Characterization of Staphylococcus aureus isolated from patients with burns in a regional burn center, Southeastern China

A 10-year retrospective study of methicillin-resistant Staphylococcus aureus from burn wound infection in southeast China from 2013 to 2022

Background

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most commonly encountered pathogens among burn patients incurring substantial morbidity and mortality. To investigate the epidemiology and features of MRSA in burn wound infections, we conducted a 10-year retrospective study on MRSA isolated from burn patients with burn wound infections from southeast China from 2013 to 2022.

Methods

One hundred MRSA isolates (10 isolates each year) from burn wound infection among burn patients from 2013 to 2022 were randomly selected and enrolled. In addition to the clinical data of the 100 burn patients, MRSA isolates were characterized by antimicrobial susceptibility testing, detection of toxin genes, and molecular typing.

Results

The median time from the onset of burns and admission to MRSA detected was 13 and 5 days, respectively. No MRSA isolate was found resistant to quinupristin/dalfopristin, linezolid, and vancomycin. Toxin gene seg was found most frequently (90%) followed by sea (70%) and eta (64%). CC8 (74%), ST239 (70%), and SCCmec III (72%) were the most common CC, ST, and SCCmec types, respectively.

Conclusion

ST239-III (70%) was the predominant clone found in MRSA from burn wound infection among burn patients in southeast China. ST239-III was less found from 2018 to 2022. A higher diversity of MRSA clones was observed in these recent 5 years than that from 2013 to 2017.

Methicillin-Resistant Staphylococcusaureus Strains Isolated from Burned Patients in a Tunisian Hospital: Molecular Typing, Virulence Genes, and Antimicrobial Resistance

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the major causes of a variety of infections in hospitals and the community. Their spread poses a serious public health problem worldwide. Nevertheless, in Tunisia and other African countries, very little molecular typing data on MRSA strains is currently available. In our study, a total of 64 MRSA isolates were isolated from clinical samples collected from burned patients hospitalized in the Traumatology and Burns Center of Ben Arous in Tunisia. The identification of the collection was based on conventional methods (phenotypic and molecular characterization). The characterization of the genetic support for methicillin resistance was performed by amplification of the mecA gene by polymerase chain reaction (PCR), which revealed that 78.12% of S. aureus harbors the gene. The resistance of all the collection to different antibiotic families was studied. Indeed, the analysis of strain antibiotic susceptibility confirmed their multi-resistant phenotype, with high resistance to ciprofloxacin, gentamicin, penicillin, erythromycin, and tetracycline. The resistance to the last three antibiotics was conferred by the blaZ gene (73.43%), the erm(C) gene (1.56%), the msr(A) gene (6.25%), and tet(M) gene (7.81%), respectively. The clonal diversity of these strains was studied by molecular typing of the accessory gene regulator (agr) system, characterization of the SCCmec type, and spa-typing. The results revealed the prevalence of agr types II and III groups, the SCCmec type III and II cassettes, and the dominance of spa type t233. The characterization of the eight enterotoxins genes, the Panton-Valentine leukocidin and the toxic shock syndrome toxin, was determined by PCR. The percentage of virulence genes detected was for enterotoxins (55%), tst (71.88%), leukocidin E/D (79.69%), and pvl (1.56%) factors. Furthermore, our results revealed that the majority of the strains harbor IEC complex genes (94%) with different types. Our findings highlighted the emergence of MRSA strains with a wide variety of toxins, leukocidin associated with resistance genes, and specific genetic determinants, which could constitute a risk of their spread in hospitals and the environment and complicate infection treatment.

Research on the possibilities of a therapeutic approach through physical interventions with Laser MLS (Multiwave Locked System) in post-combustion pathology (burns and severe burns)

Abstract: Introduction. Depending on their severity, most of the burns are "particularly disabling injuries", which is why a constant improvement of current therapeutic interventions is necessary [1]. The patient describes the severe burn as the "ultimate agony" placing an important responsibility on the medical staff to achieve a satisfactory level of recovery and reintegration into society [2]. "Burns negatively influence the main aspects of life", but also the quality of life [3]. Laser therapy has stood out in recent years in stimulating the healing process of burn patients [4]. The role of this study is to highlight the therapeutic effects of the MLS LASER in the case of burns and severe burns. Methods. We previously carried out a systematic review of the related literature through the method of filtering and selecting profile documentary material, widely used and accepted at the international level: Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Thus, we searched, using contextually, combinations/syntaxes of search keywords in the following international databases: Elsevier, PubMed, PMC, PEDro, articles published in English in ISI indexed journals Web of Knowledge/Science, during 01.01.2021-31.12.2021. Results and discussion. Seven of the selected articles have been included in our systematic literature review. The evolution of burn injuries materialized through improvements, will hopefully be achievable, both through direct observation and through the favorable dynamic progress of the scores of the quantification scales used: (VSS – Vancouver Scar Scale, VAS – Visual Analogue Scale, 5-D ITCH Scale, according to the model of the American Spinal Injury Association Impairment Scale – AIS - for sensitivity disorders, 3-step scale, ROM – Range of motion, MMT – Manual Muscle Test Scale, The Barthel Index, FIM – Functional Independence Measure scale, ADL, Timed up and go test, Walk Speed, Berg Balance Scale, Six-Minutes Walk Test). If it will be possible, sufficiently sustained medium/long-term follow-up of the cases included in our doctoral research will also be measured by the frequency of readmissions. Conclusions. Through this research, which is part of the doctoral study, we hope to be able to deepen aspects related to both the still existing limits and the identifiable possibilities for optimizing the conceptual and practical approach to patients with such pathologies. Keywords: Burns, MLS LASER, Burn wound, Burn Rehabilitation, Multiwave Locked System.

Correlation between Bacterial Wound Colonization and Skin-Graft Loss in Burn Patients

Loss of skin grafts can be a dangerous complication during the early postoperative course of patients with extensive burns. A major risk factor for impaired healing of grafts is local wound infection due to bacterial colonization. Burn wounds are particularly prone to bacterial colonization. In this retrospective cohort study, we analyzed correlations between bacteria isolates from burn wounds and loss of skin grafts after surgical treatment. A cohort of patients with burn wounds who received split-skin grafts for wound coverage was divided into groups with and without loss of skin grafts. Demographics, comorbidities, trauma characteristics and bacterial isolates from wound cultures were reviewed and compared. Bacterial colonization isolated from burn wounds upon hospital admission was found to be a significant predictor of skin-graft loss. Additionally, an Abbreviated Burn Severity Index greater 6 predicted graft loss. When comparing bacterial swab results from admission with isolates from revision surgery after graft loss, causative pathogens were found to have changed.

Prevalence of MRSA as an Infectious Agent in Sanitary Swimming Pools and Jacuzzis

INTRODUCTION

Methicillin-resistant Staphylococcus aureus (MRSA) is considered resistant to beta-lactam antibiotic groups. Infection caused by this strain is more difficult to treat with antibiotics, and hence, it will be more dangerous. This study focused on detecting the mecA gene Staphylococcus in sanitary swimming pools and Jacuzzis in Yazd city, Iran (2019). Also, the relationship between methicillin-resistant Staphylococcus aureus (MRSA) and the water quality standards has been investigated.

MATERIALS AND METHODS

60 samples were randomly collected in sterile bottles from 20 active pools and Jacuzzis. Quality parameters were analyzed by standard methods. Antibiotic resistance and the mecA gene's presence were detected by the disk diffusion and PCR method, respectively.

RESULTS

The results of this study showed that the resistance of Staphylococcus aureus isolates was high against erythromycin (41.20%), tetracycline (35.10%), clindamycin (28.90%), and cefoxitin (25.80%). Out of 97 samples, 9 (25.80%) strains of Staphylococcus aureus were identified as MRSA, 30 samples (30.92%) showed multiple patterns of antibiotic resistance, and 9 samples (9.27%) carried the mecA gene. The results revealed that water quality has greatly impacted the mecA gene strain presence, especially microbial parameters. On the other hand, in the presence of mecA gene strains, the averages of microbial qualities were higher than standard in Jacuzzis; the latter finding was confirmed for swimming pools due to physicochemical parameters.

CONCLUSION

The number of reported sanitary water is increasing, and this study's results are useful examples of these findings. Therefore, a lack of careful and regular monitoring of swimming pools and Jacuzzis can lead to MSRA prevalence and outbreak sources.

Expression of Staphylococcal Virulence Genes In Situ in Human Skin and Soft Tissue Infections

Background: Staphylococcus aureus, the most common pathogen in skin and soft tissue infections (SSTI), harbors many well-characterized virulence genes. However, the expression of many of them in SSTIs is unknown. In this study, S. aureus virulence genes expressed in SSTI were investigated. Methods: Fifty-three subjects presenting to the outpatient’s care and emergency departments with a purulent SSTI at two medical centers in Wisconsin, USA, were enrolled in the study. Total mRNA was extracted from the purulent or swab materials, made into cDNA and sequenced on MiSeq platform. The relative cDNA counts to gmk and identifications of the transcripts were carried out with respect to USA300 reference genome and using SAMTOOLS v.1.3 and BWA, respectively. Result: A significantly higher cDNA count was observed for many of the virulence and regulatory gene transcripts in the pus samples compared to the swab samples relative to the cDNA counts for gmk, a housekeeping gene. They were for lukS-PV (18.6 vs. 14.2), isaA (13.4 vs. 8.5), ssaA (4.8 vs. 3.1), hlgC (1.4 vs. 1.33), atl (17.7 vs. 8.33), clfA (3.9 vs. 0.83), eno (6.04 vs. 3.16), fnbA (5.93 vs. 0.33), saeS (6.3 vs. 1.33), saeR (5.4 vs. 3.33) and agrC (5.6 vs. 1.5). Conclusions: A relative increase in the transcripts of several toxins, adhesion and regulatory genes with respect to a gmk in purulent materials suggests their role in situ during SSTIs, perhaps in an orchestrated manner.

Burn Wound Healing: Clinical Complications, Medical Care, Treatment, and Dressing Types: The Current State of Knowledge for Clinical Practice

According to the World Health Organization (WHO), it is estimated that each year approximately 11 million people suffer from burn wounds, 180,000 of whom die because of such injuries. Regardless of the factors causing burns, these are complicated wounds that are difficult to heal and are associated with high mortality rates. Medical care of a burn patient requires a lot of commitment, experience, and multidirectional management, including surgical activities and widely understood pharmacological approaches. This paper aims to comprehensively review the current literature concerning burn wounds, including classification of burns, complications, medical care, and pharmacological treatment. We also overviewed the dressings (with an emphasis on the newest innovations in this field) that are currently used in medical practice to heal wounds.

Selective Intestinal Decontamination as a Method for Preventing Infectious Complications (Review)

Infectious complications are the most common cause of death in patients with severe burns. To date, there is no generally accepted method for preventing such complications in burn injury. One of the possible prevention options is selective intestinal decontamination (SID). This method is based on the enteral administration of non-absorbable antimicrobial agents. The preventive effect of SID involves inhibition of intestinal microflora translocation through the mucous membranes, inasmuch as studies demonstrate that endogenous opportunistic microorganisms are a common cause of infectious complications in various critical conditions.

The SID method was originally developed in the Netherlands for patients suffering from mechanical injury. Antimicrobial drugs were selected based on their high activity in relation to the main endogenous opportunistic pathogens and minimal activity against normal intestinal microflora components. The combination of polymyxin (B or E), tobramycin, and amphotericin B with intravenous cefotaxime was chosen as the first SID regimen. Other regimens were proposed afterwards, and the application field of the method was expanded. In particular, it became the method of choice for prevention of infectious complications in patients with severe burn injury.

Clinical studies demonstrate efficacy of some SID regimens for preventing infectious complications in patients with thermal injury. Concomitant administration of SID and systemic preventive antibiotics and addition of oropharyngeal decontamination increases the method efficacy. SID is generally well-tolerated, but some studies show an increased risk of diarrhea with this preventive option. In addition, SID increases the risk of developing antibiotic resistance like any other antibiotic regimens.

Application of Phagotherapy in the Treatment of Burn Patients (Review)

Treatment of patients with a burn injury is a complex process involving multicomponent multidirectional intensive therapy of the majority of organs and systems damaged by thermal effects on the skin, alternating with repeated surgical interventions aimed at removing nonviable tissues with subsequent plastic closure of wound defects. After the recovery from the burn shock, local infectious complications are considered to be the leading problem that decelerates the process of recovery and is the main cause of lethal outcomes. Since the skin integrity is broken, microorganisms penetrate readily into the internal environment of the human organism resulting in a septic state with multiple organ failure. A widespread and often uncontrollable use of antibacterial drugs in medical practice has led to the emergence of multiple drug resistance (MDR) in microorganisms. Introduction of drugs made on the basis of bacteriophages into practice is presently becoming increasingly important. This is confirmed by the growing interest in this field of pharmacology, the development of special programs aimed at studying the processes of phage and bacterial cell interaction. This review presents the main types of bacteria pertaining to MDR pathogens, principles of their classification, and the risk factors for infecting patients. The mechanisms of the selective action of phage particles on a bacterial cell and the possibility of using phage therapy in the treatment of burn injury (experimental and clinical data) based on the analysis of foreign literature are demonstrated as well as new positive properties of phages related to the changes in the macroorganism immune status caused by the interaction with bacteriophage particles.

Prevalence of antibiotic-resistant bacteria among patients in two tertiary hospitals in Eastern Uganda

OBJECTIVE

The aim of this study was to determine the prevalence and antibiotic resistance patterns of bacterial isolates from inpatients and outpatients in Mbale and Soroti regional referral hospitals in Eastern Uganda.

METHODS

A retrospective analysis of culture and antibiotic sensitivity test results from the microbiology laboratories of the two tertiary hospitals was conducted for a 3-year period (January 2016-December 2018).

RESULTS

Microbiology records of 3092 patients were reviewed and analysed, with 1305 (42.1%) samples yielding clinical isolates. The most prevalent isolates were Escherichia coli (n = 442; 33.9%), Staphylococcus aureus (n = 376; 28.8%), Klebsiella pneumoniae (n = 237; 18.2%), and Streptococcus pneumoniae (n = 76; 5.8%). High rates of antimicrobial resistance were detected across both Gram-negative and Gram-positive bacteria. Escherichia coli and K. pneumoniae were resistant to several agents such as amoxicillin/clavulanate (83.5%; 64.6%), cefotaxime (74.2%; 52.7%), ciprofloxacin (92.1%; 27.8%), gentamicin (51.8%; 76%), imipenem (3.2%; 10.5%), tetracycline (98%; 74.5%), and trimethoprim-sulfamethoxazole (74.1%; 74.3%), respectively. Staphylococcus aureus and S. pneumoniae exhibited the following resistance profile: cefoxitin (44.4%; 40.9%), chloramphenicol (69.1%; 27.6%) clindamycin (21.5%; 24.4%), gentamicin (83.2%; 66.9%), penicillin (46.5%; -) tetracycline (85.6%; 97.6%), trimethoprim-sulfamethoxazole (88%; 91.3%), and vancomycin (41.2%; -).

CONCLUSION

We observed high resistance rates to antibiotics among the majority of microorganisms that were isolated from the samples collected from patients in Eastern Uganda. Furthermore, measures should be undertaken locally to improve microbiology diagnostics and to prevent the spread of antibiotic-resistant strains as this impedes the optimal treatment of bacterial infections and narrows the choice of effective therapeutic options.

Distribution of genes encoding resistance to macrolides, lincosamides, and streptogramins among methicillin-resistant Staphylococcus aureus strains isolated from burn patients

The increasing resistance to macrolide, lincosamide, and streptogramin B agents among methicillin-resistant Staphylococcus aureus (MRSA) is a worldwide problem for the health community. This study aimed to investigate the prevalence of ermA, ermB, ermC, and msrA in MRSA strains isolated from burn patients in Ahvaz, southwest of Iran. A total of 76 isolates of S. aureus were collected from January to May 2017 from Taleghani Burn Hospital in Ahvaz. Among 76 S. aureus strains collected, 60 (78.9%) isolates were MRSA. The antimicrobial susceptibility testing for MRSA showed extreme high resistance rate to clarithromycin (100%) and azithromycin (100%), followed by erythromycin (98.3%). The PCR assay revealed that the frequency rates of msrA, ermA, and ermC genes were 23 (38.3%), 28 (46.7%), and 22 (36.7%), respectively. In addition, none of the MRSA isolates had the ermB gene. Because of the high prevalence of macrolide and lincosamide resistance found in MRSA isolates from infections of burn patients in Ahvaz, southwest of Iran, it is recommended that local periodic survey be performed for controlling the dissemination of antimicrobial resistance.

Antimicrobial resistance, virulence genes profiling and molecular relatedness of methicillin-resistant Staphylococcus aureus strains isolated from hospitalized patients in Guangdong Province, China

PURPOSE

The main objective of this study was to decipher the prevalence, antimicrobial resistance, major virulence genes and the molecular characteristics of methicillin-resistant Staphylococcus aureus (MRSA) isolated from different clinical sources in southern China.

MATERIALS AND METHODS

The present study was performed on 187 non-duplicate S. aureus clinical isolates collected from three tertiary hospitals in Guangdong Province, China, 2010-2016. Antimicrobial susceptibility testing was performed by the disk diffusion method and by measuring the minimum inhibitory concentration. Screening for resistance and virulence genes was performed. Clonal relatedness was determined using various molecular typing methods such as multilocus sequence typing, spa and staphylococcal chromosomal cassette mec (SCCmec) typing. Whole genome sequencing was performed for three selected isolates.

RESULTS

Out of 187 isolates, 103 (55%) were identified as MRSA. The highest prevalence rate was found among the skin and soft tissue infection (SSTI) samples (58/103), followed by sputum samples (25/103), blood stream infection samples (15/103) and others (5/103). Antimicrobial susceptibility results revealed high resistance rates for erythromycin (64.1%), clindamycin (48.5%), gentamicin (36.9%) and ciprofloxacin (33.98%). All isolates were susceptible to vancomycin. Resistance genes and mutation detected were as follows: aac(6')-aph(2") (24.3%), dfrG (10.7%), rpoB (21.4%), cfr (0%), fexA (1.94%), gyrA (35.92%), gyrB (0.97%), grlA (20.4%), grlB (10.68%), ermA (21.4%), ermB (18.44%), ermC (21.4%) and lnuA (18.44%). Profiling of virulence genes revealed the following: sea (11.7%), seb (21.4%), sec (0.97%), sed (0.97%), hla (86.41%), hlb (17.48%), hlg (10.68%), hld (53.4%), Tsst-1 (3.9%) and pvl (27.2%). Clonal relatedness showed that ST239-SCCmecA III-t37 clone was the most prevalent clone.

CONCLUSION

Our study elucidated the prevalence, antibiotic resistance, pathogenicity and molecular characteristics of MRSA isolated from various clinical sources in Guangdong, China. We found that the infectious rate of MRSA was higher among SSTI than other sources. The most predominant genotype was ST239-SCCmecA III-t37 clone, indicating that ST239-t30 clone which was previously predominant had been replaced by a new clone.

Molecular characteristics and virulence gene profiles of Staphylococcus aureus causing bloodstream infection

Background

The rate of methicillin-resistant Staphylococcus aureus (MRSA) among the total of S. aureus isolates decreased to 35.3% in 2017 in China. It is unclear whether the molecular characteristics of S. aureus isolates have changed as the rate decreased.

Objective

This study aimed to investigate the molecular characteristics and virulence genes profile of S. aureus isolates causing bloodstream infection and analyze the correlation between the prevalence rates of the common sequence types and MRSA.

Methods

A total of 112 S. aureus strains from eight hospitals of four cities, including 32 MRSA isolates, were identified and evaluated through multilocus sequence typing, spa typing, and determination of virulence genes.

Results

Twenty-five STs were identified, of which ST5 (21.4%) was the most prevalent, whereas the prevalence of ST239 correlated with the rate of MRSA among all S. aureus isolates. Forty-six spa types were identified, of which t2460 (14.3%) was the most common. clfa, hla, seb, fnbA and hlb were the prevailing virulence genes. 81.3% MRSA and 45.0% methicillin-sensitive S. aureus (MSSA) isolates harbored six or more tested virulence genes. ST5-t2460, seldom noted in bloodborne S. aureus isolates in China, was the most common clone. The prevalence of harboring six or more virulence genes in ST5-t2460 and ST188-t189 were 93.8% and 8.3%, respectively.

Conclusion

ST5-t2460 was the most common clone in S. aureus causing bloodstream infection followed by ST188-t189, which had never been noted in China before. Moreover, ST5-t2460 harbored more virulence genes than ST188-t189, and the prevalence of ST239 clone decreased with the proportion of MRSA among all S. aureus isolates.