Staphylococcus aureus nasal carriage and surgical-site infections

Impetigo Surgical Site Infection Following Open Reduction and Internal Fixation of a Patella Fracture

Impetigo is a pediatric skin infection characterized by the presence of pathognomonic "honey-crusted" lesions caused by either Staphylococcus aureus or Streptococcus pyogenes. The diagnosis of impetigo is largely based on clinical judgment, confirmatory skin cultures, and Gram staining. Surgical site infections following patellar surgery are a relatively uncommon occurrence, with the most common causative organisms being Staphylococcus aureus, Streptococcus pyogenes, Pseudomonas aeruginosa, and other gram-negative bacilli. Surgical site infections have a range of risk factors that largely depend on patient characteristics and surgical logistics. We report the first documented case in the literature of a surgical impetigo infection with diagnostic skin lesions following open reduction and internal fixation of a patellar fracture in a 24-year-old female.

IFI44 is an immune evasion biomarker for SARS-CoV-2 and Staphylococcus aureus infection in patients with RA

Background

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused a global pandemic of severe coronavirus disease 2019 (COVID-19). Staphylococcus aureus is one of the most common pathogenic bacteria in humans, rheumatoid arthritis (RA) is among the most prevalent autoimmune conditions. RA is a significant risk factor for SARS-CoV-2 and S. aureus infections, although the mechanism of RA and SARS-CoV-2 infection in conjunction with S. aureus infection has not been elucidated. The purpose of this study is to investigate the biomarkers and disease targets between RA and SARS-CoV-2 and S. aureus infections using bioinformatics analysis, to search for the molecular mechanisms of SARS-CoV-2 and S. aureus immune escape and potential drug targets in the RA population, and to provide new directions for further analysis and targeted development of clinical treatments.

Methods

The RA dataset (GSE93272) and the S. aureus bacteremia (SAB) dataset (GSE33341) were used to obtain differentially expressed gene sets, respectively, and the common differentially expressed genes (DEGs) were determined through the intersection. Functional enrichment analysis utilizing GO, KEGG, and ClueGO methods. The PPI network was created utilizing the STRING database, and the top 10 hub genes were identified and further examined for functional enrichment using Metascape and GeneMANIA. The top 10 hub genes were intersected with the SARS-CoV-2 gene pool to identify five hub genes shared by RA, COVID-19, and SAB, and functional enrichment analysis was conducted using Metascape and GeneMANIA. Using the NetworkAnalyst platform, TF-hub gene and miRNA-hub gene networks were built for these five hub genes. The hub gene was verified utilizing GSE17755, GSE55235, and GSE13670, and its effectiveness was assessed utilizing ROC curves. CIBERSORT was applied to examine immune cell infiltration and the link between the hub gene and immune cells.

Results

A total of 199 DEGs were extracted from the GSE93272 and GSE33341 datasets. KEGG analysis of enrichment pathways were NLR signaling pathway, cell membrane DNA sensing pathway, oxidative phosphorylation, and viral infection. Positive/negative regulation of the immune system, regulation of the interferon-I (IFN-I; IFN-α/β) pathway, and associated pathways of the immunological response to viruses were enriched in GO and ClueGO analyses. PPI network and Cytoscape platform identified the top 10 hub genes: RSAD2, IFIT3, GBP1, RTP4, IFI44, OAS1, IFI44L, ISG15, HERC5, and IFIT5. The pathways are mainly enriched in response to viral and bacterial infection, IFN signaling, and 1,25-dihydroxy vitamin D3. IFI44, OAS1, IFI44L, ISG15, and HERC5 are the five hub genes shared by RA, COVID-19, and SAB. The pathways are primarily enriched for response to viral and bacterial infections. The TF-hub gene network and miRNA-hub gene network identified YY1 as a key TF and hsa-mir-1-3p and hsa-mir-146a-5p as two important miRNAs related to IFI44. IFI44 was identified as a hub gene by validating GSE17755, GSE55235, and GSE13670. Immune cell infiltration analysis showed a strong positive correlation between activated dendritic cells and IFI44 expression.

Conclusions

IFI144 was discovered as a shared biomarker and disease target for RA, COVID-19, and SAB by this study. IFI44 negatively regulates the IFN signaling pathway to promote viral replication and bacterial proliferation and is an important molecular target for SARS-CoV-2 and S. aureus immune escape in RA. Dendritic cells play an important role in this process. 1,25-Dihydroxy vitamin D3 may be an important therapeutic agent in treating RA with SARS-CoV-2 and S. aureus infections.

Evaluation of Postoperative Development of Saphenous Vein Graft Incision Site Infections in Patients Undergoing Isolated Coronary Artery Bypass Graft Surgery: A Single Center Experience

Objective: This study aimed to evaluate surgical site infection patients developing saphenous vein graft incision site infection after isolated coronary artery bypass graft surgery performed in the cardiovascular surgery clinic of our hospital in the last 12 years to reveal the causative microorganisms, risk factors, and clinical characteristics. Material and Methods: A total of 34 surgical site infection patients (23 females, 11 males; mean age 68.0±9.0 years; range 51-86 years) who underwent isolated coronary artery bypass graft surgery in the cardiovascular surgery clinic of our hospital between March 2009 and November 2020 and who postoperatively developed saphenous vein graft incision site infection were included in the study. The patients' demographic data, underlying diseases, and preoperative, intraoperative, and postoperative risk factors were analyzed retrospectively. Results: In all isolated coronary artery bypass graft surgeries performed over a period of about 12 years, the rate of saphenous vein graft incision site surgical site infection was found to be 0.8%. Of these, 23 (67.6%) were evaluated as superficial incisional surgical site infection and 11 (32.4%) as deep incisional surgical site infection. In the patients who developed surgical site infection, the parameters of age, female sex, obesity, diabetes mellitus, smoking, emergency surgery, use of more than 1 saphenous vein graft, prolonged operation, cardiopulmonary bypass, and aortic clamp durations, intraoperative blood transfusion, length of stay in the intensive care unit, use of inotropes, and total length of hospital stay were all found to be significant. The microorganisms in purulent discharge cultures consisted of Gram-negative bacteria in 18 (53%), Gram-positive bacteria in 12 (35.3%), and fungi in 1 (2.9%). No pathogenic microorganism growth was observed in 5 (14.7%) patients. In the patients with surgical site infection, coagulase-negative staphylococci (17.6%) and Escherichia coli (17.6%) were the most frequently isolated agents. Conclusion: Particular attention should be paid to surgical site infection in patients undergoing a cardiovascular surgery intervention. It should be noted that post coronary artery bypass graft surgery surgical site infection can be reduced by determining its risk factors, modifying surgical techniques, and postoperative close monitoring of patients. Follow-up and personal care are crucial after discharge and an empirical treatment approach should be determined when an infection occurs, taking into account that coagulase-negative staphylococci and E. coli were the two leading infectious agents in our hospital.

Prevalence and phylogenetic relationship among methicillin- and vancomycin-resistant Staphylococci isolated from hospital's dairy food, food handlers, and patients

Objective:

The aim of the present work was to investigate the mutual role that may be played by the served dairy food and food handlers in the transmission of methicillin- and vancomycin-resistant Staphylococcus aureus and coagulase-negative Staphylococci to patients who were hospitalized in Qena City, Egypt.

Materials and Methods:

A total of 210 samples including 90 dairy food samples which offered to the patients in the hospital, 60 nasal and hand swabs from food handlers working in the hospital, and 60 nasal and diarrheal swabs from patients suffering from diarrhea were investigated for the presence of coagulase-positive S. aureus and coagulase-negative Staphylococci, then isolates were screened for methicillin and vancomycin resistance phenotypically and genotypically. 16s rRNA gene sequencing was employed to construct the neighbor-joining tree.

Results:

Unlike food samples, both coagulase-positive S. aureus and coagulase-negative Staphylococci occurred in human samples. Methicillin- and vancomycin-resistant coagulase-negative Staphylococci could be detected in 41.7% & 20.8%, 68% & 31.9%, and 81.3% & 55.2% of isolates obtained from dairy food, food handlers, and patients’ samples, respectively. Whereas 81% & 64.3%, and 75.4% & 38.6% of coagulase-positive S. aureus obtained from food handlers and patients’ samples exhibited resistance to methicillin and vancomycin, respectively. Phenotypic resistance was confirmed molecularly through detection of mecA and vanA genes.

Conclusion:

A significant role can be played by food and food handlers in the transmission of methicillin- and vancomycin-resistant Staphylococci to patients, which has been proved in this study through the close phylogenetic relation between S. epidermidis isolated from food, food handlers, and patients’ diarrheal samples.

Methicillin-resistant Staphylococcus aureus screening is important for surgeons

Backgrounds/Aims

Perioperative surgical site infection (SSI) remains a morbid complication even in successful surgical procedures. We encountered an unusual experience of a methicillin-resistant Staphylococcus aureus (MRSA)-related SSI outbreak in our hospital; therefore, we conducted an epidemiologic analysis to determine the origin of SSIs due to MRSA.

Methods

Among 102 consecutive patients who underwent hepatobiliopancreatic operations, SSIs occurred in eight cases. Infection surveillance regarding the operative environment was carried out. We analyzed the possible risk factors for this infectious outbreak in our institution.

Results

Patients with SSI tended to be older (p=0.293), had variable operation fields (p=0.020), more cancer-related operation (p=0.003), less laparoscopic surgery (p=0.007), performed in operation room 1 (p=0.004), prolonged operation time (p<0.001) and had longer hospital stays (p=0.002). After propensity score (PS) matching, there was the only significant difference in the participation of surgeon D as a second assistant (p=0.001) between the SSI and non-SSI group. After PS matching, surgeon D as a second assistant was the only significant risk factor for MRSA SSI in the univariate (p=0.001) and multivariate analysis (p=0.004, hazard ratio=25.088, 95% confidence interval=2.759-228.149).

Conclusions

Outbreak of SSIs occurred due to transmission of MRSA from a surgeon to patients despite the standard regulation of infection control. These SSIs were associated with an excessive incidence of surgeon's nasal and hand carriage of the MRSA strain identified in the surgeon via cultures. We recommend the preoperative regular nasal and hand screening for MRSA among surgeons.

Prevalence of methicillin-resistant Staphylococcus aureus colonisation among healthcare workers at a tertiary care hospital in southeastern China

OBJECTIVES

The aim of this study was to investigate the carriage rates of Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) among healthcare workers (HCWs) at a tertiary-care hospital in southeastern China and to analyse the epidemiological relatedness of the S. aureus isolates.

METHODS

A total of 242 pharynx swabs were collected in March-April 2016 from 242 HCWs working in seven different wards and departments. Isolates were identified as S. aureus based on morphology, coagulase test and Vitek test. Antimicrobial susceptibility testing was performed by using the Kirby-Bauer disk diffusion method. The epidemiological relatedness of the S. aureus isolates was determined by pulsed-field gel electrophoresis (PFGE).

RESULTS

From the 242 HCWs, 70 (28.9%) S. aureus strains, including 10 (4.1%) MRSA strains, were identified during screening, with the highest MRSA rate detected in nurses (8/107; 7.5%). Carriage rates of S. aureus and MRSA among surgical HCWs were 30.0% (63/210) and 4.3% (9/210), respectively. Methicillin-susceptible S. aureus (MSSA) isolates were grouped by PFGE analysis into five similar groups (A-E), with most isolates belonging to groups D and E, accounting for 63.0% of isolates. Furthermore, two MRSA isolates from gastrointestinal surgery had identical PFGE patterns.

CONCLUSIONS

The prevalence of S. aureus colonisation among HCWs was high in this hospital, although the MRSA carriage rate in surgical wards was low. The identical PFGE pattern detected in two MRSA isolates from the same surgical department supports that effective control for possible cross-infection should be implemented.

Nasal carriage of Staphylococcus aureus among surgeons and surgical residents: a nationwide prevalence study

BACKGROUND

Staphylococcus aureus nasal carriage is an independent risk factor for developing nosocomial infections and for developing surgical site infection (SSI) in particular. The number of post-operative nosocomial S. aureus infections can be reduced by screening patients and decolonizing nasal carriers. In addition to patients, health care workers may also be S. aureus nasal carriers. The aim of this study was to explore S. aureus nasal carriage rates among surgeons.

METHODS

Nasal swabs were collected from surgeons and surgical residents during a national surgical congress. The control group consisted of non-hospitalized patients. Staphylococcus aureus carriage was detected using selective chromogenic agars by use of a fully automated inoculator. Suspected colonies were identified further by positive catalase and slide coagulation reactions.

RESULTS

Samples were collected from 366 surgeons and surgical residents and 950 control patients. The S. aureus nasal carriage rate among surgeons and residents was significantly greater compared with the control group (45.4% versus 30.8%, odds ratio [OR] 1.86 [1.45-2.38], p<0.001). No significant difference in carriage rate was found between surgeons and residents (46.8% versus 43.3%, p=0.769) and years of experience as a surgeon was not associated with a greater carriage rate. Male gender was an independent risk factor for carriage among physicians odds ratio ([OR] 1.90 [95% confidence interval 1.19-3.01], p=0.007).

CONCLUSIONS

The nationwide rate of S. aureus nasal carriage among surgeons and surgical residents proved to be significantly greater compared with a non-hospitalized patient control group. Male gender is an independent risk factor for carriage among physicians. Future studies are needed to investigate the possible relation with nosocomial post-operative S. aureus infections.

Colonization and infection of the skin by S. aureus: immune system evasion and the response to cationic antimicrobial peptides

Staphylococcus aureus (S. aureus) is a widespread cutaneous pathogen responsible for the great majority of bacterial skin infections in humans. The incidence of skin infections by S. aureus reflects in part the competition between host cutaneous immune defenses and S. aureus virulence factors. As part of the innate immune system in the skin, cationic antimicrobial peptides (CAMPs) such as the β-defensins and cathelicidin contribute to host cutaneous defense, which prevents harmful microorganisms, like S. aureus, from crossing epithelial barriers. Conversely, S. aureus utilizes evasive mechanisms against host defenses to promote its colonization and infection of the skin. In this review, we focus on host-pathogen interactions during colonization and infection of the skin by S. aureus and methicillin-resistant Staphylococcus aureus (MRSA). We will discuss the peptides (defensins, cathelicidins, RNase7, dermcidin) and other mediators (toll-like receptor, IL-1 and IL-17) that comprise the host defense against S. aureus skin infection, as well as the various mechanisms by which S. aureus evades host defenses. It is anticipated that greater understanding of these mechanisms will enable development of more sustainable antimicrobial compounds and new therapeutic approaches to the treatment of S. aureus skin infection and colonization.

Simultaneous carriage of multiple genotypes of Staphylococcus aureus in children

The co-existence of multiple genotypes in colonization by Staphylococcus aureus has not been fully investigated. The aim of this study was to evaluate the heterogeneity of S. aureus carriage in children. We evaluated 125 nasal and perianal swab samples that were positive for S. aureus from 76 children scheduled for elective surgery. For each sample, at least four colonies with the same or different morphotypes were selected for analysis. Multiple-locus variable-number tandem-repeat fingerprinting was used to determine the genetic relatedness and to characterize the clonality of the S. aureus strains. Of the 125 swabs, 91 (73 %) contained meticillin-sensitive S. aureus (MSSA), 8 (6 %) contained meticillin-resistant S. aureus (MRSA), and 26 (21 %) contained MSSA and MRSA simultaneously. A total of 738 S. aureus strains were evaluated with a mean of 6 colonies (range 4-15) picked from each culture. Of the 125 swabs, 32 (26 %) samples contained two genetically distinct S. aureus strains and 6 (5 %) contained three different genotypes. Multiple S. aureus strains simultaneously carried by individual children were genetically unrelated to each other. We concluded that the co-existence of multiple genotypes of S. aureus was common. The significance of multiple carriage is yet to be determined, but this intraspecies interplay could be important to pathogenicity and virulence in S. aureus.

Characterization of staphyloferrin A biosynthetic and transport mutants in Staphylococcus aureus

Iron is critical for virtually all forms of life. The production of high-affinity iron chelators, siderophores, and the subsequent uptake of iron-siderophore complexes are a common strategy employed by microorganisms to acquire iron. Staphylococcus aureus produces siderophores but genetic information underlying their synthesis and transport is limited. Previous work implicated the sbn operon in siderophore synthesis and the sirABC operon in uptake. Here we characterize a second siderophore biosynthetic locus in S. aureus; the locus consists of four genes (in strain Newman these open reading frames are designated NWMN_2079-2082) which, together, are responsible for the synthesis and export of staphyloferrin A, a polycarboxylate siderophore. While deletion of the NWMN_2079-2082 locus did not affect iron-restricted growth of S. aureus, strains bearing combined sbn and NWMN_2079-2082 locus deletions produced no detectable siderophore and demonstrated severely attenuated iron-restricted growth. Adjacent to NWMN_2079-2082 resides the htsABC operon, encoding an ABC transporter previously implicated in haem acquisition. We provide evidence here that HtsABC, along with the FhuC ATPase, is required for the uptake of staphyloferrin A. The crystal structure of apo-HtsA was determined and identified a large positively charged region in the substrate-binding pocket, in agreement with a role in binding of anionic staphyloferrin A.

Methicillin-resistant Staphylococcus aureus endophthalmitis after phacoemulsification in a continuous ambulatory peritoneal dialysis patient

We report a case of methicillin-resistant Staphylococcus aureus (MRSA) endophthalmitis after phacoemulsification in a continuous ambulatory peritoneal dialysis (CAPD) patient with a history of MRSA infection. This case raised the problem of preoperative identification and subsequent management of MRSA carrier status, which might reduce the risk for sight- or life-threatening infection.

Staphylococcus aureus evasion of innate antimicrobial defense

Bacterial pathogens colonize human body surfaces soon after birth. In order to survive the constant threat of invasion and infection, the human innate immune system has evolved several efficient mechanisms to prevent harmful microorganisms from traversing epithelial barriers. These include cationic antimicrobial peptides (CAMPs) such as defensins and the cathelicidin LL-37, bacteriolytic enzymes such as lysozyme, antimicrobial fatty acids, toxic oxygen- or nitrogen-containing molecules, the bacteriolytic complement components and further mechanisms with indirect impacts on bacterial multiplication. Staphylococcus aureus is an important human commensal and pathogen. In order to successfully establish an infection, S. aureus has evolved several mechanisms to resist the innate immune system. In this review, we focus on the mechanisms employed by S. aureus to achieve protection against antimicrobial host defense molecules with special emphasis on CAMPs. Lessons from recent studies on antimicrobial host defense molecules and cognate bacterial resistance adaptation should help in the development of more sustainable anti-infective compounds.

Childhood epistaxis and nasal colonization with Staphylococcus aureus

OBJECTIVE

Epistaxis is very common in children but its cause remains unknown. We postulate that nasal colonization with Staphylococcus aureus leads to inflammation, crusting, and ultimately new vessel formation.

STUDY DESIGN

A prospective case-control study.

SUBJECTS AND METHODS

Sixty-seven children were recruited, 42 with epistaxis (22 had crusting in the nasal vestibule; 20 did not) and 25 control subjects. A microbiology swab was taken from the anterior nasal cavity of each child.

RESULTS

All groups were equally likely to have a positive culture. S aureus was more common in the epistaxis group (P = 0.008) compared with the control group. There was no difference in the prevalence of S aureus between crust and noncrust groups. Epistaxis patients were much less likely to have isolates of respiratory pathogens or a skin commensal.

CONCLUSION

Children with epistaxis are more likely to have nasal colonization with S aureus than controls. Our data would support the hypothesis that S aureus replaces existing nasal flora and causes inflammation and new vessel formation.

Staphylococcus aureus, the major pathogen in orthopaedic and cardiac surgical site infections: a literature review

Due to the increasing number of orthopaedic and cardiac procedures, these units are considered as high-risk areas because of the potentially serious consequences of surgical site infections (SSI), primarily caused by Staphylococcus aureus. The goal of this review was to evaluate the impact of S. aureus on the incidence of SSI in these high risk wards. Studies were identified by a search on the MEDLINE literature using the following mesh terms: S. aureus, cardiac, orthopaedic, surgery, SSI. Beside, data from different surveillance systems were also included. Overall, biological investigation was performed only on a small proportion of identified SSIs. Of those identified, S. aureus represented the most common pathogen accounting for approximately 20% of all SSIs. Of the 59,274 hip prostheses reported from the HELICS surveillance network, S. aureus formed 48.6% of the pathogens (416 bacteria isolated). Similarly, it represented 43.7% of pathogens after coronary artery bypass grafting. Although S. aureus turned out to be the major pathogen, this work identifies the relative lack of knowledge on the overall incidence of S. aureus infections and on the impact of this pathogenic agent when taking into consideration the degree of wound contamination and category of SSI. There is a need for more detailed information on the role of S. aureus in the burden of surgical site infections and consequently how to establish multiple approach prevention programs.

Nasal carriage of Staphylococcus aureus: which sequence types do orthopedic surgical healthcare workers carry?

Using sequence typing methods, we found that healthcare workers on our orthopedic surgery unit were persistent carriers of a limited number of sequence types of Staphylococcus aureus for a limited time. Multilocus sequence typing characterized 3 clonal complexes that accounted for more than 80% of the clonal complexes identified.

Controlling the usage of intranasal mupirocin does impact the rate of Staphylococcus aureus deep sternal wound infections in cardiac surgery patients

BACKGROUND

Staphylococcus aureus (S aureus) is the major cause of surgical site infections (SSI). At The Christ Hospital, Cincinnati, OH, S aureus accounted for over 80% of sternal wound infections in cardiac surgery patients. Approximately 700 cardiac surgeries are performed each year, with an associated infection rate of 1.8% per 100 procedures performed. In an attempt to reduce S aureus sternal wound infections, the use of prophylactic intranasal mupirocin was examined.

METHODS

Each patient undergoing cardiac surgery was nasally cultured before entering the operating room, and then intranasal mupirocin was applied and continued every 12 hours. Culture results were finalized within 48 hours. Mupirocin was discontinued when the culture returned negative and continued for 7 days when the culture returned positive for S aureus.

RESULTS

Cultures showed a S aureus carrier rate of 21%. These patients received mupirocin for 7 days. A decrease in S aureus-associated SSI rates was observed from a case rate of 1.68% to 0.37% per 100 procedures over a 17-month period.

CONCLUSION

Identifying and treating S aureus carriers with a full course of mupirocin does impact the rate of S aureus surgical site infections.

The investigation of Staphylococcus aureus and coagulase-negative staphylococci nasal carriage among patients undergoing haemodialysis

The frequency of nasal staphylococcal colonization among haemodialysed patients was investigated. The swabs were collected in 1998 and 2004 from 28 and 43 patients, respectively. Staphylococcus aureus colonization rates were 57.1% and 27.9% in 1998 and 2004, respectively. Twenty-six coagulase-negative staphylococci (CNS) isolates were cultured: S. epidermidis (21), S. lugdunensis (2), single S. haemolyticus, S. warneri, and S. capitits isolates. One S. aureus and 10 CNS isolates were methicillin resistant. The methicillin-resistant S. aureus (MRSA) was resistant to beta-lactams, tetracycline, and harbored the pvl gene encoding the Panton-Valentine leukocidin. The decrease in S. aureus colonization at 6-year interval was observed. The presence of the pvl gene and a favorable antibiotic susceptibility pattern of the MRSA suggest that the isolate was a member of community-acquired MRSA (CA-MRSA). Concluding, screening of haemodialysed patients for staphylococcal colonization accompanied by characterization of cultured isolates is important to understand its epidemiology and to develop infection prevention measures and treatment strategies.

Diabetes mellitus and cardiothoracic surgical site infections

Persons afflicted with diabetes mellitus compose over one fourth of patients undergoing cardiothoracic surgery and create a particular challenge to surgical and critical care practitioners. This paper reviews the impact of diabetes mellitus on cardiothoracic surgical site infection (SSI) risk, with specific attention to recent data regarding the role of perioperative hyperglycemia as well as the use of continuous insulin infusion for SSI risk reduction in the cardiothoracic surgical population.

Current strategies for prevention of surgical site infections

Surgical site infections (SSIs) are a common complication that follows all types of operative procedures. These infections are usually caused by the exogenous and endogenous microorganisms that enter the operative wound during the course of surgery. The general and procedure-specific risk factors for the development of SSI have been identified and are discussed in this article. Factors that influence the SSI rate and the current strategies for prevention of SSIs are also presented. Emphasis is placed on the efficacious use of antibiotic prophylaxis in surgery. A discussion of the principles of antibiotic prophylaxis, including choice of agents, route of administration, and timing, is offered. It appears that the use of less invasive laparoscopic surgical approaches, as practiced widely today, will be associated with an overall decreased incidence of SSI.