Cephalosporins, carbapenems, and monobactams

Reasons and riddance of Agrobacterium tumefaciens overgrowth in plant transformation

Agrobacterium tumefaciens-mediated plant transformation has become routine work across the world to study gene function and the production of genetically modified plants. However, several issues hamper the transformation process in a profound way, both directly and indirectly. One of the major concerns is the overgrowth of Agrobacterium, which occasionally appears after the co-cultivation phase of the explant. This phenomenon is reported in several species and seems to spoil the whole transformation process. There are multiple approaches being employed to counter this unwanted growth of bacteria in a few plant species. In reality, once the overgrowth appears, it becomes nearly impossible to cure it. Hence, for the prevention of this phenomenon, numerous factors are regulated. These factors are: explant nature, A. tumefaciens strain, T-DNA vector, co-cultivation (time and condition), acetosyringone, washing medium, antibiotics (type, concentration, combination, incubation period), etc. In this article, we discuss these factors based on available reports. It can be of immense help in formulating viable strategies to control A. tumefaciens overgrowth.

Complex-Forming Properties of Ceftazidime with Fe(III) Ions in an Aqueous Solution

In the present study, the complexing properties of ceftazidime with Fe(III) ions in aqueous solutions were characterized by UV-vis spectrophotometric and potentiometric methods. Using the UV-vis spectrophotometric method, the absorbance values for Fe(III) ions, a third-generation cephalosporin antibiotic (ceftazidime), and the Fe(III)-ceftazidime system were determined. Based on pH-metric studies, the value of the stability constant for the Fe(III)-ceftazidime complex was calculated.

Antimicrobial activity and mode of action of 1,8-cineol against carbapenemase-producing Klebsiella pneumoniae

Antimicrobial resistance remains one of the most challenging issues that threatens the health of people around the world. Plant-derived natural compounds have received considerable attention for their potential role to mitigate antibiotic resistance. This study was carried out to assess the antimicrobial activity and mode of action of a monoterpene, 1,8-cineol (CN) against carbapenemase-producing Klebsiella pneumoniae (KPC-KP). Results showed that resazurin microplate assay and time-kill analysis revealed bactericidal effects of CN at 28.83 mg/mL. Zeta potential showed that CN increased the surface charge of bacteria and an increase of outer membrane permeability was also detected. CN was able to cause leakage of proteins and nucleic acids in KPC-KP cells upon exposure to CN and ethidium bromide influx/efflux experiment showed the uptake of ethidium bromide into the cell; this was attributed to membrane damage. CN was also found to induce oxidative stress in CN-treated KPC-KP cells through generation of reactive oxygen species which initiated lipid peroxidation and thus damaging the bacterial cell membrane. Scanning and transmission electron microscopies further confirmed the disruption of bacterial cell membrane and loss of intracellular materials. In this study, we demonstrated that CN induced oxidative stress and membrane damage resulting in KPC-KP cell death.

Emerging Strategies to Combat β-Lactamase Producing ESKAPE Pathogens

Since the discovery of penicillin by Alexander Fleming in 1929 as a therapeutic agent against staphylococci, β-lactam antibiotics (BLAs) remained the most successful antibiotic classes against the majority of bacterial strains, reaching a percentage of 65% of all medical prescriptions. Unfortunately, the emergence and diversification of β-lactamases pose indefinite health issues, limiting the clinical effectiveness of all current BLAs. One solution is to develop β-lactamase inhibitors (BLIs) capable of restoring the activity of β-lactam drugs. In this review, we will briefly present the older and new BLAs classes, their mechanisms of action, and an update of the BLIs capable of restoring the activity of β-lactam drugs against ESKAPE (Enterococcus spp., Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.) pathogens. Subsequently, we will discuss several promising alternative approaches such as bacteriophages, antimicrobial peptides, nanoparticles, CRISPR (clustered regularly interspaced short palindromic repeats) cas technology, or vaccination developed to limit antimicrobial resistance in this endless fight against Gram-negative pathogens.

Global travel and Gram-negative bacterial resistance; implications on clinical management

INTRODUCTION

Antimicrobial resistance (AR) is escalating worldwide with the potential for dire consequences, global travel contributes to the dissemination of resistant pathogens from one region to another. The World Health Organization identified the rapid emergence and prevalence of carbapenem-resistant Gram-negative species, including Enterobacterales, Acinetobacter baumannii, and Pseudomonas aeruginosa, as an international crisis due to treatment challenges, poor health outcomes, increased mortality, and high economic costs caused by these pathogens.

AREAS COVERED

This review describes key carbapenem-resistant (CR) Gram-negative species, changes in current global and regional trends, AR surveillance and reporting, and identifies drivers of change, specifically travel. Finally, we review clinical implications and challenges of treating CR infections which exist due to widespread dissemination of CR bacteria. A literature search was conducted using PubMed, Google Scholar, Ebsco, and ProQuest (from 2000 to December 2019).

EXPERT OPINION

The level of global travel is increasing, and antimicrobial resistance continues to disseminate worldwide. Healthcare providers risk assessment for AR needs to consider a patient's recent travel history, including pre-travel and intra-travel antimicrobial prescription, and potential exposure based on geography. Patient education, healthcare provider awareness, and access to data and surveillance resources are critical to inform antimicrobial selection and improve health outcomes.

Double-carbapenem therapy in the treatment of multidrug resistant Gram-negative bacterial infections: a systematic review and meta-analysis

BACKGROUND

To compare the efficacy and safety of double-carbapenem therapy (DCT) with other antibiotics for the treatment of multidrug resistant (MDR) Gram-negative bacterial infections.

METHODS

Cochrane Library, PubMed, Embase and Web of Science as well as Chinese databases were searched from database establishment to February 2019. All types of studies were included if they had evaluated efficacy and safety of DCT regimens in patients with MDR Gram-negative bacterial infections. Clinical response, microbiological response, adverse events and mortality were the main outcomes. The protocol was registered with PROSPERO No. CRD42019129979.

RESULTS

Three cohort or case-control studies consisting of 235 patients and 18 case series or case reports consisting of 90 patients were included. The clinical and microbiological responses were similar between DCT and other regimens in patients with carbapenem-resistant Enterobacteriaceae (CRE) infection. DCT achieved a lower mortality than comparators in patients with CRE infection (OR = 0.44, 95% CI = 0.24-0.82, P = 0.009). Ertapenem was the most reported antibiotic in DCT regimens in case series or case reports. Moreover, clinical and microbiological improvements were found in 59 (65.6%) and 63 (70%) in total 90 cases, respectively.

CONCLUSIONS

DCT was as effective as other antibiotics in treating MDR Gram-negative bacterial infections, with similar efficacy response and lower mortality. DCT could be an alternative therapeutic option in the treatment of MDR Gram-negative bacterial infections. High-quality randomized controlled trials were required to confirm the beneficial effects of DCT.

Impacto en el consumo de amikacina y ceftriaxona en una unidad de emergencias de adultos, luego de la implementación de una guía para el tratamiento de la infección urinaria alta

Introducción: los programas de optimización del uso de antimicrobianos son fundamentales para mejorar los resultados clínicos de los pacientes.Objetivos: determinar el impacto en el consumo de amikacina y ceftriaxona, además de cambios de sensibilidad de las principales bacterias en la unidad de emergencias del hospital Carlos van Buren de Valparaíso, Chile, luego de la implementación de una guía para el tratamiento de la ITU alta.Materiales y método: estudio cuasi-experimental antes/después. Se implementó una guía de tratamiento para la ITU alta, la cual fue enviada vía WhatsApp a los médicos de la unidad. Luego se midieron las dosis diarias definidas (DDD) de amikacina y ceftriaxona y se compararon con las DDD de los mismos meses del año anterior. Además se extrajo la sensibilidad de E.coli, K. pneumonia y P.mirabilis aisladas de urocultivos.Resultados: posterior a la intervención hubo un aumento de las DDD de amikacina y una disminución de las de ceftriaxona. K.pneumoniae mantuvo su sensibilidad a amikacina y la aumentó para cefotaxima, ertapenem y meropenem.Conclusiones: la implementación de una guía de tratamiento de la ITU alta aumentó el consumo de amikacina y disminuyó el de ceftriaxona. K.pneumoniae aumentó su sensibilidad a cefotaxima, ertapenem y meropenem.

Penicillin G Treatment in Infective Endocarditis Patients - Does Standard Dosing Result in Therapeutic Plasma Concentrations?

Penicillin G is frequently used to treat infective endocarditis (IE) caused by streptococci, penicillin-susceptible staphylococci and enterococci. Appropriate antibiotic exposure is essential for survival and reduces the risk of complications and drug resistance development. We determined penicillin G plasma concentration [p-penicillin] once weekly in 46 IE patients. The aim was to evaluate whether penicillin G 3 g every 6 hr (q6 h) resulted in therapeutic concentrations and to analyse potential factors that influence inter- and intra-individual variability, using linear regression and a random coefficient model. [P-penicillin] at 3 hr and at 6 hr was compared with the minimal inhibitory concentration (MIC) of the bacteria isolated from blood cultures to evaluate the following PK/PD targets: 50% fT > MIC and 100% fT > MIC. [P-penicillin] varied notably between patients and was associated with age, weight, p-creatinine and estimated creatinine clearance (eCLcr). Additionally, an increase in [p-penicillin] during the treatment period showed strong correlation with age, a low eCLcr, a low weight and a low p-albumin. Of the 46 patients, 96% had [p-penicillin] that resulted in 50% fT > MIC, while 71% had [p-penicillin] resulting in 100% fT > MIC. The majority of patients not achieving the 100% fT > MIC target were infected with enterococci. Streptococci and staphylococci isolated from blood cultures were highly susceptible to penicillin G. Our results suggest that penicillin G 3 g q6 h is suitable to treat IE caused by streptococci and penicillin-susceptible staphylococci, but caution must be taken when the infection is caused by enterococci. When treating enterococci, therapeutic drug monitoring should be applied to optimize penicillin G dosing and exposure.

A Review of Antibiotics in Dermatology

Background:

Since the early 1930s when antibiotics were first introduced, they have revolutionized the way physicians treat infections. Skin conditions from acne to leprosy, which were once shunned by society, are now easily treated with oral antibiotics.

Objective:

Antibiotics are chemicals derived from bacteria and fungi that uniquely have antibacterial action. The most notable example is penicillin, which is derived from a mold. With hundreds of antibiotics available to the practicing physician, improper use of these drugs has become widespread and expensive and has spawned resistant strains. For the dermatologist, antibiotics are vital weapons in the drug armamentarium for treating various skin conditions.

Conclusion:

This review explores the newest and most common oral, parenteral, and topical antibiotics used in dermatology, their indications, adverse effects, dosage, and spectrum of activity. Furthermore, systemic antibacterial prophylaxis and vaccines pertinent to dermatology are discussed. The penicillins, cephalosporins, tetracyclines, macrolides, fluoroquinolones, sulfonamides, aminoglycosides, lincosamides, folate inhibitors, and a new synthetic class of drugs, the oxazolidinones, are reviewed. These antibiotics are used to treat a variety of organisms.

Effect of antibiotics on callus regeneration during transformation of IR 64 rice

We report here the effect of antibiotics on the regeneration potential of recalcitrant indica rice cultivar, IR64. Different protocols reporting high-efficiency agro-bacterium-mediated transformation of mature seed-derived regenerative calli were used and compared. The putative transgenic (T0) plants were analyzed for integration of the transgene through polymerase chain reaction and Southern blotting analyses. It was observed that the high-efficiency transformation of scutellar-derived regenerative calli could be obtained by using maltose as a carbon source and increased quantity of 2,4-D on a medium containing a higher concentration of gelling agent. The percentage of regeneration is greatly affected by the presence of antibiotics.

Antimicrobial agents, drug adverse reactions and interactions, and cancer

The intent of this chapter is to review the types of adverse drug reactions and interactions associated with antimicrobial agents, specifically in the setting of patients with malignancies. The initial sections will discuss categorizing and describing the mechanisms of adverse reactions and interactions. The later sections include a detailed discussion about adverse reactions and drug interactions associated with commonly used antibacterial, antiviral, and antifungal agents in this subpopulation. Where relevant, the clinical use and indication for the drugs will be reviewed. The antibacterial section will specifically address the emergence of antimicrobial resistance and drugs of last resort (newer agents, such as linezolid and daptomycin and novel uses of older previously retired agents, such as polymyxin B). The antifungal section will address the ramification of pharmacokinetic interactions and the need to measure drug levels. The chapter is not meant to be exhaustive and as such will not extensively address all antimicrobials or all interactions for each of these agents.

The Rg1 allele as a valuable tool for genetic transformation of the tomato 'Micro-Tom' model system

BACKGROUND

The cultivar Micro-Tom (MT) is regarded as a model system for tomato genetics due to its short life cycle and miniature size. However, efforts to improve tomato genetic transformation have led to protocols dependent on the costly hormone zeatin, combined with an excessive number of steps.

RESULTS

Here we report the development of a MT near-isogenic genotype harboring the allele Rg1 (MT-Rg1), which greatly improves tomato in vitro regeneration. Regeneration was further improved in MT by including a two-day incubation of cotyledonary explants onto medium containing 0.4 μM 1-naphthaleneacetic acid (NAA) before cytokinin treatment. Both strategies allowed the use of 5 μM 6-benzylaminopurine (BAP), a cytokinin 100 times less expensive than zeatin. The use of MT-Rg1 and NAA pre-incubation, followed by BAP regeneration, resulted in high transformation frequencies (near 40%), in a shorter protocol with fewer steps, spanning approximately 40 days from Agrobacterium infection to transgenic plant acclimatization.

CONCLUSIONS

The genetic resource and the protocol presented here represent invaluable tools for routine gene expression manipulation and high throughput functional genomics by insertional mutagenesis in tomato.

Agrobacterium-mediated transformation of the dwarf pomegranate (Punica granatum L. var. nana)

The dwarf pomegranate (Punica granatum L. var. nana) is a dwarf ornamental plant that has the potential to be the model plant of perennial fruit trees because it bears fruits within 1 year of seedling. We established an Agrobacterium-mediated transformation system for the dwarf pomegranate. Adventitious shoots regenerated from leaf segments were inoculated with A. tumefaciens strain EHA105 harboring the binary vector pBin19-sgfp, which contains neomycin phosphotransferase (npt II) and green fluorescent protein (gfp) gene as a selectable and visual marker, respectively. After co-cultivation, the inoculated adventitious shoots were cut into small pieces to induce regeneration, and then selected on MS medium supplemented with 0.5 muM alpha-naphthaleneacetic acid (NAA), 5 muM N(6)-benzyladenine (BA), 0.3% gellan gum, 50 mg/l kanamycin, and 10 mg/l meropenem. Putative transformed shoots were regenerated after 6-8 months of selection. PCR and PCR-Southern blot analysis revealed the integration of the transgene into the plant genome. Transformants bloomed and bore fruits within 3 months of being potted, and the inheritance of the transgene was confirmed in T(1) generations. The advantage of the transformation of dwarf pomegranate was shown to be the high transformation rate. The establishment of this transformation system is invaluable for investigating fruit-tree-specific phenomena.

Evaluation of 12 beta-lactam antibiotics for Agrobacterium-mediated transformation through in planta antibacterial activities and phytotoxicities

The antibacterial activities of 12 beta-lactam antibiotics against Agrobacterium tumefaciens strains LBA4404 and EHA101 living in tobacco (Nicotiana tabacum L.) leaf tissues, and their phytotoxicities to tobacco leaf tissues were evaluated. All beta-lactams at minimum bactericidal concentration (MBC) or higher showed weak bactericidal activities against agrobacteria persisting in tobacco leaf tissues. The beta-lactams evaluated were classified into two major groups according to their inhibitory effect on shoot regeneration of tobacco leaf tissues: (1) highly phytotoxic drugs, and (2) moderately phytotoxic drugs. According to these results, suitable kind and concentration of beta-lactam antibiotics were evaluated for Agrobacterium-mediated transformation.

Changes in infection control practice to reduce MRSA infection

An increase in the incidence of methicillin-resistant Staphylococcus aureus (MRSA) led to a review of infection control practice within the cardiothoracic directorate in a South London teaching hospital. Several changes in aspects of care were implemented including educational initiative, extension of the admission screening policy, a specific isolation nursing team and the development of a care pathway. This led to a considerable reduction in cross-infection rates. It was recognized that high-quality, high nurse-to-patient ratio and education on fundamental aspects of barrier nursing were necessary to maintain the low infection rates.

A review of antibiotics in dermatology

BACKGROUND

Since the early 1930s when antibiotics were first introduced, they have revolutionized the way physicians treat infections. Skin conditions from acne to leprosy, which were once shunned by society, are now easily treated with oral antibiotics.

OBJECTIVE

Antibiotics are chemicals derived from bacteria and fungi that uniquely have antibacterial action. The most notable example is penicillin, which is derived from a mold. With hundreds of antibiotics available to the practicing physician, improper use of these drugs has become widespread and expensive and has spawned resistant strains. For the dermatologist, antibiotics are vital weapons in the drug armamentarium for treating various skin conditions.

CONCLUSION

This review explores the newest and most common oral, parenteral, and topical antibiotics used in dermatology, their indications, adverse effects, dosage, and spectrum of activity. Furthermore, systemic antibacterial prophylaxis and vaccines pertinent to dermatology are discussed. The penicillins, cephalosporins, tetracyclines, macrolides, fluoroquinolones, sulfonamides, aminoglycosides, lincosamides, folate inhibitors, and a new synthetic class of drugs, the oxazolidinones, are reviewed. These antibiotics are used to treat a variety of organisms.