Comparison of Antimicrobial Resistance in Escherichia coli Strains Isolated From Swine, Poultry, and Farm Workers in the Respective Livestock Farming Units in Greece

Human health is at risk because commensal intestinal bacteria in livestock have been developing increased antibiotic resistance, mainly due to antibiotics' extensive use in recent years. In this study, we compared the antibiotic resistance of E. coli strains isolated from fecal samples obtained from swine, poultry, and farm workers in the corresponding livestock farming units. The study aimed to investigate the correlation between the antibiotic resistance patterns of E. coli in livestock and in humans closely interacting with them. Antibiotic resistance is determined using the microdilution method, which measures the minimum inhibitory concentration (MIC) for seven commonly used antimicrobial agents. Most E. coli isolates displayed significant resistance to tetracycline and ampicillin. Resistance to sulfamethoxazole was observed, too, in swine and swine farmers. In contrast, high resistance rates to nalidixic acid were observed in E. coli strains isolated from poultry and poultry farmers, with percentages of 66.7% and 50%, respectively. Furthermore, 31.57% of the isolated strains from swine and swine farmers were resistant to at least one antibiotic. In comparison, 44.44% of the poultry strains and 33.33% of the poultry farmers' strains were resistant to at least two antibiotics. Additionally, a high prevalence of multidrug resistance was observed among the E. coli strains isolated from all four categories. The study's results provide evidence that the use of antibiotics and the increased resistance of intestinal bacteria affect the resistance of intestinal bacteria in people working on farms. These findings highlight the potential role of antibiotic use in animals as a contributing factor to the development of antibiotic resistance in both animals and humans. Additionally, it suggests that individuals working on farms may be at an increased risk of acquiring antibiotic-resistant strains of E. coli due to their proximity to and interaction with animals.

In Vitro Susceptibility of Clinical Isolates to Ceftriaxone Alone and Ceftriaxone in Combination With Sulbactam or Tazobactam: A Comparative Study of Broad-Spectrum β-Lactam Antibiotics in India

Background This study was designed to evaluate the current in vitro susceptibility of clinical isolates to broad-spectrum β-lactam antibiotics. Methodology Bacterial isolates, cultured from 180 non-repetitive clinical samples between April and November 2022 at three hospitals in India, were used to evaluate the minimum inhibitory concentration (MIC) of broad-spectrum β-lactam antibiotics using the Epsilometer test (E-test) method. Test antibiotics were ceftriaxone and ceftriaxone in combination with β-lactamase inhibitors (BLIs) sulbactam and tazobactam. Comparator antibiotics included amoxicillin + BLI clavulanic acid, piperacillin + tazobactam, cefotaxime, and cefepime. The MIC values obtained were used to assess the susceptibility of the isolates and to compute the efficacy ratios (ERs) of the antibiotics. Results Among the 180 clinical isolates, ~89% were gram-negative bacteria, the most prevalent ones being Escherichia coli and Klebsiella pneumoniae. Of the gram-negative isolates, ~37% were susceptible/intermediately susceptible to ceftriaxone, and ~29% were susceptible to ceftriaxone + BLIs. The test antibiotics had ER >10 against 85%-95% E. coli isolates, whereas comparator antibiotics had ER >10 against 31%-68% isolates. The differences between the test antibiotics and piperacillin + tazobactam or cefotaxime were statistically significant. Ceftriaxone, ceftriaxone + sulbactam, and ceftriaxone + tazobactam had ER >10 against 78%, 100%, and 90% of K. pneumoniae isolates, while the corresponding percentages for cefotaxime, piperacillin + tazobactam, and cefepime were 100%, 64%, and 80%, respectively. The difference between ceftriaxone + BLIs and piperacillin + tazobactam was statistically significant. Ceftriaxone + BLIs had ER >10 against all E. coli isolates producing extended-spectrum β-lactamases (ESBLs); the percentage of isolates was significantly higher than that for piperacillin + tazobactam. Ceftriaxone + tazobactam had ER >10 against all ESBL-producing K. pneumoniae isolates; ceftriaxone and ceftriaxone + sulbactam had ER ranging 6-10. Conclusions Ceftriaxone and ceftriaxone in combination with sulbactam and tazobactam are promising antibiotics to explore against prevalent infectious microorganisms such as E. coli and K. pneumoniae. Ceftriaxone + tazobactam also holds promise against ESBL-producing variants.

Antimicrobial Efficacy of Essential Oils and Their Combination Against Microorganisms Associated With Postradiation Therapy in Patients With Head and Neck Cancer: An In Vitro Study

Background Head and neck cancer ranks as the sixth most common cancer globally. Reduced saliva production brought on by postradiation therapy upsets the delicate balance between bacterial load and a weakened immune system. Oral hygiene is commonly neglected in patients who have undergone radiotherapy and they often develop dry mouth, mucositis due to radiation therapy, etc., as side effects. Despite being a part of the current standard, chlorhexidine carries numerous disadvantages such as taste alteration, teeth staining, and dry mouth. An extensive review of the literature demonstrates the antibacterial properties of essential oils (EOs) derived from plant materials, which may be able to prevent the development of such opportunistic microorganisms in the oral cavity. Methodology The cinnamon bark EO and Cajeput EO were procured and checked for their solubility. The final ratio at which the oils were found to be soluble was the 1:1 (w/v) ratio. The minimum inhibitory concentration (MIC) of cinnamon bark oil (Cinnamomum verum) and Cajeput oil (Melaleuca leucadendron) against Staphylococcus aureus, Enterococcus faecalis, and Candida albicans was determined by serial dilution method using Resazurin dye, and the minimum bactericidal concentration (MBC) was done by a spread plating method. The polyherbal mouthwash was subjected to cytotoxicity assay against human gingival fibroblasts. All the experiments were performed in triplicates. Results The overall results showed that cinnamon bark EO had the strongest efficacy against S. aureus (0.33 ± 0.14 mg/mL) and E. faecalis (0.41 ± 0.14 mg/mL), but not against C. albicans (2.85 ± 2.11 mg/mL). Cajeput EO showed the least efficacy against all the groups; whereas the combination of EOs proved to be the most efficacious and showed good antimicrobial activity against these most commonly encountered microorganisms in head and neck cancer postradiotherapy. Conclusions Cinnamon and Cajeput EOs in combination proved to be effective in this in vitro study against the most common microorganisms encountered in patients with head and neck cancer postradiotherapy and are comparable to 0.2% chlorhexidine.

Characteristics of Asymptomatic Bacteriuria in Diabetes Mellitus Patients: A Retrospective Observational Study

Background and objective

The term asymptomatic bacteriuria (ASB) refers to the isolation of bacteria in a urine specimen of individuals without any symptoms of urinary tract infection (UTI). Diabetes mellitus (DM) is a disease involving multiple organ systems, characterized by its chronicity and hence endless complications including ASB. This study aimed to determine the characteristics of ASB and antibiotic susceptibility patterns among patients with diabetes.

Materials and methods

This was a retrospective observational study conducted in a tertiary care hospital. The study included patients with a diagnosis of diabetes with no signs and symptoms of UTI but who still showed the growth of an organism in urine culture. A total of 222 urine cultures were analyzed retrospectively, ensuring that they met the inclusion criteria through non-probability consecutive sampling.

Results

The mean age of the study participants was 62.89 ± 13.77 years; 76% of them were females, and 61% had a family history of diabetes. The most frequent organisms isolated were Escherichia coli (E. coli), Enterococcus, Klebsiella pneumonia, Pseudomonas aeruginosa, and Enterobacter species. A total of 20 subjects had dual bacterial growth in their cultures, with Enterococcus species (n=17) being the most common organism. Gender, family history of diabetes, levels of hemoglobin A1c (HbA1c), and advanced age were all found significantly associated with ASB.

Conclusion

Our study is the first of its kind to analyze and examine the risk factors associated with ASB in DM patients, and to identify the pathogens involved, along with assessing their antibiotic resistance profiles.

Minimum Inhibitory Concentrations of Vancomycin and Daptomycin Against Methicillin-resistant Staphylococcus Aureus Isolated from Various Clinical Specimens: A Study from South India

Background Staphylococci are Gram-positive cocci arranged in clusters. They are colonized in humans and animals. Also, Staphylococcus aureus (S. aureus) is frequently associated with various superficial to deep-seated infections in humans. Due to the potential for easy transmission, Staphylococci are associated with both hospital-acquired and community-associated infections. Strains of S. aureus resistant to methicillin (MRSA) pose treatment challenges. In such cases, vancomycin is the treatment of choice. Due to the indiscriminate use of vancomycin, recently, we are seeing the emergence of vancomycin-intermediate sensitive S. aureus (VISA) and vancomycin-resistant S. aureus (VRSA). The present study aims to evaluate the minimum inhibitory concentrations (MICs) of vancomycin and daptomycin among MRSA strains isolated from human clinical specimens Methods The study included 115 MRSA isolates collected over 26 months from July 2010 to September 2012. The strains were isolated from pus, urine, wound swabs, catheters, blood, and sputum. The bacteria were acquired from different inpatient and outpatient departments of Prathima Institute of Medical Sciences, Karimnagar, Telangana, India. Kirby-Bauer disk diffusion method using cefoxitin was used to confirm the MRSA isolates. The agar dilution and the Epsilometer method (E-test) were used to test the MICs of MRSA isolates against vancomycin and daptomycin, respectively, by the standard procedures recommended by the clinical laboratory standards institute (CLSI). Results Of the 115 S. aureus isolates, seven (6.08%) strains were resistant to vancomycin (VRSA) and 53 (46.08%) were found to be VISA using the new CLSI breakpoints. The MIC of the daptomycin was found to be ≤1 µg/ml for all the MRSA isolates. Conclusion The study results depicted an increasing trend in the vancomycin MICs among the MRSA isolates. Several tested strains show MICs in the intermediate sensitive range (VISA). The daptomycin was effective against all the MRSA isolates.

Can we prevent antimicrobial resistance by using antimicrobials better?

Since their development over 60 years ago, antimicrobials have become an integral part of healthcare practice worldwide. Recently, this has been put in jeopardy by the emergence of widespread antimicrobial resistance, which is one of the major problems facing modern medicine. In the past, the development of new antimicrobials kept us one step ahead of the problem of resistance, but only three new classes of antimicrobials have reached the market in the last thirty years. A time is therefore approaching when we may not have effective treatment against bacterial infections, particularly for those that are caused by Gram-negative organisms. An important strategy to reduce the development of antimicrobial resistance is to use antimicrobials more appropriately, in ways that will prevent resistance. This involves a consideration of the pharmacokinetic and pharmacodynamics properties of antimicrobials, the possible use of combinations, and more appropriate choice of antimicrobials, which may include rapid diagnostic testing and antimicrobial cycling. Examples given in this review include Mycobacterium tuberculosis, Gram-negative and Gram-positive organisms. We shall summarise the current evidence for these strategies and outline areas for future development.

Antimicrobial activity of PVP from an Antarctic bacterium, Janthinobacterium sp. Ant5-2, on multi-drug and methicillin resistant Staphylococcus aureus

Multiple drug resistant (MDR) and methicillin-resistant Staphylococcus aureus (MRSA) have become increasingly prevalent as a community acquired infection. As a result limited treatment options are available with conventional synthetic antibiotics. Bioprospecting natural products with potent antimicrobial activity show promise for developing new drugs against this pathogen. In this study, we have investigated the antimicrobial activity of a purple violet pigment (PVP) from an Antarctic bacterium, Janthinobacterium sp. Ant5-2 on 15 clinical MDR and MRSA strains. The colorimetric resazurin assay was employed to determine the minimum inhibitory concentration (MIC₉₀) of PVP against MDR and MRSA. The MIC₉₀ ranged between 1.57 µg/mL and 3.13 µg/mL, which are significantly lower than many antimicrobials tested from natural sources against this pathogen. The spectrophotometrically determined growth analysis and total microscopic counts using Live/dead® BacLight™ fluorescent stain exhibited a steady decrease in viability of both MDR and MRSA cultures following treatment with PVP at the MIC levels. In silico predictive molecular docking study revealed that PVP could be a DNA-targeting minor groove binding antimicrobial compound. The continued development of novel antimicrobials derived from natural sources with the combination of a suite of conventional antibiotics could stem the rising pandemic of MDR and MRSA along with other deadly microbial pathogens.

Minimum inhibitory concentrations of medicinal plants used in Northern Peru as antibacterial remedies

AIM

The plant species reported here are traditionally used in Northern Peru to treat bacterial infections, often addressed by the local healers as "inflammation". The aim of this study was to evaluate the minimum inhibitory concentration (MIC) of their antibacterial properties against gram-positive and gram-negative bacteria.

MATERIALS AND METHODS

The antimicrobial activity of ethanolic and water extracts of 141 plant species was determined using a deep-well broth microdilution method on commercially available bacterial strains.

RESULTS

The ethanolic extracts of 51 species inhibited Escherichia coli, and 114 ethanolic extracts inhibited Staphylococcus aureus. In contrast, only 30 aqueous extracts showed activity against Escherichia coli and 38 extracts against Staphylococcus aureus. The MIC concentrations were mostly very high and ranged from 0.008 to 256 mg/ml, with only 36 species showing inhibitory concentrations of <4 mg/ml. The ethanolic extracts exhibited stronger activity and a much broader spectrum of action than the aqueous extracts. Hypericum laricifolium, Hura crepitans, Caesalpinia paipai, Cassia fistula, Hyptis sidifolia, Salvia sp., Banisteriopsis caapi, Miconia salicifolia and Polygonum hydropiperoides showed the lowest MIC values and would be interesting candidates for future research.

CONCLUSIONS

The presence of antibacterial activity could be confirmed in most species used in traditional medicine in Peru which were assayed in this study. However, the MIC for the species employed showed a very large range, and were mostly very high. Nevertheless, traditional knowledge might provide some leads to elucidate potential candidates for future development of new antibiotic agents.