Multidrug-Resistant Gram-Negative Bacterial Infections in the Hospital Setting: Overview, Implications for Clinical Practice, and Emerging Treatment Options

Pharmacokinetic/pharmacodynamic analysis of high-dose tigecycline, by Monte Carlo simulation, in plasma and sputum of patients with hospital-acquired pneumonia

WHAT IS KNOWN AND OBJECTIVE

To Investigate the pharmacokinetic/pharmacodynamic (PK/PD) parameters of high-dose tigecycline in plasma and sputum of patients with hospital-acquired pneumonia (HAP), and provide a therapeutic regimen of multidrug-resistant bacteria (MDRB) infections.

METHODS

Blood/sputum samples were collected at intervals after tigecycline had reached a steady-state. Tigecycline concentrations in specimens were determined by high-performance liquid chromatography (HLPC), PK parameters were evaluated by WinNonlin software using a non-compartment model. The probability of target attainments (PTAs) at different minimal inhibitory concentrations (MICs) were calculated for achieving the PK/PD index with Crystal Ball software by 10,000-patient Monte Carlo Simulation.

RESULTS

In plasma, the maximum concentration (C_max ) and area under the concentration-time curve from 0 to 12 h (AUC_0-12h ) were 2.21 ± 0.17 mg/L and 15.29 ± 1.13 h mg/L, respectively. In sputum, they were 2.48 ± 0.21 mg/L and 19.46 ± 1.82 h mg/L, respectively. The mean lung penetration rate was 127.27%. At the MIC ≤4 mg/L, the PTAs in plasma and sputum were 100.00%. When the MIC increased to 8 mg/L, the PTAs in plasma and sputum mostly were < 90.00% according to two criteria.

WHAT IS NEW AND CONCLUSION

In this study, we explored PK/PD of high-dose tigecycline in plasma and sputum. From a PK/PD perspective, high-dose tigecycline had greater therapeutic outcomes in HAP treatment caused by MDRB. Antimicrobial-drug concentrations should be determined to optimize their clinical use.

Antibiotic Resistance Profile of Listeria monocytogenes Recovered from Ready-to-Eat Foods Surveyed in South Africa

ABSTRACT

In recent decades, there has been an increase in the reports of antimicrobial resistance of Listeria monocytogenes, which constitutes a serious threat to the therapeutic management of listeriosis infection. Our study profiled the antibiogram fingerprint of L. monocytogenes isolates (n = 194) recovered from common South African ready-to-eat foods. L. monocytogenes isolates recovered from foods were tested against a panel of 22 antibiotics using the disk diffusion method. Antimicrobial resistance (>50%) against ceftriaxone (53.1%), trimethoprim (56.2%), streptomycin, cefotetan (59.3%), sulfamethoxazole (61.9%), vancomycin, and oxytetracyclines (62.9%) were observed. Thirty of the isolates (15.5%) were resistant against only one or two antibiotics, whereas 162 (83.5%) exhibited phenotypic multiple antibiotic resistance. Only two (1%) of the isolates did not exhibit phenotypic resistance against any antibiotics screened. Multiple antibiotic phenotypes revealed high resistance patterns, and the multiple antibiotic indices were greater than the Krumperman permissible (>0.2) benchmark. Of the 44 genes screened, 22 antimicrobial resistance genes were detected among ready-to-eat food isolates, including resistance determinants that encode sulfonamides (n = 125, 64.4%), β-lactams (n = 86, 44.3%), phenicols (n = 25, 12.9), and aminoglycosides (n = 93, 47.9%) resistance. We conclude that the presence of resistant L. monocytogenes isolates harboring corresponding antimicrobial resistance genes in foods could compromise safety and constitute severe health consequences if consumed.

HIGHLIGHTS

Impact of multi-drug resistance on clinical outcomes of dogs with corneal ulcers infected with Staphylococcus pseudintermedius

Objective

Compare characteristics and clinical outcomes of dogs with infectious keratitis from Staphylococcus pseudintermedius considered to be multidrug-resistant (MDR) or not.

Procedures

Staphylococcus pseudintermedius isolated as the primary pathogen from canine patients with ulcerative keratitis were considered MDR if resistant to at least one agent in three or more classes of antibiotics. Medical records were reviewed for history, patients' characteristics, clinical appearance, therapeutic interventions, and clinical outcomes.

Results

Twenty-eight dogs (28 eyes) were included. Compared to non-MDR cases, MDR diagnosis was significantly more common in dogs with recent (≤30 days) anesthesia (7/15 vs. 1/13, P = 0.038) and more common in non-brachycephalic dogs (8/15 vs. 2/13, P = 0.055). Clinical appearance (ulcer size/depth, anterior chamber reaction, etc.) did not differ significantly between groups (P ≥ 0.055). Median (range) time to re-epithelialization was longer in MDR vs. non-MDR eyes [29 (10-47) vs. 22 (7-42) days] but the difference was not significant (P = 0.301). Follow-up time was significantly longer in dogs with MDR keratitis [47 (29-590) vs. 29 (13-148) days, P = 0.009]. No other significant differences were noted between MDR and non-MDR eyes in regard to time for ulcer stabilization [4 (1-17) days vs. 4 (1-12), P = 0.699], number of eyes requiring surgical stabilization (7/15 vs. 7/13, P = 0.246) or enucleation (1/15 vs. 2/13, P = 1.000), success in maintaining globe (14/15 vs. 11/13, P = 0.583) or success in maintaining vision (12/15 vs. 10/13, P = 1.000).

Conclusions

MDR infections may prolong corneal healing time but did not appear to affect overall clinical outcomes in dogs with bacterial keratitis. Further research is warranted in a larger canine population and other bacterial species.

Characteristics of bloodstream infection and initial antibiotic use in critically ill burn patients and their impact on patient prognosis

To investigate the bacterial epidemiology of blood cultures taken during the treatment of critically ill burn patients, the use of antibiotics at admission and before the observation of positive blood cultures, and their effect on prognosis. A retrospective study method was used. From January 1, 2010, to December 31, 2019, burn patients who met the inclusion criteria and were treated at the Burn Department, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, were enrolled in the study. Data were collected from the patients' electronic medical records. General patient information, including length of hospital stay, length of intensive care unit (ICU) stay, in-hospital mortality, the bacteria epidemiological characteristics of blood cultures, and the use of antibiotics within 24 h after admission and before a positive blood culture was observed, was collected. Independent sample t tests and χ² tests were used to compare the effects of a positive blood culture and the use of appropriate antibiotics within 24 h after admission and before the observation of a positive blood culture on prognosis. (1) The three most frequently detected bacteria in the blood cultures were Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii, and the amount of K. pneumoniae detected increased gradually. (2) Compared with the group of patients who were negative for bloodstream infection , the positive bloodstream infection group had a larger total body burn surface area (TBSA) (t = - 5.097, P = 0.000) and third-degree burn area (t = - 5.133, P = 0.000), a significantly longer length of hospital stay (t = 3.003, P = 0.003) and the length of ICU stay (t = 4.258, P = 0.000), and a significantly higher rate of in-hospital mortality (χ² = 8.485, P = 0.004). When K. pneumoniae was detected, the length of hospital stay (t = 2.148, P = 0.035) and the length of ICU stay (t = 2.880, P = 0.005) were significantly prolonged. (3) The two antibiotics that were most frequently used in patients with acute burns within 24 h after admission were lincomycin (90 cases, 29.32%) and carbapenems (79 cases, 25.73%). Comparing the clinical characteristics of the lincomycin group and the carbapenem group, the TBSA (t = - 3.34, P = 0.001) and the third-degree burn area (t = - 6.08, P = 0.000) of the patients in the carbapenem group were larger, and the length of hospital stay (t = - 2.136, P = 0.035) and length of ICU stay (t = - 5.18, P = 0.000) were longer, but the difference in in-hospital mortality was not statistically significant (χ² = 1.983, P = 0.159). (4) Comparing the group with appropriate initial antibiotic use within 24 h of admission to the inappropriate use group, the TBSA (t = - 0.605, P = 0.547), the third-degree burn area (t = 0.348, P = 0.729), the length of hospital stay (t = - 0.767, P = 0.445), the length of ICU stay (t = - 0.220, P = 0.827) and in-hospital mortality (χ² = 1.271, P = 0.260) were not significantly different. (5) Comparing the group with appropriate antibiotic use before a positive blood culture was observed to the group with inappropriate antibiotic use, the TBSA (t = - 0.418, P = 0.677), the third-degree burn area (t = 0.266, P = 0.791), the length of hospital stay, the length of ICU stay (t = 0.995, P = 0.322) and in-hospital mortality (χ² = 1.274, P = 0.259) were not significantly different. We found that patients with a positive blood culture had a larger burn area and a worse prognosis; that the greater the amount of K. pneumoniae in the bloodstream of burn patients was, the longer the hospital and ICU stays were; that whether appropriate antibiotics were administered to acute critical burn patients 24 h after admission had no effect on the prognosis; and that whether appropriate antibiotics were administered before a positive blood culture was observed had no effect on prognosis.

Essential Oil Stabilisation by Response Surface Methodology (RSM): Nanoemulsion Formulation, Physicochemical, Microbiological, and Sensory Investigations

This manuscript aimed to optimise the encapsulation of Thymus capitatus essential oil into nanoemulsion. Response Surface Methodology results were best fitted into polynomial models with regression coefficient values of more than 0.95. The optimal nanoemulsion showed nanometer-sized droplets (380 nm), a polydispersity index less than 0.5, and a suitable Zeta potential (−10.3 mV). Stability results showed that nanoemulsions stored at 4 °C were stable with the lowest d3,2, PolyDispersity Index (PDI), and pH (day 11). Significant ameliorations in the capacity to neutralise DPPH radical after the encapsulation of the antimicrobial efficacy of thyme essential oil were recorded. S. typhimurium growth inhibition generated by nanoencapsulated thyme essential oil was 17 times higher than by bulk essential oil. The sensory analysis highlighted that the encapsulation of thyme essential oil improved enriched milk’s sensory appreciation. Indeed, 20% of the total population attributed a score of 4 and 5 on the scale used for milk enriched with nanoemulsion. In comparison, only 11% attributed the same score to milk enriched with bulk essential oil. The novel nanometric delivery system presents significant interest for agroalimentary industries.

Occurrence of Healthcare-Associated Infections (HAIs) by Escherichia coli and Klebsiella spp. Producing Extended-Spectrum β-lactamases (ESBL) and/or Carbapenemases in Portuguese Long-Term Care Facilities

Extended-spectrum-β-lactamase (ESBL)- and carbapenemase-producing bacteria are widespread in hospitals, but the extent of this problem in long-term care facilities (LTCFs) is poorly understood. We aimed to elucidate, in the Portuguese regional clinical context, the relevance of LTCFs as a reservoir of Escherichia coli and Klebsiella spp. producing ESBL- and/or carbapenemases (Ec/Kp-ESBL/CARB). Fourteen LTCFs from Portugal, corresponding to units of convalescence (UC/n = 3), medium-term internment and rehabilitation (UMDR/ n = 5), or long-term internment and maintenance (ULDM/n = 6), were analyzed (2016–2019). All patients with Ec/Kp-ESBL/CARB infections acquired during LTCF stay were included, and detailed information was collected. Prevalence of patients with healthcare-associated infections (HAIs) by Ec/Kp-ESBL/CARB did not vary significantly over time (1.48% in 2016–2017, 1.89% in 2017–2018, and 1.90% in 2018–2019), but a statistically significant association with the LTCF typology (ULDM, UMDR) was observed. HAIs were caused by K. pneumoniae (n = 51/54.3%), E. coli (n = 41/43.6%), or both (n = 2/2.1%), producing ESBL (96%) or carbapenemases (4%). Prior colonization (n = 14/16%) corresponded to seven Kp-CARB and seven Ec/Kp-ESBL. The worrying prevalence of patients acquiring HAIs by Ec/Kp-ESBL/CARB, associated with the estimated rates of those already colonized at admission, highlights a relevant role for LTCFs as a reservoir of Ec/Kp-ESBL/CARB. Epidemiological surveillance should be extended to the national level, and colonization screening at LTCF admission implemented systematically.

Large-Scale Studies on Antimicrobial Resistance and Molecular Characterization of Escherichia coli from Food Animals in Developed Areas of Eastern China

Widely distributed multidrug-resistant (MDR) bacteria threaten animals and human health. Nevertheless, few antimicrobial resistance (AMR) surveys of large-scale animal-derived bacteria have been explored. Here, 1,468 (97.54%) Escherichia coli strains were isolated from 1,505 pig (1,060) and chicken (445) anal swab samples from 11 cities in Zhejiang Province, China, in 2020. These isolates had a high resistance to tetracycline (92.92%), sulfisoxazole (93.05%), florfenicol (83.11%), and ampicillin (78.27%). More than 88.68% of the strains were MDR bacteria. A low AMR ratio to the "last-resort" antimicrobials tigecycline (0.75%), colistin (1.36%), and meropenem (0.75%) were found. The AMR of E. coli from pigs was higher than that of chickens. Eighteen strains among 31 MDR strains that were resistant to "last-resort" antimicrobials could transfer the AMR genes (mcr-1, tet(X), and blaNDM) to the recipient strain J53, which confer colistin, tigecycline, and carbapenem resistance, respectively. The homology among mcr-1-carrying isolates was relatively high, and the sequence types were mainly ST5529, ST101, and ST354, while the homology of isolates harboring tet(X4) and blaNDM-5 genes were different. The mcr-1, blaNDM-5, and tet(X4) genes in strains LS45, JH51, and TZ118 were identified on the Incl2, IncHI2, and IncX1 plasmids, respectively. Moreover, tet(A), sul2, floR, and blaTEM-1B were the most common ARGs in 31 strains. Additionally, the heavy metals copper and zinc had a significant correlation with amoxicillin/clavulanate and tetracycline resistance. Controlling the movement of animals between cities and reducing the use of antimicrobials are effective methods to reduce the threat of AMR bacteria. IMPORTANCE Pigs and chickens are the most common food animals that are the important vectors for spreading antimicrobial-resistant pathogens among animals and humans. Limited systematic AMR monitoring of these food animal origin bacteria had been reported, especially in developed areas of China. Our study provides a comprehensive and systematic study of AMR in Escherichia coli from eastern China. The AMR of E. coli strains among the animals or cities has statistically significant differences. Moreover, the mcr-1, tet(X4), and blaNDM-5 genes, considered resistant to the last line of AMR, were identified in part of farms. The transferability and the prevalence of these AMR strains were intensively studied. Our monitoring is comparable to human clinical research and has an essential reference for public health safety. These findings will provide early warning for AMR strains and guide the clinical use of antibiotics to control the spread of antibiotic resistance.

Early and Appropriate Use of Ceftazidime-Avibactam in the Management of Multidrug-Resistant Gram-Negative Bacterial Infections in the Indian Scenario

The increasing prevalence of antibiotic-resistant pathogens exerts a substantial burden on the healthcare infrastructure worldwide. The World Health Organization (WHO) has declared that multidrug-resistant (MDR) Gram-negative pathogens, especially, carbapenem-resistant Enterobacterales (CRE), Acinetobacter baumannii, and Pseudomonas aeruginosa as the topmost priority while developing newer antimicrobials. The increasing prevalence of infectious diseases caused by MDR Gram-negative bacteria also poses a challenge when choosing the empiric antimicrobial therapy for seriously ill hospitalized patients. The infections caused by MDR Gram-negative organisms ultimately result in increased mortality, morbidity, prolonged hospital stay, and increased cost of management. To tackle these challenges, newer antimicrobials like ceftazidime-avibactam were explored. The article also discusses the in vitro activity and therapeutic efficacy of ceftazidime-avibactam along with its pharmacokinetic properties and the role it will play in the management of MDR Gram-negative organisms in the Indian setting. Several studies have highlighted the role of early and appropriate antibiotic use in the reduction of mortality in patients with Gram-negative infections. Timely initiation of appropriate antibiotic therapy for serious infections leads to favorable clinical outcomes. Early and appropriate use of ceftazidime-avibactam while treating MDR Gram-negative infections has been associated with improved clinical outcomes. The aim of this review is to highlight the efficacy of ceftazidime-avibactam in the treatment of MDR Gram-negative infections. We have also summarized the information on outcomes achieved by early and appropriate use of ceftazidime-avibactam.

Antimicrobial effects of inhaled sphingosine against Pseudomonas aeruginosa in isolated ventilated and perfused pig lungs

Background

Ex-vivo lung perfusion (EVLP) is a save way to verify performance of donor lungs prior to implantation. A major problem of lung transplantation is a donor-to-recipient-transmission of bacterial cultures. Thus, a broadspectrum anti-infective treatment with sphingosine in EVLP might be a novel way to prevent such infections. Sphingosine inhalation might provide a reliable anti-infective treatment option in EVLP. Here, antimicrobial potency of inhalative sphingosine in an infection EVLP model was tested.

Methods

A 3-hour EVLP run using pig lungs was performed. Bacterial infection was initiated 1-hour before sphingosine inhalation. Biopsies were obtained 60 and 120 min after infection with Pseudomonas aeruginosa. Aliquots of broncho-alveolar lavage (BAL) before and after inhalation of sphingosine were plated and counted, tissue samples were fixed in paraformaldehyde, embedded in paraffin and sectioned. Immunostainings were performed.

Results

Sphingosine inhalation in the setting of EVLP rapidly resulted in a 6-fold decrease of P. aeruginosa CFU in the lung (p = 0.016). We did not observe any negative side effects of sphingosine.

Conclusion

Inhalation of sphingosine induced a significant decrease of Pseudomonas aeruginosa at the epithelial layer of tracheal and bronchial cells. The inhalation has no local side effects in ex-vivo perfused and ventilated pig lungs.

Cefiderocol for Carbapenem-Resistant Bacteria: Handle with Care! A Review of the Real-World Evidence

(1) Background: healthcare-associated infections are one of the most frequent adverse events in healthcare delivery worldwide. Several antibiotic resistance mechanisms have been developed, including those to carbapenemase. Cefiderocol (CFD) is a novel siderophore cephalosporin designed to treat carbapenem-resistant bacteria. (2) Methods: we performed a systematic review of all cases reported in the literature to outline the existing evidence. We evaluated real-world evidence studies of CFD in the treatment of carbapenem-resistant (CR) bacteria. (3) Results: a total of 19 publications treating cases of infection by CR bacteria were included. The three most frequent CR pathogens were Acinetobacter baumannii, Pseudomonas aeruginosa, and Klebsiella pneumoniae. A regimen of 2 g every 8 h was most frequently adopted for CFD with a mean treatment duration of 25.6 days. CFD was generally well tolerated, with fewer side effects. The success rate of CFD therapy was satisfactory and almost 70% of patients showed clinical recovery; of these, nearly half showed negative blood cultures and infection-free status. (4) Conclusions: This review indicates that CFD is active against important GN organisms including Enterobacteriaceae, P. aeruginosa, and A. baumannii. CFD seems to have a safe profile.

Assessment of multidrug-resistant Listeria monocytogenes in milk and milk product and One Health perspective

The occurrence and the antibiogram signatures of Listeria monocytogenes (Lm) recovered from 65 milk samples and its products within the Eastern Cape province were examined. The EN ISO 11290:2017 procedures Parts 1 and 2 described by the International Organization for Standardization for the enumeration and isolation of Lm was adopted for the study. Lm was detected in 18.46% of all the samples examined, and the strains recovered from the samples belong to serotypes 4b and 1/2b. The virulence determinants including prfA, plcA, plcB, inlA, inlC, hly, mpl, actA, inlJ and inlB were detected in all the isolates. About 95.24% of the studied Lm isolates demonstrated potential capacity for biofilm formation. The antibiogram profile revealed high resistance against sulfamethoxazole (71.43%), trimethoprim (52.86%); erythromycin, cefotetan and oxytetracycline (42.86% respectively). About 85.71% exhibited multiple antibiotic resistance phenotypes against the test antibiotics. The resistance determinants encoding resistance against the β-lactamase antibiotics [such as the bla_TEM, bla_SHV, bla_TEMvariants (TEM-1 and TEM-2) and the bla_Z], the tetracycline resistance genes (including tetA, tetD, tetG and tetM and tetK) were detected among resistant isolates. In addition, the aminoglycoside resistance gene aph (3)-IIa (aphA2)^a was detected only in one isolate. Finally, the sulfonamide resistance genes including the sul2 and the sul1 genes were the most frequently observed among Lm isolates. Generally, 71.43% of all Lm isolates recovered from the samples investigated harboured one or more resistance genes encoding resistance against various antibiotics. The antibiogram signatures of Lm isolates observed in this study is an indication that empirical treatment of listeriosis may be challenging in the future as the pathogen may obliterate the success of antibiotics. We, therefore, advocate for the recognition of the One Health approach to ensuring food safety and curbing the spread of antimicrobial resistance in food.

Empiric Usage of “Anti-Pseudomonal” Agents for Hospital-Acquired Urinary Tract Infections

Hospital-acquired urinary tract infection (HAUTI) is one of the most common hospital-acquired infections, and over 80% of HAUTI are catheter-associated (CAUTI). Pseudomonas aeruginosa, as well as other non-glucose fermenting Gram negative organisms (NGFGN, e.g., Acinetobacter baumannii), are frequently covered empirically with “anti-Pseudomonals” being administered for every HAUTI (and CAUTI). However, this common practice was never trialed in controlled settings in order to quantify its efficacy and its potential impacts on hospitalization outcomes. There were 413 patients with HAUTI that were included in this retrospective cohort study (2017–2018), 239 (57.9%) had CAUTI. There were 75 NGFGN infections (18.2% of HAUTI, 22.3% of CAUTI). P. aeruginosa was the most common NGFGN (82%). Despite multiple associations per univariable analysis, recent (3 months) exposure to antibiotics was the only independent predictor for NGFGN HAUTI (OR = 2.4, CI-95% = 1.2–4.8). Patients who received empiric anti-Pseudomonals suffered from worse outcomes, but in multivariable models (one for each outcome), none were independently associated with the empiric administration of anti-Pseudomonals. To conclude, approximately one of every five HAUTI (and CAUTI) are due to NGFGN, which justifies the practice of empiric anti-Pseudomonals for patients with HAUTI (and CAUTI), particularly patients who recently received antibiotics. The practice is not associated with independent deleterious impacts on outcomes.

Risk of polymyxin B-induced acute kidney injury with a non adjusted dose versus adjusted dose based on renal function

Aim: To observe the difference in the risk of polymyxin B (PMB)-induced acute kidney injury (AKI) with or without dose adjustment based on the patients renal function. Materials & methods: This retrospective cohort analysis was carried out in 115 patients treated with PMB from November 2018 to October 2019. Results: No significant difference in the incidence of AKI as well as secondary outcomes was observed between these two groups (47.5 vs 37.14%; p = 0.304). Conclusion: Dosing adjustment based on renal function does not significantly lower the risk of PMB-induced AKI. A non adjusted dosing strategy for PMB is recommended in patients exhibiting various levels of renal impairment.

Multi-drug resistant gram-negative bacterial pneumonia: etiology, risk factors, and drug resistance patterns

Bacterial pneumonia is one of the most serious public health issues owing to its medical and economic costs, which result in increased morbidity and mortality in people of all ages around the world. Furthermore, antimicrobial resistance has risen over time, and the advent of multi-drug resistance in GNB complicates therapy and has a detrimental impact on patient outcomes. The current review aimed to summarize bacterial pneumonia with an emphasis on gram-negative etiology, pathogenesis, risk factors, resistance mechanisms, treatment updates, and vaccine concerns to tackle the problem before it causes a serious consequence. In conclusion, the global prevalence of GNB in CAP was reported 49.7% to 83.1%, whereas in VAP patients ranged between 76.13% to 95.3%. The most commonly reported MDR-GNB causes of pneumonia were A. baumannii, K. pneumoniae, and P. aeruginosa, with A. baumannii isolated particularly in VAP patients and the elderly. In most studies, ampicillin, tetracyclines, amoxicillin-clavulanic acid, cephalosporins, and carbapenems were shown to be highly resistant. Prior MDR-GNB infection, older age, previous use of broad-spectrum antibiotics, high frequency of local antibiotic resistance, prolonged hospital stays, ICU admission, mechanical ventilation, and immunosuppression are associated with the MDR-GNB colonization. S. maltophilia was reported as a severe cause of HAP/VAP in patients with mechanically ventilated and having hematologic malignancy due to its ability of biofilm formation, site adhesion in respiratory devices, and its intrinsic and acquired drug resistance mechanisms. Effective combination therapies targeting PDR strains and drug-resistant genes, antibiofilm agents, gene-based vaccinations, and pathogen-specific lymphocytes should be developed in the future.

Facile Green Synthesis of Silver Nanoparticles Using Aqueous Leaf Extract of Origanum majorana with Potential Bioactivity against Multidrug Resistant Bacterial Strains

The high prevalence of nosocomial bacterial resistance contributes to significant mortality and morbidity around the world; thus, finding novel antibacterial agents is of vital concern. Accordingly, the present study attempted to synthesize silver nanoparticles (AgNPs) using a green approach. Aqueous leaf extract of Origanum majorana was used to synthesize AgNPs and the antibacterial efficiency against multidrug resistant bacterial strains was detected. Characterization of the biogenic AgNPs was performed using ultraviolet-visible spectrophotometry (UV-Vis), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FT-IR) analysis, and X-ray diffraction analysis (XRD). The disc diffusion method was used to detect the antibacterial activity of AgNPs against three nosocomial multidrug-resistant strains. Preliminary UV-Vis analysis revealed the biosynthesis of AgNPs due to peak formation at 374 nm, corresponding to the surface plasmon resonance (SPR) of biogenic AgNPs. TEM micrographs detected the synthesis of small AgNPs with an average particle size of 26.63 nm. EDX analysis revealed the presence of the following elements: oxygen (3.69%), carbon (2.93%), aluminum (1.29), silicon (2.83%), chloride (17.89%), and silver (71.37%). Furthermore, XRD analysis revealed the presence of diffraction peaks at 2 theta (θ) degrees of 38.18°, 44.36°, 64.35°, and 77.54°, assigned to the planes of silver crystals (111), (200), (220), and (311), respectively. Collectively, these findings affirm the synthesis of biogenic AgNPs with potential physicochemical characteristics. The antimicrobial efficiency of the biogenic AgNPs indicated that Klebsiella pneumoniae strain was the most susceptible strain at concentrations of 50 and 100 µg/disk, with inhibitory zones of 21.57 and 24.56 mm, respectively. The minimum inhibitory concentration (MIC) of AgNPs against Klebsiella pneumoniae strain was found to be 10 µg/mL, while the minimum bactericidal concentration (MBC) was found to be 20 µg/mL. In conclusion, aqueous leaf extract of O. majorana mediated synthesis of small sized AgNPs, with potential antimicrobial effectiveness against multidrug-resistant bacterial pathogens.

Antimicrobial Susceptibility Testing of Clinical Isolates of Gram-Negative Bacilli Collected in Morocco by the ATLAS Global Surveillance Program from 2018 to 2020

OBJECTIVE

To report reference method antimicrobial susceptibility testing results for recent clinical isolates of Gram-negative bacilli from Morocco.

METHODS

CLSI broth microdilution antimicrobial susceptibility testing was performed by a central laboratory for isolates of Enterobacterales (n=810), Pseudomonas aeruginosa (n=321), and Acinetobacter baumannii (n=191) collected in 2018-2020 by three hospital laboratories in Morocco. MICs were interpreted using both CLSI (2021) and EUCAST (2021) breakpoints. Molecular testing for β-lactamase genes was performed on isolates meeting defined screening criteria.

RESULTS

Most isolates of Enterobacterales were susceptible (CLSI/EUCAST breakpoints) to amikacin (98.0%/96.2%), ceftazidime-avibactam (94.8%/94.8%), and meropenem (92.5%/94.2%). Of Enterobacterales isolates eligible for β-lactamase gene screening (n=210), 174 were ESBL-positive, 40 were metallo-β-lactamase-positive (all NDM), 39 were serine carbapenemase-positive (all OXA); and 7 isolates carried both OXA-48 and NDM-1. Amikacin (89.1%/89.1%) and ceftazidime-avibactam (88.2%/88.2%) were the most active agents tested against P. aeruginosa. Applying CLSI and EUCAST breakpoints, MDR rates were 21.9% and 29.3% for Enterobacterales and 18.4% and 21.8% for P. aeruginosa. Susceptible rates for amikacin, ceftazidime-avibactam, and meropenem were 93.2%/89.5%, 77.4%/82.3%, and 67.8%/80.2% for MDR Enterobacterales and 50.8%/57.1%, 40.7%/45.7%, and 27.1/32.9% for MDR P. aeruginosa. ≥70% of A. baumannii isolates were resistant to all agents tested (except colistin, EUCAST breakpoints only) including amikacin and meropenem.

CONCLUSION

Newer β-lactam/β-lactamase inhibitor combinations such as ceftazidime-avibactam warrant testing and reporting for Enterobacterales and P. aeruginosa in Morocco given the presence of significant resistance to first-line β-lactams and fluoroquinolones, pervasive ESBLs and carbapenemases, and toxicity concerns associated with some second-line agents.

Potent and Broad-Spectrum Bactericidal Activity of a Nanotechnologically Manipulated Novel Pyrazole

The antimicrobial potency of the pyrazole nucleus is widely reported these days, and pyrazole derivatives represent excellent candidates for meeting the worldwide need for new antimicrobial compounds against multidrug-resistant (MDR) bacteria. Consequently, 3-(4-chlorophenyl)-5-(4-nitrophenylamino)-1H-pyrazole-4-carbonitrile (CR232), recently reported as a weak antiproliferative agent, was considered to this end. To overcome the CR232 water solubility issue and allow for the determination of reliable minimum inhibitory concentration values (MICs), we initially prepared water-soluble and clinically applicable CR232-loaded nanoparticles (CR232-G5K NPs), as previously reported. Here, CR232-G5K NPs have been tested on several clinically isolates of Gram-positive and Gram-negative species, including MDR strains. While for CR232 MICs ≥ 128 µg/mL (376.8 µM) were obtained, very low MICs (0.36–2.89 µM) were observed for CR232-G5K NPs against all of the considered isolates, including colistin-resistant isolates of MDR Pseudomonas aeruginosa and Klebsiella pneumoniae carbapenemases (KPCs)-producing K. pneumoniae (0.72 µM). Additionally, in time–kill experiments, CR232-G5K NPs displayed a rapid bactericidal activity with no significant regrowth after 24 h on all isolates tested, regardless of their difficult-to-treat resistance. Conjecturing a clinical use of CR232-G5K NPs, cytotoxicity experiments on human keratinocytes were performed, determining very favorable selectivity indices. Collectively, due to its physicochemical and biological properties, CR232-G5K NPs could represent a new potent weapon to treat infections sustained by broad spectrum MDR bacteria.

Population Pharmacokinetic Modeling and Probability of Pharmacodynamic Target Attainment for Ceftazidime-Avibactam in Pediatric Patients Aged 3 Months and Older

Increasing prevalence of infections caused by antimicrobial-resistant gram-negative bacteria represents a global health crisis, and while several novel therapies that target various aspects of antimicrobial resistance have been introduced in recent years, few are currently approved for children. Ceftazidime-avibactam is a novel β-lactam β-lactamase inhibitor combination approved for adults and children 3 months and older with complicated intra-abdominal infection, and complicated urinary tract infection or hospital-acquired ventilator-associated pneumonia (adults only in the United States) caused by susceptible gram-negative bacteria. Extensive population pharmacokinetic (PK) data sets for ceftazidime and avibactam obtained during the adult clinical development program were used to iteratively select, modify, and validate the approved adult dosage regimen (2,000-500 mg by 2-hour intravenous (IV) infusion every 8 hours (q8h), with adjustments for renal function). Following the completion of one phase I (NCT01893346) and two phase II ceftazidime-avibactam studies (NCT02475733 and NCT02497781) in children, adult PK data sets were updated with pediatric PK data. This paper describes the development of updated combined adult and pediatric population PK models and their application in characterizing the population PK of ceftazidime and avibactam in children, and in dose selection for further pediatric evaluation. The updated models supported the approval of ceftazidime-avibactam pediatric dosage regimens (all by 2-hour IV infusion) of 50-12.5 mg/kg (maximum 2,000-500 mg) q8h for those ≥6 months to 18 years old, and 40-10 mg/kg q8h for those ≥3 to 6 months old with creatinine clearance > 50 mL/min/1.73 m2 .

Comparative proteomics and secretomics revealed virulence, and coresistance-related factors in non O1/O139 Vibrio cholerae recovered from 16 species of consumable aquatic animals

Vibrio cholerae can cause pandemic cholera in humans. The bacterium resides in aquatic environments worldwide. Identification of risk factors of V. cholerae in aquatic products is imperative for assuming food safety. In this study, we determined virulence-associated genes, cross-resistance between antibiotics and heavy metals, and genome fingerprinting profiles of non O1/O139 V. cholerae isolates (n = 20) recovered from 16 species of consumable aquatic animals. Secretomes and proteomes of V. cholerae with distinct genotypes and phenotypes were obtained by using two-dimensional gel electrophoresis (2D-GE) and/or liquid chromatography-tandem mass spectrometry (LC-MS/MS) techniques. Comparative secretomic analysis revealed 4 common and 45 differential extracellular proteins among 20 V. cholerae strains, including 13 virulence- and 8 resistance-associated proteins. A total of 21,972 intracellular proteins were identified, and comparative proteomic analysis revealed 215 common and 913 differential intracellular proteins, including 22 virulence- and 8 resistance-associated proteins. Additionally, different secretomes and proteomes were observed between V. cholerae isolates of fish and shellfish origins. A number of novel proteins with unknown function and strain-specific proteins were also discovered in the V. cholerae isolates. SIGNIFICANCE: V. cholerae can cause pandemic cholera in humans. The bacterium is distributed in aquatic environments worldwide. Identification of risk factors of V. cholerae in aquatic products is imperative for assuming food safety. Non-O1/O139 V. cholerae has been reported to cause sporadic cholera-like diarrhea and bacteremia diseases, which indicates virulence factors rather than the major cholera toxin (CT) exist. This study for the first time investigated proteomes and secretomes of non-O1/O139 V. cholerae originating from aquatic animals. This resulted in the identification of a number of virulence and coresistance-related factors, as well as novel proteins and strain-specific proteins in V. cholerae isolates recovered from 16 species of consumable aquatic animals. These results fill gaps for better understanding of pathogenesis and resistance of V. cholerae, and also support the increasing need for novel diagnosis and vaccine targets against the leading waterborne pathogen worldwide.

Combined With Mefloquine, Resurrect Colistin Active in Colistin-Resistant Pseudomonas aeruginosa in vitro and in vivo

Colistin is a polymyxin antibiotic that is widely used for the treatment of multidrug resistant (MDR) Pseudomonas aeruginosa infections, as the last resort. Over the past few years, unreasonable use of antibiotics has resulted in an increase in MDR strains, including colistin-resistant P. aeruginosa. The present study aimed to explore the synergistic effects of mefloquine in combination with colistin for the treatment of colistin-resistant P. aeruginosa in vivo and in vitro. The synergistic effect of the combination of mefloquine and colistin was investigated in vitro using checkerboard method, time-killing assay, biofilm formation inhibition test, and biofilm eradication test. The study also explored the synergistic effects of this combination of drugs in vivo, using a Galleria mellonella infection model. The results for checkerboard method and time killing curve indicated that mefloquine in combination with colistin showed a good antibacterial activity. Furthermore, the combination of these two drugs inhibited biofilm formation and eradicated pre-formed mature biofilms. This synergistic effect was visualized using scanning electron microscopy (SEM), wherein the results showed that the combination of mefloquine and colistin reduced biofilm formation significantly. Further, the application of this combination of drugs to in vivo infection model significantly increased the survival rate of G. mellonella larvae. Altogether, the combination of mefloquine and colistin showed a good synergistic effect in vitro and in vivo, and highlighted its potential to be used as an alternative therapy for the treatment of colistin-resistant P. aeruginosa infection.

Management of pneumonia in critically ill patients

Severe pneumonia is associated with high mortality (short and long term), as well as pulmonary and extrapulmonary complications. Appropriate diagnosis and early initiation of adequate antimicrobial treatment for severe pneumonia are crucial in improving survival among critically ill patients. Identifying the underlying causative pathogen is also critical for antimicrobial stewardship. However, establishing an etiological diagnosis is challenging in most patients, especially in those with chronic underlying disease; those who received previous antibiotic treatment; and those treated with mechanical ventilation. Furthermore, as antimicrobial therapy must be empiric, national and international guidelines recommend initial antimicrobial treatment according to the location's epidemiology; for patients admitted to the intensive care unit, specific recommendations on disease management are available. Adherence to pneumonia guidelines is associated with better outcomes in severe pneumonia. Yet, the continuing and necessary research on severe pneumonia is expansive, inviting different perspectives on host immunological responses, assessment of illness severity, microbial causes, risk factors for multidrug resistant pathogens, diagnostic tests, and therapeutic options.

Plant-derived nanotherapeutic systems to counter the overgrowing threat of resistant microbes and biofilms

Since antiquity, the survival of human civilization has always been threatened by the microbial infections. An alarming surge in the resistant microbial strains against the conventional drugs is quite evident in the preceding years. Furthermore, failure of currently available regimens of antibiotics has been highlighted by the emerging threat of biofilms in the community and hospital settings. Biofilms are complex dynamic composites rich in extracellular polysaccharides and DNA, supporting plethora of symbiotic microbial life forms, that can grow on both living and non-living surfaces. These enforced structures are impervious to the drugs and lead to spread of recurrent and non-treatable infections. There is a strong realization among the scientists and healthcare providers to work out alternative strategies to combat the issue of drug resistance and biofilms. Plants are a traditional but rich source of effective antimicrobials with wider spectrum due to presence of multiple constituents in perfect synergy. Other than the biocompatibility and the safety profile, these phytochemicals have been repeatedly proven to overcome the non-responsiveness of resistant microbes and films via multiple pathways such as blocking the efflux pumps, better penetration across the cell membranes or biofilms, and anti-adhesive properties. However, the unfavorable physicochemical attributes and stability issues of these phytochemicals have hampered their commercialization. These issues of the phytochemicals can be solved by designing suitably constructed nanoscaled structures. Nanosized systems can not only improve the physicochemical features of the encapsulated payloads but can also enhance their pharmacokinetic and therapeutic profile. This review encompasses why and how various types of phytochemicals and their nanosized preparations counter the microbial resistance and the biofouling. We believe that phytochemical in tandem with nanotechnological innovations can be employed to defeat the microbial resistance and biofilms. This review will help in better understanding of the challenges associated with developing such platforms and their future prospects.

Influence of Concentration and Temperature on Stability of Imipenem Focused on Solutions for Extended Infusion

Background

Imipenem remains active against most Gram-positive and Gram-negative organisms. This study aimed to evaluate chemical stability of imipenem in 2 commonly used concentrations when stored in 3 various temperatures.

Methods

Imipenem injection powder was used to prepare 5 mL and 10 mg/mL of imipenem in .9% sodium chloride solution. Prepared solutions in PVC bags were stored at 25°C, 30°C, and 40°C. The solutions were investigated over 0, 1, 2, 3, 4, and 6 hours using HPLC analysis. The association between drug stability, temperature, and concentration was determined.

Results

The 5 mg/mL solutions of brand A and B imipenem mL were stable for 6 hours at 25°C, 30°C, and 40°C, respectively. For 10 mg/mL, the solution of brand A was stable for 3 hours and brand B was stable for 6 hours at 25°C. Also, brand A and B imipenem solutions at the concentration of 10 mg/mL were stable for less than 1 hour at 30°C and 40°C.

Conclusion

The stability of imipenem injection solution was affected by temperature and concentration. Increasing in temperature and drug concentration resulted in decreased stability of imipenem. Suitable temperature and drug concentration should be concerned when this drug is given by extended infusion.

Review of Ceftazidime-Avibactam, Meropenem-Vaborbactam, and Imipenem/Cilastatin-Relebactam to Target Klebsiella pneumoniae Carbapenemase-Producing Enterobacterales

Objective: To provide a review of 3 novel antimicrobial agents-ceftazidime-avibactam, meropenem-vaborbactam, and imipenem/cilastatin-relebactam-regarding treatment of Klebsiella pneumoniae carbapenemase-producing Enterobacterales (KPC). Data Sources: A literature search of PubMed and OVID (MEDLINE) was performed up to March 2020 using the following search terms: Vabomere, meropenem-vaborbactam, vaborbactam, RPX7009, Klebsiella pneumoniae carbapenemase, KPC, carbapenem-resistant Enterobacteriaceae, CRE, relebactam, imipenem-relebactam, MK-7655, ceftazidime-avibactam. Abstracts from conferences, article bibliographies, and product information were also reviewed. Study Selection and Data Extraction: Articles were first screened by English language, then title, then abstract, and finally by review of the full article. Fifty-five clinical and preclinical studies were included. Data Synthesis: These 3 novel β-lactam/β-lactamase inhibitor combinations have shown considerable improvement in safety and efficacy as compared with traditional polymyxin-based combination therapy for the treatment of KPC infections. While meropenem-vaborbactam has not shown improved activity against Pseudomonas aeruginosa, it has shown decreased rates of resistance to KPC versus ceftazidime-avibactam. Conclusions: With increasing incidence of KPC infections on a global scale, pharmacists should be aware of the notable similarities and differences between these 3 agents, and the current data supporting their use. Pharmacists may want to consider meropenem-vaborbactam over ceftazidime-avibactam for KPC infections due to decreased likelihood of resistance.

Management of urinary tract infections and antibiotic susceptibility patterns of bacterial isolates

AIM OF STUDY

Urinary tract infections (UTIs) are among the most common infections affecting individuals of different ages worldwide. Antimicrobial agents are usually the first-line treatment for UTIs, and the use of the prescribed antibiotic is escalating, resulting in increased rates of bacterial resistance and UTI recurrence. The current study aimed to identify the causative bacteria in Jordan, to explore their resistance pattern to antibiotics and to describe drug-related problems (DRPs) associated with UTI management.

METHODS

This prospective, descriptive study was conducted in two major health institutions in two cities in Jordan over a period of six months. The study population included inpatients and outpatients diagnosed with UTIs. Patients' data were collected directly from patients using data collection sheet and from patients' charts.

RESULTS

A total of 273 patients were included, of whom 56.4% were women. Urine cultures were obtained from 81% of the patients. Escherichia coli was the most common causative pathogen (50.6%), followed by Klebsiella pneumonia (10.8%). Extended spectrum beta-lactamase (ESBL) producing E. coli was the most commonly detected organism across all types of UTIs. Ceftriaxone and imipenem/cilastatin were most commonly administered to hospitalised patients, whilst ciprofloxacin and co-triamzaxole were the most commonly prescribed in outpatient clinics. The susceptibility results for parenteral antibiotics showed high rates of resistance to cefazolin and ticarcillin. Additionally, high rates of resistance to fluoroquinolones were identified. Further, several DRPs were identified. High rates of resistance to commonly prescribed antibiotics were detected. DRPs (ie, inappropriate antibiotic dosage, unnecessary antibiotic prescribing, inappropriate duration of therapy and prescribing of ineffective antibiotics) were relatively common.

CONCLUSION

The present study highlights the need for clinical pharmacists to manage the high level of drug related problems by providing updated information about proper drug selection, rational drug use and patient education and counselling.

Anti-biofilm and anti-inflammatory effects of Lycosin-II isolated from spiders against multi-drug resistant bacteria

Currently, multidrug-resistant bacteria are rapidly increasing worldwide because of the misuse or overuse of antibiotics. In particular, few options exist for treating infections caused by long-persisting oxacillin-resistant strains and recently proliferating carbapenem-resistant strains. Therefore, alternative treatments are urgently needed. The antimicrobial peptide (AMP) Lycosin-II is a peptide consisting of 21 amino acids isolated from the venom of the spider Lycosa singoriensis. Lycosin-II showed strong antibacterial activity and biofilm inhibition effects against gram-positive and gram-negative bacteria including oxacillin-resistant Staphylococcus aureus (S. aureus) and meropenem-resistant Pseudomonas aeruginosa (P. aeruginosa) isolated from patients. In addition, Lycosin-II was not cytotoxic against human foreskin fibroblast Hs27 or hemolytic against sheep red blood cells at the concentration of which exerted antibacterial activity. The mechanism of action of Lycosin-II involves binding to lipoteichoic acid and lipopolysaccharide of gram-positive and gram-negative bacterial membranes, respectively, to destroy the bacterial membrane. Moreover, Lycosin-II showed anti-inflammatory effects by inhibiting the expression of pro-inflammatory cytokines that are increased during bacterial infection in Hs27 cells. These results suggest that Lycosin-II can serve as a therapeutic agent against infections with multidrug-resistant strains.

Blocking of Birc3/TLR4/Myd88 signaling protects carbapenem-resistant klebsiella pneumoniae in a mouse model of infection

BACKGROUND

Klebsiella pneumonia (KP) and carbapenem-resistant Klebsiella pneumonia (CRKP) lung infections significantly increase the morbidity and mortality of pneumonia. Recent studies have shown that baculoviral IAP repeat-containing 3 (Birc3) plays an important role in the prevention and treatment of pneumonia. However, the role of Birc3 in CRKP-induced pneumonia has not been widely reported.

METHODS

In vivo, we successfully established a mouse model of pneumonia induced by KP and CRKP. In vitro, we established a macrophage model treated with KP and CRKP. The phagocytosis of macrophages treated with CRKP was measured by Flow cytometry and coated plate counting. STRING and Co-IP assays were used to predict and verify the relationship between Birc3 and toll-like receptor 4 (TLR4) or myeloid differentiation factor 88 (Myd88). HE staining was used to detect the lung pathological changes of anti-Birc3 IgG inhibited CRKP-induced inflammatory cells. The levels of inflammatory factors and proteins were detected by ELISA and Western blot, respectively.

RESULTS

The phagocytic ability of macrophages was reduced, and the cytokine storm was enhanced in CRKP treated Raw264.7 cells. Macrophages treated with CRKP impaired phagocytosis. Birc3 could interact with TLR4 and MyD88. Anti-Birc3 IgG inhibited CRKP-induced inflammatory cell lung infiltration. In addition, mice treated with anti-Birc3 IgG improved the CRKP-induced inflammatory cell lung infiltration, bacterial spread, and cytokine storm by inhibiting the Birc3/TLR4/Myd88 signaling pathway.

CONCLUSION

The results suggest that Birc3 may serve as a target for the treatment of bacterial infection and lung inflammation in CRKP-induced pneumonia.

Rectal Colonization by Drug Resistant Bacteria in Nursing Home Residents in Crete, Greece

(1) Background: In an area with a high prevalence of multi-drug resistant Gram-negative bacteria (MDR-GNB), we investigated the colonization of nursing home residents by such organisms. (2) Methods: A point prevalence study was performed in six nursing homes of the Heraklion area on the island of Crete. A rectal swab was taken and cultured from each participant, while additional risk factors such as recent hospitalization or antimicrobial usage were recorded and evaluated. (3) Results: A total of 137 nursing home residents were included in the study. Their mean age was 82.1 years and 19.7% were males. In total, cultures yielded 255 GNB; E. coli, K. pneumoniae and P. aeruginosa were the most common. Among the microorganisms cultured, 17.6% had the extended-spectrum beta-lactamase phenotype, while 18% were MDR. A statistically significant association was found between recent antimicrobial use and colonization by MDR-GNB; (4) Conclusions: Colonization by MDR-GNB was found to be highly prevalent in nursing home residents. Recent antimicrobial use was associated with MDR-GNB carriage.

In Vitro Activity of Imipenem/Relebactam and Ceftolozane/Tazobactam Against Clinical Isolates of Gram-negative Bacilli With Difficult-to-Treat Resistance and Multidrug-resistant Phenotypes-Study for Monitoring Antimicrobial Resistance Trends, United States 2015-2017

BACKGROUND

Multidrug-resistant (MDR) bacteria are frequently defined using the criteria established by Magiorakos et al [Clin Microbiol Infect 2012;18:268-81]. Difficult-to-treat resistance (DTR) [Kadri et al, Clin Infect Dis 2018;67:1803-14] is a novel approach to defining resistance in gram-negative bacilli focusing on treatment-limiting resistance to first-line agents (all β-lactams and fluoroquinolones).

METHODS

Clinical and Laboratory Standards Institute-defined broth microdilution minimum inhibitory concentrations (MICs) were determined for imipenem/relebactam, ceftolozane/tazobactam, and comparators against respiratory, intraabdominal, and urinary isolates of Enterobacterales (n = 10 516) and Pseudomonas aeruginosa (n = 2732) collected in 26 US hospitals in 2015-2017.

RESULTS

Among all Enterobacterales, 1.0% of isolates were DTR and 15.6% were MDR; 8.4% of P. aeruginosa isolates were DTR and 32.4% were MDR. MDR rates for Enterobacterales and DTR and MDR rates for P. aeruginosa were significantly higher (P < .05) in isolates collected in intensive care units (ICUs) than in non-ICUs and in respiratory tract isolates than in intraabdominal or urinary tract isolates. In addition, 82.4% of DTR and 92.1% of MDR Enterobacterales and 62.2% of DTR and 82.2% of MDR P. aeruginosa were imipenem/relebactam-susceptible, and 1.5% of DTR and 65.8% of MDR Enterobacterales and 67.5% of DTR and 84.0% of MDR P. aeruginosa were ceftolozane/tazobactam-susceptible.

CONCLUSIONS

MDR phenotypes defined using the Magiorakos criteria may overcall treatment-limiting resistance in gram-negative bacilli. In the US, DTR Enterobacterales were infrequent, while MDR Enterobacterales isolates and DTR and MDR P. aeruginosa were common. Imipenem/relebactam (Enterobacterales, P. aeruginosa) and ceftolozane/tazobactam (P. aeruginosa) retained in vitro activity against most DTR and MDR isolates.

High Carbapenem Resistance Caused by VIM and NDM Enzymes and OprD Alteration in Nonfermenter Bacteria Isolated from a Libyan Hospital

Acinetobacter baumannii and Pseudomonas aeruginosa are among the most prevalent pathogens causing a wide range of serious infections in hospitalized patients and contaminating intensive care units and inanimate surfaces. The purpose of this study was to investigate the mechanism of carbapenem resistance in clinical and hospital environmental isolates of A. baumannii and P. aeruginosa recovered from a Libyan hospital. From a total of 82 Gram-negative bacteria, 8 isolates of A. baumannii and 3 isolates of P. aeruginosa exhibited resistance to imipenem with minimum inhibitory concentrations ranging from 16 to >32 μg/mL. Five isolates of A. baumannii harbored bla_OXA-23 gene, from which three isolates were collected from patients and two from hospital environment. Only one isolate harbored bla_NDM-1 gene, which was responsible for carbapenem resistance in A. baumannii. The OprD gene seems to be disturbed by an insertion sequence (IS) in two isolates and affected by polymorphism in one isolate. Pulsed-field gel electrophoresis results showed high genetic diversity among carbapenemase producing A. baumannii. This study highlights the dissemination of bla_OXA-23 and bla_NDM-1 genes in a Libyan setting. Therefore, infection prevention and control practices, antimicrobial stewardship initiatives, and antimicrobial resistance surveillance systems should be implemented to prevent the wide spread of antimicrobial resistance.

Evaluation of prognosis and nephrotoxicity in patients treated with colistin in intensive care unit

Introduction

Nephrotoxicity is the most important adverse effect of colistin therapy. We investigated the frequency of nephrotoxicity, risk factors related to nephrotoxicity, and its relationship with mortality in patients who received intravenous colistin in intensive care units (ICUs).

Materials and methods

We retrospectively reviewed the data of patients who received intravenous colistin in ICUs between 2011 and 2017. Acute kidney injury (AKI) diagnosis and staging were made based on the Kidney Disease Improving Global Outcome criteria.

Results

There were 149 patients included in the study with 61% being male. The mean age was 58.7 ± 20.3 years. AKI was detected in 96 (64.4%) patients. There were 25 patients with AKI stage 1 (16.8%) and 71 patients with AKI stage 2 or 3 (47.7%). Advanced age (65.0 vs. 47.4 years; p < .001), diabetes mellitus (p < .001), heart failure (p = .01), high APACHE II score (31.7 vs. 28.08, p = .019), and inotrope usage (p = .01) were found as risk factors for AKI. The 14-day mortality rate was higher in the AKI group (p = .027).

Discussion

Higher AKI and mortality rates are observed in patients with diabetes, heart failure, advanced age and the hemodynamically impaired. However, it is a fact that there are no alternative therapies other than colistin in the treatment of multidrug-resistant Gram-negative bacterial infections. Therefore, the development of AKI in this patient group should not be considered a sufficient reason for discontinuing colistin treatment. Understanding the risk factors in this potential nephrotoxic treatment can provide a more careful patient follow-up.

Early prediction models for extended-spectrum β-lactamase-producing Escherichia coli infection in emergency department: A protocol for systematic review and meta analysis

BACKGROUND

Resistance in gram-negative bacteria has gained great importance in recent decades and one reason is the rapid increase of extended spectrum β-lactamase (ESBL)-producing bacteria as a growing problem worldwide. The increasing proportion of ESBL-producing Enterobacteriaceae (ESBL-E) infections acquired in the emergency community is a new feature of ESBLs epidemiology. Early recognition of patients with extended-spectrum β-lactamase-producing Escherichia coli infection is important in the emergency department. To mitigate the burden on the healthcare system, while also providing the best possible care for patients, early recognition of the infection is needed.

METHODS

For the acquisition of required data of eligible prospective/retrospective cohort study or randomized controlled trials (RCTs), we will search for publications from PubMed, Web of science, EMBASE, Cochrane Library, Google scholar. Two independent reviewers will read the full English text of the articles, screened and selected carefully, removing duplication. Then we evaluate the quality and analyses data by Review Manager (V.5.4). Results data will be pooled and meta-analysis will be conducted if there's 2 eligible studies considered.

RESULTS

This systematic review and meta-analysis will evaluate the value of the early prediction models for Extended-spectrum β-lactamase-producing E coli infection in emergency department.

CONCLUSIONS

This systematic review and meta-analysis will provide clinical evidence for predicting Extended-spectrum β-lactamase-producing E coli infection in emergency department, inform our understanding of the value of the predictive model in predicting Extended-spectrum β-lactamase-producing E coli infection in emergency department in the early stage. The conclusions drawn from this study may be beneficial to patients, clinicians, and health-related policy makers.

STUDY REGISTRATION NUMBER

INPLASY202130049.

Molecular detection of carbapenem resistance genes in rectal swabs from patients in Gulf Cooperation Council hospitals

BACKGROUND

Gram-negative organisms harbouring carbapenem resistance genes (CRGs) are spreading globally, including in Gulf Cooperation Council (GCC) countries. However, relatively few data are available about carriage of CRGs in hospitalized patients in this region.

AIM

To determine prevalence of CRG carriage and risk factors for colonization among patients in GCC hospitals.

METHODS

Rectal swabs were obtained from ∼50 intensive care unit (ICU) patients from each of 11 hospitals in five GCC countries between March and November 2019. The swabs were tested for the presence of bla_KPC, bla_NDM, bla_VIM, bla_IMP, and bla_OXA-48 CRG using a commercial polymerase chain reaction test. Data on risk factors for colonization were collected and analysed.

FINDINGS

Of 529 specimens screened, 138 (26.1%) were positive for one or more CRGs. The positivity rates among the hospitals ranged from 8.0% to 67.3%; ∼20% of the positive specimens harboured ≥2 CRGs. The most common CRG detected was bla_OXA-48, which was present in 82 specimens (15.5%). Additional CRGs included bla_NDM, bla_VIM, bla_KPC, and bla_IMP either alone or in combination. Overall, 31.1% of patients on antibiotics on admission to the ICU were positive for CRGs compared to 16.5% not on antibiotic therapy (P < 0.001). CRG detection was also more common among patients aged >65 years (P = 0.027) and increased with hospital length of stay (P = 0.025).

CONCLUSION

The rate of CRGs detected in hospitalized patients in GCC countries varied considerably. Prior antibiotic exposure, increasing age, and prolonged length of stay were associated with CRG detection.

In Vitro Activity of Imipenem/Relebactam Against Gram-Negative Bacilli from Pediatric Patients-Study for Monitoring Antimicrobial Resistance Trends (SMART) global surveillance program 2015-2017

BACKGROUND

Studies describing the activity of imipenem/relebactam against gram-negative bacilli (GNB) isolated from pediatric patients are lacking in the peer-reviewed literature. We address this deficiency by reporting on GNB tested against imipenem/relebactam as part of the Study for Monitoring Antimicrobial Resistance Trends global surveillance program.

METHODS

In 2015-2017, 221 laboratories in 59 countries collected 9149 consecutive, aerobic or facultative GNB from pediatric patients (age <18 years) and 100 785 from adult patients with intraabdominal, respiratory, and urinary tract infections. Susceptibility was determined using Clinical and Laboratory Standards Institute (CLSI) broth microdilution methodology and CLSI breakpoints (and US Food and Drug Administration breakpoints for imipenem/relebactam).

RESULTS

The 4 most common species of GNB isolated from pediatric patients were Escherichia coli (40.4%), Pseudomonas aeruginosa (17.1%), Klebsiella pneumoniae (13.9%), and Enterobacter cloacae (4.7%); non-Morganellaceae Enterobacterales (NME) accounted for 70.1% of isolates. Imipenem/relebactam inhibited 97.8% of NME from pediatric patients; susceptibility to imipenem was 1.9% lower, and susceptibility to β-lactam comparators (cefepime, ceftazidime, ceftriaxone, piperacillin/tazobactam) was 9.2-25.2% lower. Imipenem/relebactam inhibited 94.2% of P. aeruginosa from pediatric patients; susceptibility to imipenem was 16.2% lower, and susceptibility to β-lactam comparators was 10.2-15.6% lower. Susceptibility was generally slightly higher for isolates from pediatric than adult patients. All K. pneumoniae carbapenemase (KPC)-positive isolates, 93.3% of multidrug-resistant (MDR) NME isolates, and 70.5% of MDR P. aeruginosa isolates from pediatric patients were susceptible to imipenem/relebactam.

CONCLUSIONS

Imipenem/relebactam provides a new treatment option for infections caused by resistant gram-negative bacilli, including KPC-positive NME, MDR NME, and MDR P. aeruginosa.

In-vitro activity of tigecycline against multidrug-resistant Gram negative bacteria: The experience of a university hospital

The emergence of multidrug-resistant Gram negative bacteria has given rise to significant therapeutic challenges. These pathogens may have developed resistance to tigecycline, which is an alternative antibiotic used empirically in the treatment of serious infections. The objectives of this study were to identify the in-vitro activity of tigecycline against multidrug-resistant Gram negative strains isolated from clinical specimens and their related genes, at a university hospital. For this, 150 clinical isolates of multidrug-resistant Gram negative cultures from various clinical specimens were collected. Bacterial isolates were cultured, identified and their antibiotic susceptibilities were determined. Polymerase chain reaction was performed to amplify AcrB, AmpC, RamR, MexR, AdeB, TetA genes. Results revealed that all isolates were multidrug-resistant. The resistance of isolates was 91.4% to aztreonam, 94.6% to piperacillin, 34% to imipenem, 38.7% to meropenem, 71.3% to levofloxacin, 97.3% to ceftriaxone, 94.7% to cefepime, 9.3% to colistin, 78% to tetracycline, 21.4% to tigecycline and 68% to trimethoprim. AcrB, AmpC, RamR, MexR, AdeB, TetA genes were present in multidrug-resistant Gram negative bacteria. AcrB, RamR, TetA genes were related to tigecycline resistance. It is concluded that infections caused by multidrug-resistant Gram negative bacteria occur at a high rate. Most isolates were multi drug resistant, with 21.4% being resistant to tigecycline.

A literature survey on antimicrobial and immune-modulatory effects of butyrate revealing non-antibiotic approaches to tackle bacterial infections

The excessive prescription of antibiotics has led to an increasing number of antimicrobial resistances, posing a major public health concern. Therefore, the pharmacological research has shifted its focus to the identification of natural compounds that exhibit anti-pathogenic properties without triggering antibiotic resistance. Butyrate has received increasing attention as a promising candidate for the treatment of bacterial infections in the gastrointestinal tract, particularly when antibiotic treatment is contraindicated. This literature survey summarizes recently investigated antibacterial and immunemodulatory effects of butyrate. This survey revealed that butyrate exerts direct antimicrobial effects against distinct strains of Acinetobacter baumannii, Escherichia coli, Bacillus, and Staphylococcus species. In addition, in vitro and in vivo studies confirmed indirect antimicrobial effects of butyrate, which were exhibited via induction of host defensin production as well as by activation of innate and adaptive immune responses. Finally, the synergistic action of butyrate in combination with other antimicrobial compounds results in a striking clearance of bacterial pathogens. In conclusion, butyrate and its derivatives might be considered as promising antibacterial and immune-modulatory agents in order to tackle bacterial infections without antibiotics.

Impact of an Evidence-Based Antibiotic Protocol on Common Gram-Negative Bacteria's Antibiotic Resistance in a Cardiac Surgical Intensive Care Unit

Background Based on the analysis of infections and antibiotic usage in the years 2013 and 2014, an evidence-based antibiotic protocol was developed and implemented in our cardiac surgical intensive care unit (CSICU). This study intends to study the impact of this new protocol on the sensitivity profiles of common gram-negative bacteria in our CSICU.

Methods The medical records of patients who underwent cardiac surgery at our center, between January 2017 and December 2018, were reviewed and the incidence of different hospital-acquired bacteria and their antibiotic sensitivity profiles were recorded. The antibiotic-sensitivity profiles of common gram-negative bacteria, for the years 2017 and 2018, were compared with the published data of 2013 and 2014 from our department.

Results There was a significant decrease in the incidence of Acinetobacter baumannii, Klebsiella pneumoniae, Escherichia coli, and Pseudomonas aeruginosa resistant to carbapenems during 2017 and 2018. The incidence of colistin-resistant A. baumannii and P. aeruginosa also decreased significantly in 2017 and 2018. A significant increase in the proportion of amikacin resistant A. baumannii and E. coli and A. baumannii resistant to B lactam/B lactamase inhibitors also occurred.

Conclusion Antibiotic stewardship can reverse the antibiotic resistance of common gram-negative bacteria in the ICU.

Investigation of Gram-Negative Bacilli Bacteraemia in a Tertiary Hospital in Nigeria: Epidemiology and Antimicrobial Susceptibility Pattern

Background: The re-emergence of gram-negative bacilli (GNB) as the predominant cause of bacteraemia remains a major concern, given the increasing trend of antimicrobial resistance among this group of organisms. Prompt and effective empirical antibiotic treatment is vital for preventing adverse outcomes; therefore, a good knowledge of the local bacteria profile is required. Objective: This study was designed to aid the establishment of local antibiogram and empirical treatment for GNB bacteremia in patients referred to the University of Port Harcourt Teaching Hospital (UPTH), Nigeria. Materials and Methods: A total of 230 blood samples were obtained from inpatients in different units/departments from December 2017 to November 2018. The blood cultures were processed using BACTEC 9060 automated blood culture system, and the isolates were identified using MICROBACT 12E identification kits (Oxoid, UK) at the microbiology laboratory of UPTH. Susceptibility and resistance tests were done according to CLSI guidelines. Relevant information was obtained from the laboratory request forms and patients’ clinical files. Results: The prevalence of GNB in the study was 28.9% (71/246). The distribution of GNB bacteraemia was as follows: surgical unit (26.8%), special care baby unit (SCBU) (23.9%), intensive care unit (ICU) (21.1%), and paediatric ward (8.5%). The most common source of bacteraemia was pneumonia (35.2%) followed by puerperal sepsis (15.1%) and urinary tract infection (UTI) (15.1%). Klebsiella pneumoniae was the most frequently isolated gram-negative bacillus (26.6%). The overall resistance rate of extended spectrum lactamase producing Enterobacteriaceae (ESBL) producers, carbapenemase producers, and multi-drug resistant (MDR) organisms was 32.4%, with Acinetobacter baumannii (50%) and Pseudomonas aeruginosa (27.3%) exhibiting the highest level of resistance to carbapenems. Conclusion: This study showed a high MDR rate among GNB causing bacteraemia in patients at UPTH. An urgent review of the current antimicrobial prescription policy and infection control measures is recommended.

Acute toxicity is a dose-limiting factor for intravenous polymyxin B: A safety and pharmacokinetic study in healthy Chinese subjects

OBJECTIVES

Polymyxin B is a last-line antibiotic for multidrug-resistant gram-negative bacterial infections. However, limited safety and pharmacokinetic information is available. We investigated the safety and pharmacokinetics of intravenous polymyxin B in healthy subjects.

METHODS

An open-label, single-dose clinical trial was conducted in healthy Chinese subjects. Polymyxin B (sulphate) was administered intravenously at 0.75 or 1.5 mg/kg (n = 10 per dose, 5 males and 5 females) to examine the safety and pharmacokinetics.

RESULTS

One female subject in the 1.5-mg/kg group discontinued due to abdominal pain during administration. The most frequently reported adverse events were perioral paraesthesia, dizziness, and numbness of extremities (7/10 subjects in the 0.75-mg/kg group, all subjects in the 1.5-mg/kg group). All neurotoxicity-related events dissipated without treatment within a maximum of 23 h. Notably, abdominal pain (3/5) and vulvar pruritus (2/5), colpitis (2/5) or abnormal uterine bleeding (1/5) were reported in female subjects receiving the 1.5-mg/kg dose. In the 0.75-mg/kg group, the total clearance, volume of distribution and half-life of polymyxin B were 0.028±0.002 L/h/kg, 0.219±0.023 L/kg and 5.44±0.741 h, respectively; similar values were observed in the 1.5-mg/kg group. Urinary recovery was 3.7 ± 1.1% and 8.1 ± 1.3% in the 0.75- and 1.5-mg/kg groups, respectively. Population pharmacokinetics of polymyxin B was consistent with a three-compartment model. The clearance and distribution of the central compartment were 0.027 L/h/kg and 0.071 L/kg, respectively.

CONCLUSIONS

This study is the first to examine the safety and pharmacokinetics of polymyxin B in healthy subjects. Our results highlight that acute toxicity is a dose-limiting factor for intravenous polymyxin B.

RESTORE-IMI 1: A Multicenter, Randomized, Double-blind Trial Comparing Efficacy and Safety of Imipenem/Relebactam vs Colistin Plus Imipenem in Patients With Imipenem-nonsusceptible Bacterial Infections

Background

The β-lactamase inhibitor relebactam can restore imipenem activity against imipenem-nonsusceptible gram-negative pathogens. We evaluated imipenem/relebactam for treating imipenem-nonsusceptible infections.

Methods

Randomized, controlled, double-blind, phase 3 trial. Hospitalized patients with hospital-acquired/ventilator-associated pneumonia, complicated intraabdominal infection, or complicated urinary tract infection caused by imipenem-nonsusceptible (but colistin- and imipenem/relebactam-susceptible) pathogens were randomized 2:1 to 5–21 days imipenem/relebactam or colistin+imipenem. Primary endpoint: favorable overall response (defined by relevant endpoints for each infection type) in the modified microbiologic intent-to-treat (mMITT) population (qualifying baseline pathogen and ≥1 dose study treatment). Secondary endpoints: clinical response, all-cause mortality, and treatment-emergent nephrotoxicity. Safety analyses included patients with ≥1 dose study treatment.

Results

Thirty-one patients received imipenem/relebactam and 16 colistin+imipenem. Among mITT patients (n = 21 imipenem/relebactam, n = 10 colistin+imipenem), 29% had Acute Physiology and Chronic Health Evaluation II scores >15, 23% had creatinine clearance <60 mL/min, and 35% were aged ≥65 years. Qualifying baseline pathogens: Pseudomonas aeruginosa (77%), Klebsiella spp. (16%), other Enterobacteriaceae (6%). Favorable overall response was observed in 71% imipenem/relebactam and 70% colistin+imipenem patients (90% confidence interval [CI] for difference, –27.5, 21.4), day 28 favorable clinical response in 71% and 40% (90% CI, 1.3, 51.5), and 28-day mortality in 10% and 30% (90% CI, –46.4, 6.7), respectively. Serious adverse events (AEs) occurred in 10% of imipenem/relebactam and 31% of colistin+imipenem patients, drug-related AEs in 16% and 31% (no drug-related deaths), and treatment-emergent nephrotoxicity in 10% and 56% (P = .002), respectively.

Conclusions

Imipenem/relebactam is an efficacious and well-tolerated treatment option for carbapenem-nonsusceptible infections.

Clinical Trials Registration

NCT02452047.

Risk Factors and Outcomes of Antibiotic-resistant Pseudomonas aeruginosa Bloodstream Infection in Adult Patients With Acute Leukemia

BACKGROUND

Pseudomonas aeruginosa (PA) bloodstream infection (BSI) is a common complication in patients with acute leukemia (AL), and the prevalence of antibiotic-resistant strains poses a serious problem. However, there is limited information regarding antibiotic resistance, clinical characteristics, and outcomes of PA BSI in AL patients. This study explored characteristics associated with the clinical outcomes of AL patients with PA BSI and analyzed factors associated with BSI caused by multidrug-resistant (MDR) or carbapenem-resistant strains.

METHODS

This single-center retrospective study enrolled hospitalized AL patients who developed PA BSI during January 2014-December 2019. The Kaplan-Meier method was used to plot survival curves. Multivariate logistic regression analyses were also performed.

RESULTS

Of 293 eligible patients with PA BSI, 55 (18.8%) received inappropriate empirical antibiotic therapy within 48 hours of BSI onset, whereas up to 65.8% MDR-PA BSI patients received inappropriate empirical treatment. The 30-day mortality rate was 8.5% for all patients. However, the 30-day mortality rates were 28.9% and 5.5% in MDR-PA BSI and non-MDR-PA BSI patients, respectively (P < .001). On multivariate analysis, previous use of quinolones (odds ratio [OR], 5.851 [95% confidence interval {CI}, 2.638-12.975]) and piperacillin/tazobactam (OR, 2.837 [95% CI, 1.151-6.994]) were independently associated with MDR-PA BSI; and MDR-PA BSI (OR, 7.196 [95% CI, 2.773-18.668]), perianal infection (OR, 4.079 [95% CI, 1.401-11.879]), pulmonary infection (OR, 3.028 [95% CI, 1.231-7.446]), and age ≥55 years (OR, 2.871 [95% CI, 1.057-7.799]) were independent risk factors for 30-day mortality.

CONCLUSIONS

MDR increases mortality risk in PA BSI patients, and previous antibiotic exposure is important in MDR-PA BSI development. Rational antibiotic use based on local antimicrobial susceptibility and clinical characteristics can help reduce antibiotic resistance and mortality.

The Use of Moxisaxin for Treatment of a Decompensated Cirrhosis Patient with Severe Pulmonary Infection

Introduction: Moxifloxacin is recommended for empirical antibiotic treatment of patients with cirrhosis. However, due to a lack of clinical safety data on moxifloxacin in Child-Pugh C patients, it is unknown how to use moxifloxacin in clinical practice. Case Presentation: A 76-year-old female with decompensated cirrhosis developed pneumonia during hospitalization. She had an initial failure to respond to imipenem/cilastatin + linezolid therapy. After three-day therapy with imipenem/cilastatin + moxisaxin, her infection symptoms rapidly improved. At this time, she presented a poor response with suspected hepatic encephalopathy. Given the worsening clinical symptoms caused by drug hepatotoxicity, moxisaxin was discontinued. Then, her body temperature rapidly raised. Conclusions: Moxisaxin may be a potentially useful antibiotic for hospital-acquired pneumonia in patients with decompensated cirrhosis, but further studies are needed to validate its hepatotoxicity.

Dietary Indole-3-Carbinol Alleviated Spleen Enlargement, Enhanced IgG Response in C3H/HeN Mice Infected with Citrobacter rodentium

Enteropathogenic and enterohemorrhagic Escherichia coli are important enteric pathogens that induce hemorrhagic colitis or even fatal hemolytic uremic syndrome. Emerging evidence shows that some bio-actives derived from fruits and vegetables may serve as alternatives to antibiotics for overcoming multidrug resistant E. coli infections. In this study, the Citrobacter rodentium (Cr) infection model was utilized to mimic E. coli-induced acute intestinal inflammation, and the effects of a cruciferous vegetable-derived cancer protective compound, indole-3-carbinol (I3C), on the immune responses of Cr-susceptible C3H/HeN mice were investigated. Dietary I3C significantly inhibited the loss of body weight and the increase in spleen size in Cr infected mice. In addition, I3C treatment reduced the inflammatory response to Cr infection by maintaining anti-inflammatory cytokine IL-22 mRNA levels while reducing expression of other pro-inflammatory cytokines including IL17A, IL6, IL1β, TNF-α, and IFN-γ. Moreover, the serum cytokine levels of IL17, TNF-α, IL12p70, and G-CSF also were down-regulated by I3C in Cr-infected mice. Additionally, dietary I3C specifically enhanced the Cr-specific IgG response to Cr infection. In general, dietary I3C reduced the Cr-induced pro-inflammatory response in susceptible C3H/HeN mice and alleviated the physiological changes and tissue damage induced by Cr infection but not Cr colonization.

Bio fabrication of silver nanoparticles with antibacterial and cytotoxic abilities using lichens

Recently, increase bacterial resistance to antimicrobial compounds issue constitutes a real threat to human health. One of the useful materials for bacterial control is Silver nanoparticles (AgNPs). Researchers tend to use biogenic agents to synthesize stable and safe AgNPs. The principal aim of this study was to investigate the ability of lichen in AgNPs formation and to find out their suppression ability to MDR bacteria as well as their cytotoxic activity. In the current study, lichens (Xanthoria parietina, Flavopunctelia flaventior) were collected from the south of the Kingdom of Saudi Arabia. Lichens methanolic extracts were used for conversion of Ag ions to AgNPs. Prepared biogenic AgNPs were characterized by Ultraviolet–Visible (UV–Vis) Spectroscopy, Transmission electron microscopy (TEM), Dynamic Light Scattering (DLS) and Zeta potential and Energy-Dispersive X-ray Spectroscopy (EDS). Lichens Secondary metabolites were determined by Fourier-Transform Infrared Spectroscopy (FTIR) and Gas Chromatography–Mass Spectrometry (GC–MS). The antibacterial activity and synergistic effect of AgNPs were evaluated against pathogenic bacteria, including gram-positive; Methicillin-resistant Staphylococcus aureus (MRSA), Vancomycin-resistant Enterococcus (VRE), and gram-negative; (Pseudomonas aeruginosa, Escherichia coli) as well as the reference strains (ATCC) using the agar disk diffusion method. Cytotoxic effect of biogenic AgNPs was tested against HCT 116 (Human Colorectal Cancer cell), MDA-MB-231 (Breast cancer cell), and FaDu (Pharynx cancer cell) by MTT test. TEM imaging showed well-dispersed spherical particles of 1–40 nm size as well as zeta size showed 69–145 nm. Furthermore, FTIR and GC–MS identified various lichen chemical molecules. On the other hand, the highest antibacterial activity of AgNPs was noticed against P. aeruginosa, followed by MRSA, VRE, and E. coli. AgNPs influence on gram-negative bacteria was greater than that on gram-positive bacteria and their synergistic effect with some antibiotics was noted against examined microbes. Moreover, higher cytotoxicity for biogenic AgNPs against FaDu and HCT 116 cell line in relation to MDA-MB-231 was noted. Given the current findings, the biogenic AgNPs mediated by lichens had positive antibacterial, synergistic and cytotoxic powers. Therefore, they might be considered as a promising candidate to combat the multi-drug resistance organisms and some cancer cells.