Broad-spectrum Β-lactam Antibiotics Research Articles

Triggered Release of Ampicillin from Metallic Implant Coatings for Combating Periprosthetic Infections.

Periprosthetic infections caused by Staphylococcus aureus (S. aureus) pose unique challenges in orthopedic surgeries, in part due to the bacterium's capacity to invade surrounding bone tissues besides forming recalcitrant biofilms on implant surfaces. We previously developed prophylactic implant coatings for the on-demand release of vancomycin, triggered by the cleavage of an oligonucleotide (Oligo) linker by micrococcal nuclease (MN) secreted by the Gram-positive bacterium, to eradicate S. aureus surrounding the implant in vitro and in vivo. Building upon this coating platform, here we explore the feasibility of extending the on-demand release to ampicillin, a broad-spectrum aminopenicillin β-lactam antibiotic that is more effective than vancomycin in killing Gram-negative bacteria that may accompany S. aureus infections. The amino group of ampicillin was successfully conjugated to the carboxyl end of an MN-sensitive Oligo covalently integrated in a polymethacrylate hydrogel coating applied to titanium alloy pins. The resultant Oligo-Ampicillin hydrogel coating released the β-lactam in the presence of S. aureus and successfully cleared nearby S. aureus in vitro. When the Oligo-Ampicillin-coated pin was delivered to a rat femoral canal inoculated with 1000 cfu S. aureus, it prevented periprosthetic infection with timely on-demand drug release. The clearance of the bacteria from the pin surface as well as surrounding tissue persisted over 3 months, with no local or systemic toxicity observed with the coating. The negatively charged Oligo fragment attached to ampicillin upon cleavage from the coating did diminish the antibiotic's potency against S. aureus and Escherichia coli (E. coli) to varying degrees, likely due to electrostatic repulsion by the anionic surfaces of the bacteria. Although the on-demand release of the β-lactam led to adequate killing of S. aureus but not E. coli in the presence of a mixture of the bacteria, strong inhibition of the colonization of the remaining E. coli on hydrogel coating was observed. These findings will inspire considerations of alternative broad-spectrum antibiotics, optimized drug conjugation, and Oligo linker engineering for more effective protection against polymicrobial periprosthetic infections.

154. Impact of Rapid Blood Culture Identification (BCID) PCR Panel on Optimal Antibiotic Use in Methicillin-Susceptible Staphylococcus aureus (MSSA) Bacteremia

Abstract Background Optimal anti-MSSA antibiotic choices are nafcillin, oxacillin, and cefazolin. Vancomycin, often used empirically for S. aureus infections, and other broad-spectrum β-lactam antibiotics, such as piperacillin/tazobactam and ceftriaxone, are linked with suboptimal outcomes compared to anti-MSSA β-lactam therapy. BCID PCR testing allows for faster pathogen identification, which may improve antibiotic use and clinical outcomes. The objective of this study was to assess the impact of BioFire BCID PCR panel implementation on antibiotic use and clinical outcomes in patients with MSSA bacteremia. Methods This was a retrospective chart review of adult inpatients with MSSA bacteremia during the pre-PCR (Jun 2018 - Dec 2019) and post-PCR (Jun 2020 - Dec 2021) study periods. Patients were excluded if they did not have PCR testing performed (post-PCR group only), never achieved optimal antibiotic therapy, had a polymicrobial infection, had positive blood cultures in the prior 90 days, underwent penicillin-skin testing or β-lactam desensitization, or were transitioned to comfort care or deceased within 24 hours of the gram stain. The primary endpoint was the difference in time to starting optimal MSSA antibiotic therapy (oxacillin or cefazolin) between the pre-PCR and post-PCR groups. Secondary endpoints included duration of anti-MRSA antibiotic use, in-hospital mortality, hospital and ICU lengths of stay, duration of bacteremia, and 30-day MSSA-related and all-cause readmissions. Results A total of 200 patients were included in the study, with 100 patients in each group. Time to optimal therapy was reduced by 19.9 hours in the post-PCR group (p < 0.001). Fewer patients in the post-PCR group were initiated on empiric anti-MRSA antibiotic therapy than in the pre-PCR group (84% vs 98%, respectively, p = 0.001). PCR implementation was also associated with shorter empiric anti-MRSA antibiotic use and duration of bacteremia. There were no significant differences in length of stay, in-hospital mortality, or 30-day MSSA-related or all-cause readmissions (Table 1). Table 1: Primary and Secondary Endpoints Conclusion In patients with MSSA bacteremia, BCID PCR panel testing decreased time to optimal MSSA antibiotic therapy and reduced durations of bacteremia and empiric anti-MRSA antibiotic therapy, including vancomycin. Disclosures All Authors: No reported disclosures

Spectrophotometric Determination of Ampicillin Using Chromogenic Reagents (MBTH and PDAC) and their Application in Pharmaceutical Formulations

The present work highlights the spectrophotometric method development and validation for the assay of ampicillin, a broad-spectrum β-lactam antibiotic. Two methods have been proposed by employing popular chromogenic reagents viz 3-methyl 2-benzothiazolinone hydrazone (MBTH) and para dimethyl amino cinnamaldehyde (PDAC). Method A involves the coupling of ampicillin with MBTH in the presence of ferric chloride through the oxidative mechanism, resulting in the formation of green coloured solution with a maximum absorption peak at 620 nm. In method B, the condensation reaction of ampicillin with an acidic solution of PDAC gave a coloured reddish-brown complex, showing a maximum absorption peak at 514nm. Linear calibration curve for MBTH and PDAC has been obtained while obeying Beer’s law in the concentration range of 0.5 -1 and 5-15 μg/ml having a good correlation coefficient of 0.9985 and 0.9974 respectively. The sensitivity of the submitted methods was found to be more than the reported methods. Both methods were successfully applied to a pharmaceutical formulation for quantifying the ampicillin effectively. Therefore, the developed spectrophotometric methods can serve as a good analytical assay procedure for ampicillin to undergo quality control in pharmaceutical setups.

Global impact of antibacterial resistance in patients with hematologic malignancies and hematopoietic cell transplant recipients.

Patients with hematologic malignancies and hematopoietic cell transplant (HCT) recipients are at high risk of developing bacterial infections. These patients may suffer severe consequences from these infections if they do not receive immediate effective therapies, and thus are uniquely threatened by antimicrobial-resistant bacteria. Here, we outline how the emergence of specific resistant bacteria threatens the effectiveness of established approaches to prevent and treat infections in this population. The emergence of fluoroquinolone resistance among Enterobacterales and viridans group streptococci may decrease the effectiveness of fluoroquinolone prophylaxis during neutropenia. The emergence of Enterobacterales that produce extended-spectrum β-lactamases or carbapenemases and of increasingly resistant Pseudomonas aeruginosa may result in neutropenic patients experiencing delayed time to active antibacterial therapy, and consequently worse clinical outcomes. The ability to select targeted antibacterial therapies after the availability of susceptibility data may be limited in patients infected with metallo-β-lactamase-producing Enterobacterales and difficult-to-treat P. aeruginosa. Vancomycin-resistant enterococci and Stenotrophomonas maltophilia can cause breakthrough infections in patients already being treated with broad-spectrum β-lactam antibiotics. Resistance can also limit the ability to provide oral stepdown antibacterial therapy for patients who could otherwise be discharged from hospitalization. We also outline strategies that have the potential to mitigate the negative impact of antimicrobial resistance, including interventions based on active screening for colonization with resistant bacteria and the use of novel rapid diagnostic assays. Additional research is needed to better understand how these strategies can be leveraged to combat the emerging crisis of antimicrobial resistance in patients with hematologic malignancies and HCT recipients.

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.

Klebsiella pneumoniae carbapenamases in Escherichia coli isolated from humans and livestock in rural south-western Uganda.

The accumulation of resistance genes in Escherichia coli (E. coli) strains imposes limitations in the therapeutic options available for the treatment of infections caused by E.coli. Production of Klebsiella pneumoniae carbapenemase (KPC) by E. coli renders it resistant to broad-spectrum β-lactam antibiotics. Globally there is existing evidence of spread of carbapenem-resistant E. coli in both humans and livestock driven by acquisition of the several other carbapenemase genes. Overall, there is little information regarding the extent of KPC gene distribution in E. coli. We set out to determine the prevalence, and evaluate the phenotypic and genotypic patterns of KPC in E. coli isolated from humans and their livestock in rural south western Uganda. A laboratory-based, descriptive cross-sectional study was conducted involving 96 human and 96 livestock isolates collected from agro-pastoralist communities in Mbarara district in south western Uganda. Phenotypic and molecular methods (PCR) were used for presence and identification of KPC genes in the E. coli isolates. A chi-square test of independence was used to evaluate the differences in resistant patterns between carbapenems and isolates. The overall prevalence of carbapenem resistance by disk diffusion susceptibility testing (DST) for both humans and livestock isolates were 41.7% (80/192). DST-based resistance was identical in both human and livestock isolates (41.7%). The prevalence of carbapenem resistance based on Modified Hodge Test (MHT) was 5% (2/40) and 10% (4/40) for humans and livestock isolates respectively. Both human and livestock isolates, 48.7% (95/192) had the KPC gene, higher than phenotypic expression; 41.7% (80/192). blaKPC gene prevalence was overall similar in human isolates (51%; 49/96) vs livestock isolates (47.9%; 46/96). Approximately, 19% (15/80) of the isolates were phenotypically resistant to carbapenems and over 70% (79/112) of the phenotypically sensitive strains harbored the blaKPC gene. Our results suggest that both human and livestock isolates of E. coli in our setting carry the blaKPC gene with a high percentage of strains not actively expressing the blaKPC gene. The finding of fewer isolates carrying the KPC gene than those phenotypically resistant to carbapenems suggests that other mechanisms are playing a role in this phenomenon, calling for further researcher into this phenomenon.

Highly selective fluorescent probe for benzidine determination using carbon dots fabricated from amoxicillin and sodium carbonate

Amoxicillin is one of the most important semi-synthetic penicillin broad-spectrum β-lactam antibiotics and has achieved many applications. There are few reports on its application for synthesizing carbon dots (CDs). Present work explored the possibility of amoxicillin converted into CDs with sodium carbonate used as the co-reactant employing facile hydrothermal method. The obtained CDs exhibited good selectivity and sensitivity to benzidine and could be explored as an effective fluorescence probe for monitoring benzidine. The fluorescence intensity of CDs was quenched based on the principle of static quenching due to the formation of a non-fluorescent complex between CD and benzidine. Within the range of 0.2–2 μM and 2–16 μM, CDs possessed good linear characteristics, high sensitivity, and a low detection limit of 0.08 μM. The results demonstrated that the fluorescence probe possessed the merits of simplicity, rapidity, low cost, short analytical time, high selectivity and sensitivity, and good stability. According to the verification results from the real water samples, the fluorescence probe had high reliability and feasibility, and could be employed for monitoring benzidine in waters.

Impact of Antibiotic Treatment on the Gut Microbiome and its Resistome in Hematopoietic Stem Cell Transplant Recipients.

Antibiotic-resistant bacterial infections are increasingly an issue in allogenic hematopoietic stem cell transplant patients. How antibiotic treatment impacts antibiotic resistance in the human gut microbiome remains poorly understood in vivo. Here, a total of 577 fecal samples from 233 heavily antibiotic-treated transplant patients were examined using high-resolution prescription data and shotgun metagenomics. The 13 most frequently used antibiotics were significantly associated with 154 (40% of tested associations) microbiome features. Use of broad-spectrum β-lactam antibiotics was most markedly associated with microbial disruption and increase in resistome features. The enterococcal vanA gene was positively associated with 8 of the 13 antibiotics, and in particular piperacillin/tazobactam and vancomycin. Here, we highlight the need for a high-resolution approach in understanding the development of antibiotic resistance in the gut microbiome. Our findings can be used to inform antibiotic stewardship and combat the increasing threat of antibiotic resistance.

Loss of outer membrane protein A (OmpA) impairs the survival of Salmonella Typhimurium by inducing membrane damage in the presence of ceftazidime and meropenem.

Salmonella enterica serovar Typhimurium is one of the significant non-typhoidal Salmonella serovars that causes gastroenteritis. The rapid development of antimicrobial resistance necessitates studying new antimicrobials and their therapeutic targets in this pathogen. Our study aimed to investigate the role of four prominent outer membrane porins of S. Typhimurium, namely OmpA, OmpC, OmpD and OmpF, in developing resistance against ceftazidime and meropenem. The antibiotic-mediated inhibition of bacterial growth was determined by measuring the absorbance and the resazurin assay. DiBAC4 (Bis-(1,3-Dibutylbarbituric Acid)Trimethine Oxonol), 2,7-dichlorodihydrofluoroscein diacetate (DCFDA) and propidium iodide were used to determine the outer membrane depolarization, reactive oxygen species (ROS) generation and subsequent killing of Salmonella. The expression of oxidative stress-response and efflux pump genes was quantified by quantitative RT-qPCR. HPLC was done to determine the amount of antibiotics that entered the bacteria. The damage to the bacterial outer membrane was studied by confocal and atomic force microscopy. The in vivo efficacy of ceftazidime and meropenem were tested in the C57BL/6 mouse model. Deleting ompA reduced the survival of Salmonella in the presence of ceftazidime and meropenem. Massive outer membrane depolarization and reduced expression of oxidative stress-response genes in S. Typhimurium ΔompA hampered its growth in the presence of antibiotics. The enhanced uptake of antibiotics and decreased expression of efflux pump genes in S. Typhimurium ΔompA resulted in damage to the bacterial outer membrane. The clearance of the S. Typhimurium ΔompA from C57BL/6 mice with ceftazidime treatment proved the role of OmpA in rendering protection against β-lactam antibiotics. OmpA protects S. Typhimurium from two broad-spectrum β-lactam antibiotics, ceftazidime and meropenem, by maintaining the stability of the outer membrane.

Enhancing antimicrobial activity of β-lactam antibiotic via functionalized mesoporous carbon-based delivery platforms

Bacterial immunity to antibiotics is currently increasing as a result of inadequate drug use and the generation of antimicrobial resistance. Developing new antibiotics is challenging, hence suitable carriers are sought to enhance activity of already known drugs. The ordered mesoporous carbons modified with urea, thiourea, and cetyltrimethylammonium bromide (CTAB), presented in this study, show great potential as carrier platforms for tebipenem pivoxil - a broad-spectrum orally-administered β-lactam antibiotic. The functional groups generated on the surface of carbon materials contributed to the reduction of their negative surface charge, which turned into positive under low pH conditions. At the same time, they led to a decrease in the hexagonal structure ordering of the carbon samples and a deterioration of the textural parameters. The effect of the amount of modifier used on the ability of carbon materials to release the selected antibiotic was investigated. The drug release process was carried out in two different environments (neutral and strongly acidic). It has been shown that the presence of functional groups on the surface of carbon carriers determines the amount of antibiotic liberated, especially at pH 7.0. The antimicrobial activity of the tebipenem pivoxil-loaded into the carbon carriers was assessed on a group of gram-positive and gram-negative bacteria. The highest decrease in the minimal inhibitory concentration value for the CTAB-modified systems was demonstrated, indicating a better antimicrobial efficiency against pathogenic strains coupled with an improvement in tebipenem pivoxil solubility. Small and negatively charged worm-like particles of the surfactant-functionalized carbon carrier are characterized by better dispersion in the receptor fluid resulting in faster and more effective diffusion of the antibiotic molecules from their outer surface. Ordered mesoporous carbons in addition to increased antibiotic dissolution rate, have no impact on drug permeability in the gastrointestinal tract in the in vitro model.

Radiolytic degradation of β-lactam and tetracycline antibiotics in the presence of protein

In this study, to explore the influence of protein on antibiotics degradation during ionizing irradiation, the binding interaction between bovine serum albumin (BSA) and the broad spectrum β-lactam and tetractycline antibiotics and its effect on antibiotic degradation were investigated. Static quenching happened between BSA and antibiotics involving penicillin G (PEG), cephalosporin C (CPC), oxytetracycline (OTC) and tetracycline hydrochloride (TTC), indicating the formation of non-fluorescence complexes. The binding capacity followed the order: TTC > CPC > OTC > PEG. As exposed to γ-irradiation, the β-lactam antibiotics showed a higher degradation rate than the tetracyclines. The degradation rate constant (k) of CPC and PEG was 1.4–2.0 times higher than that of OTC and TTC. In presence of BSA, the k values (kBSA) of all the four antibiotics decreased greatly and the degradation rate of CPC and PEG was still higher by 1.2–1.3 times than that of OTC and TTC. No correlation between k/kBSA and the binding affinity was observed. The presence of BSA has little effect on the trend of abatement of antimicrobial activity to S. aureus during γ-irradiation. This suggests that the inhibition of protein to antibiotic degradation was mainly attributed to the competition of protein for the active species such as ·OH radical formed during γ-irradiation, while the binding ability of protein to antibiotics has no obvious effect. The results of this study contributed to develop technical strategies to improve the removal of antibiotics completely in real water matrices.

PREVALENCE OF PHENOTYPIC CARBAPENEM-RESISTANT ENTEROBACTERALES ISOLATES AND THEIR DISTRIBUTION BY SEX, AGE GROUPS, STATE AND SPECIES IN SOUTH-EAST NIGERIA

Background: Carbapenems are broad spectrum β-lactam antibiotics that were introduced in response to the emergence of ESBL-producing Gram-negative bacteria. This study aimed at determining the occurence of carbapenem resistant Enterobacterales isolates among patients attending five tertiary hospitals with southeastern region of Nigeria. Methods: A total of 400 Enterobacterales were isolated from different participants. Carbapenem-resistance was detected using Kirby-Bauer disc diffusion method with ertapenem, meropenem, imipenem, and doripenem. Results: A total of 117 isolates (29.2%) were resistant to the four carbapenems. When compared among the states, the prevalence were 33.6%, 29.1%, 28.8%, 26.9% and 24.7% for Enugu, Ebonyi, Imo, Anambra and Abia states respectively. The highest resistance was observed among P. mirabilis (52.6%) followed by K. oxytoca (35.7%), S. enterica (35.7%) and K. pneumoniae (33.8%). Conclusion: The overall prevalence was high and this is a cause for concern and urgent need for emergency intervention to forestall widespread emergence of pandrug resistant infections.

Determination of amoxicillin trihydrate impurities 4-hydroxyphenylglycine (4-HPG) and 6-Aminopenicylanic acid (6-APA) by means of ultraviolet spectroscopy

Amoxicillin is one of the broad-spectrum β-lactam antibiotics widely used in the treatment of many diseases. It is inevitable that 4-hydroxyphenylglycine (4-HPG) and 6-Aminopenicylanic acid (6-APA), which are used during the production of this antibiotic, are incorporated into the molecular lattice of the product as impurities. Today, many expensive methods and chemical devices are used for the purification of Amoxicillin by determining 6-APA and 4-HPG, which are defined as impurities. In this study, it was aimed to develop a fast, simple, and specific UV-spectrophotometric method for the determination of 4-HPG and 6-APA. Another aim of this article is to cause as little harm as possible to the environment and human health by using as few chemicals as possible throughout the study. In this study, all attempts to determine 6-APA and 4-HPG, which are impurities in the production of amoxicillin, were carried out with the help of a UV/VIS spectrophotometer. Also, Four different concentrations of NaOH were used as a solvent for each impurity. UV spectra of 4-HPG and 6-APA concentrations between 210 and 400 nm were measured. In the literature, the UV spectrum of 4-HPG has been revealed for the first time in this study and examined in detail. The UV spectrum of 4-HPG was characterized in 3 regions. Again, the response of 6-APA to different NaOH concentrations was demonstrated for the first time in this study. It was determined that the peaks of 6-APA dissolved in NaOH shifted from 222 nm to 227 nm depending on the concentration amount. In addition, it is an ideal green procedure that makes a difference in the literature, as the study is carried out for the control and determination of impurities without the use of any organic solvents or chemicals harmful to the environment.

Pneumococcal urinary antigen testing for antimicrobial guidance in community-acquired pneumonia–A register-based cohort study

ObjectivesTo evaluate the effect of pneumococcal urinary antigen test (UAT) usage on broad-spectrum antibiotic treatment in community-acquired pneumonia (CAP). MethodsPatients admitted to 32 Swedish hospitals between 2011 and 2014 were retrospectively included from the Swedish National Quality Register of CAP. Using propensity score matched data, stratified by CRB-65 score, we studied the effect of performing UAT and of positive test results on treatment with broad-spectrum β-lactam monotherapy (BSBM) and antibiotics with coverage for atypical bacteria compared to narrow-spectrum β-lactam monotherapy (NSBM). ResultsUAT was performed for 4,995/14,590 (34.2%) patients, 603/4,995 (12.1%) of whom had positive test results. At day three, performing UAT was not associated with decreased use of BSBM (OR 1.07, 95% CI 0.94–1.23) but was associated with increased atypical coverage among patients with CRB-65 score 2 (OR 1.47, 95% CI 1.06–2.02). A positive UAT was associated with decreased BSBM use (OR 0.39, 95% CI 0.25–0.60) and decreased atypical coverage (OR 0.25, 95% CI 0.16–0.37), predominantly in non-severe CAP. At day one, performing UAT was associated with atypical coverage among patients with CRB-65 scores 2 (OR 2.60, 95% CI 1.69–3.98) and 3–4 (OR 3.69, 95% CI 1.55–8.79), and a positive test reduced the odds of BSBM treatment among CRB-65 score 3–4 patients (OR 3.49, 95% CI 1.02–12.0). ConclusionsPerforming UAT had no overall effect on decreasing the use of BSBM treatment by day three of hospitalization, yet non-severely ill patients with positive UAT results were less likely to be treated with BSBM and antibiotics with atypical coverage.

A Suitable Therapeutic Drug Monitoring Method for Amoxicillin in Plasma by High Performance Liquid Chromatography–UV (HPLC–UV) in Neonates

Amoxicillin, a broad-spectrum β-lactam antibiotic, is widely used for treatment of neonatal infections. Despite the unmet need in neonates, an adapted analytical method is still missing in clinical practice. The purpose of this study was to develop and test an easy and credible high performance liquid chromatography–UV (HPLC–UV) method to determine amoxicillin in small volumes of human plasma and use it in routine therapeutic drug monitoring (TDM) of neonates. After a protein precipitation, amoxicillin for standards, quality control samples, and patient samples were separated by LC and measured by UV detection, and tinidazole was used as the internal standard. The calibration range was 0.50–20.0 μg/mL. Intra- and inter-day precisions were less than 4.7%. The acceptance criteria of accuracy (between 85–115%) were met in all cases. A plasma volume of 50 μL was required to achieve the limit of quantification of 0.50 μg/mL. Thus, a simple, rapid, and accurate HPLC–UV method has been developed to detect the concentration of amoxicillin in human plasma. This method was adapted to do TDM of amoxicillin in neonates.

Worldwide distribution and environmental origin of the Adelaide imipenemase (AIM-1), a potent carbapenemase in Pseudomonas aeruginosa.

Carbapenems are potent broad-spectrum β-lactam antibiotics reserved for the treatment of serious infections caused by multidrug-resistant bacteria such as Pseudomonas aeruginosa . The surge in P. aeruginosa resistant to carbapenems is an urgent threat, as very few treatment options remain. Resistance to carbapenems is predominantly due to the presence of carbapenemase enzymes. The assessment of 147 P . aeruginosa isolates revealed that 32 isolates were carbapenem non-wild-type. These isolates were screened for carbapenem resistance genes using PCR. One isolate from wastewater contained the Adelaide imipenemase gene (bla AIM-1) and was compared phenotypically with a highly carbapenem-resistant clinical isolate containing the bla AIM-1 gene. A further investigation of wastewater samples from various local healthcare and non-healthcare sources as well as river water, using probe-based qPCR, revealed the presence of the bla AIM-1 gene in all the samples analysed. The widespread occurrence of bla AIM-1 throughout Adelaide hinted at the possibility of more generally extensive spread of this gene than originally thought. A blast search revealed the presence of the bla AIM-1 gene in Asia, North America and Europe. To elucidate the identity of the organism(s) carrying the bla AIM-1 gene, shotgun metagenomic sequencing was conducted on three wastewater samples from different locations. Comparison of these nucleotide sequences with a whole-genome sequence of a P. aeruginosa isolate revealed that, unlike the genetic environment and arrangement in P. aeruginosa , the bla AIM-1 gene was not carried as part of any mobile genetic elements. A phylogenetic tree constructed with the deduced amino acid sequences of AIM-1 suggested that the potential origin of the bla AIM-1 gene in P. aeruginosa might be the non-pathogenic environmental organism, Pseudoxanthomonas mexicana .

Disruption of Metallostasis in the Anaerobic Human Pathogen Fusobacterium nucleatum by the Zinc Ionophore PBT2.

The Gram-negative anaerobe Fusobacterium nucleatum is an opportunistic human pathogen, most frequently associated with periodontal disease through dental biofilm formation and, increasingly, with colorectal cancer development and progression. F. nucleatum infections are routinely treated by broad-spectrum β-lactam antibiotics and metronidazole. However, these antibiotics can negatively impact the normal microflora. Therefore, the development of novel narrow-spectrum antimicrobials active against anaerobic pathogens is of great interest. Here, we examined the antimicrobial Zn ionophore PBT2, an 8-hydroxyquinoline analogue with metal chelating properties, against a single type isolate F. nucleatum ATCC 25586. PBT2-Zn was a potent inhibitor of growth and exhibited synergistic bactericidal (>3-log10 killing) activity at 5× MIC in planktonic cells, and at the MIC in biofilms grown in vitro. Physiological and transcriptional analyses uncovered a strong cellular response relating to Zn and Fe homeostasis in PBT2-Zn treated cells across subinhibitory and inhibitory concentrations. At 1× MIC, PBT2 alone induced a 3.75-fold increase in intracellular Zn, whereas PBT2-Zn challenge induced a 19-fold accumulation of intracellular Zn after 2 h. A corresponding 2.1-fold loss of Fe was observed at 1× MIC. Transcriptional analyses after subinhibitory PBT2-Zn challenge (0.125 μg/mL and 200 μM ZnSO4) revealed significant differential expression of 15 genes at 0.5 h, and 12 genes at 1 h. Upregulated genes included those with roles in Zn homeostasis (e.g., a Zn-transporting ATPase and the Zn-sensing transcriptional regulator, smtB) and hemin transport (hmuTUV) to re-establish Fe homeostasis. A concentration-dependent protective effect was observed for cells pretreated with hemin (50 μg/mL) prior to PBT2-Zn challenge. The data presented here supports our proposal that targeting the disruption of metallostasis by Zn-translocating ionophores is a strategy worth investigating further for the treatment of Gram-negative anaerobic pathogens.

Selective and fast removal and determination of β-lactam antibiotics in aqueous solution using multiple templates imprinted polymers based on magnetic hybrid carbon material

Selective and fast adsorption of five broad-spectrum β-lactam antibiotics included amoxicillin, cephalexin, cefazolin, penicillin G and oxacillin was achieved by novel surface molecular imprinting polymers (MIPs) with magnetic hybrid carbon material as the substrate. The characteristics of MIPs were studied by scanning electron microscope, Fourier transform infrared spectrometer, thermogravimetric analysis, etc. And through a series of adsorption experiments to examine the kinetics, isotherms, thermodynamics, selectivity and reusability for sorption of β-lactam antibiotics onto the MIPs. The adsorption equilibriums were accomplished in about 60 min with adsorption capacities of 4.57–24.55 mg g−1, while the adsorption process was preferably fitted with pseudo-second-order kinetic model and Freundlich model. The imprinting factors ranged from 1.88 to 9.94 indicated the MIPs possessed excellent recognition ability, and its good reusability was demonstrated after five times adsorption–desorption cycles without a large drop in adsorption capacity. Furthermore, a new detection method was developed by combining of MIPs with solid phase extraction and high performance liquid chromatography (MIPs-SPE-HPLC). Under the optimal SPE conditions, the limits of detection (LODs) for the five BLAs were 0.24–0.56 µg L−1, with RSDs of 0.76–5.39%. The synthesized MIPs and the proposed MIPs-SPE-HPLC method can be applied for the efficient, simultaneous separation and detection of BLAs.

Carbapenem-Resistant Enterobacteriaceae-Implications for Treating Acute Leukemias, a Subgroup of Hematological Malignancies.

Acute leukemias (AL) are a group of aggressive malignant diseases associated with a high degree of morbidity and mortality. Patients with AL are highly susceptible to infectious diseases due to the disease itself, factors attributed to treatment, and specific individual risk factors. Enterobacteriaceae presence (e.g., Klebsiella pneumonia and Escherichia coli) is a frequent cause of bloodstream infections in AL patients. Carbapenem-resistant Enterobacteriaceae (CRE) is an emerging health problem worldwide; however, the incidence of CRE varies greatly between different regions. Carbapenem resistance in Enterobacteriaceae is caused by different mechanisms, and CRE may display various resistance profiles. Bacterial co-expression of genes conferring resistance to both broad-spectrum β-lactam antibiotics (including carbapenems) and other classes of antibiotics may give rise to multidrug-resistant organisms (MDROs). The spread of CRE represents a major treatment challenge for clinicians due to lack of randomized clinical trials (RCTs), a limited number of antibiotics available, and the side-effects associated with them. Most research concerning CRE infections in AL patients are limited to case reports and retrospective reviews. Current research recommends treatment with older antibiotics, such as polymyxins, fosfomycin, older aminoglycosides, and in some cases carbapenems. To prevent the spread of resistant microbes, it is of pivotal interest to implement antibiotic stewardship to reduce broad-spectrum antibiotic treatment, but without giving too narrow a treatment to neutropenic infected patients.

A Matched Case-Case-Control Study of the Impact of Clinical Outcomes and Risk Factors of Patients with IMP-Type Carbapenemase-Producing Carbapenem-Resistant Enterobacteriaceae in Japan.

IMP-type carbapenemase, found in various Gram-negative bacteria, has been increasingly detected worldwide. We aimed to study the outcomes and risk factors for acquisition of IMP-type carbapenemase-producing carbapenem-resistant Enterobacteriaceae (IMP-CRE), as this has not been evaluated in detail. We conducted a matched case-case-control study of patients from whom IMP-CRE isolates were obtained. All patients who tested positive for IMP-CRE were included; they were matched with patients with carbapenem-susceptible Enterobacteriaceae (CSE) and with controls at a ratio of 1:1:2. The risk factors for acquisition for the CRE and CSE groups and mortality rates, which were calculated using multivariate logistic regression models with weighting according to the inverse probability of propensity scores, were compared. In total, 192 patients (96 patients each in the CRE and CSE groups, with 130 Enterobacter cloacae isolates and 62 Klebsiella sp. isolates) were included. The IMP-11 type was present in 43 patients, IMP-1 in 33, and IMP-60 and IMP-66 in 1 each; 31 patients with CRE (32.3%) and 34 with CSE (35.4%) developed infections. Multivariate analysis identified the following independent risk factors: gastrostomy, history of intravenous therapy or hemodialysis, and previous exposure to broad-spectrum β-lactam antibiotics, including penicillin with β-lactamase inhibitors, cephalosporins, and carbapenems. In propensity score-adjusted analysis, mortality rates for the CRE and CSE groups were similar (15.0% and 19.5%, respectively). We found that IMP-CRE may not contribute to worsened clinical outcomes, compared to CSE, and gastrostomy, previous intravenous therapy, hemodialysis, and broad-spectrum antimicrobial exposure were identified as risk factors for CRE isolation. Fluoroquinolone and aminoglycosides are potentially useful antibiotics for IMP-CRE infections.