Antibiotic-resistant Species Research Articles

Ameliorative effects of clindamycin - nanoceria conjugate: A ROS responsive smart drug delivery system for diabetic wound healing study

BackgroundIncreased incidence of antibiotic-resistant species calls for development of new types of nano-medicine that can be used for healing of bacteria-caused wounds, such as diabetic foot ulcer. As diabetic patients have inefficient defense mechanism against reactive oxygen species (ROS) produced in our body as a by-product of oxygen reduction, the process of wound healing takes longer epithelialisation period. Ceria nanoparticles (CNPs) are well-known for their antibacterial and ROS-scavenging nature. Yet till now no significant effort has been made to conjugate ceria nanoparticles with drugs to treat diabetic wounds. MethodsIn this experiment, CNPs were synthesized in-house and clindamycin hydrochloride was loaded onto it by physical adsorption method for reactive oxygen species responsive drug delivery. Various physico-chemical characterisations such as Transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, Energy dispersive X-ray, Thermogravimetric study etc. were performed to affirm the formation of both nanoceria along with drug encapsulated nanoceria. ResultsBoth of these as-prepared formulations inhibited the growth of Gram-positive as well as Gram-negative bacteria confirmed by Disk diffusion study; exhibiting their antibacterial effect. In-vitro drug release study was carried out in physiological environment both in absence and presence of hydrogen peroxide solution to test the reactive ROS-responsiveness of the drug loaded nanocomposites. It also exhibited faster wound healing in diabetes-induced rats. Therefore, it could successfully lower the amount of serum glucose level, inflammation cytokines, hepatotoxic and oxidative stress markers in diabetic rats as confirmed by various ex vivo tests conducted. ConclusionThus, drug loaded ceria nanoparticles have the potential to heal diabetic wounds successfully and can be considered to be useful for the fabrication of appropriate medicated suppositories beneficial for diabetic foot ulcer treatment in future.

Antibiotic-resistant microbial populations in urban receiving waters and wastewaters from Tanzania

Antimicrobial resistance against certain medications in the pathogenic microbial community is globally increasing due to the continual discharge and disposal of pharmaceuticals in the environment. The phenomenon resulted in significant antibiotic resistance among several exposed Enterobacteriaceae species, with wastewater treatment plants (WWTPs) and rivers serving as significant reservoirs. Despite antibiotic resistance being a tragedy, particularly in treating diseases by using antibiotics, local and regional studies indicating the severity, resistant species and the molecular level insight into these pathogens are scarce, thus requiring immediate intervention. This study, therefore, investigated wastewater from wastewater treatment ponds and receiving waters for the presence of resistant pathogens through phenotypical and molecular approach screening of their genes. Among the 57 analyzed samples, 18 (67%, n = 27) isolates of Klebsiella spp.., 4 (80%, n = 5) isolates of Proteus spp., 1 (100%, n = 1) of isolated Pseudomonas aeruginosa and 6 (18%, n = 34) of E. coli found were resistant to at least 1 among the tested antibiotics. E. coli had an 83% higher proportion of multi-drug resistance (MDR) than Klebsiella spp.., which had 68.5%, and no MDR was shown by P. aeruginosa isolates. Among the 20 bacterial isolates of antibiotic-resistant genes, showed that E. coli harboured 39%, followed by 22% of Klebsiella spp. Eleven (11) isolates of these 20 (55%) contained sulphonamides resistant genes: Sul 1 (n = 4) and Sul 2 (n = 7). Ten (10) isolates (50%) contained the tetracycline-resistant genes in which 4 isolates showed the Tet A, Tet B – 1 and 5 isolates contained Tet D. β-lactamases (bla CTX-M and bla SHV) were found in 7 isolates (35%). The existence of these antibiotic-resistant species in the urban receiving and wastewater presents a threat of transmission of diseases to humans and animals that are not cured by the existing medications, jeopardizing public health safety.

The dangerous transporters: A study of microplastic-associated bacteria passing through municipal wastewater treatment

Microplastics (MPs) provide a stable and protective habitat for diverse wastewater bacteria, including pathogenic and antibiotic-resistant species. Therefore, MPs may potentially transport these bacteria through wastewater treatment steps to the environment and far distances. This study investigated bacterial communities of MP-associated bacteria from different stages of municipal wastewater treatment processes to evaluate the potential negative effect of these biofilms on the environment. The results showed a high diversity of bacteria that were strongly attached to MPs. After all treatment steps, the core bacterial groups remained attached to MPs and escaped from the wastewater treatment plant with effluent water. Several pathogenic bacteria were identified in MP samples from all treatment steps, and most of them were found in effluent water. These data provide new insights into the possible impacts of wastewater-derived MPs on the environment. MP-associated biofilms were proved to be important sources of pathogens and antibiotic-resistant genes in natural waters.

Effects of microencapsulated essential oils on growth performance and biomarkers of inflammation in broiler chickens challenged with salmonella enteritidis

Feed ingredients are the potential sources, which can be contaminated with Salmonella. Therefore, the alternative strategies should be found for controlling pathogenic microbes and promoting the performance of broiler chicks. Although antibiotics have been used for the treatment of the infection induced by microbes, the use of which faces with some limitations such as bacteria resistance. The antibiotic substitute should be natural with no residue in poultry meat. Compounds such as phytobiotics can be incorporated into the diet for enhancing the production of poultry with no concern about the appearance of antibiotic-resistant microbial species and remaining the residue in the meat. This study aims to synthesize the microcapsules preserving the mixture of essential oils including thyme, peppermint, savory, and black pepper by using spray drying technique and to evaluate the growth performance, antioxidant status, immune response, and gut health parameters in broiler chickens challenged by salmonella enteritidis. The mixture of essential oils including thyme (50%), summer savory (25%), peppermint (12.5%) and black pepper seed (12.5%) was encapsulated in the protecting wall materials (20% WPC, 25% MS and 55% MD) for forming the essential oil-loaded spherical microcapsules with particle size of 323 nm and encapsulation efficiency of 96.2%. Thymol, carvacrol, p-cymene, γ-terpinene, and menthol existed in the core of the microcapsules as the main bioactive compounds. The microcapsules possessed the antioxidant and antibacterial activities, and its dietary application as the feed additive at the concentrations of 0.5, 1 and 2 kg/ton in broiler chickens challenged by S. enteritidis improved the final weight, total feed intake, FCR, body antioxidant status, ileal morphostructure, intestinal microbial population and regulated the antioxidant and inflammation genes in ileal tissue and upregulated the expression of occludin and SOD genes.

Role of the Housefly as a Biological Vector for Bacteria and Fungi at Some Slaughterhouses.

<b>Background and Objective:</b> The housefly, <i>Musca domestica</i> L. is the most widespread species of fly in the world. It is in close association with many human pathogens that which can cause serious and life-threatening diseases are known to be carried by house flies, including bacteria, viruses, fungi and parasites, Therefore, this study came intending to determine the role of house flies isolated from some slaughterhouses in the city of Al-Diwaniyah/Iraq in the spread of bacterial and fungal pathogens to humans. <b>Materials and Methods:</b> The 120 insects of house flies were collected randomly from some slaughterhouses for the period September to November, 2021 by special networks prepared for this purpose and transferred to the laboratory and then the bacteria and fungi were isolated and identified from the external surface of house flies by using appropriate culture media. <b>Results:</b> In this study, 148 bacterial isolates belonging to 15 species of bacteria were isolated and diagnosed from the external body of house flies that isolated, 91 samples had given positive growth of bacteria and <i>Escherichia coli</i> was the most occurrence and frequent from the other bacterial isolates, the occurrence rate of it was 16/91 (17.582%) with a frequency rate of 27/148 (18.243%). The 154 fungal isolates belonging to 16 species of fungi were isolated and diagnosed from the external body of house flies, 87 samples had given a positive growth of fungi and <i>Aspergillus niger</i> was the most occurrence and frequent from the other fungal isolates, as its occurrence rate reached 14/87 (16.091%) and the frequency rate of 21/154 (13.636%). <b>Conclusion:</b> House flies transmit many pathological microorganisms such as bacteria, fungi, viruses, etc., which causes various diseases for humans and animals and it may help the spread of antibiotic-resistant species and there is an urgent need to conduct many studies to know the new types of microorganisms that house flies can transmit.

Caerin 1 Peptides, the Potential Jack-of-All-Trades for the Multiple Antibiotic-Resistant Bacterial Infection Treatment and Cancer Immunotherapy.

Antibiotic resistance-related bacterial infections and cancers become huge challenges in human health in the 21st century. A number of naturally derived antimicrobial peptides possess multiple functions in host defense, including anti-infective and anticancer activities. One of which is known as the caerin 1 family peptides. The microbicidal properties of these peptides have been long discussed. The recent studies also established the usage of two members in this family, caerin 1.1 and caerin 1.9, in antimultiple antibiotic-resistant bacteria species. It is increasingly evident that caerin 1.1 and caerin 1.9 also contain additional activities in the suppression of tumor. In this review, we briefly outline the therapeutic potentials and possible mechanism of action of caerin 1.1 and 1.9 in the treatment of multiple antibiotic-resistant bacterial infection and cancer immunotherapy.

Electrochemical Sensors for Antibiotic Susceptibility Testing: Strategies and Applications

Increasing awareness of the impacts of infectious diseases has driven the development of advanced techniques for detecting pathogens in clinical and environmental settings. However, this process is hindered by the complexity and variability inherent in antibiotic-resistant species. A great deal of effort has been put into the development of antibiotic-resistance/susceptibility testing (AST) sensors and systems to administer proper drugs for patient-tailored therapy. Electrochemical sensors have garnered increasing attention due to their powerful potential to allow rapid, sensitive, and real-time monitoring, alongside the low-cost production, feasibility of minimization, and easy integration with other techniques. This review focuses on the recent advances in electrochemical sensing strategies that have been used to determine the level of antibiotic resistance/susceptibility of pathogenic bacteria. The recent examples of the current electrochemical AST sensors discussed here are classified into four categories according to what is detected and quantitated: the presence of antibiotic-resistant genes, changes in impedance caused by cell lysis, current response caused by changes in cellular membrane properties, and changes in the redox state of redox molecules. It also discusses potential strategies for the development of electrochemical AST sensors, with the goal of broadening their practical applications across various scientific and technological fields.

Synthesis and characterization of new Schiff-bases as Methicillin resistant Staphylococcus aureus (MRSA) inhibitors

Methicillin-resistant Staphylococcus aureus (MRSA) is the most common and widespread antibiotic-resistant species. Novel Schiff-bases (2–8) have been synthesized and characterized using FTIR, 1H NMR, 13C NMR and ESI-Mass spectroscopy. An in vitro anti-MRSA study with the ATCC 43300 strain revealed that compounds 2, 4 and 6 inhibited the MRSA strain significantly (MIC 256–512 µg/mL). The molecular docking study against the FabI enzyme from S. aureus indicated that potent compound 6 has significant docking score (-8.756 Kcal/mol) and forms hydrogen bonding and pi-pi stacking with Tyr157 and additional hydrogen bond with Ser197. All the tested derivatives showed lower toxicity with IC50 values >278 µM and none of them were cytotoxic against mammalian Vero cell line.

Photodynamic Therapy in Endodontics: A Helpful Tool to Combat Antibiotic Resistance? A Literature Review.

Background: Antibiotic resistance has become a growing global problem where overprescription is a contributing factor for its development. In the endodontics field, complementary treatments, such as antimicrobial photodynamic therapy (aPDT), have been described to eliminate residual bacteria from the root canal space and reduce complications. The aim of this review is to describe the literature evidence up to now regarding the advantages, efficiency, and clinical outcomes of this therapy in endodontics as a possible tool to combat antibiotic resistance. Methods: A review of the literature from 2010 to 2021 was carried out using the PubMed and Web of Science databases. Two steps were taken: First, articles were compiled through the terms and MeSH terms “Photochesdmotherapy” and “endodontics.” Then, a second search was conducted using “photodynamic therapy” and “antibiotic resistance” or “drug resistance, microbial.” Results: A total of 51 articles were included for evaluation: 27 laboratory studies, 14 reviews, and 10 clinical studies. Laboratory studies show that aPDT achieves significant bacterial elimination, even against antibiotic-resistant species, and is also effective in biofilm disruption. Clinical studies suggest that aPDT can be considered a promising technique to reduce bacterial complications, and reviews about the issue confirm its advantages. Conclusion: The benefits of aPDT in reducing complications due to its antibacterial effects means a possible decrease in systemic antibiotic prescription in endodontics. In addition, it could be an alternative to local intracanal antibiotic therapy, avoiding the appearance of possible antibiotic resistance, as no bacterial resistance with aPDT has been described to date.

From the Farms to the Dining Table: The Distribution and Molecular Characteristics of Antibiotic-Resistant Enterococcus spp. in Intensive Pig Farming in South Africa.

Foodborne pathogens, including antibiotic-resistant species, constitute a severe menace to food safety globally, especially food animals. Identifying points of concern that need immediate mitigation measures to prevent these bacteria from reaching households requires a broad understanding of these pathogens’ spread along the food production chain. We investigated the distribution, antibiotic susceptibility, molecular characterization and clonality of Enterococcus spp. in an intensive pig production continuum in South Africa, using the farm-to-fork approach. Enterococcus spp. were isolated from 452 samples obtained along the pig farm-to-fork continuum (farm, transport, abattoir, and retail meat) using the IDEXX Enterolert®/Quanti-Tray® 2000 system. Pure colonies were obtained on selective media and confirmed by real-time PCR, targeting genus- and species-specific genes. The susceptibility to antibiotics was determined by the Kirby–Bauer disk diffusion method against 16 antibiotics recommended by the WHO-AGISAR using EUCAST guidelines. Selected antibiotic resistance and virulence genes were detected by real-time PCR. Clonal relatedness between isolates across the continuum was evaluated by REP-PCR. A total of 284 isolates, consisting of 79.2% E. faecalis, 6.7% E. faecium, 2.5% E. casseliflavus, 0.4% E. gallinarum, and 11.2% other Enterococcus spp., were collected along the farm-to-fork continuum. The isolates were most resistant to sulfamethoxazole-trimethoprim (78.8%) and least resistant to levofloxacin (5.6%). No resistance was observed to vancomycin, teicoplanin, tigecycline and linezolid. E. faecium displayed 44.4% resistance to quinupristin-dalfopristin. Also, 78% of the isolates were multidrug-resistant. Phenotypic resistance to tetracycline, aminoglycosides, and macrolides was corroborated by the presence of the tetM, aph(3′)-IIIa, and ermB genes in 99.1%, 96.1%, and 88.3% of the isolates, respectively. The most detected virulence gene was gelE. Clonality revealed that E. faecalis isolates belonged to diverse clones along the continuum with major REP-types, mainly isolates from the same sampling source but different sampling rounds (on the farm). E. faecium isolates revealed a less diverse profile. The results suggest that intensive pig farming could serve as a reservoir of antibiotic-resistant bacteria that could be transmitted to occupationally exposed workers via direct contact with animals or consumers through animal products/food. This highlights the need for more robust guidelines for antibiotic use in intensive farming practices and the necessity of including Enterococcus spp. as an indicator in antibiotic resistance surveillance systems in food animals.

Occurrence and antibiogram signatures of some Vibrio species recovered from selected rivers in South West Nigeria.

Vibrio species, widely distributed in water environments, has emerged as a prominent cause of water and food-related disease outbreaks posing significant risk to human and animal health worldwide. About 40% of presumptive isolates recovered from four selected rivers in Southwest Nigeria and, established as Vibrio species genus through polymerase chain reaction techniques., were subjected to antibiotic susceptibility testing against a panel of 18 commonly used antibiotics. The relative prevalence of key Vibrio species (V. parahaemolyticus, V. vulnificus, V. mimicus, V. harveyi, and V. cholerae) was in the order 17%, 13.3%, 4.4%, 2.2%, and 2.2% respectively. Antibiotic resistance by all Vibrio species was mostly observed against doxycycline (71-89%), erythromycin (86-100%), tetracycline (71-89%), rifampicin (86-100%), and sulfamethoxazole (87-100%), though susceptibility to meropenem (86-100%), cephalothin (60-100%), norfloxacin (93-100%), ciprofloxacin (88-100%), amikacin (64-100%), gentamicin (57-74%), and trimethoprim/sulfamethoxazole (57-81%) was equally observed in all species. Vibrio mimicus expressed highest resistance against streptomycin and chloramphenicol (64%), while V. vulnificus (52%) and V. cholerae (57%) had the highest resistance against cephalothin. High resistance against ampicillin (57%) and amoxicillin (50%) was exhibited by V. cholerae and V. mimicus respectively. Indexes of multiple antibiotic resistances (MARI) among Vibrio species ranged between 0.11 and 0.72 with the highest MAR index of 0.72 observed in one isolate of V. vulnificus. This study reveals high prevalence of Vibrio species in the selected rivers as well as elevated resistance against some first-line antibiotics, which suggests possible inappropriate antimicrobial usage around study communities. We conclude that the freshwater resources investigated are unfit for domestic, industrial, and recreational uses without treatment prior to use and are potential reservoirs of antibiotic-resistant Vibrio species in this environment.

EUCAST rapid antimicrobial susceptibility testing (RAST): analytical performance and impact on patient management.

The emergence of antibiotic-resistant species calls for fast and reliable phenotypic susceptibility testing to adapt clinical management as fast as possible. We assessed the real-life performance of EUCAST rapid antimicrobial susceptibility testing (RAST) and analysed its impact on patient management. RAST was performed on clinical blood cultures containing Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa or Acinetobacter baumannii complex. Categorical agreement with VITEK2 was analysed. A pre-post quasi-experimental observational study was designed to compare antibiotic treatment in sepsis patients in the RAST patient group (n = 51) and a historical control cohort (n = 54). In total, 436 isolates, corresponding to 2314 disc diameters, were measured; 18.4% of these measurements were in the area of technical uncertainty. For the 81.6% categorical results, which could be compared, 94.7% were in agreement, whereas 5.3% of the results were not. In the RAST group, optimal therapy was initiated on the same day as blood culture positivity, while this was the case in the historical group after 24 h. In six cases, RAST allowed for rapid antibiotic escalation. The 30 day mortality rate was lower in the RAST group, although this was not statistically significant. RAST provides a reliable tool to improve clinical management of sepsis patients by providing rapid phenotypic susceptibility data. While not necessarily being an instrument for de-escalation, especially in areas of low prevalence, early detection allows for timely coverage of resistant isolates. Thus, RAST significantly adds to successful antibiotic stewardship programmes.

Global evolutionary epidemiology and resistome dynamics of Citrobacter species, Enterobacter hormaechei, Klebsiella variicola, and Proteeae clones.

Citrobacter spp., Enterobacter hormaechei subsp., Klebsiella variicola and Proteae tribe members are rarely isolated Enterobacterales increasingly implicated in nosocomial infections. Herein, we show that these species contain multiple genes encoding resistance to important antibiotics and are widely and globally distributed, being isolated from human, animal, plant, and environmental sources in 67 countries. Certain clones and clades of these species were internationally disseminated, serving as reservoirs and mediums for the global dissemination of antibiotic resistance genes. As they can easily transmit these genes to more pathogenic species, additional molecular surveillance studies should be undertaken to identify and contain these antibiotic-resistant species.

Infection control response to an outbreak of OXA-23 carbapenemase-producing carbapenem-resistant Acinetobacter baumannii in a skilled nursing facility in Utah

Antibiotic-resistant Acinetobacter species are a growing public health threat, yet are not nationally notifiable, and most states do not mandate reporting. Additionally, there are no standardized methods to detect Acinetobacter species colonization. An outbreak of carbapenem-resistant Acinetobacter baumannii (CRAB) was identified at a Utah ventilator unit in a skilled nursing facility. An investigation was conducted to identify transmission modes in order to control spread of CRAB. Culture-based methods were used to identify patient colonization and environmental contamination in the facility. Of the 47 patients screened, OXA-23-producing CRAB were detected in 10 patients (21%), with 7 patients (15%) having been transferred from out-of-state facilities. Of patients who screened positive, 60% did not exhibit any signs or symptoms of active infection by chart review. A total of 38 environmental samples were collected and CRAB was recovered from 37% of those samples. Whole genome sequencing analyses of patient and environmental isolates suggested repeated CRAB introduction into the facility and highlighted the role of shared equipment in transmission. The investigation demonstrated this ventilated skilled nursing facility was an important reservoir for CRAB in the community and highlights the need for improved surveillance, strengthened infection control and inter-facility communication within and across states.

Inappropriate empirical antibiotic therapy for bloodstream infections based on discordant in-vitro susceptibilities: a retrospective cohort analysis of prevalence, predictors, and mortality risk in US hospitals

The prevalence and effects of inappropriate empirical antibiotic therapy for bloodstream infections are unclear. We aimed to establish the population-level burden, predictors, and mortality risk of in-vitro susceptibility-discordant empirical antibiotic therapy among patients with bloodstream infections. Our retrospective cohort analysis of electronic health record data from 131 hospitals in the USA included patients with suspected-and subsequently confirmed-bloodstream infections who were treated empirically with systemic antibiotics between Jan 1, 2005, and Dec 31, 2014. We included all patients with monomicrobial bacteraemia caused by common bloodstream pathogens who received at least one systemic antibiotic either on the day blood cultures were drawn or the day after, and for whom susceptibility data were available. We calculated the prevalence of discordant empirical antibiotic therapy-which was defined as receiving antibiotics on the day blood culture samples were drawn to which the cultured isolate was not susceptible in vitro-overall and by hospital type by using regression tree analysis. We used generalised estimating equations to identify predictors of receiving discordant empirical antibiotic therapy, and used logistic regression to calculate adjusted odds ratios for the relationship between in-hospital mortality and discordant empirical antibiotic therapy. 21 608 patients with bloodstream infections received empirical antibiotic therapy on the day of first blood culture collection. Of these patients, 4165 (19%) received discordant empirical antibiotic therapy. Discordant empirical antibiotic therapy was independently associated with increased risk of mortality (adjusted odds ratio 1·46 [95% CI, 1·28-1·66]; p<0·0001), a relationship that was unaffected by the presence or absence of resistance or sepsis or septic shock. Infection with antibiotic-resistant species strongly predicted receiving discordant empirical therapy (adjusted odds ratio 9·09 [95% CI 7·68-10·76]; p<0·0001). Most incidences of discordant empirical antibiotic therapy and associated deaths occurred among patients with bloodstream infections caused by Staphylococcus aureus or Enterobacterales. Approximately one in five patients with bloodstream infections in US hospitals received discordant empirical antibiotic therapy, receipt of which was closely associated with infection with antibiotic-resistant pathogens. Receiving discordant empirical antibiotic therapy was associated with increased odds of mortality overall, even in patients without sepsis. Early identification of bloodstream pathogens and resistance will probably improve population-level outcomes. US National Institutes of Health, US Centers for Disease Control and Prevention, and US Agency for Healthcare Research and Quality.

The Faecal Microbiome of Building-Dwelling Insectivorous Bats (Myotis myotis and Rhinolophus hipposideros) also Contains Antibiotic-Resistant Bacterial Representatives.

The bacteriome of bat faeces and bat guano is still not well known, despite the increasing knowledge of it as a potential source of pathogenic and/or antibiotic-resistant species. In this study, the faecal microbiome composition of two building-dwelling insectivorous bat species (Myotis myotis and Rhinolophus hipposideros) was analysed using cultivation-based and non-cultivation-based approaches. The cultivation analyses indicate the dominance of Gram-positive bacteria, represented by the genera Enterococcus, Lactococcus and Lactobacillus. Non-cultivation analysis based on 16S rRNA DGGE assays provided a different pattern, with the genus Rahnella found to predominate in the faecal microbiome. The analyses showed bat species to be the most important factor influencing the structure of the guano-associated microbial population. The presence of several possible human pathogens (Hafnia alvei, Serratia fonticola, S. liquefaciens) and antibiotic-resistant bacteria (e.g. vancomycin resistant Staphylococcus nepalensis) was detected in faeces samples, indicating possible human health risks associated with bat guano. Although the bat-human transmission of infection caused by pathogenic bacteria has not been reliably confirmed to date, this possibility should not be underestimated. Given the very important ecosystem services of bats, particular those studied herein, it is time to think about appropriate management of bat populations inhabiting man-made buildings and potential conflicts with humans.

Ex vivo anti-microbial efficacy of various formaldehyde releasers against antibiotic resistant and antibiotic sensitive microorganisms involved in infectious keratitis

BackgroundCorneal infections with antibiotic-resistant microorganisms are an increasingly difficult management challenge and chemically or photochemically cross-linking the cornea for therapy presents a unique approach to managing such infections since both direct microbial pathogens killing and matrix stabilization can occur simultaneously. The present study was undertaken in order to compare the anti-microbial efficacy, in vitro, of 5 candidate cross-linking solutions against 5 different microbial pathogens with relevance to infectious keratitis.MethodsIn vitro bactericidal efficacy studies were carried out using 5 different FARs [diazolidinyl urea (DAU), 1,3-bis(hydroxymethyl)-5,5-dimethylimidazolidine-2,4-dione (DMDM), sodium hydroxymethylglycinate (SMG), 2-(hydroxymethyl)-2-nitro-1,3-propanediol (NT = nitrotriol), 2-nitro-1-propanol (NP)] against 5 different microbial pathogens including two antibiotic-resistant species [methicillin-sensitive Staphylococcus aureus (MSSA), methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), Pseudomonas aeruginosa (PA), and Candida albicans (CA)]. Standard in vitro antimicrobial testing methods were used.ResultsThe results for MSSA were similar to those for MRSA. DAU, DMDM, and SMG all showed effectiveness with greater effects generally observed with longer incubation times and higher concentrations. Against MRSA, 40 mM SMG at 120 min showed a > 95% kill rate, p < 0.02. Against VRE, 40 mM DAU for 120 min showed a > 94% kill rate, p < 0.001. All FARs showed bactericidal effect against Pseudomonas aeruginosa, making PA the most susceptible of the strains tested. Candida showed relative resistance to these compounds, requiring high concentrations (100 mM) to achieve kill rates greater than 50%.ConclusionOur results show that each FAR compound has different effects against different cultures. Our antimicrobial armamentarium could potentially be broadened by DAU, DMDM, SMG and other FARs for antibiotic-resistant keratitis. Further testing in live animal models are indicated.

A Systematic Review and Meta-analysis on the Epidemiology of Antibiotic-resistant Yersinia Species in Food and Clinical Specimens in Iran

Objective: The aim of the present study was to investigate the antimicrobial susceptibility profiles of Yersinia species, especially Y. enterocolitica from non-clinical and clinical isolates in Iran. Materials and Methods: We systematically searched PubMed, Scopus, Google Scholar, and the Scientific Information Database (SID) using "antibiotic resistance", "Yersinia", and "Iran" as major keywords until June 10, 2019. According to the predefined article selection criteria, published studies addressing the epidemiology of antibiotic-resistant Yersinia species in Iran were included in the meta-analysis. Data were extracted and exported to the Comprehensive Meta-Analysis Software to evaluate antibiotic resistance rates, heterogeneity of studies and publication bias. Results: Twelve studies reported antimicrobial susceptibility testing using disk diffusion method. The pooled prevalence of antibiotic-resistant Yersinia species in food and clinical specimens in Iran was as follows: 22.4% to amoxicillin, 41.9% to ampicillin, 6% to gentamicin, 17% to trimethoprim/ sulfamethoxazole, 19% to tetracycline, 10.3% to ciprofloxacin, 10.5% to streptomycin, 3.8% to chloramphenicol, 79.3% to cephalothin, 18.4% to nalidixic acid, 6.6% to cefotaxime, and 12.2% to trimethoprim. Conclusion: This study revealed a high prevalence of resistant Y. enterocolitica strains isolated from food and clinical specimens in Iran to β-lactams, while the resistance rates to aminoglycosides, fluoroquinolone and chloramphenicol were low. Our findings recommended the necessity of a continuous surveillance of the resistance patterns and prudent use of trimethoprim/ sulfamethoxazole, tetracycline, and nalidixic acid to prevent the development of antibioticresistant Y. enterocolitica strains in Iran.

Oral Antimicrobial Agents for Urinary Tract Infections Due to Enterobacteriales Species

Background Urinary tract infections (UTIs) due to Enterobacteriales continue to pose a challenge because of increasing resistance rate to antimicrobial agents. The aim of this study was to evaluate in vitro susceptibility of oral antimicrobial agents against urinary isolates of Enterobacteriales species in patients with suspected UTIs at Hamilton Health Sciences hospitals in 2016. Methods Positive urine cultures for Enterobacteriales species in all patients 18 years or older with diagnosis of UTIs from 2 acute care hospitals in 2016 were included. Susceptibility rates were calculated for first- and second-line oral antimicrobial agents commonly used to treat UTIs. Results A total of 2773 urinary isolates of Enterobacteriales species were included in the analysis. The rates of susceptibility to nitrofurantoin were 96.3% (1925/1999) and 46.9% (188/401), respectively, for Escherichia coli and Klebsiella pneumoniae. The rates of susceptibility to trimethoprim-sulfamethoxazole and ciprofloxacin were 73.9% (1478/1999) and 84% (337/401), and 72.3% (1446/1999) and 86.3% (346/401), respectively, for E. coli and K. pneumoniae. The rate of E. coli susceptibility to oral cephalosporins was approximately 83%. The proportions of Enterobacteriales isolates that produced extended-spectrum β-lactamases (ESBLs) for E. coli and K. pneumoniae were 11.6% (231/1999) and 11.2% (45/401), respectively. The rates of ESBLs E. coli susceptibility to nitrofurantoin, trimethoprim-sulfamethoxazole, and ciprofloxacin were 91.3% (211/231), 30.3% (70/231), and 16% (37/231), respectively. Conclusions Oral antimicrobial agents have a limited role as empiric treatment of UTIs due to antibiotic-resistant Enterobacteriales species, with the exception of nitrofurantoin for E. coli including ESBL-producing strains. Oral cephalosporins were the second most susceptible agents to E. coli.

Role of Prophylactic Antibiotic Administration in Growth of Methicillin Resistant Staphylococcus Aureus in Rhinoplasty

Background: Septoplasty and septorhinoplasty are common surgical procedures in modern surgical practice. Pre or postoperative antibiotic administration has raised concerns about the possible increase in the antibiotic-resistant species. The aim of this study was to evaluate the role of postoperative antibiotic prophylaxis in increasing Methicillin-Resistant Staphylococcus Aaureus species (MRSA) in patients, who underwent septoplasty or septorhinoplasty in Loghman Hakim Hospital in Tehran, Iran.Methods: A total of 102 patients, who were planned to undergo septoplasty or septorhinoplasty, participated in this double-blind randomized clinical trial. The patients were divided into the case (n=60, mean age of 28.2 years) and control (n=38, mean age of 28.9 years) groups. Overall, 98 patients participated in the study. The case group received a preoperative injection of cephalothin (1g) and postoperative oral cephalexin regimen (500mg 4 times a day for 7 days). The control group only received a preoperative injection of cephalothin (1g). Vestibular nasal swab cultures were obtained preoperatively and on postoperative day 7. The samples were, then, quickly transferred to the laboratory and cultured on proper media. The results indicated that five MRSA species in the case group and tow MRSA species in the control group were present, postoperatively.Results: The findings of this study suggest that oral antibiotic prophylaxis may lead to a statically non-significant increase in MRSA infection in patients, who require this treatment. Conclusion: Further knowledge of the endogenous nasal flora and the microbiology of common pathogens in patients undergoing septorhinoplasty will help reduce the incidence of infectious complications to a greater level.