Incidence of methicillin resistant Staphylococcus aureus (MRSA) in burn intensive care unit: a systematic review

Molecular characteristics and antimicrobial resistance profiles of Staphylococcus aureus isolates from burns

BACKGROUND

Burns are a problem that affects millions of individuals around the world.

OBJECTIVE

This research aimed to analyze the genetic characteristics and antibiotic resistance of Staphylococcus aureus strains isolated from patients with burns. Identifying the genetic variations of three local strains of Staphylococcus aureus isolated from burns.

MATERIALS AND METHODS

Swab samples were collected from eighty sources (burns). Using sterile swabs containing media collected from patients treated at Baqubah Teaching Hospital between July 2022 and the end of September 2022, these samples were then cultured on blood agar and brain heart infusion agar. A total of twenty-four hours were spent incubating the cultured samples in an aerobic environment at 37 °C. During this time, isolated growing colonies showed characteristic growth, color, and hemolysis, while suspicious colonies were cultured for further identification.

RESULTS

Our results indicated the presence of several polymorphisms that were distributed in the investigated samples. However, almost all observed variations were concentrated only in the S2 isolates. The construction of phylogenetic trees confirmed this notion by positioning these S2-based amplicons to distinct categories within Staph. aureus organisms. Furthermore, the phylogenetic tree offered additional tools for the guaranteed identity of the samples that were analyzed. Consequently, the utilization of the PCR-sequencing approach in three DNA samples belonging to these local bacterial isolates has resulted in the confirmation of the identity of this strain. However, particular emphasis should be placed on S2 isolate as it has special variants that differ from its mates, in terms of its metabolic as well as phylogenetic consequences. Therefore, S2 isolates may represent a new strain that requires a whole genome sequencing strategy to validate its identity within Staph. aureus organisms. S.aureus resistance was 100% (Augmentin and Tetracycline), and 90% (Azithromycin and Trimethoprim), while Cefotaxime and Chloramphenicol recorded (75%, and 85%) respectively.

Impact of the implementation of the Intelligent Antimicrobial System (iAMS) on clinical outcomes among patients with bacteraemia caused by methicillin-resistant Staphylococcus aureus

OBJECTIVES

This study aimed to investigate the clinical impact of the Intelligent Antimicrobial System (iAMS) on patients with bacteraemia due to methicillin-resistant (MRSA) and methicillin-susceptible Staphylococcus aureus (MSSA).

METHODS

A total of 1008 patients with suspected SA infection were enrolled before and after the implementation of iAMS. Among them, 252 with bacteraemia caused by SA, including 118 in the iAMS and 134 in the non-iAMS groups, were evaluated.

RESULTS

The iAMS group exhibited a 5.2% (from 55.2% to 50.0%; P = 0.96) increase in the 1-year survival rate. For patients with MRSA and MSSA compared to the non-iAMS group, the 1-year survival rate increased by 17.6% (from 70.9% to 53.3%; P = 0.41) and 7.0% (from 52.3% to 45.3%; P = 0.57), respectively, both surpassing the rate of the non-iAMS group. The iAMS intervention resulted in a higher long-term survival rate (from 70.9% to 52.3%; P = 0.984) for MRSA patients than for MSSA patients. MRSA patients experienced a reduced length of hospital stay (from 23.3% to 35.6%; P = 0.038), and the 45-day discharge rate increased by 20.4% (P = 0.064). Furthermore, the intervention resulted in a significant 97.3% relative decrease in near miss medication incidents reported by pharmacists (P = 0.013).

CONCLUSIONS

Implementation of iAMS platform improved long-term survival rates, discharge rates, hospitalization days, and medical cost (although no significant differences were observed) among patients with MRSA bacteraemia. Additionally, it demonstrated significant benefits in ensuring drug safety.

Methicillin-Resistant Staphylococcus aureus Colonization in Intensive Care and Burn Units: A Narrative Review

Methicillin-resistant Staphylococcus aureus (MRSA) is a common hospital-acquired pathogen and can cause a wide spectrum of infections. In recent years, MRSA has emerged as a significant public health concern, particularly in hospitals. Intensive care units (ICUs) and burn units are high-risk areas for hospital-acquired MRSA infections, which can lead to increased morbidity, mortality, and healthcare costs. MRSA exhibits resistance to multiple antibiotics and can cause serious infections, including but not limited to pneumonia, endocarditis, and cutaneous infections, particularly in patients with burn injuries. The prevention and effective management of MRSA infections in both burn patients and those in ICUs is crucial, with strategies like isolation, regular disinfection, and prophylactic intranasal mupirocin. Early diagnosis of MRSA infection and isolation of patients is vital to prevent the spread of MRSA. Implementation of prevention strategies faces many challenges, such as cost, and the most successful infection management practices are still debated. This review has highlighted the substantial concern of MRSA colonization in intensive care and burn units. MRSA poses a significant risk to vulnerable patients, influenced by factors such as compromised immunity and invasive procedures. The prevalence of MRSA colonization varies, influenced by regional factors and infection control practices. Combating MRSA requires a multifaceted approach, including stringent infection control measures and education for healthcare workers and patients. As we move forward, continued research and cooperation are essential to reduce the burden of MRSA in these critical care settings.

Etiology and Multi-Drug Resistant Profile of Bacterial Infections in Severe Burn Patients, Romania 2018-2022

Infections in severe burns and their etiology are and will remain a big concern for the medical field. The multi-drug resistant strains of bacteria are a challenge of today's medicine. The aim of our study was to identify the etiological spectrum of bacterial infections in severe burn patients in Romania and their multi-drug resistant patterns. We performed a prospective study that included 202 adult patients admitted to the intensive care unit (ICU) of the Clinical Emergency Hospital of Plastic, Reconstructive Surgery and Burns, Bucharest, Romania (CEHPRSB), from 1 October 2018 to 1 April 2022, a period which includes the first 2 years of the outbreak of COVID-19. From each patient, wound swabs, endotracheal aspirates, blood for blood culture, and urine were collected. The most frequently isolated bacterium was Pseudomonas aeruginosa (39%), followed by Staphylococcus aureus (12%), Klebsiella spp. (11%), and Acinetobacter baumannii (9%). More than 90% of Pseudomonas aeruginosa and Acinetobacter baumannii were MDR, regardless of the clinical specimen from which they were isolated.

Functional annotation of rhizospheric phageome of the wild plant species Moringa oleifera

Introduction

The study aims to describe phageome of soil rhizosphere of M.oleifera in terms of the genes encoding CAZymes and other KEGG enzymes.

Methods

Genes of the rhizospheric virome of the wild plant species Moringa oleifera were investigated for their ability to encode useful CAZymes and other KEGG (Kyoto Encyclopedia of Genes and Genomes) enzymes and to resist antibiotic resistance genes (ARGs) in the soil.

Results

Abundance of these genes was higher in the rhizospheric microbiome than in the bulk soil. Detected viral families include the plant viral family Potyviridae as well as the tailed bacteriophages of class Caudoviricetes that are mainly associated with bacterial genera Pseudomonas, Streptomyces and Mycobacterium. Viral CAZymes in this soil mainly belong to glycoside hydrolase (GH) families GH43 and GH23. Some of these CAZymes participate in a KEGG pathway with actions included debranching and degradation of hemicellulose. Other actions include biosynthesizing biopolymer of the bacterial cell wall and the layered cell wall structure of peptidoglycan. Other CAZymes promote plant physiological activities such as cell-cell recognition, embryogenesis and programmed cell death (PCD). Enzymes of other pathways help reduce the level of soil H₂O₂ and participate in the biosynthesis of glycine, malate, isoprenoids, as well as isoprene that protects plant from heat stress. Other enzymes act in promoting both the permeability of bacterial peroxisome membrane and carbon fixation in plants. Some enzymes participate in a balanced supply of dNTPs, successful DNA replication and mismatch repair during bacterial cell division. They also catalyze the release of signal peptides from bacterial membrane prolipoproteins. Phages with the most highly abundant antibiotic resistance genes (ARGs) transduce species of bacterial genera Pseudomonas, Streptomyces, and Mycobacterium. Abundant mechanisms of antibiotic resistance in the rhizosphere include "antibiotic efflux pump" for ARGs soxR, OleC, and MuxB, "antibiotic target alteration" for parY mutant, and "antibiotic inactivation" for arr-1.

Discussion

These ARGs can act synergistically to inhibit several antibiotics including tetracycline, penam, cephalosporin, rifamycins, aminocoumarin, and oleandomycin. The study highlighted the issue of horizontal transfer of ARGs to clinical isolates and human gut microbiome.

Niosomal entrapment improved the bactericidal properties of azithromycin against methicillin-resistant Staphylococcus aureus

Aim: This study seeks to optimize niosomal formulations of azithromycin (AZ) and evaluate their activities against methicillin-resistant Staphylococcus aureus (MRSA). Methods: The thin-film hydration was used to prepare niosomes containing various molar ratios of span 60, cholesterol, dicetylphosphate and AZ. Formulation 5, with 5:1:1:1 molar ratio, was optimized based on entrapment efficiency. Solid state analyses and accelerated stability were carried out. The antibacterial properties against MRSA was determined by agar well diffusion method. Results: Physico-chemical characterization of formulation 5 confirmed successful encapsulation of AZ with slightly improved stability at 30°C for 6 months. Niosomal AZ at 0.1% is as effective as vancomycin in inhibiting the growth of MRSA. Conclusion: The antibacterial activities of AZ against MRSA is enhanced when encapsulated within niosomes.

Amphiphilic Chitosan Porous Membranes as Potential Therapeutic Systems with Analgesic Effect for Burn Care

Eliminating or at least lessening the pain is a crucial aspect of burns management, as pain can negatively affect mental health and quality of life, and it can also induce a delay on wound healing. In this context, new amphiphilic chitosan 3D porous membranes were developed and investigated as burns therapeutic systems with analgesic effect for delivery of lidocaine as local anesthetic. The highly porous morphology of the membranes and the structural modifications were evidenced by scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis and infrared spectroscopy (FTIR). Improved compression mechanical properties, long-term hydrolytic degradation (28 days) evaluation and high swelling capacities (ranging from 8 to 22.6 g/g) indicate an increased capacity of the prepared membranes to absorb physiological fluids (burns exudate). Lidocaine in vitro release efficiency was favored by the decreased content of cross-linking agent (reaching maximum value of 95.24%) and the kinetic data modeling, indicating that lidocaine release occurs by quasi-Fickian diffusion. In addition to the in vitro evaluation of analgesic effect, lidocaine-loaded chitosan membranes were successfully investigated and proved antibacterial activity against most common pathogens in burns infections: Staphylococcus aureus and Methicillin-resistant Staphylococcus aureus.

Abundant antibiotic resistance genes in rhizobiome of the human edible Moringa oleifera medicinal plant

Moringa oleifera (or the miracle tree) is a wild plant species widely grown for its seed pods and leaves, and is used in traditional herbal medicine. The metagenomic whole genome shotgun sequencing (mWGS) approach was used to characterize antibiotic resistance genes (ARGs) of the rhizobiomes of this wild plant and surrounding bulk soil microbiomes and to figure out the chance and consequences for highly abundant ARGs, e.g., mtrA, golS, soxR, oleC, novA, kdpE, vanRO, parY, and rbpA, to horizontally transfer to human gut pathogens via mobile genetic elements (MGEs). The results indicated that abundance of these ARGs, except for golS, was higher in rhizosphere of M. oleifera than that in bulk soil microbiome with no signs of emerging new soil ARGs in either soil type. The most highly abundant metabolic processes of the most abundant ARGs were previously detected in members of phyla Actinobacteria, Proteobacteria, Acidobacteria, Chloroflexi, and Firmicutes. These processes refer to three resistance mechanisms namely antibiotic efflux pump, antibiotic target alteration and antibiotic target protection. Antibiotic efflux mechanism included resistance-nodulation-cell division (RND), ATP-binding cassette (ABC), and major facilitator superfamily (MFS) antibiotics pumps as well as the two-component regulatory kdpDE system. Antibiotic target alteration included glycopeptide resistance gene cluster (vanRO), aminocoumarin resistance parY, and aminocoumarin self-resistance parY. While, antibiotic target protection mechanism included RbpA bacterial RNA polymerase (rpoB)-binding protein. The study supports the claim of the possible horizontal transfer of these ARGs to human gut and emergence of new multidrug resistant clinical isolates. Thus, careful agricultural practices are required especially for plants used in circles of human nutrition industry or in traditional medicine.

Human organoid biofilm model for assessing antibiofilm activity of novel agents

Bacterial biofilms cause 65% of all human infections and are highly resistant to antibiotic therapy but lack specific treatments. To provide a human organoid model for studying host-microbe interplay and enabling screening for novel antibiofilm agents, a human epidermis organoid model with robust methicillin-resistant Staphylococcus aureus (MRSA) USA300 and Pseudomonas aeruginosa PAO1 biofilm was developed. Treatment of 1-day and 3-day MRSA and PAO1 biofilms with antibiofilm peptide DJK-5 significantly and substantially reduced the bacterial burden. This model enabled the screening of synthetic host defense peptides, revealing their superior antibiofilm activity against MRSA compared to the antibiotic mupirocin. The model was extended to evaluate thermally wounded skin infected with MRSA biofilms resulting in increased bacterial load, cytotoxicity, and pro-inflammatory cytokine levels that were all reduced upon treatment with DJK-5. Combination treatment of DJK-5 with an anti-inflammatory peptide, 1002, further reduced cytotoxicity and skin inflammation.

Development and in vitro evaluation of microparticles of fluoxetine in galactomannan against biofilms of S. aureus methicilin resistant

The emergence of multidrug-resistant (MDR) bacteria is a global problem, by reducing the effectiveness of traditional antibiotics and decreasing the therapeutic arsenal to treat bacterial infections. This has led to an increase in researches about how to overcome this resistance to antibiotics. One strategy is the repositioning (or repurposing) of existing drugs not previously used to combat microorganisms, rather than the development of new drugs. Fluoxetine (FLX) is a selective serotonin reuptake inhibitor (SSRIs) and is considered one of the first highly selective antidepressants of the monoamine neurotransmitter serotonin (5-HT). The objective of this study is to prepare and physically characterize fluoxetine microparticles with galactomannan and evaluate their efficacy against strains of Staphylococcus aureus sensitive and resistant to methicillin. The microparticles were analyzed by differential scanning calorimetry (DSC), infrared analysis (IR) and X-ray diffraction (XRD). In addition, the percentage of encapsulation efficiency (EE%) and drug release kinetics were determined in vitro, along with the determination of the minimum inhibitory concentration (MIC) and evaluation of the action against biofilms. Physical tests were conducted to characterize galactomannan (GAL), FLX, oxacillin (OXA) and the galactomannan/fluoxetine microparticles (GFM). The EE% value was 98 % and, in regard the release, tests with the microparticles released about 60 % of the drug in 200 min. The isolated MIC results for FLX (255 μg/mL) and OXA MIC (1.97-15.62 μg/mL) showed that the strains were resistant. Furthermore, in the biofilms, microparticles showed statically significant improvement for all concentrations used. The study revealed that fluoxetine encapsulated in microparticles has the potential to act as an effective antimicrobial agent.

The Evaluation of Antibiotic Resistance and nalB Mutants in Pseudomonas eruginosa Isolated from Burnt Patients of Shohada Mehrab Yazd Hospital Burn Ward

Background

Due to extensive damage to the skin, burn victims may acquire life-threatening infections. Though the skin primarily protects against microbial invasions, a large number of bacteria, fungi, and viruses can be isolated from burn patients, specifically Pseudomonas aeruginosa, a gram-negative bacterium with both intrinsic and acquired antibiotic resistance (AR) properties. nalB mutations can be found on the mexR in the P. aeruginosa chromosome. This mutation can induce overexpression of the mexAB-oprMoperon, and affect the MexAB-OprM efflux pump, which removes antimicrobial agents from the bacterial cell. Identifying nalB mutants can be useful for monitoring factors affecting AR.

Methods

In this study, 70 P. aeruginosa isolates identified from burn patients and antibacterial sensitivity was evaluated using the Kirby-Bauer method. We also investigated nalB mutations in samples using molecular methods including Polymerase reaction chain (PCR) and Sequencing.

Results

We identified nalB mutations in 16 isolates. We also found that the increasing effect of nalB mutants induces hyper production activity of MexAB-OprM resulting in AR. Overall, these findings compliment the findings of previous reports.

Conclusion

According to the resistance patterns of the samples, both Amikacin and Ciprofloxacin showed the highest resistance (%). Further, the relationship between Ciprofloxacin resistance and nalB mutations was statistically significant (p= 0.016). The results confirm that the increasing effect of nalB mutants on hyper production activity of MexAB-OprM leads to AR.

Molecular Detection of Genes Involved in Biofilm Formation in Staphylococcus aureus Strains Isolates: Evidence From Shahid Motahari Hospital in Tehran

Background: Infections caused by Staphylococcus aureus strains are a major public health challenge worldwide, especially in specialized burn hospitals. Infections caused by S. aureus account for more than 50% of burn-related deaths. Objectives: Since data on characteristics of these isolates are not sufficient, the current study aimed to assess the prevalence of resistance to antibacterial agents and to analyze the distribution of biofilm, and adhesion encoding genes among S. aureus strains isolated from burn patients in Motahari Hospital, Tehran, Iran. Methods: A total of 83 S. aureus strains were collected from burn wounds of patients admitted to a referral burn center in Tehran for 10 months. In vitro antibacterial susceptibility of isolates was evaluated using the Kirby-Bauer disk diffusion method. Strains were subjected to polymerase chain reaction (PCR) to determine the presence of nucA, mecA, ebps, cna, bbp, fnbA, fnbB, clfA, and clfB genes. Results: The highest frequency of resistance was found to cephalexin and cefoxitin (87.9%), followed by clindamycin (75.9%), erythromycin (72.3%), and ciprofloxacin (60.2%). Five resistance patterns were identified in which cephalexin, cefoxitin, clindamycin, erythromycin, and ciprofloxacin had the most predominant resistance profile (36.1%). Biofilm gene detection indicated a markedly high prevalence of cna (74.7%), clfB (54.2%), clfA (50.6%), fnbA (42.1%), ebp (13.2%), and fnbB (12%). Six different biofilm genetic patterns were identified, wherein clfA, clfB, fnbA, ebp, and cna (30.1%), clfA, clfB, fnbA, fnbB, ebp, and cna (12%), and clfA, clfB, and cna (8.4%) were the top three most frequently identified patterns. Conclusions: The prevalence of biofilm encoding genes, which are associated with multidrug resistance in S. aureus strains isolated from burn patients, is high. Therefore, identification of epidemiology, molecular characteristics, and biofilm management of S. aureus infection in burn units would be helpful.

Fatores associados à infecção por Staphylococcus aureus resistente à meticilina em unidade de terapia intensiva

OBJECTIVE

To identify factors associated with methicillin-resistant Staphylococcus aureus (MRSA) infection in adult patients admitted to the Intensive Care Unit (ICU), and to compare them with a control group.

METHODS

Retrospective case-control study carried out in an adult ICU, from January 2015 to June 2017, with 61 patients who developed methicillin-resistant Staphylococcus aureus infection and the same number of control patients.

RESULTS

Most participants were male 65 (60.6%), with a neurological diagnosis 43 (35.2%) and hypertensive 61 (50.0%). In the comparison of the groups, there was a statistically significant difference in relation to mechanical ventilation (p=0.0107), tracheostomy (p=0.0083), death (p=0.0401), urinary catheter (p=0.0420), length of stay (p<0.0001) and severity (p=0.0003). The main factors associated with methicillin-resistant Staphylococcus aureus infection were: severity (OR= 65.69; CI=3.726-4.808; p=0.0018), use of antimicrobials (OR= 0.047;CI=0.028-0.122;p=0.0024), length of stay (OR=1.19; CI=0.952-1.031; p=0.0285).

CONCLUSION

methicillin-resistant Staphylococcus aureus infection is multifactorial and has been associated with length of stay and severity. Use of antimicrobials was a protective factor.

Streptomyces sp. Strain MUSC 125 from Mangrove Soil in Malaysia with Anti-MRSA, Anti-Biofilm and Antioxidant Activities

There is an urgent need to search for new antibiotics to counter the growing number of antibiotic-resistant bacterial strains, one of which is methicillin-resistant Staphylococcus aureus (MRSA). Herein, we report a Streptomyces sp. strain MUSC 125 from mangrove soil in Malaysia which was identified using 16S rRNA phylogenetic and phenotypic analysis. The methanolic extract of strain MUSC 125 showed anti-MRSA, anti-biofilm and antioxidant activities. Strain MUSC 125 was further screened for the presence of secondary metabolite biosynthetic genes. Our results indicated that both polyketide synthase (pks) gene clusters, pksI and pksII, were detected in strain MUSC 125 by PCR amplification. In addition, gas chromatography-mass spectroscopy (GC-MS) detected the presence of different chemicals in the methanolic extract. Based on the GC-MS analysis, eight known compounds were detected suggesting their contribution towards the anti-MRSA and anti-biofilm activities observed. Overall, the study bolsters the potential of strain MUSC 125 as a promising source of anti-MRSA and antibiofilm compounds and warrants further investigation.

Bacterial Virulence Factors and Their Contribution to Pathophysiology after Thermal Injury

Background: Bacterial infections are the leading cause of morbidity and mortality in burn-injured patients. Pseudomonas aeruginosa and Staphylococcus aureus are among the most common pathogens responsible for infections in thermally injured patients. These and other pathogens have developed a variety of virulence factors to colonize and infect hosts. Methods: A comprehensive literature review was conducted to best summarize the current knowledge of how virulence factors contribute to bacterial pathogenicity. Results: The review highlights the unique mechanisms bacteria utilize to evade host defense systems and further complicate the treatment of burn-injured patients. Conclusion: Further research on virulence factors and their contribution to bacterial pathogenicity is warranted and could potentially lead to development of neutralizing pharmacotherapy that would complement antimicrobial treatment.

The Antimicrobial Activity of Ciprofloxacin-Loaded Niosomes against Ciprofloxacin-Resistant and Biofilm-Forming Staphylococcus aureus

Purpose

The threat of Staphylococcus aureus antimicrobial resistance is increasing worldwide. Niosomes are a new drug delivery system that enhances the antimicrobial potential of antibiotics. We hereby aim to evaluate the antimicrobial and antibiofilm activity of ciprofloxacin-loaded niosomes.

Methods

The antimicrobial susceptibility of clinical S. aureus isolates (n=59) was determined by Kirby-Bauer disk diffusion method. Their biofilm formation activity was tested by Christensen's method. Two ciprofloxacin-loaded niosomal formulations were prepared by thin-film hydration method, and their minimum inhibitory concentrations (MIC) were determined by agar dilution method, against ciprofloxacin-resistant and biofilm-forming isolates (n=24). Their ability to inhibit biofilm formation and eradicate already formed biofilms was evaluated and further confirmed by scanning electron microscope images. Non-synonymous mutations, in a quinolone resistance-determining regions of S. aureus isolates, were detected by polymerase chain reaction.

Results

Most of the isolates were methicillin- (47/59) and ciprofloxacin-resistant (45/59). All except two isolates were capable of biofilm production. Niosomal preparation I reduced ciprofloxacin MIC by twofold in four isolates, whereas preparation II reduced ciprofloxacin MIC of most isolates by 8- to 32-fold, with three isolates that became ciprofloxacin-susceptible. Non-synonymous mutations were detected in isolates that maintained phenotypic ciprofloxacin resistance against ciprofloxacin-loaded niosomal preparation II. Ciprofloxacin-loaded niosomes reduced the minimum biofilm inhibitory concentration and the minimum biofilm eradication concentration in 58% and 62% of the tested isolates, respectively.

Conclusion

Ciprofloxacin-loaded niosomes can restore ciprofloxacin activity against resistant S. aureus isolates. To our knowledge, this is the first report on the inhibition of biofilm formation and eradication of formed biofilms by ciprofloxacin-loaded niosomes.

Multidrug Resistance (MDR) and Collateral Sensitivity in Bacteria, with Special Attention to Genetic and Evolutionary Aspects and to the Perspectives of Antimicrobial Peptides-A Review

Antibiotic poly-resistance (multidrug-, extreme-, and pan-drug resistance) is controlled by adaptive evolution. Darwinian and Lamarckian interpretations of resistance evolution are discussed. Arguments for, and against, pessimistic forecasts on a fatal “post-antibiotic era” are evaluated. In commensal niches, the appearance of a new antibiotic resistance often reduces fitness, but compensatory mutations may counteract this tendency. The appearance of new antibiotic resistance is frequently accompanied by a collateral sensitivity to other resistances. Organisms with an expanding open pan-genome, such as Acinetobacter baumannii, Pseudomonas aeruginosa, and Klebsiella pneumoniae, can withstand an increased number of resistances by exploiting their evolutionary plasticity and disseminating clonally or poly-clonally. Multidrug-resistant pathogen clones can become predominant under antibiotic stress conditions but, under the influence of negative frequency-dependent selection, are prevented from rising to dominance in a population in a commensal niche. Antimicrobial peptides have a great potential to combat multidrug resistance, since antibiotic-resistant bacteria have shown a high frequency of collateral sensitivity to antimicrobial peptides. In addition, the mobility patterns of antibiotic resistance, and antimicrobial peptide resistance, genes are completely different. The integron trade in commensal niches is fortunately limited by the species-specificity of resistance genes. Hence, we theorize that the suggested post-antibiotic era has not yet come, and indeed might never come.

The global prevalence of Daptomycin, Tigecycline, Quinupristin/Dalfopristin, and Linezolid-resistant Staphylococcus aureus and coagulase-negative staphylococci strains: a systematic review and meta-analysis

Objective

Methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant coagulase-negative Staphylococcus (MRCoNS) are among the main causes of nosocomial infections, which have caused major problems in recent years due to continuously increasing spread of various antibiotic resistance features. Apparently, vancomycin is still an effective antibiotic for treatment of infections caused by these bacteria but in recent years, additional resistance phenotypes have led to the accelerated introduction of newer agents such as linezolid, tigecycline, daptomycin, and quinupristin/dalfopristin (Q/D). Due to limited data availability on the global rate of resistance to these antibiotics, in the present study, the resistance rates of S. aureus, Methicillin-resistant S. aureus (MRSA), and CoNS to these antibiotics were collected.

Method

Several databases including web of science, EMBASE, and Medline (via PubMed), were searched (September 2018) to identify those studies that address MRSA, and CONS resistance to linezolid, tigecycline, daptomycin, and Q/D around the world.

Result

Most studies that reported resistant staphylococci were from the United States, Canada, and the European continent, while African and Asian countries reported the least resistance to these antibiotics. Our results showed that linezolid had the best inhibitory effect on S. aureus. Although resistances to this antibiotic have been reported from different countries, however, due to the high volume of the samples and the low number of resistance, in terms of statistical analyzes, the resistance to this antibiotic is zero. Moreover, linezolid, daptomycin and tigecycline effectively (99.9%) inhibit MRSA. Studies have shown that CoNS with 0.3% show the lowest resistance to linezolid and daptomycin, while analyzes introduced tigecycline with 1.6% resistance as the least effective antibiotic for these bacteria. Finally, MRSA and CoNS had a greater resistance to Q/D with 0.7 and 0.6%, respectively and due to its significant side effects and drug-drug interactions; it appears that its use is subject to limitations.

Conclusion

The present study shows that resistance to new agents is low in staphylococci and these antibiotics can still be used for treatment of staphylococcal infections in the world.

Nonwoven fabric supported, chitosan membrane anchored with curcumin/TiO2 complex: Scaffolds for MRSA infected wound skin reconstruction

Use of biomaterial scaffolds as drug carriers for infected wounds treatment is of wide scope. A series of curcumin/TiO₂ complex loaded chitosan scaffolds are fabricated for the same. Synthesized wound dressing material is screened for their morphology, water absorption capacity; in vitro drug release patterns, in vitro antibacterial studies against gram +ve and a gram -ve bacteria, cell viability for 3T3-L1 cell lines as well as in vivo MRSA infected wound healing capability. Formation of curcumin/TiO₂ complex was confirmed by X-ray diffraction studies, the anchoring pattern of them on the chitosan scaffold was analyzed by FESEM and EDS mapping. All membranes showed a better performance towards in vitro antibacterial and in vivo wound healing properties than the control ones in 14 days. The bacterial count on wound for a regular time period was measured and the scaffold with higher amount of curcumin in its complex is found to give the better performance, along with skin regeneration due to synergistic effect of curcumin and TiO₂.

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.

MRSA colonization and acquisition in the burn unit: A systematic review and meta-analysis

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most commonly encountered bacteria in the burn unit. In order to investigate the magnitude of this challenge, we assessed the prevalence of MRSA colonization on admission and the incidence of MRSA acquisition within burn units.

METHODS

We searched PubMed and EMBASE for studies reporting MRSA colonization among patients admitted in burn units.

RESULTS

We identified 16 articles that fulfilled our inclusion criteria and found an overall pooled prevalence of MRSA colonization upon the first 72 h of admission (colonization on admission) to the burn unit of 4.1% (95% CI: 2.7%-5.7%). MRSA acquisition in studies without a decolonization protocol was 21.2% (95% CI: 13.2%-30.5%) with a statistically significant downward trend over the years. Studies that implemented a decolonization protocol yielded a MRSA acquisition incidence rate of 4.5% (95% CI: 0.9%-10.6%). MRSA acquisition was higher among patients that have had inhalation injury (OR 3.96, 95% CI: 2.51-6.23), flame burns (OR 1.85, 95% CI: 1.25-2.73), or ICU admission (OR 3.12, 95% CI: 2.18-4.47).

CONCLUSION

Our study yielded that among burn victims, MRSA colonization prevalence on admission is not negligible and the risk of becoming MRSA colonized during hospitalization is higher when no decolonization protocols are implemented. Flame burns, admission to ICU, and inhalation injury were found to be associated with MRSA acquisition.

A Computer-Driven Approach to Discover Natural Product Leads for Methicillin-Resistant Staphylococcus aureus Infection Therapy

The risk of methicillin-resistant Staphylococcus aureus (MRSA) infection is increasing in both the developed and developing countries. New approaches to overcome this problem are in need. A ligand-based strategy to discover new inhibiting agents against MRSA infection was built through exploration of machine learning techniques. This strategy is based in two quantitative structure–activity relationship (QSAR) studies, one using molecular descriptors (approach A) and the other using descriptors (approach B). In the approach A, regression models were developed using a total of 6645 molecules that were extracted from the ChEMBL, PubChem and ZINC databases, and recent literature. The performance of the regression models was successfully evaluated by internal and external validation, the best model achieved R² of 0.68 and RMSE of 0.59 for the test set. In general natural product (NP) drug discovery is a time-consuming process and several strategies for dereplication have been developed to overcome this inherent limitation. In the approach B, we developed a new NP drug discovery methodology that consists in frontloading samples with 1D NMR descriptors to predict compounds with antibacterial activity prior to bioactivity screening for NPs discovery. The NMR QSAR classification models were built using 1D NMR data (¹H and ¹³C) as descriptors, from crude extracts, fractions and pure compounds obtained from actinobacteria isolated from marine sediments collected off the Madeira Archipelago. The overall predictability accuracies of the best model exceeded 77% for both training and test sets.