Coagulase-negative Staphylococci Research Articles

Clinical applications of metagenomic next-generation sequencing in the identification of pathogens in periprosthetic joint infections: a retrospective study

BackgroundThis study aimed to evaluate the application of metagenomic next-generation sequencing (mNGS) technology to identify pathogens in periprosthetic joint infection (PJI).MethodsA retrospective analysis was conducted on 65 patients suspected of having PJI between April 2020 and July 2023. The patients were categorized into PJI (46 patients) and non-PJI (19 patients) groups based on the 2018 International Consensus Meeting criteria. Clinical data were collected, and both conventional bacterial culture and mNGS were performed. The diagnostic performance of the two methods was compared and analyzed.ResultsmNGS exhibited a sensitivity of 89.13%, a specificity of 94.74%, a positive predictive value of 97.62%, a negative predictive value of 78.26%, and an overall diagnostic accuracy of 90.77%. Compared to microbial culture, mNGS demonstrated superior diagnostic sensitivity while maintaining similar specificity. A total of 48 pathogens were successfully identified using mNGS, with Coagulase-negative staphylococci, Streptococci, Staphylococcus aureus, and Cutibacterium acnes being the most common infectious agents. Notably, mNGS was used to identify 17 potential pathogens in 14 culture-negative PJI samples, highlighting its ability to detect rare infectious agents, including Cutibacterium acnes (n = 5), Granulicatella adiacens (n = 1), Mycobacterium tuberculosis complex (n = 1), and Coxiella burnetii (n = 1), among others, which are not detectable by routine culture methods. However, mNGS failed to detect the pathogen in 4 culture-positive PJI patients, indicating its limitations. Among the 46 PJI patients, 27 had positive culture and mNGS results. The results of mNGS were concordant with those of culture at the genus level in 6 patients with PJI and at the species level in 18 patients. Furthermore, the present study revealed a significantly greater proportion of Staphylococcus aureus in the sinus tract group (45.45%) than in the non-sinus tract group (14.29%), indicating the association of this pathogen with sinus formation in PJI (P = 0.03). Additionally, there was no significant difference in the occurrence of polymicrobial infections between the sinus tract group (27.27%) and the non-sinus tract group (33.33%) (P = 0.37).ConclusionsMetagenomic next-generation sequencing can serve as a valuable screening tool in addition to traditional culture methods to improve diagnostic accuracy through optimized culture strategies.

STERNAL WOUND INFECTION AFTER CARDIAC SURGERY: LOOKING FOR INTERACTIONS BETWEEN PERIOPERATIVE VARIABLES AND PATHOGEN AGENTS

Abstract Background Sternal wound infection (SWI) can be a major complication of cardiac surgery. Both the risk factors and the pathogens agents are well known today. Yet, possible interactions between perioperative variables and pathogens have not been explored. Methods Between Jan 1st, 2006 and Nov 30, 2023 (∼18 years), perioperative data of all patients undergoing cardiac operations through median sternotomy at the Cardio–Thoraco–Vascular Department of the University Hospital of Trieste, Italy, were recorded prospectically in a computed database. Every patient developing a sternal complication was followed in a dedicated outpatient clinic and, in the presence of infection, the causative pathogen was always searched for by cultural examination of tissue speciments. Different strategies of unsupervised clustering were applied to find groups of patients with similar clinical, surgical and microbiological profiles. Results Of 9,680 consecutive cardiac surgery patients, 516 (5.3%) experienced a SWI that involved superficial soft tissue in 25.6% of cases, deep soft tissue in 51%, sternal bone in 16.7%, or mediastinum in 6.8% of cases. Staphylococcus aureus, coagulase–negative Staphylococci, Enterobacteriaceae, and Pseudomonas aeruginosa were pathogens in 100 (19.4%), 158 (30.6%), 89 (17.2%) and 36 (7%) patients, respectively; other pathogens, polymicrobial and negative cultures were found in 27 (5.2%), 26 (5%) and 80 (15.5%) patients, respectively. Following statistical analyses, significant associations were found between the Pseudomonas aeruginosa etiology of SWI and some variables such as female gender (p<0.0001) and preoperative renal failure (p=0.008); significant associations between the Pseudomonas aeruginosa etiology were found also with more serious forms of sepsis (p=0.025), as well as with early postoperative death (p=0.02) and complications such as acute kidney injury (p=0.006), multiple transfusion (p=0.003), and prolonged mechanical ventilation (p=0.005). Conclusion For women having renal impairment and undergoing cardiac surgery through median sternotomy, in the case of SWI, the Pseudomonas aeruginosa etiology may be more frequent and a really life–threating complication.

Bullet-related bacterial wound infections among injured personnel at emergency site hospitals in Bahir Dar: prevalence, antimicrobial susceptibility and associated factors.

Bullet-related bacterial wound infection can be caused by high-velocity bullets and shrapnel injuries. In Ethiopia, significant injuries were reported that may cause severe wound infections, persistent systemic infections and may lead to amputation and mortality. The magnitude, antimicrobial susceptibility profiles, and factors associated with bacterial wound infections among patients with bullet-related injuries are not yet studied particularly at health facilities in Bahir Dar, Northwest Ethiopia. Therefore, this study was aimed to determine the prevalence, bacterial profiles, antimicrobial susceptibility profiles, and factors associated with bacterial infections among patients with bullet-related injuries at referral health facilities in Bahir Dar, Northwest Ethiopia. A Hospital-based cross-sectional study was conducted among patients with bullet-related injuries at three referral health facilities in Bahir Dar from May 25 to July 27, 2022. A total of 384 patients with bullet-related injuries were included in the study. Sociodemographic and clinical data were collected using a structured questionnaire. Wound swabs were collected aseptically and cultured on Blood and MacConkey agar following bacteriological standards. Biochemical tests were performed to differentiate bacteria for positive cultivation and antimicrobial susceptibility profiles of the isolates were done on Muller Hinton agar using the Kirby-Bauer disk diffusion technique according to the 2021 Clinical Laboratory Standard Institute (CLSI) guideline. The data were entered using Epi-Info version 7.3 and analyzed using SPSS version 25. Descriptive data were presented using frequency, percentages, figures, and charts. Logistic regression was carried out to identify factors associated with bacterial wound infections. P-value < 0.05 was considered statistically significant. The prevalence of bullet-related bacterial wound infection among three referral hospitals in Bahir Dar city was 54.7%. The most commonly isolated Gram-negative organism was Klebsiella spps 49 (23.3%) while among Gram-positive organism, Staphylococcus aureus 58 (27.6%) and coagulase-negative staphylococci (CONS) 18 (8.6%). Contamination, hospitalization and smoking habit were significantly associated with the presence of bullet-related bacterial wound infections. Over 97% multidrug resistant (MDR) bacterial isolates were identified and of theses, E. coli, Proteus species, Citrobactor, and Staphylococcus aureus were highly drug resistant. Increased prevalence of bullet-related bacterial wound infection was noticed in this study. S. aureus followed by Klebsiella species were most commonly isolated bacteria. High frequency of resistance to Ampicillin, Oxacillin, Cefepime, Ceftriaxone, Ceftazidime, Vancomycin, and Norfloxacin was observed. Therefore, proper handling of bullet injuries, prompt investigation of bacterial infections, monitoring of drug sensitivity patterns and antibiotic usage are critical.

Bacteriological Study of Post-Operative Wound Infection and its Antibiograms

INTRODUCTIONPostoperative wound infections are a significant complication of surgical procedures, which increases morbidity, mortality, prolonged hospital stay, and increased healthcare costs. The study was undertaken with an aim to investigate the etiological agents of postoperative wounds and their sensitivity to commonly used antibiotics. MATERIAL AND METHODSThis study was a descriptive cross-sectional prospective study, carried out at Universal College Of Medical Sciences-Teaching Hospital, Bhairahawa, Nepal, on 100 postoperatively wounded infected cases, during April 2023 – August 2023, Non Probability sampling method (Purposive sampling) was used, and specimens were collected by sterile cotton swabs and pus was aspirated with a sterile needle and syringe and processed using standard bacteriological techniques. Antibiotic sensitivity test was conducted by disc diffusion (Kirby-Bauer) method. RESULTSPostoperative wound infections caused by Gram negative bacilli were more frequent and predominant pathogens involved were Pseudomonas aeruginosa, followed by Klebsiella spp and Enterobacter aerogenes. Among Gram positive bacteria Staphylococcus aureus was predominant. Gram positive cocci were highly sensitive to Ampicillin, and Gram negative bacilli were highly sensitive to Ceftazidime, Gentamicin, and Amikacin. Coagulase negative staphylococci were resistant to all drugs tested. CONCLUSIONPseudomonas aeruginosa was the commonest etiological agent for postoperative wound infections. Gram positive cocci and E.coli were highly sensitive to Ampicillin and Gram negative bacilli were highly sensitive to Ceftazidime, Gentamicin, Amikacin. Staphylococcus aureus was resistant to vancomycin and Teicoplanin and coagulase staphylococci were resistant to all drugs tested. Gram negative bacilli were resistant to Polymyxin B and Tigecycline. Increasing resistance to commonly used antibiotics warrants the judicious use of antibiotics and establishment of antibiotic policy in the hospital.

Effects of bovine casein hydrolysate as a dry cow therapy on prevention and cure of bovine intramammary infection,

The objectives were to investigate the efficacy of bovine casein hydrolysate (bCNH) as a dry cow therapy on: 1) preventing new intramammary infection (IMI) postpartum of all bacteria and coagulase-negative staphylococci (CNS); 2) curing existing subclinical infections, mainly of CNS; and 3) affecting on milk yield, composition and somatic cell count (SCC) during the post-calving lactation.

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

BackgroundRecently, linezolid-resistant staphylococci have become an emerging problem worldwide. Understanding the mechanisms of resistance, molecular epidemiology and transmission of linezolid-resistant CoNS in hospitals is very important.MethodsThe antimicrobial susceptibilities of all isolates were determined by the microdilution method. The resistance mechanisms and molecular characteristics of the strains were determined using whole-genome sequencing and PCR.ResultsAll the strains were resistant to oxacillin and carried the mecA gene; 13 patients (36.1%) had prior linezolid exposure. Most S. epidermidis and S. hominis isolates were ST22 and ST1, respectively. MLST typing and evolutionary analysis indicated most linezolid-resistant CoNS strains were genetically related. In this study, we revealed that distinct CoNS strains have different mechanisms of linezolid resistance. Among ST22-type S. epidermidis, acquisition of the T2504A and C2534T mutations in the V domain of the 23 S rRNA gene, as well as mutations in the ribosomal proteins L3 (L101V, G152D, and D159Y) and L4 (N158S), were linked to the development of linezolid resistance. In S. cohnii isolates, cfr, S158Y and D159Y mutations in the ribosomal protein L3 were detected. Additionally, emergence of the G2576T mutation and the cfr gene were major causes of linezolid resistance in S. hominis isolates. The cfr gene, G2576T and C2104T mutations, M156T change in L3 protein, and I188S change in L4 protein were found in S. capitis isolates.ConclusionThe emergence of linezolid-resistant CoNS in the environment is concerning because it involves clonal dissemination and frequently coexists with various drug resistance mechanisms.

Clinical characteristics and risk factors for right-sided infective endocarditis in Korea: a 12-year retrospective cohort study

Right-sided infective endocarditis (RSIE) is less common than left-sided infective endocarditis (LSIE) and exhibits distinct epidemiological, clinical, and microbiological characteristics. Previous studies have focused primarily on RSIE in patients with intravenous drug use. We investigated the characteristics and risk factors for RSIE in an area where intravenous drug use is uncommon. A retrospective cohort study was conducted at a tertiary hospital in South Korea. Patients diagnosed with infective endocarditis between November 2005 and August 2017 were categorized into LSIE and RSIE groups. Of the 406 patients, 365 (89.9%) had LSIE and 41 (10.1%) had RSIE. The mortality rates were 31.7% in the RSIE group and 31.5% in the LSIE group (P = 0.860). Patients with RSIE had a higher prevalence of infection with Staphylococcus aureus (29.3% vs. 13.7%, P = 0.016), coagulase-negative staphylococci (17.1% vs. 6.0%, P = 0.022), and gram-negative bacilli other than HACEK (12.2% vs. 2.2%, P = 0.003). Younger age (adjusted odds ratio [aOR] 0.97, 95% confidence interval [CI] 0.95–0.99, P = 0.006), implanted cardiac devices (aOR 37.75, 95% CI 11.63–141.64, P ≤ 0.001), and central venous catheterization (aOR 4.25, 95% CI 1.14–15.55, P = 0.029) were independent risk factors for RSIE. Treatment strategies that consider the epidemiologic and microbiologic characteristics of RSIE are warranted.

Metrisor: A novel diagnostic method for metritis detection in cattle based on machine learning and sensors

The Metrisor device has been developed using gas sensors for rapid, highly accurate and effective diagnosis of metritis. 513 cattle uteri were collected from abattoirs and swabs were taken for microbiological testing. The Metrisor device was used to measure intrauterine gases. The results showed a bacterial growth rate of 75.75 % in uteri with clinical metritis. In uteri positive for clinical metritis, the most commonly isolated and identified bacteria were Trueperella pyogenes, Fusobacterium necrophorum and Escherichia coli. Measurements taken with Metrisor to determine the presence of metritis in the uterus yielded the most successful results in evaluations of relevant machine learning algorithms. The ICO (Iterative Classifier Optimizer) algorithm achieved 71.22 % accuracy, 64.40 % precision and 71.20 % recall. Experiments were conducted to examine bacterial growth in the uterus and the random forest algorithm produced the most successful results with accuracy, precision and recall values of 78.16 %, 75.30 % and 78.20 % respectively. ICO also showed high performance in experiments to determine bacterial growth in metritis-positive uteri, with accuracy, precision and recall values of 78.97 %, 77.20 % and 79.00 %, respectively. In conclusion, the Metrisor device demonstrated high accuracy in detecting metritis and bacterial growth in uteri and could identify bacteria such as E. coli, S. aureus, coagulase-negative staphylococci, T. pyogenes, Bacillus spp., Clostridium spp. and F. necrophorum with rates up to 80 %. It provides a reliable, rapid and effective means of detecting metritis in animals in the field without the need for laboratory facilities.

Post-intravitreal injection and post-cataract extraction endophthalmitis visual outcomes by organism: A systematic review and meta-analysis

Purpose: To compare visual outcomes of endophthalmitis following intravitreal injections (IVI) and cataract extraction (CE) by causative organism. Methods: Searches in Cochrane Central Register of Controlled Trials, MEDLINE, and Embase identified articles reporting visual outcome by causative organism in post-IVI and CE endophthalmitis cases from January 2010-February 2022. A random-effects meta-analysis compared visual improvement amongst endophthalmitis cases by causative organism. Results: 85 out of 3317 retrieved studies were included. The highest degree of VA improvement in both post-IVI and post-CE endophthalmitis was seen in cases caused by coagulase-negative staphylococci (CONS), followed by gram-negative organisms, and other gram-positive organisms such as streptococci and enterococci. Culture negative cases showed more VA improvement than culture positive cases in post-IVI endophthalmitis. These results remained consistent when accounting for endophthalmitis treatment, IVI type, condition requiring IVI treatment, follow-up period and initial pre-procedural VA. Conclusion: CONS and gram-negative organisms show the most VA improvement in both post-IVI and post-CE endophthalmitis. Other gram-positive organisms such as streptococci and enterococci are associated with less visual improvement. This updated systematic review and meta-analysis reveals that the results of the Endophthalmitis Vitrectomy Study are consistent decades later despite advancements to surgical practices and evolution of microorganisms over time.

Hospital-acquired bloodstream infections in critically ill cirrhotic patients: a post-hoc analysis of the EUROBACT-2 international cohort study

BackgroundHospital-acquired bloodstream infections are common in the intensive care unit (ICU) and have a high mortality rate. Patients with cirrhosis are especially susceptible to infections, yet there is a knowledge gap in the epidemiological distinctions in hospital-acquired bloodstream infections between cirrhotic and non-cirrhotic patients in the ICU. It has been suggested that cirrhotic patients, present a trend towards more gram-positive infections, and especially enterococcal infections. This study aims to describe epidemiological differences in hospital-acquired bloodstream infections between cirrhotic and non-cirrhotic patients hospitalized in the ICU regarding infection sources, microorganisms and mortality.MethodsUsing prospective Eurobact-2 international cohort study data, we compared hospital-acquired bloodstream infections sources and microorganisms in cirrhotic and non-cirrhotic patients. The association between Enterococcus faecium and cirrhosis was studied using a multivariable mixed logistic regression. The association between cirrhosis and mortality was assessed by a multivariable frailty Cox model.ResultsAmong the 1059 hospital-acquired bloodstream infections patients included from 101 centers, 160 had cirrhosis. Hospital-acquired bloodstream infection source in cirrhotic patients was primarily abdominal (35.6%), while it was pulmonary (18.9%) for non-cirrhotic (p < 0.01). Gram-positive hospital-acquired bloodstream infections accounted for 42.3% in cirrhotic patients compared to 33.2% in non-cirrhotic patients (p = 0.02). Hospital-acquired bloodstream infections in cirrhotic patients were most frequently caused by Klebsiella spp (16.5%), coagulase-negative Staphylococci (13.7%) and E. faecium (11.5%). E. faecium bacteremia was more frequent in cirrhotic patients (11.5% versus 4.5%, p < 0.01). After adjusting for possible confounding factors, cirrhosis was associated with higher E. faecium hospital-acquired bloodstream infections risk (Odds ratio 2.5, 95% CI 1.3–4.5, p < 0.01). Cirrhotic patients had increased mortality compared to non-cirrhotic patients (Hazard Ratio 1.3, 95% CI 1.01–1.7, p = 0.045).ConclusionsCritically ill cirrhotic patients with hospital-acquired bloodstream infections exhibit distinct epidemiology, with more Gram-positive infections and particularly Enterococcus faecium.

A five-year retrospective antibiogram review in the paediatric burns unit at a tertiary South African Hospital

BackgroundThere is a global concern regarding increasing colonization and/or infection of paediatric burns patients with multi-drug-resistant organisms, especially in Africa. Surveillance of antimicrobial resistant patterns enables clinicians to opt for the most appropriate empiric antimicrobial agent according to the unit’s susceptibility profile. ObjectiveThis study sought to compile unit-specific antibiograms comparing the organism prevalence and their antimicrobial resistance trends in the paediatric burns unit, Chris Hani Baragwanath Academic Hospital (CHBAH) from January 2015 to December 2019. MethodsA retrospective, laboratory-based review was conducted of bacterial and fungal isolates including antimicrobial susceptibility testing (AST) data from blood cultures and tissue samples. Enterobacterales, non-fermenters, gram-positive organisms, and yeasts were analysed as a percentage of total positive blood cultures comparing 2015–2017 to 2018–2019 data. Analysis of antimicrobial resistance trends was performed for extended-spectrum beta-lactamases (ESBLs), carbapenem-resistant Enterobacterales (CRE), extensively-drug-resistant (XDR) Acinetobacter baumannii, and meticillin-resistant Staphylococcus aureus (MRSA) for the years 2015, 2017, and 2019. ResultsA total of 1243 blood culture isolates were studied with A.baumannii (208/1243;17 %), coagulase negative staphylococci (141/1243; 11 %) and Candida auris (53/1243; 4 %) representing the predominant gram-negative bacteria, gram-positive bacteria, and yeast, respectively. A significant decrease in ESBLs (p = 0.00) was noted with a rise in CREs (p = 0.00) during the study period. Majority of the A. baumannii were XDR (≥77 %) despite an appreciable decrease. A notable decrease in MRSA (p = 0.00) isolates was observed. pseudomonas aeruginosa (72/275; 26 %) was the leading organism recovered from a total of 275 tissue isolates. ConclusionThe results of this study encourage review of the current antimicrobial choices in the unit for empiric antibacterial cover. Due to the low numbers of yeasts, we cannot comment on the institution of early antifungal strategies. We support reinforced infection prevention and control practices as well as antimicrobial stewardship initiatives.

Bacterial diversity, antibiogram and nutritional assessment of cowhide (Ponmo) in Ilishan-Remo central market, Nigeria

The demand for cowhide (ponmo) is currently very high, particularly in Nigeria, due to rising commodity prices, including animal proteins, which has forced a larger percentage of the population who cannot afford meat, chicken, turkey or eggs to rely on other meat products such as “ponmo,” “kundi,” and “tinko” as an alternative source of protein. This research aims to identify microorganisms associated with ponmo, determine the antibiogram of the isolates, and assess the nutritional value of ponmo marketed in Ilishan-Remo central market. Six ponmo vendors were sampled for Dry White Ponmo (DWP), Wet White Ponmo (WWP), Wet Brown Ponmo (WBP) and Brown Ponmo Water (BPW) and transported in sterile containers to the Laboratory for analysis to determine the microbial load, sensitivity, and proximate analysis using standardized methods. For microbiological analysis, samples were tested in triplicate. All samples analyzed had a high microbial load count (from 1.1 x 106 to 1.4 x 107). The organisms isolated were Escherichia coli (34.21 %), Staphylococcus aureus (26.31 %), Klebsiella spp. (18.42 %), Pseudomonas spp. (13.15 %) and Coagulase-negative staphylococci (7.89 %). All the isolates were multidrug-resistant (MDR). Septrin had the highest resistivity (86.84 %) while gentamicin had the lowest resistance (7.89 %). Pefloxacin sensitivity was observed in 37 of the 38 isolates (97.37 % sensitivity). Ciprofloxacin and gentamicin came second and third (84.2 % and 73.68 % sensitivity) respectively. According to the proximate analysis, the WWP has more protein, fat, and fiber, whereas the WBP has more moisture. Food handlers should follow Good Hygiene Practices and take a Food Handlers Test regularly.

The Emergence of Linezolid-Resistant Staphylococcus Epidermidis in the COVID-19 Hospitalized Intubated Patients in North Khorasan, Iran.

The present study aimed to investigate secondary bacterial infections among patients infected with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Coagulase-negative Staphylococci can infect immunocompromised patients. Linezolid resistance among Staphylococcus epidermidis is one of the most critical issues. In 2019, 185 SARS-CoV-2-positive patients who were admitted to North Khorasan Province Hospital (Bojnurd, Iran), were investigated. Patients having positive SARS-CoV-2 reverse transcriptase real-time polymerase chain reaction (RT-PCR) test results, who had a history of intubation, mechanical ventilation, and were hospitalized for more than 48 hours were included. After microbiological evaluation of pulmonary samples, taken from intubated patients with clinical manifestation of pneumonia, co-infections were found in 11/185 patients (5.94%) with S. epidermidis, Staphylococcus aureus, and Acinetobacter baumani, respectively. Remarkably, seven out of nine S. epidermidis isolates were linezolid resistant. Selected isolates were characterized using antimicrobial resistance patterns and molecular methods, such as Staphylococcal cassette chromosome mec (SCCmec) typing, and gene detection for ica, methicillin resistance (mecA), vancomycin resistance (vanA), and chloramphenicol-florfenicol resistance (cfr) genes. All of the isolates were resistant to methicillin, and seven isolates were resistant to linezolid. Nine out of 11 isolated belonged to the SCCmec I, while two belonged to the SCCmec IV. It should be noted that all patients had the underlying disease, and six patients had already passed away. The increasing linezolid resistance in bacterial strains becomes a real threat to patients, and monitoring such infections, in conjunction with surveillance and infection prevention programs, is very critical for reducing the number of linezolid-resistant Staphylococcal strains. A preprint of this study was published at https://europepmc.org/article/ppr/ppr417742.

In Vitro Analysis of Various Antibiotic and Cement Combinations Against S. epidermidis and S. lugdunensis for Treatment of Periprosthetic Shoulder Infection

IntroductionPeriprosthetic joint infections (PJI) are devastating potential complications after arthroplasty surgery with significant therapeutic challenges. Many authors advocate for two-stage revision arthroplasty for PJI of the shoulder which includes explanation with antibiotic spacer placement. The optimal antibiotic/cement combination for PJI in the shoulder is not known. The purpose of this study is to analyze various cement and antibiotic concentrations against Coagulase negative staphylococcus species, S. epidermidis and S. lugdunensis. MethodsFive strains of coagulase negative Staph were taken from clinically documented orthopedic infections Both Simplex and Palacos cement were used to create antibiotic laden beads and mixed with either ertapenem, vancomycin, gentamicin, or a combination of ertapenem + vancomycin or ertapenem + gentamicin. The bacteria were plated on LB agar plates and 3 beads were added per plate. Samples were analyzed for zone of inhibition at 24 hours, 72 hours, and 1 week. After 1 week, beads were transferred to new plates with bacteria and the process was repeated for 6 weeks. ResultsResults showed that ertapenem beads with both Simplex and Palacos cement showed the largest zones of inhibition for all samples. Vancomycin in Palacos cement and vancomycin in combination with ertapenem in Simplex and Palacos cement showed consistent zones of inhibition for the duration of the experiments. Ertapenem in combination with either vancomycin or gentamicin may allow for a powerful initial burst of killing followed by consistent antibiotic elution as opposed to gentamicin alone. ConclusionWhile many premade spacers on the market are infused with gentamicin, our in vitro models demonstrate more efficacious bacterial eradication for antibiotics such as ertapenem and vancomycin specifically for certain low virulence organisms that are commonly found in PJI around the shoulder.

The Influence of Biologically Synthesized Copper Nanoparticles on the Biofilm Produced by Staphylococcus haemolyticus 1solated from Seminal Fluid

Staphylococcus haemolyticus is one of the most frequently isolated coagulase-negative staphylococci. The ability to form biofilm is considered as one of the most important virulence factors of coagulase negative staphylococci. There is only limited knowledge of the nature of S. haemolyticus biofilms. This study was aimed at evaluating the ability of S. haemolyticus strains to produce biofilm in the presence of copper oxide nanoparticles (CuONPs). The biological synthesis of nanoparticles is an environmentally friendly approach for large-scale production of nanoparticles. Copper oxide nanoparticles were produced in the current study from the S. haemolyticus viable cell filtrate. UV-visible (UV-Vis) spectroscopy, X-ray diffraction (XRD), atomic force microscope (AFM), field emission scanning electron microscope (FE-SEM), energy-dispersive X-ray spectroscopy (EDX) and zeta potential (ZP) analysis were used to analyze the newly synthesized CuONPs. Our findings revealed that at minimum inhibitory concentration (MIC), CuONPs showed remarkable inhibition on the biofilms produced by multidrug resistant (MDR) S. haemolyticus isolates.

A 10-year Retrospective Review of Patient-to-Patient Transmitted Pathogens in Culture-Positive Burn Wounds at a Tertiary Burn Center

Introduction: Burn wound infection can progress to sepsis and is a significant source of morbidity and mortality. Prevalence of multidrug-resistant organisms are high in burn patients; these organisms can be transmitted between patients leading to poor outcomes. Objectives: To characterize patient-to-patient transmission of pathogens causing burn wound colonization at a single tertiary hospital burn center in Hamilton, Canada from 2011 to 2020. Methods: Retrospective chart review of patients admitted to the burn trauma unit at Hamilton General Hospital between 2011 and 2020. Antibiotic susceptibility panels of pathogens cultured from burn patients’ wound swab/tissue cultures were compared against pathogens cultured from other burn/nonburn patients with overlapping admission dates. Pathogens were categorized into likely, possible, or unlikely transmission, or normal skin flora on a case-by-case basis. Results: There were 173 burn patients with positive wound culture and 613 nonburn patients included in the study. Included burn patients had median age 52 years, mostly male (73%) with flame injury (65%), and median total body surface area 18%. There were 18 patients (10%) with likely transmission and 54 patients (31%) with possible transmission. Most frequently implicated pathogens for likely patient-to-patient transmission were methicillin-resistant Staphylococcus aureus (MRSA) (7 patients) and methicillin-resistant coagulase-negative Staphylococci (4 patients). Both burn and nonburn patients were implicated. Conclusion: The burden of patient-to-patient transmission in culture-positive burn wounds was estimated to be between 10% and 41%. Greater care should be taken to avoid patient-to-patient transmission of pathogens to minimize burn infection morbidity and mortality. Prospective studies should be conducted with genomic sequencing and correlation with clinical outcomes.

A Retrospective Descriptive Study of Staphylococcus Species Isolated from Canine Specimens Submitted to a Diagnostic Laboratory in South Africa, 2012-2017.

There is a scarcity of published studies on the occurrence of Staphylococcus spp. Among dogs in South Africa. The objective of the study was to characterise the Staphylococcus spp. Isolated from dog samples submitted to a veterinary diagnostic laboratory in South Africa in terms of time, place, and person. This study utilised a dataset of 1627 positive Staphylococcus isolates obtained from a veterinary diagnostic laboratory in South Africa from 2012 to 2017. Out of the 1627 confirmed isolates, 10 different species of Staphylococcus were identified. Among these, 92.0% were classified as coagulase-positive staphylococci (CoPS), 6.0% were coagulase-negative staphylococci (CoNS), and 3.0% were coagulase-variable. Male dogs contributed just over half (53.2%) of the Staphylococcus isolates, while female dogs contributed the remaining 46.8%. The largest proportion of isolates (23.2%) were obtained from dogs aged ≥ 9 years, with the highest number of isolates originating from KwaZulu-Natal Province (45.0%) and the least from Northern Cape Province (0.1%). Out of the total samples included in the records, the majority (46.0%) were skin specimens. The number of Staphylococcus isolates recorded showed limited variation between the seasons (24.3% in autumn, 26.3% in winter, 26.0% in spring, and 24.0% in summer). This study highlighted the diversity of Staphylococcus spp. isolated from dogs, and the burden of staphylococcal carriage among dogs in South Africa. Further research is required to examine the factors that contribute to the observed discrepancies in the proportions of Staphylococcus spp. between the provinces.

Impact of postoperative skin disinfection with chlorhexidine on bacterial colonisation following shoulder arthroplasty surgery: a controlled randomised study

Surgical site infections are a significant threat to patient safety. Shoulder arthroplasty carries an increased risk due to foreign implants. Skin preparation in general is a key preoperative preventive intervention, and the use of chlorhexidine can have a prolonged effect on bacterial colonisation. There is a lack of evidence regarding whether postoperative disinfection has an impact on bacterial colonisation during the first 48 hours after surgery. Our hypothesis was that applying postoperative antiseptic with 5 mg/ml chlorhexidine in 70% ethanol would lead to reduced bacterial colonisation with Staphylococcus aureus, coagulase-negative staphylococcus and Cutibacterium acnes around the surgical wound within the initial 48 hours after elective shoulder surgery, compared with the use of sodium chloride. A single-blinded, controlled study was conducted at a county hospital in Sweden. Swabs from the skin were collected four times: at baseline, preoperatively, after the intervention and after 48 hours. Our hypothesis was not confirmed. Although not statistically significant, the chlorhexidine group had a higher prevalence of bacterial colonisation of clinically relevant bacteria. Our study could not confirm that postoperative disinfection with chlorhexidine reduces bacterial colonisation compared with sodium chloride. The results highlight the complexity of SSIs and the importance of evidence-based preventive skin preparation to ensure patient safety. Further research is needed, considering the study's limitations, to explore and evaluate the effectiveness of different skin cleansing solutions and preventive strategies in diverse surgical contexts.

Co-resistance to methicillin and clindamycin among coagulase-negative staphylococci isolates recovered from pet food in Brazil

Pet food have been considered as possible vehicles of bacterial pathogens. The sudden boom of the pet food industry due to the worldwide increase in companion animal ownership calls for pet food investigations. Herein, this study aimed to determine the frequency, antimicrobial susceptibility profile, and molecular characteristics of coagulase-negative staphylococci (CoNS) in different pet food brands in Brazil. Eighty-six pet food packages were screened for CoNS. All isolates were identified at species level by MALDI-TOF MS and species-specific PCR. Antimicrobial susceptibility testing was performed by disc diffusion and broth microdilution (vancomycin and teicoplanin only) methods. The D-test was used to screen for inducible clindamycin phenotype (MLS-B). SCCmec typing and detection of mecA, vanA, vanB, and virulence-encoding genes were done by PCR. A total of 16 (18.6 %) CoNS isolates were recovered from pet food samples. Isolates were generally multidrug-resistant (MDR). All isolates were completely resistant (100 %) to penicillin. Resistances (12.5 % - 75 %) were also observed for fluoroquinolones, sulfamethoxazole-trimethoprim, tetracycline, rifampicin, erythromycin, and tobramycin. Isolates were susceptible to vancomycin (MICs <0.25–1 μg/mL) and teicoplanin (MICs <0.25–4 μg/mL). Intriguingly, 3/8 (37.5 %) CoNS isolates with the ERYRCLIS antibiotype expressed MLS-B phenotype. All isolates harboured blaZ gene. Seven (43.8 %) isolates carried mecA; and among them, the SCCmec Type III was the most frequent (n = 5/7; 71.4 %). Isolates also harboured seb, see, seg, sej, sem, etb, tsst, pvl, and hla toxin virulence-encoding genes (6.3 % - 25 %). A total of 12/16 (75 %) isolates were biofilm producers, while the icaAB gene was detected in an S. pasteuri isolate. Herein, it is shown that pet food is a potential source of clinically important Gram-positive bacterial pathogens. To the best of our knowledge, this is the first report of MLS-B phenotype and MR-CoNS in pet food in Latin America.

Characteristics and Outcomes of Occult Infections in Presumed Aseptic Nonunions: A Retrospective Cohort Study

Objectives: To determine (1) the rate of positive cultures in presumed aseptic nonunions, (2) the rate and microbial spectrum of positive cultures that represented occult infection, and (3) rates of nonunion healing. Design: Retrospective cohort study. Setting: Tertiary referral center. Patients Selection Criteria: Adult patients with a presumed aseptic nonunion treated with single-stage revision between 2002 and 2022. Outcome Measures and Comparisons: The rate of positive cultures compared for two protocols: old: 1 – 2 samples cultured 7 days vs. new: 5 samples cultured 14 days. The rate of positive cultures meeting occult infection criteria with the new protocol (≥ 2 samples with phenotypically indistinguishable microorganisms, or ≥1 sample with a high virulent microorganism). Nonunion healing rates between protocols and between groups based on culture results with the new protocol. Results: 179 patients were included. The rate of positive cultures was 14% (n = 15/105) with the old protocol, and 51% (n = 38/74) with the new protocol (p &lt; 0.001). With the new protocol, the rate of positive cultures meeting occult infection criteria was 19% (n = 14/74), and Coagulase-negative staphylococci (48%) and Cutibacterium acnes (38%) were the most common microorganisms. Nonunion healing rates after the primary revision did not differ between protocols (old: 82% vs. new: 86%, p = 0.41) and groups based on culture result (sterile: 86% vs. occultly infected: 93%, p = 0.66). The final overall nonunion healing rate was 97%. Conclusion: Occult infections were identified in 1 in 5 presumed aseptic nonunions using a standardized protocol with 5 intraoperative samples cultured 14 days, and were predominantly caused by slow growing, gram-positive microorganisms. The local spectrum and antimicrobial sensitivity of occult infections should be considered when developing empiric antimicrobial protocols. Patients with presumed aseptic nonunions can expect high healing rates regardless of the culture result. Level of evidence: Diagnostic Level III. See Instructions for Authors for a complete description of levels of evidence.