Antibiotic susceptibility of Moraxella catarrhalis biofilms in a continuous flow model

Exploring the intricacies of antimicrobial resistance: Understanding mechanisms, overcoming challenges, and pioneering innovative solutions

Antimicrobial resistance (AMR) poses a growing global threat. This review examines AMR from diverse angles, tracing the story of antibiotic resistance from its origins to today's crisis. It explores the rise of AMR, from its historical roots to the urgent need to counter this escalating menace. The review explores antibiotic classes, mechanisms, resistance profiles, and genetics. It details bacterial resistance mechanisms with illustrative examples. Multidrug-resistant bacteria spotlight AMR's resilience. Modern AMR control offers hope through precision medicine, stewardship, combination therapy, surveillance, and international cooperation. Converging traditional and innovative treatments presents an exciting frontier as novel compounds seek to enhance antibiotic efficacy. This review calls for global unity and proactive engagement to address AMR collectively, emphasizing the quest for innovative solutions and responsible antibiotic use. It underscores the interconnectedness of science, responsibility, and action in combatting AMR. Humanity faces a choice between antibiotic efficacy and obsolescence. The call is clear: unite, innovate, and prevail against AMR.

Dynamic In Vitro PK/PD Infection Models for the Development and Optimisation of Antimicrobial Regimens: A Narrative Review

The antimicrobial concentration-time profile in humans affects antimicrobial activity, and as such, it is critical for preclinical infection models to simulate human-like dynamic concentration-time profiles for maximal translatability. This review discusses the setup, principle, and application of various dynamic in vitro PK/PD infection models commonly used in the development and optimisation of antimicrobial treatment regimens. It covers the commonly used dynamic in vitro infection models, including the one-compartment model, hollow fibre infection model, biofilm model, bladder infection model, and aspergillus infection model. It summarises the mathematical methods for the simulation of the pharmacokinetic profile of single or multiple antimicrobials when using the serial or parallel configurations of in vitro systems. Dynamic in vitro models offer reliable pharmacokinetic/pharmacodynamic data to help define the initial dosing regimens of new antimicrobials that can be developed further in clinical trials. They can also help in the optimisation of dosing regimens for existing antimicrobials, especially in the presence of emerging antimicrobial resistance. In conclusion, dynamic in vitro infection models replicate the interactions that occur between microorganisms and dynamic antimicrobial exposures in the human body to generate data highly predictive of the clinical efficacy. They are particularly useful for the development new treatment strategies against antimicrobial-resistant pathogens.

Antimicrobial Properties of Mono- and Di-fac-rhenium Tricarbonyl 2-Pyridyl-1,2,3-triazole Complexes

A family of mono- and di-fac-rhenium tricarbonyl 2-pyridyl-1,2,3-triazole complexes with different aliphatic and aromatic substituents was synthesized in good-to-excellent yields (46–99 %). The complexes were characterized by 1H and 13C NMR spectroscopy, infrared spectroscopy, electronic (UV-visible) spectroscopy, high-resolution electrospray mass spectrometry, and elemental analyses. In four examples, the solid-state structures of the rhenium(i) complexes were confirmed by X-ray crystallography. The family of the mono- and di-rhenium(i) complexes and the corresponding 2-pyridyl-1,2,3-triazole was tested for antimicrobial activity in vitro against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) microorganisms. Agar-based disk diffusion assays indicated that most of the rhenium(i) complexes were active against Staphylococcus aureus and that the cationic rhenium(i) complexes were more active than the related neutral systems. However, in all cases, the minimum inhibitory concentrations for all the complexes were modest (i.e. 16–1024 µg mL–1).

Growth of MRSA and Pseudomonas aeruginosa in a fine-celled foam model containing sessile commensal skin bacteria

Sessile cultures of the skin bacteria Staphylococcus saprophyticus and Corynebacterium xerosis were grown using novel fine-celled foam substrata to test the outcome of challenge by methicillin-resistant Staphylococcus aureus or Pseudomonas aeruginosa under three growth medium regimens (simulated sweat, simulated serum or simulated sweat substituted with simulated serum during the microbial challenge). S. saprophyticus and C. xerosis significantly limited MRSA and P. aeruginosa immigration respectively, under the simulated sweat and serum medium regimes. Under the substitution medium regime however, MRSA and P. aeruginosa integrated into pre-established biofilms to a significantly greater extent, attaining cell densities similar to the axenic controls. The outcome of challenge was influenced by the medium composition and test organism but could not be predicted based on planktonic competition assays or growth dynamics. Interactions between skin and wound isolates could be modelled using the fine-celled foam-based system. This model could be used to further investigate interactions and also in preclinical studies of antimicrobial wound care regimens.

Detection of biofilm in bronchoalveolar lavage from children with non-cystic fibrosis bronchiectasis

BACKGROUND

The presence of Pseudomonas aeruginosa biofilms in lower airway specimens from cystic fibrosis (CF) patients is well established. To date, biofilm has not been demonstrated in bronchoalveolar lavage (BAL) from people with non-CF bronchiectasis. The aim of this study was to determine (i) if biofilm was present in BAL from children with and without bronchiectasis, and (ii) if biofilm detection differed between sequentially collected BAL.

METHODS

Testing for biofilm in two sequentially collected BAL from children with and without bronchiectasis was done using BacLight™ live-dead staining and lectin staining for extracellular polymeric biofilm matrices. Bacterial culture and cytological measures were performed on the first and second lavages, respectively. Clinically important BAL infection was defined as >10⁴  cfu of respiratory pathogens/ml BAL.

RESULTS

Biofilm was detected in BAL from seven of eight (87.5%) children with bronchiectasis (aged 0.8-6.9 years), but was not detected in any of three controls (aged 1.3-8.6 years). The biofilms contained both live and dead bacteria irrespective of antibiotic use prior to bronchoscopy. Biofilm was detected more frequently in the second lavage than the first. Three of the seven biofilm-positive BAL were culture-positive for respiratory pathogens at clinically important levels.

CONCLUSIONS

Biofilm is present in BAL from children with non-CF bronchiectasis even when BAL-defined clinically important infection was absent. Studies to characterize lower airway biofilms and determine how biofilm contributes to bronchiectasis disease progression and treatment outcomes are necessary. Pediatr Pulmonol. 2015; 50:284-292. © 2014 Wiley Periodicals, Inc.

Do orally administered antibiotics reach concentrations in the middle ear sufficient to eradicate planktonic and biofilm bacteria? A review

INTRODUCTION

Infectious conditions of the middle ear are a common and significant cause of morbidity and mortality worldwide. Systemic antibiotics are frequently used, but their effectiveness will depend on whether an adequate antibiotic concentration is achieved in the middle ear; this is especially important in biofilm infections such as otitis media with effusion (OME), where high antibiotic concentrations are typically required for effective treatment.

OBJECTIVE

This review examines what antibiotic levels can be reached in the middle ear with oral administration, as a means of guiding rational antibiotic choice in the clinic and future research, and to determine whether levels high enough for biofilm eradication are reached.

METHODS

A literature search of studies measuring levels of antibiotics in the plasma and in the middle ear after oral administration was conducted. These levels were compared to the minimum inhibitory concentrations (MIC) provided by the European Committee for Antimicrobial Susceptibility Testing (EUCAST) to determine if antibiotic doses were reaching sufficient levels to inhibit planktonic bacteria. The middle ear concentrations were then calculated as a multiple of the MIC to determine if the concentrations were reaching biofilm eradication concentrations (typically up to 1000×MIC).

RESULTS

The highest antibiotic levels against Staphylococcus aureus reach 8.3×MIC, against Moraxella catarrhalis 33.2×MIC, against Haemophilus influenzae 31.2×MIC, and against Streptococcus pneumoniae 46.2×MIC. The macrolide antibiotics reach higher levels in the middle ear than in plasma.

CONCLUSIONS

Orally administered antibiotics reach levels above the MIC in the middle ear. However, they do not reach levels that would be likely to eradicate biofilms.