Comparison of agar dilution, broth dilution, and disk diffusion testing of ampicillin against Haemophilus species by using in-house and commercially prepared media

Encapsulation of Alpinia leaf essential oil in nanophytosome-embedded gel as novel strategy to treat periodontal infections: evaluation of antimicrobial effectiveness, pharmacokinetic, in vitro-ex vivo correlation and in silico studies

AIM

The work reports a novel nanophytosomal gel encapsulating Alpinia galanga (L.) Willd leaf essential oil to treat periodontal infections.

METHODS

Alpinia oil-loaded nanophytosomes (ANPs) were formulated by lipid layer hydration technique and were evaluated by FESEM, cryo-TEM, loading efficiency, zeta potential, particle size, release profile etc. Selected ANPs-loaded gel (ANPsG) was evaluated by both in vitro and in vivo methods.

RESULTS

Selected ANPs were spherical, unilamellar, 49.32 ± 2.1 nm size, 0.45 PDI, -46.7 ± 0.8 mV zeta potential, 9.8 ± 0.5% (w/w) loading, 86.4 ± 3.02% (w/w) loading efficiency with sustained release profile. ANPsG showed good spreadability (6.8 ± 0.3 gm.cm/sec), extrudability (79.33 ± 1.5%), viscosity (36522 ± 0.82 cps), mucoadhesive strength (44.56 ± 3.5 gf) with sustained ex vivo release tendency. Satisfied ZOI and MIC was observed for ANPsG against periodontal bacteria vs. standard/control. ANPsG efficiently treated infection in ligature induced periodontitis model. Key pharmacokinetic parameters like AUC, MRT, Vd were enhanced for ANPsG.

CONCLUSION

ANPsG may be investigated for futuristic clinical studies.

Ring-opening metathesis polymerization of N-methylpyridinium-fused norbornenes to access antibacterial main-chain cationic polymers

Cationic polymers have been identified as a promising type of antibacterial molecules, whose bioactivity can be tuned through structural modulation. Recent studies suggest that the placement of the cationic groups close to the core of the polymeric architecture rather than on appended side chains might improve both their bioactivity and selectivity for bacterial cells over mammalian cells. However, antibacterial main-chain cationic polymers are typically synthesized via polycondensations, which do not afford precise and uniform molecular design. Therefore, accessing main-chain cationic polymers with high degrees of molecular tunability hinges upon the development of controlled polymerizations tolerating cationic motifs (or cation progenitors) near the propagating species. Herein, we report the synthesis and ring-opening metathesis polymerization (ROMP) of N-methylpyridinium-fused norbornene monomers. The identification of reaction conditions leading to a well-controlled ROMP enabled structural diversification of the main-chain cationic polymers and a study of their bioactivity. This family of polyelectrolytes was found to be active against both Gram-negative (Escherichia coli) and Gram-positive (Methicillin-resistant Staphylococcus aureus) bacteria with minimal inhibitory concentrations as low as 25 µg/mL. Additionally, the molar mass of the polymers was found to impact their hemolytic activity with cationic polymers of smaller degrees of polymerization showing increased selectivity for bacteria over human red blood cells.

Antibacterial activity of Putranjiva Roxburghii wall

Medicinal plants can be defined as plants that possess therapeutic properties or exert a beneficial pharmacological effect on the human or animal body. P. roxburghii is a good moderate sized evergreen medicinal tree with pendent branches and the leaves are simple and alternately arranged. The aim of this study was to screen and determine significant antibacterial activity of dry seeds of P. roxburghii. The ethanol extract of P. roxburghii seed showed highest zone of inhibition in all the bacterial strains tested Staphylococcus aureus (G+) (16mm).  Streptococcus mutans (G+) (19mm) Bacilus subtilis (G+) (20mm). E.coli (G-) (21mm). Klebsiella pneumonia (G-) (14mm) Proteus vulgaris (G-) (16mm). The  acetone  extract of  P. roxburghii seeds showed a minimum zone  of  inhibition against the bacterial pathogens. They are Staphylococcus aureus (G+) (11mm).  Streptococcus mutans (G+) (8mm) Bacilus subtilis (G+) (14mm). E.coli (G-) (15mm). Klebsiella pneumonia (G-) (13mm) Proteus vulgaris (G-) (15mm). The  aqueous  extract of  P. roxburghii seeds showed the lowest zone  of  inhibition against the bacterial strains. They are  Staphylococcus aureus (G+) (13mm).  Streptococcus mutans (G+) (9mm) . E.coli (G-) (14mm).

An automated and portable antimicrobial susceptibility testing system for urinary tract infections

Urinary tract infections (UTIs) are bacterial infections that 1) commonly affect females, 2) can pose high risks to impair kidney function, 3) are often treated with broad-spectrum antibiotics, and 4) are associated with high recurrence rates due to the evolution of drug-resistant strains. To choose the appropriate antibiotic, the minimum inhibitory concentration (MIC) among a panel of antibiotics should be determined before administration to avoid inadequate dosing or use of wrong antibiotics. To meet with the unmet needs, we developed a bead-based method for bacterial preconcentration with capture rates ranging from 20-50% and then automatically performed on-chip AST on an automated device which was composed of a pneumatic control module, a temperature control module and a chip image processing module. The developed portable system was capable of automatically conducting AST and MIC measurements using urine samples (via image analysis) in only 4.5-9 h and tested on four common UTIs bacterial strains. This compact system may therefore be promising for point-of-care personalized medicine in the near future.

Comparison of agar dilution, broth dilution, disk diffusion, and the E-test for susceptibility testing of penicillin-susceptible and penicillin-resistant Streptococcus pneumoniae

An evaluation to determine the optimal methods for the in vitro susceptibility testing of 41 clinical isolates and the ATCC 49619 strain of Streptococcus pneumoniae to penicillin was undertaken. No very major or major interpretive errors were observed with the following test methods and media: agar dilution using either Mueller-Hinton medium with lysed horse blood or Haemophilus test medium; broth dilution using cation-adjusted Mueller-Hinton medium with lysed horse blood, Haemophilus test medium, or Todd-Hewitt medium; and the epsilo-meter test (E-test) using agar containing Mueller-Hinton medium and 5% sheep blood. The disk diffusion method using agar containing Mueller-Hinton medium and 5% sheep blood agar was an effective screening method, requiring confirmation by a dilution susceptibility test method.

Comparison of in-house and commercially prepared haemophilus test media for disk diffusion testing of ampicillin against Haemophilus species

The performance characteristics of two lots of Haemophilus Test Medium (HTM) prepared in-house at Mayo Clinic, one lot obtained from BBL (Cockeysville, Md.) and one lot obtained from Remel (Lenexa, Kans.), for disk diffusion susceptibility testing of ampicillin against 81 Haemophilus strains were assessed. Insufficient growth occurred in 2.5 to 13.6% of strains, depending on the HTM used, and was most frequent for beta-lactamase-negative, ampicillin-resistant strains when they were tested with one lot of HTM prepared in-house. Results for all 14 beta-lactamase-positive Haemophilus strains were in complete agreement for all lots of HTM when either 1990 or 1993 National Committee for Clinical Laboratory Standards (NCCLS) interpretive guidelines were followed. However, these beta-lactamase-positive Haemophilus strains could be as precisely, but more rapidly, identified by the cefinase disk method. Results for 56 beta-lactamase-negative, ampicillin-susceptible strains and 11 beta-lactamase-negative, ampicillin-resistant strains varied significantly among all HTM lots tested and as to whether 1990 or 1993 NCCLS interpretive guidelines were followed. We conclude that in our hands disk diffusion testing with HTM prepared in-house or obtained from two commercial sources and following either 1990 or 1993 NCCLS guidelines is an unacceptable method for determining the susceptibilities of Haemophilus strains to ampicillin.