simulans. The isolates were randomly selected from different sources of infection, including blood isolates, as well as deep and superficial infections. Antibiotic susceptibility was tested with the gradient test method.

Results

There was a statistically significant difference (ANOVA; P < 0.0001) in the MIC distribution for dalbavancin between different CoNS species. S. sciuri was the least susceptible species, with 90% of the isolates having an MIC value for dalbavancin above the EUCAST breakpoint of 0.125 mg/L. The lowest MIC90 values were seen for S. capitis, S. simulans and S. caprae (all 0.032 mg/L).

Conclusions

This study demonstrated a difference in dalbavancin susceptibility between different CoNS species, suggesting that species-specific breakpoints for CoNS should be further investigated.

Whole Genome Sequence Analysis of Two Oxacillin-Resistant and mecA-Positive Strains of Staphylococcus haemolyticus Isolated from Ear Swab Samples of Patients with Otitis Media

Objective

Staphylococcus haemolyticus can cause a series of infections including otitis media (OM), and the oxacillin-resistant S. haemolyticus has become a serious health concern. This study aimed to investigate the genomic characteristics of two strains of oxacillin-resistant and mecA-positive S. haemolyticus isolated from the samples of ear swabs from patients with OM and explore their acquired antibiotic resistance genes (ARGs) and the mobile genetic elements (MGEs).

Methods

Two oxacillin-resistant S. haemolyticus strains, isolated from ear swab samples of patients with OM, underwent antimicrobial susceptibility evaluation, followed by whole-genome sequencing. The acquired ARGs and the MGEs carried by the ARGs, harbored by the genomes of two strains of S. haemolyticus were identified.

Results

The two strains of oxacillin-resistant S. haemolyticus (strain SH1275 and strain SH9361) both carried the genetic contexts of mecA with high similarity with the SCCmec type V(5C2&5) subtype c. Surprisingly, the chromosomal aminoglycoside resistance gene aac(6')-aph(2") harbored by S. haemolyticus strain SH936 was flanked by two copies of IS256, forming the IS256-element (IS256-GNAT-[aac(6')-aph(2")]-IS256), which was widely present in strains of both Staphylococcus and Enterococcus genus. Furthermore, the two strains of oxacillin-resistant and MDR S. haemolyticus were found to harbor antimicrobial resistance plasmids, including one 26.9-kb plasmid (pSH1275-2) containing msr(A)-mph(C)) and qacA, one mobilizable plasmid pSH1275-3 harboring vga(A)LC, one plasmid (pSH9361-1) carrying erm(C), and one plasmid (pSH9361-2) carrying qacJ.

Conclusion

The systematic analysis of whole-genome sequences provided insights into the mobile genetic elements responsible for multi-drug resistance in these two strains of oxacillin-resistant and mecA-positive S. haemolyticus, which will assist clinicians in devising precise, personalized, and clinical therapeutic strategies for treating otitis media caused by multi-drug resistant S. haemolyticus.

The Home Environment Is a Reservoir for Methicillin-Resistant Coagulase-Negative Staphylococci and Mammaliicocci

Coagulase-negative staphylococci (CoNS) and mammaliicocci are opportunistic human and animal pathogens, often resistant to multiple antimicrobials, including methicillin. Methicillin-resistant CoNS (MRCoNS) have traditionally been linked to hospitals and healthcare facilities, where they are significant contributors to nosocomial infections. However, screenings of non-hospital environments have linked MRCoNS and methicillin-resistant mammaliicocci (MRM) to other ecological niches. The aim of this study was to explore the home environment as a reservoir for MRCoNS and MRM. A total of 33 households, including households with a dog with a methicillin-resistant staphylococcal infection, households with healthy dogs or cats and households without pets, were screened for MRCoNS and MRM by sampling one human, one pet (if present) and the environment. Samples were analyzed by a selective culture-based method, and bacterial species were identified by MALDI-TOF MS and tested for antibiotic susceptibility by the agar disk diffusion method. Following whole-genome sequencing, a large diversity of SCCmec elements and sequence types was revealed, which did not indicate any clonal dissemination of specific strains. Virulome and mobilome analyses indicated a high degree of species specificity. Altogether, this study documents that the home environment is a reservoir for a variety of MRCoNS and MRM regardless of the type of household.

Epidemiological differences, clinical aspects, and short-term prognosis of patients with healthcare-associated and community-acquired infective endocarditis

Background

The prevalence of healthcare-associated infective endocarditis in Brazil is poorly known.

Aim

To analyze the epidemiological, clinical and microbiological characteristics, and the prognosis of healthcare-associated infective endocarditis (HAIE) compared with community-acquired infective endocarditis (CIE) and identify the associated factors with hospital mortality.

Method

A historical cohort study was carried out, with a data collection period from January 2009 to December 2019 at the Federal University of São Paulo. Data were collected from medical records of patients with infective endocarditis (IE) hospitalized during the study period. Patients were classified into three groups: CIE, non-nosocomial HAIE (NN-HAIE) and nosocomial HAIE (NHAIE).

Results

A total of 204 patients with IE were included; of these, 127 (62.3%) were cases of HAIE, of which 83 (40.7%) were NN-HAIE and 44 (21.6%) were NHAIE. Staphylococcus spp. Were the main causative agents, especially in HAIE groups (P<0.001). Streptococcus spp. were more prevalent in the CIE group (P<0.001). In-hospital mortality was 44.6%, with no differences between groups. Independent risk factors for in-hospital mortality were age ≥ 60 years (odds ratio (OR): 6.742), septic shock (OR 5.264), stroke (OR 3.576), heart failure (OR 7.296), and Intensive Care Unit admission (OR 7.768).

Conclusion

HAIE accounted for most cases in this cohort, with a higher prevalence of non-nosocomial infections. Staphylococcus spp. were the main causative agents. Hospital mortality was high, 44.6%, with no difference between groups.

Staphylococcus capitis Bloodstream Isolates: Investigation of Clonal Relationship, Resistance Profile, Virulence and Biofilm Formation

Staphylococcus capitis has been recognized as a relevant opportunistic pathogen, particularly its persistence in neonatal ICUs around the world. Therefore, the aim of this study was to describe the epidemiological profile of clinical isolates of S. capitis and to characterize the factors involved in the persistence and pathogenesis of these strains isolated from blood cultures collected in a hospital in the interior of the state of São Paulo, Brazil. A total of 141 S. capitis strains were submitted to detection of the mecA gene and SCCmec typing by multiplex PCR. Genes involved in biofilm production and genes encoding enterotoxins and hemolysins were detected by conventional PCR. Biofilm formation was evaluated by the polystyrene plate adherence test and phenotypic resistance was investigated by the disk diffusion method. Finally, pulsed-field gel electrophoresis (PFGE) was used to analyze the clonal relationship between isolates. The mecA gene was detected in 99 (70.2%) isolates, with this percentage reaching 100% in the neonatal ICU. SCCmec type III was the most prevalent type, detected in 31 (31.3%) isolates and co-occurrence of SCCmec was also observed. In vitro biofilm formation was detected in 46 (32.6%) isolates but was not correlated with the presence of the ica operon genes. Furthermore, biofilm production in ICU isolates was favored by hyperosmotic conditions, which are common in ICUs because of the frequent parenteral nutrition. Analysis of the clonal relationship between the isolates investigated in the present study confirms a homogeneous profile of S. capitis and the persistence of clones that are prevalent in the neonatal ICU and disseminated across the hospital. This study highlights the adaptation of isolates to specific hospital environments and their high clonality.

Etiology, persistence, and risk factors of subclinical mastitis in a meat-producing sheep flock

Subclinical mastitis, the asymptomatic inflammation of the udder often caused by bacterial infection, is an important economic and welfare concern in meat-producing flocks. We conducted a longitudinal observational study to: (1) characterize the etiology, prevalence, incidence, and persistence of intramammary infections during the first 8 wk of lactation, and (2) investigate the potential risk factors of lactation stage, parity, and the number of lambs reared. Duplicate milk samples (n = 592) were collected aseptically from each udder half of 37 clinically healthy ewes (9 Hampshire, 22 Polypay, and 6 Targhee) weekly for their first 8 wk of lactation. A sample was considered a true infection if at least 100 CFU/mL of a bacterial species were isolated. Out of a total of 560 non-contaminated duplicate udder half samples, 186 (33.2%) were infected. The prevalence of subclinical mastitis in the first week of lactation was 26.0% at the udder half level and increased over lactation to 47.1% by 8 wk. Over the course of lactation, 34 of the 37 (91.9%) ewes had an intramammary infection in at least one udder half. The most common bacteria isolated were non-aureus Staphylococci (72.1%), Staphylococcus aureus (7.5%), and Mannheimia haemolytica (5.9%). The weekly incidence rate of new infections was 18.0% ± 10.2% (mean ± SD). Infections lasted 2.1 ± 2.1 wk, with 9.0% present the full 8 wk of observation. Spontaneous cures occurred in 36.0% of infection bouts but varied from 0% to 100% depending on the pathogen. The probability of subclinical mastitis infection increased as lactation progressed for ewes rearing single or multiple lambs and for ewes in their first or second parity, but not for ewes in later parities. In conclusion, intramammary infections in this flock were prevalent across lactation, parities, and litter sizes, and varied in their duration and spontaneous cure rate. Improved knowledge of the etiological agents and risk factors involved in subclinical mastitis is important in developing effective control measures in meat-producing flocks.

Molecular characteristics and clinical features of Staphylococcus epidermidis healthcare-associated late-onset bacteremia among infants hospitalized in neonatal intensive care units

BACKGROUND

Though Staphylococcus epidermidis was the most common pathogen of late-onset sepsis (LOS) in neonatal intensive care units (NICUs), there haves been scanty reports on molecular epidemiology of S. epidermidis isolates from infants stayed in NICU and on correlation of molecular characteristics with clinical features in these infants.

METHODS

We collected and characterized S. epidermidis bloodstream isolates from infants hospitalized in NICU of a medical center in Taiwan between 2018 and 2020. Medical records of these infants were retrospectively reviewed.

RESULTS

A total of 107 isolates identified from 78 episodes of bacteremia in 75 infants were included for analysis. Of the 78 isolates (episodes), 24 pulsotypes, 11 sequence types (STs), and 5 types of staphylococcal chromosomal cassette (type I-V) were identified. ST59 and its single locus variant ST1124 (37.2%) comprised the most common strain, followed by ST35 (14.1%), ST2 (11.5%), and ST89 (10.3%). All but 5 isolates (73/78, 93.6%) belonged to clonal complex (CC) 2. Comparing infants infected with genetically different strains, the patients with underlying immune disease were significantly associated with ST2 infection (P = 0.021), while no statistically significant differences were found in terms of clinical and laboratory characteristics. Only 3.8% of the isolates were susceptible to oxacillin.

CONCLUSIONS

More than 90% of S. epidermidis bloodstream isolates from infants in NICU in Taiwan were resistant to oxacillin. Though diverse, more than 90% of the isolates (episodes) belonged to CC2. No statistically significant differences were found in terms of clinical characteristics among the infants infected with genetically different strains.

Dynamics of antimicrobial resistance and virulence of staphylococcal species isolated from foods traded in the Cape Coast metropolitan and Elmina municipality of Ghana

The impact of staphylococci on food poisoning and infections could be higher than previously reported. In this study, we characterised the occurrence and coexistence of antimicrobial resistance and virulence genes of staphylococci isolates in foods. Staphylococci were isolated from 236 samples of selected street-vended foods and identified. The pattern of antimicrobial resistance and virulence genes in the staphylococci were assessed using disc diffusion, PCR and analysis of next-generation sequencing data. The food samples (70.76 %) showed a high prevalence of staphylococci and differed among the food categories. Forty-five Staphylococcus species were identified and comprised coagulase-negative and positive species. Staphylococcus sciuri (now Mammaliicoccus sciuri), S. aureus, S. kloosii, S. xylosus, S. saprophyticus, S. haemolyticus and S. succinus were the most abundant species. The staphylococcal isolates exhibited resistance to tetracycline, levofloxacin, ciprofloxacin, norfloxacin, gentamicin and amikacin and susceptibility to nitrofurantoin. Antimicrobial susceptibilities were also reported for cefoperazone, ceftriaxone, cefotaxime, nalidixic acid and piperacillin-tazobactam. The antimicrobial resistance and virulence genes commonly detected consisted of tet, arl, macB, van, gyr, nor, optrA, bcrA, blaZ, taeA and S. aureus lmrS. The isolates frequently exhibited multiple resistance (30.42 %) of up to eight antimicrobial drug classes. The isolates predominantly harboured genes that express efflux pump proteins (50.53 %) for antibiotic resistance compared with inactivation (10.05 %), target alteration (26.72 %), protection (7.67 %) and replacement (3.17 %). The virulence determinants comprised genes of pyrogenic toxin superantigens (eta, etb, tst), adhesions (clf, fnbA, fnbB, cna, map, ebp, spA, vWbp, coa) and genes that express exoproteins (nuclease, metalloprotease, γ-hemolysin, hyaluronate lyase). There was a statistically significant difference in the prevalence of staphylococci isolates and their antimicrobial resistance and virulence profile as revealed by the phenotypic, PCR and next-generation sequencing techniques. The findings suggest a higher health risk for consumers. We recommend a critical need for awareness and antimicrobial susceptibility and anti-virulence strategies to ensure food safety and counteract the spread of this clinically relevant genus.

Characterisation of neonatal Staphylococcus capitis NRCS-A isolates compared with non NRCS-A Staphylococcus capitis from neonates and adults

Staphylococcus capitis is a frequent cause of late-onset sepsis in neonates admitted to Neonatal Intensive Care Units (NICU). One clone of S. capitis, NRCS-A has been isolated from NICUs globally although the reasons for the global success of this clone are not well understood.We analysed a collection of S. capitis colonising babies admitted to two NICUs, one in the UK and one in Germany as well as corresponding pathological clinical isolates. Genome analysis identified a population structure of three groups; non-NRCS-A isolates, NRCS-A isolates, and a group of 'proto NRCS-A' - isolates closely related to NRCS-A but not associated with neonatal infection. All bloodstream isolates belonged to the NRCS-A group and were indistinguishable from strains carried on the skin or in the gut. NRCS-A isolates showed increased tolerance to chlorhexidine and antibiotics relative to the other S. capitis as well as enhanced ability to grow at higher pH values. Analysis of the pangenome of 138 isolates identified characteristic nsr and tarJ genes in both the NRCS-A and proto groups. A CRISPR-cas system was only seen in NRCS-A isolates which also showed enrichment of genes for metal acquisition and transport.We found evidence for transmission of S. capitis NRCS-A within NICU, with related isolates shared between babies and multiple acquisitions by some babies. Our data show NRCS-A strains commonly colonise uninfected babies in NICU representing a potential reservoir for potential infection. This work provides more evidence that adaptation to survive in the gut and on skin facilitates spread of NRCS-A, and that metal acquisition and tolerance may be important to the biology of NRCS-A. Understanding how NRCS-A survives in NICUs can help develop infection control procedures against this clone.

The Occurrence and Characteristics of Methicillin-Resistant Staphylococcal Isolates from Foods and Containers

Antimicrobial resistance (AMR) has emerged as an urgent global public health issue that requires immediate attention. Methicillin-resistant staphylococci (MRS) is a major problem, as it may cause serious human and animal infections, eventually resulting in death. This study determined the proportional distribution, genetic characteristics, and antimicrobial susceptibility of mecA- or mecC-carrying staphylococci isolated from food chain products. A total of 230 samples were taken from meat, food, fermented food, and food containers. Overall, 13.9% (32/230) of the samples were identified to have Staphylococcus aureus isolates; of those, 3.9% (9/230) were MRS, with eight mecA-positive and one mecC-positive samples, and 1.3% (3/230) methicillin-resistant Staphylococcus aureus (MRSA). MRSA strains belonging to three sequence types (ST9, ST22, and a newly identified ST), three different spa types (T005, t526, and a newly identified type), and three different SCCmec types (IV, V, and an unidentified SCCmec) were detected. Additionally, eight mecA-positive staphylococcal isolates were identified as S. haemolyticus, S. sciuri, S. simulans, and S. warneri, while the mecC-harboring isolate was S. xylosus. The enterotoxin gene, SEm, was detected at 1.56% in S. aureus, whereas SEq was detected at 0.31%, and SEi was also found in MRSA. Our study emphasizes the importance of enhanced hygiene standards in reducing the risk of occupational and foodborne MRSA infections associated with the handling or consumption of meat, food, and preserved food products.

Resistance pattern of isolated microorganisms from 783 clinical specimen cultures in patients admitted to Yasuj Educational Hospitals, Iran

BACKGROUND

Infectious diseases are still one of the leading causes of morbidity and mortality in resource-limited settings. Serious infection caused mostly by gram-negative pathogens causes significant morbidity. According to the Centers for Disease Control and Prevention, antimicrobial resistance kills over 700,000 people worldwide. Antibiotic resistance is on the rise, and as a consequence, serious public health issues are arising. The present study investigated isolated clinical samples from Yasuj teaching hospitals to determine the antimicrobial resistance profile to various antibiotics.

MATERIALS AND METHODS

Microbial isolates regarding cultures from urine, blood, wound, abdominal tap, throat, stool, cerebrospinal fluid, endotracheal tube, sputum, skin lesion, nasal, and mouth secretion were collected from patients admitted to hospitals affiliated with Yasuj teaching hospitals. Antibiotic susceptibility profiles were determined by using the Kirby-Bauer disc diffusion method. Data were tabulated and analyzed with SPSS version 26.0.

RESULTS

A total of 783 samples were evaluated in our study, with an average of 30.6 years and 54.5% female patients. Most of the bacterial isolates were gram-negative (64.2%). The majority of cultures were Escherichia coli (49.9%), mainly among urine samples (64.2%). The frequency distribution of norfloxacin antibiotic resistance was more common in internal medicine (66.7%), infectious (63.6%), and emergency wards (58.8%). The frequency distribution of penicillin antibiotic resistance was statistically significant in different wards. All cases of oxacillin were resistant.

CONCLUSION

Our data showed a high level of antibiotic resistance among bacterial isolates in our center. Considering widespread empirical antibiotic therapy in Iran, the rate of increasing resistance to common antibiotics prescribed for ambulatory and hospitalized patients is concerning. We recommend providing more strict guidelines and policies to control the overuse and overprescription of antimicrobials by health policy-making organizations.

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.

Trends in coagulase-negative staphylococci (CoNS), England, 2010-2021

Objective

To review the epidemiology of coagulase-negative staphylococci (CoNS) in England over the recent 12 year period.

Methods

Laboratory-confirmed CoNS reported from sterile sites in patients in England to the UK Health Security Agency (UKHSA) between 2010 and 2021 were extracted from the national laboratory database and analysed.

Results

Overall, 668 857 episodes of CoNS were reported. Unspeciated CoNS accounted for 56 % (374 228) of episodes, followed by Staphylococcus epidermidis (26 %; 174 050), S. hominis (6.5 %; 43 501) and S. capitis (3.9 %; 25 773). Unspeciated CoNS increased by 8.2 % (95 % CI, 7.1-9.3) annually between 2010 and 2016, then decreased annually by 6.4 % (95 % CI: -4.8 to -7.9) until 2021. Speciated CoNS increased by 47.6 % (95 % CI, 44.5-50.9) annually between 2010 and 2016 and increased annually by 8.9 % (95 % CI: 5.1 to 12.8) until 2021. Antimicrobial susceptibility profiles differed by species.

Conclusions

Reports of CoNS from normally sterile body sites in patients in England increased between 2010 and 2016 and remained stable between 2017 and 2021. There has been a striking improvement in species-level identification of CoNS in recent years. Monitoring trends in CoNS epidemiology is crucial for development of observational and clinical intervention studies on individual species.

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.

Antimicrobial Resistant Coagulase-Negative Staphylococci Carried by House Flies (Musca domestica) Captured in Swine and Poultry Farms

House flies (Musca domestica) are very diffuse insects attracted by biological materials. They are abundantly present in farm environments and can frequently come in contact with animals, feed, manure, waste, surfaces, and fomites; consequently, these insects could be contaminated, carry, and disperse several microorganisms. The aim of this work was to evaluate the presence of antimicrobial-resistant staphylococci in house flies collected in poultry and swine farms. Thirty-five traps were placed in twenty-two farms; from each trap, 3 different kinds of samples were tested: attractant material present in the traps, the body surface of house flies and the body content of house flies. Staphylococci were detected in 72.72% of farms, 65.71% of traps and 43.81% of samples. Only coagulase-negative staphylococci (CoNS) were isolated, and 49 isolates were subjected to an antimicrobial susceptibility test. Most of the isolates were resistant to amikacin (65.31%), ampicillin (46.94%), rifampicin (44.90%), tetracycline (40.82%) and cefoxitin (40.82%). Minimum Inhibitory concentration assay allowed to confirm 11/49 (22.45%) staphylococci as methicillin-resistant; 4 of them (36.36%) carried the mecA gene. Furthermore, 53.06% of the isolates were classified as multidrug-resistant (MDR). Higher levels of resistance and multidrug resistance were detected in CoNS isolated from flies collected in poultry farms than in swine farms. Therefore, house flies could carry MDR and methicillin-resistant staphylococci, representing a possible source of infection for animals and humans.

Improved Genomic Prediction of Staphylococcus epidermidis Isolation Sources with a Novel Polygenic Score

Staphylococcus epidermidis infections can be challenging to diagnose due to the species frequent contamination of clinical specimens and indolent course of infection. Nevertheless, S. epidermidis is the major cause of late-onset sepsis among premature infants and of intravascular infection in all age groups. Prior work has shown that bacterial virulence factors, antimicrobial resistances, and strains have up to 80% in-sample accuracy to distinguish hospital from community sources, but are unable to distinguish true bacteremia from blood culture contamination. Here, a phylogeny-informed genome-wide association study of 88 isolates was used to estimate effect sizes of particular genomic variants for isolation sources. A "polygenic score" was calculated for each isolate as the summed effect sizes of its repertoire of genomic variants. Predictive models of isolation sources based on polygenic scores were tested with in-samples and out-samples from prior studies of different patient populations. Polygenic scores from accessory genes (AGs) distinguished hospital from community sources with the highest accuracy to date, up to 98% for in-samples and 65% to 91% for various out-samples, whereas scores from single nucleotide polymorphisms (SNPs) had lower accuracy. Scores from AGs and SNPs achieved the highest in-sample accuracy to date, up to 76%, in distinguishing infection from contaminant sources within a hospital. Model training and testing data sets with more similar population structures resulted in more accurate predictions. This study reports the first use of a polygenic score for predicting a complex bacterial phenotype and shows the potential of this approach for enhancing S. epidermidis diagnosis.

Long-Term Monitoring of Bioaerosols in an Environment without UV and Desiccation Stress, an Example from the Cave Postojnska Jama, Slovenia

A natural cave environment subject to regular human visitation was selected for aerobiological study to minimize the effects of severe temperature fluctuations, UV radiation, and desiccation stress on the aerobiome. The longer sampling period of bioaerosols, up to 22 months, was generally not associated with a proportionally incremental and cumulative increase of microbial biomass. The culture-independent biomass indicator ATP enabled quick and reliable determination of the total microbial biomass. Total airborne microbial biomass was influenced by human visitation to the cave, as confirmed by significantly higher concentrations being observed along tourist footpaths (p < 0.05). Airborne beta-glucans (BG) and lipopolysaccharide (LPS) are present in cave air, but their impact on the cave remains to be evaluated. Staphylococcus spp., as an indicator of human presence, was detected at all sites studied. Their long-term survival decrease is likely due to high relative humidity, low temperature, the material to which they adhere, and potentially natural elevated radon concentration. The most commonly recorded species were: S. saprophyticus, which was identified in 52% of the studied sites, S. equorum in 29%, and S. warneri in 24% of the studied sites. Only a few isolates were assigned to Risk group 2: S. aureus, S. epidermidis, S. haemolyticus, S. pasteuri, and S. saprophyticus.

The Role of Coagulase-Negative Staphylococci Biofilms on Late-Onset Sepsis: Current Challenges and Emerging Diagnostics and Therapies

Infections are one of the most significant complications of neonates, especially those born preterm, with sepsis as one of the principal causes of mortality. Coagulase-negative staphylococci (CoNS), a group of staphylococcal species that naturally inhabit healthy human skin and mucosa, are the most common cause of late-onset sepsis, especially in preterms. One of the risk factors for the development of CoNS infections is the presence of implanted biomedical devices, which are frequently used for medications and/or nutrient delivery, as they serve as a scaffold for biofilm formation. The major concerns related to CoNS infections have to do with the increasing resistance to multiple antibiotics observed among this bacterial group and biofilm cells’ increased tolerance to antibiotics. As such, the treatment of CoNS biofilm-associated infections with antibiotics is increasingly challenging and considering that antibiotics remain the primary form of treatment, this issue will likely persist in upcoming years. For that reason, the development of innovative and efficient therapeutic measures is of utmost importance. This narrative review assesses the current challenges and emerging diagnostic tools and therapies for the treatment of CoNS biofilm-associated infections, with a special focus on late-onset sepsis.

The added value of a commercial 16S/18S-PCR assay (UMD-SelectNA, Molzym) for microbiological diagnosis of spondylodiscitis: an observational study

In spondylodiscitis, pathogen identification is important to guide therapy strategies. Here the use of an rDNA PCR assay (Molzym UMDSelectNA) for pathogen detection in spondylodiscitis was evaluated in 182 specimens from 124 spondylodiscitis patients. In 81% of specimens rDNA PCR and conventional culture produced concordant results. Compared to conventional culture, sensitivity and specificity of rDNA PCR were 75% and 83.9%, respectively. The rDNA PCR performed better than conventional culture in identification of Streptococcus spp.. However, overall sensitivity was suboptimal, e.g., in cases with low bacterial burden, and only 5 of 124 patients (4%) received a microbiological diagnosis by employing rDNA PCR. Thus, the added value of routine use of rDNA PCR on spondylodiscitis specimens is limited. Targeted use of the assay in culture-negative cases may be efficient and moderately increase diagnostic yield. The need for susceptibility information implies that 16S rDNA PCR may only be used as an add-on tool to culture.

Molecular Analysis of Pathogenicity, Adhesive Matrix Molecules (MSCRAMMs) and Biofilm Genes of Coagulase-Negative Staphylococci Isolated from Ready-to-Eat Food

This paper provides a snapshot on the pathogenic traits within CoNS isolated from ready-to-eat (RTE) food. Eighty-five strains were subjected to biofilm and slime production, as well as biofilm-associated genes (icaA, icaD, icaB, icaC, eno, bap, bhp, aap, fbe, embP and atlE), the insertion sequence elements IS256 and IS257 and hemolytic genes. The results showed that the most prevalent determinants responsible for the primary adherence were eno (57.6%) and aap (56.5%) genes. The icaADBC operon was detected in 45.9% of the tested strains and was correlated to slime production. Moreover, most strains carrying the icaADBC operon simultaneously carried the IS257 insertion sequence element. Among the genes encoding for surface proteins involved in the adhesion to abiotic surfaces process, atlE was the most commonly (31.8%) followed by bap (4.7%) and bhp (1.2%). The MSCRAMMs, including fbe and embp were detected in the 11.8% and 28.2% of strains, respectively. A high occurrence of genes involved in the hemolytic toxin production were detected, such as hla_yiD (50.6%), hlb (48.2%), hld (41.2%) and hla_haem (34.1%). The results of the present study revealed an unexpected occurrence of the genes involved in biofilm production and the high hemolytic activity among the CoNS strains, isolated from RTE food, highlighting that this group seems to be acquiring pathogenic traits similar to those of S. aureus, suggesting the need to be included in the routine microbiological analyses of food.

Infectious complications of radiologically placed upper arm ports: A single center analysis

OBJECTIVES

Infections are common complications in venous access ports. The presented analysis aimed to investigate the incidence, microbiological spectrum, and acquired resistances of pathogens in upper arm port associated infections to provide a decision aid in the choice of therapy.

MATERIALS AND METHODS

In total, 2667 implantations and 608 explantations were performed at a high-volume tertiary medical center between 2015 and 2019. In cases with infectious complications (n = 131, 4.9%), procedural conditions and results of microbiological testing were reviewed retrospectively.

RESULTS

Of 131 port associated infections (median dwell time 103 days, interquartile range 41-260), 49 (37.4%) were port pocket infections (PPI) and 82 (62.6%) were catheter infections (CI). Infectious complications occurred more often after implantation in inpatients compared to outpatients (P < 0.01). PPI were mainly caused by Staphylococcus aureus (S. aureus, 48.3%) and coagulase-negative staphylococci (CoNS, 31.0%). Other gram-positive and gram-negative species were encountered in 13.8% and 6.9%, respectively. CI were caused less frequently by S. aureus (8.6%) than CoNS (39.7%). Other gram-positive and gram-negative strains were isolated in 8.6% and 31.0%, respectively. Candida species were seen in 12.1% of CI. An acquired antibiotic resistance was detected in 36.0% of all significant isolates, occurring especially in CoNS (68.3%) and gram-negative species (24.0%).

CONCLUSIONS

Staphylococci comprised the largest group of pathogens in upper arm port associated infections. However, gram-negative strains and Candida species should also be considered as a cause of infection in CI. Due to the frequent detection of potential biofilm-forming pathogens, port explantation is an important therapeutic measure, especially in severely ill patients. Acquired resistances must be anticipated when choosing an empiric antibiotic treatment.

Trends in Occurrence and Phenotypic Resistance of Coagulase-Negative Staphylococci (CoNS) Found in Human Blood in the Northern Netherlands between 2013 and 2019

Background: For years, coagulase-negative staphylococci (CoNS) were not considered a cause of bloodstream infections (BSIs) and were often regarded as contamination. However, the association of CoNS with nosocomial infections is increasingly recognized. The identification of more than 40 different CoNS species has been driven by the introduction of matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. Yet, treatment guidelines consider CoNS as a whole group, despite increasing antibiotic resistance (ABR) in CoNS. This retrospective study provides an in-depth data analysis of CoNS isolates found in human blood culture isolates between 2013 and 2019 in the entire region of the Northern Netherlands. Methods: In total, 10,796 patients were included that were hospitalized in one of the 15 hospitals in the region, leading to 14,992 CoNS isolates for (ABR) data analysis. CoNS accounted for 27.6% of all available 71,632 blood culture isolates. EUCAST Expert rules were applied to correct for errors in antibiotic test results. Results: A total of 27 different CoNS species were found. Major differences were observed in occurrence and ABR profiles. The top five species covered 97.1% of all included isolates: S. epidermidis, S. hominis, S. capitis, S. haemolyticus, and S. warneri. Regarding ABR, methicillin resistance was most frequently detected in S. haemolyticus (72%), S. cohnii (65%), and S. epidermidis (62%). S. epidermidis and S. haemolyticus showed 50–80% resistance to teicoplanin and macrolides while resistance to these agents remained lower than 10% in most other CoNS species. Conclusion: These differences are often neglected in national guideline development, prompting a focus on ‘ABR-safe’ agents such as glycopeptides. In conclusion, this multi-year, full-region approach to extensively assess the trends in both the occurrence and phenotypic resistance of CoNS species could be used for evaluating treatment policies and understanding more about these important but still too often neglected pathogens.

It’s not you, it’s SOSA: a case study on breaking up with an FDA-cleared susceptibility testing system’s oxacillin results for Staphylococcus spp. other than S. aureus and S. lugdunensis

Background

In 2021, the Clinical and Laboratory Standards Institute revised its susceptible oxacillin minimum inhibitory concentration (MIC) breakpoint for Staphylococcus spp. other than S. aureus and S. lugdunensis (SOSA) from  ≤0.25 to  ≤0.5 µg/mL. Here, we describe the response to this breakpoint change, which at the time of this study was not yet recognized by the US Food and Drug Administration (FDA), in our laboratory, where the primary method for antimicrobial susceptibility testing (AST) of SOSA is VITEK 2. VITEK 2 uses the Automated Expert System (AES) to integrate the results of oxacillin MIC and cefoxitin screen tests into a final interpretation; our laboratory also adjudicates discordant oxacillin and cefoxitin results using a PBP2a test.

Methods

We retrospectively reviewed and assessed the yield of PBP2a testing for 189 SOSA isolates with discordant (when applying the FDA susceptible oxacillin breakpoint of ≤0.25 µg/mL) VITEK 2 oxacillin and cefoxitin results, and then prospectively incorporated PBP2a testing for isolates with oxacillin MICs of 0.5 µg/mL and positive cefoxitin screens into our algorithm.

Results

Compared with accepting the VITEK 2 AES interpretation, PBP2a testing substantially improved the accuracy of mecA-mediated resistance classification in both scenarios, especially for the ∼4.7% of isolates with oxacillin MICs ≤0.5 µg/mL and positive cefoxitin screens.

Conclusions

Although detection of mecA or PBP2a is the gold standard for assessment of β-lactam resistance in staphylococci, targeting a subset of isolates for mecA or PBP2a testing based on phenotypic AST results that predict an increased risk of misclassification may be a pragmatic, labor- and cost-saving approach.

Molecular Characterization of Staphylococci Recovered from Hospital Personnel and Frequently Touched Surfaces in Tianjin, China

Staphylococci are major hospital-associated pathogens, and the dissemination of methicillin-resistant staphylococci in hospitals poses a great challenge for managing hospital-acquired infections. Little is known about the dissemination of staphylococci recovered from the hospital environment and personnel in China. In this study, antimicrobial susceptibility tests, mecA gene detection, SCCmec typing, and multilocus sequence typing (MLST) were performed to clarify the molecular epidemiology of staphylococci in a large hospital in Tianjin, China. One hundred and ninety-five staphylococci were recovered, and 94% of isolates were resistant to at least one antibiotic. Eighty-five staphylococci were mecA gene-positive, and 40% of them harbored SCCmec IV and V. The genotype of Staphylococcus aureus (S. aureus) was ST25, and the dominant genotype of methicillin-resistant Staphylococcus epidermidis (MRSE) was ST59. Three new sequence types were assigned as ST840, ST841, and ST842. One (2%) frequently touched surface was contaminated by S. aureus, which suggested that environmental contamination occurred in the hospital in China. Nineteen (39%) frequently touched surfaces were contaminated by methicillin-resistant coagulase-negative staphylococci (MRCoNS), and 46% of HP carried MRCoNS. Varied staphylococcal species and antimicrobial-resistance rates were observed between staphylococci that were recovered from hospital personnel and frequently touched surfaces. The transmission of MRSE and S. aureus between hospital personnel and frequently touched surfaces was detected. Hospital items and personnel may act as reservoirs of antimicrobial-resistant staphylococci, and cleaning strategies should be carried out to decrease the dissemination of antimicrobial-resistant staphylococci in hospitals in China.

Development of an artificial synovial fluid useful for studying Staphylococcus epidermidis joint infections

Staphylococcus epidermidis is a major causative agent of prosthetic joint infections (PJI). The ability to form biofilms supports this highly selective pathogenic potential. In vitro studies essentially relying on phenotypic assays and genetic approaches have provided a detailed picture of the molecular events contributing to biofilm assembly. A major limitation in these studies is the use of synthetic growth media, which significantly differs from the environmental conditions S. epidermidis encounters during host invasion. Building on evidence showing that growth in serum substantially affects S. epidermidis gene expression profiles and phenotypes, the major aim of this study was to develop and characterize a growth medium mimicking synovial fluid, thereby facilitating research addressing specific aspects related to PJI. Using fresh human plasma, a protocol was established allowing for the large-scale production of a medium that by biochemical analysis matches key characteristics of synovial fluid and therefore is referred to as artificial synovial fluid (ASF). By analysis of biofilm-positive, polysaccharide intercellular adhesion (PIA)-producing S. epidermidis 1457 and its isogenic, PIA- and biofilm-negative mutant 1457-M10, evidence is provided that the presence of ASF induces cluster formation in S. epidermidis 1457 and mutant 1457-M10. Consistent with the aggregative properties, both strains formed multilayered biofilms when analyzed by confocal laser scanning microscopy. In parallel to the phenotypic findings, expression analysis after growth in ASF found upregulation of genes encoding for intercellular adhesins (icaA, aap, and embp) as well as atlE, encoding for the major cell wall autolysin being responsible for eDNA release. In contrast, growth in ASF was associated with reduced expression of the master regulator agr. Collectively, these results indicate that ASF induces expression profiles that are able to support intercellular adhesion in both PIA-positive and PIA-negative S. epidermidis. Given the observation that ASF overall induced biofilm formation in a collection of S. epidermidis isolates from PJI, the results strongly support the idea of using growth media mimicking host environments. ASF may play an important role in future studies related to the pathogenesis of S. epidermidis PJI.

Emerging vancomycin-non susceptible coagulase negative Staphylococci associated with skin and soft tissue infections

Backgrounds

Observable emergence of Vancomycin-Non susceptible Coagulase-negative Staphylococci (VNS-CoNS) associated with skin and soft tissue infections spreading among the urban and rural populace is gradually intensifying severe complications. The isolated VNS-CoNS were evaluated with Matrix-assisted Laser Desorption/ionization Time of Flight Mass Spectrometry (MALDI ToF MS) for species characterization and pan-antimicrobial resistance pattern.

Methods

Out of 256 clinical samples collected including pus, abscess, ear swabs, eye swabs, and aspirates, 91 CoNS isolates were biotyped and further characterized with MALDI-TOF MS. Staphylococci marker genes, Vancomycin susceptibility, and biofilm assays were performed.

Results

Of 91 CoNS isolates, S.cohnii (2.3%), S.condimentii (3.4%), S. saprophyticus (6.7%), and S.scuri (21.1%) were characterized with MALDI-TOF with significant detection rate (99.4%; CI 95, 0.775–0.997, positive predictive values, 90.2%) compared to lower biotyping detection rate (p = 0.001). Hemolytic VNS-CoNS lacked nuc, pvl and spa genes from wound, ear, and aspirates of more 0.83 MARI clustered into a separate phylo-diverse group and were widely distributed in urban and peri-urban locations. MALDI TOF–MS yielded a high discriminatory potential of AUC-ROC score of 0.963 with true-positivity prediction. VNS-CoNS of MIC ≥ 16 µg/mL were observed among all the ages with significant resistance at 25th and 75th quartiles. More than 10.5% of CoNS expressed multi-antibiotic resistance with more than 8 µg/mL vancomycin cut-off values (p < 0.05).

Conclusion

Antibiotic resistant CoNS should be considered significant pathogens rather than contaminant. Biofilm producing VNS-S. sciuri and S. condimentii are potential strains with high pathological tropism for skin, soft tissues and wound infections, and these strains require urgent surveillance in peri-urban and rural communities.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12941-022-00516-4.

Whole-Genome Sequence of Multidrug-Resistant Methicillin-Resistant Staphylococcus epidermidis Carrying Biofilm-Associated Genes and a Unique Composite of SCCmec

Staphylococcus epidermidis is part of the normal human flora that has recently become an important opportunistic pathogen causing nosocomial infections and tends to be multidrug-resistant. In this investigation, we aimed to study the genomic characteristics of methicillin-resistant S. epidermidis isolated from clinical specimens. Three isolates were identified using biochemical tests and evaluated for drug susceptibility. Genomic DNA sequences were obtained using Illumina, and were processed for analysis using various bioinformatics tools. The isolates showed multidrug resistance to most of the antibiotics tested in this study, and were identified with three types (III(3A), IV(2B&5), and VI(4B)) of the mobile genetic element SCCmec that carries the methicillin resistance gene (mecA) and its regulators (mecI and mecR1). A total of 11 antimicrobial resistance genes (ARGs) was identified as chromosomally mediated or in plasmids; these genes encode for proteins causing decreased susceptibility to methicillin (mecA), penicillin (blaZ), fusidic acid (fusB), fosfomycin (fosB), tetracycline (tet(K)), aminoglycosides (aadD, aac(6′)-aph(2′’)), fluoroquinolone (MFS antibiotic efflux pump), trimethoprim (dfrG), macrolide (msr(A)), and chlorhexidine (qacA)). Additionally, the 9SE strain belongs to the globally disseminated ST2, and harbors biofilm-formation genes (icaA, icaB, icaC, icaD, and IS256) with phenotypic biofilm production capability. It also harbors the fusidic acid resistance gene (fusB), which could increase the risk of device-associated healthcare infections, and 9SE has been identified as having a unique extra SCC gene (ccrB4); this new composite element of the ccr type needs more focus to better understand its role in the drug resistance mechanism.

Exploring the Biofilm Formation Capacity in S. pseudintermedius and Coagulase-Negative Staphylococci Species

The ability of biofilm formation seems to play an important role in the virulence of staphylococci. However, studies reporting biofilm formation of coagulase-negative staphylococci isolated from animals are still very scarce. Thus, we aimed to evaluate the biofilm-forming capacity of CoNS and S. pseudintermedius isolated from several animal species and to investigate the effect of conventional antimicrobials on biofilm reduction. A total of 35 S. pseudintermedius and 192 CoNS were included. Biofilm formation was accessed by the microtiter plate assay and the biofilms were stained by crystal violet. Association between biofilm formation and staphylococci species and antimicrobial resistance was also performed. Biofilm susceptibility testing was performed with tetracycline and amikacin at the minimum inhibitory concentration (MIC) and 10 × MIC. The metabolic activity of the biofilm cells after antimicrobial treatment was accessed by the XTT assay. All isolates formed biofilm, with S. urealyticus producing the most biofilm biomass and S. pseudintermedius producing the least biomass. There was a positive association between biofilm formation and multidrug resistance as well as resistance to individual antimicrobials. Neither tetracycline nor amikacin were able to eradicate the biofilm, not even at the highest concentration used. This study provides new insights into biofilm formation and the effects of antimicrobials on CoNS species.

PDIA, an Iminosugar Compound with a Wide Biofilm Inhibitory Spectrum Covering Both Gram-Positive and Gram-Negative Human Bacterial Pathogens

Many difficult-to-treat human infections related to catheters and other indwelling devices are caused by bacteria residing in biofilms. One of the key properties of microorganisms residing in a biofilm is decreased susceptibility towards antimicrobial agents. Therefore, many different approaches have been researched to destroy or inhibit biofilm production by bacteria. Different iminosugars (IS) were reported to inhibit biofilm formation in S. mutans, S. aureus, and P. aeruginosa. The aim of this study was to look for a spectrum of the activity in one of these IS. The iminosugar PDIA beta-1-C-propyl-1,4-dideoxy-1,4-imino-L-arabinitol was tested in vitro at the same concentration against 30 different strains of the most important Gram-negative and Gram-positive human pathogens looking for their biofilm production and viability at different time intervals. It appeared that PDIA inhibited biofilm production of Enterobacter spp., P. aeruginosa, Enterococcus spp. and S. aureus in 8 h, and Klebsiella spp., Acinetobacter spp. and S.epidermidis in 24 h. PDIA caused no growth inhibition of the tested bacteria at a concentration of 0.9 mM. Our results indicate a broad-spectrum biofilm inhibitory activity of PDIA. which may be the basis for future application studies that will help in control of the associated device and biofilm-related infections caused by a wide spectrum of the causative agents.

Prosthetic Knee Infection With Coagulase-Negative Staphylococcus: A Harbinger of Poor Outcomes

BACKGROUND

Coagulase-negative staphylococci (CoNS) are biofilm-producing pathogens whose role in periprosthetic joint infection (PJI) is increasing. There is little data on the prognosis and treatment considerations in the setting of PJI. We sought to evaluate the clinical characteristics, outcomes, and complications in these patients.

METHODS

This is a retrospective cohort study of adult patients at a single tertiary medical center from 2009 to 2020 with culture-proven CoNS PJI after total knee arthroplasty, as diagnosed by Musculoskeletal Infection Society criteria. The primary outcome was treatment success, with failure defined as recurrent CoNS PJI, recurrent PJI with a new pathogen, and/or chronic oral antibiotic suppression at one year postoperatively.

RESULTS

We identified 55 patients with a CoNS total knee arthroplasty PJI with a mean follow-up of 29.8 months (SD: 16.3 months). The most commonly isolated organism was Staphylococcus epidermidis (n = 36, 65.5%). The overall prevalence of methicillin resistance was 63%. Surgical treatment included surgical debridement, antibiotics, and implant retention in 25 (45.5%) cases and two-stage revision (22 articulating and eight static antibiotic-impregnated spacers). At one-year follow-up, only 47% of patients had successful management of their infection. The surgical debridement, antibiotics, and implant retention cohort had the higher rate of treatment failure (60.0%) compared to two-stage revision (46.7%).

CONCLUSION

These results indicate a poor rate of success in treating CoNS PJI. This likely represents the interplay of inherent virulence through biofilm formation and decreased antibiotic efficacy.