Methicillin-resistant Staphylococcus aureus (MRSA) is a clinically prevalent bacterium and is resistant to many drugs. Genetic factors such as mec genes are considered to be responsible for this resistance. Recently, Staphylococcal Cassette Chromosome mec (SCCmec) element mutations produced mecC, a new genetic variant that encodes a transpeptidase enzyme (63% similarity with mecA-encoded PBP2a). This cross-sectional study was conducted to establish the prevalence of the mecA and mecC genes among phenotypically identified MRSA and their effectiveness against different antibiotics in clinical specimens. The prevalence of Staphylococcus aureus was 10.2% (n = 102) in the total number of clinical specimens collected (n = 1000). However, the prevalence of MRSA was 6.3% (n = 63) of the total samples collected, while it was 61.8% among total Staphylococcus aureus isolates. mec genes were confirmed in 96.8% (n = 61) isolates of MRSA, while 3.2% (n = 2) were found to be negative for mec genes. The combination of mecA and mecC was detected in 57.1% (n = 36) of the MRSA isolates. The prevalence of lone mecA was 31.8% (n = 20) and that of lone mecC was 7.9% (n = 5) among all the MRSA samples. Penicillin and amoxicillin/clavulanic acid were the most resistant antibiotics followed by norfloxacin (91.2%), levofloxacin (87.1%), ciprofloxacin (83.9%), azithromycin (78.6%), erythromycin (77.4%), moxifloxacin (69.8%), and sulfamethoxazole/trimethoprim (54.9%). On the other hand, vancomycin and teicoplanin (98.4%) were more effective drugs against MRSA followed by linezolid (96.7%), clindamycin (84.6%), chloramphenicol (83.7%), fusidic acid (70.6%), gentamicin (67.7%), and tetracycline (56.8%). In conclusion, a significant prevalence of mecA and mecC has been found among MRSA isolated from clinical specimens, which is likely responsible for antibiotic resistance in MRSA in our clinical settings. However, vancomycin, teicoplanin, and linezolid were found the top three most effective drugs against MRSA in our clinical settings. Thus, MRSA endemics in local areas require routine molecular and epidemiological investigation.

Calcium carbonate (CaCO₃), a natural common inorganic material with good biocompatibility, low toxicity, pH sensitivity, and low cost, has a widespread use in the pharmaceutical and chemical industries. In recent years, an increasing number of CaCO₃-based nano-drug delivery systems have been developed. CaCO₃ as a drug carrier and the utilization of CaCO₃ as an efficient Ca²⁺ and CO₂ donor have played a critical role in tumor diagnosis and treatment and have been explored in increasing depth and breadth. Starting from the CaCO₃-based nano-drug delivery system, this paper systematically reviews the preparation of CaCO₃ nanoparticles and the mechanisms of CaCO₃-based therapeutic effects in the internal and external tumor environments and summarizes the latest advances in the application of CaCO₃-based nano-drug delivery systems in tumor therapy. In view of the good biocompatibility and in vivo therapeutic mechanisms, they are expected to become an advancing biomedicine in the field of tumor diagnosis and treatment.

Chitosan-based nano-sized particles increase the penetration of the drug through the narrow junction into the bloodstream and target the specific site. The objective of this study was to prepare chitosan nanoparticles to entrap a hydrophobic drug (tamoxifen citrate), followed by the alginate coating of the developed nanoparticles to decrease their degradation in the acidic pH. Drug-loaded chitosan nanoparticles were prepared by the ionic gelation method. Alginate coating was done by dissolving sodium alginate to buffer solution and drug-loaded chitosan nanoparticles drop-wise under mild agitation. The size of alginate coated chitosan nanoparticles, zeta potential, surface morphology, in-vitro drug release, and entrapment efficiency was measured. The optimised formulation of both uncoated (SH3) and coated (SH7) formulation showed the particle size, PDI, and zeta potential with values 221 & 338 nm, 0.161 & 0.230 and 36.5 & −20.7 mV, respectively. The resulted nanoparticle surface was non-porous. The percentage yield of the optimised formulation SH3 was 28% and SH6 was 33%. The entrapment efficiency of the optimised formulation SH3 (uncoated formulation) and SH6 (coated formulation) is 69.5 and 58.51%, respectively. Chitosan nanoparticles were successfully prepared to entrap tamoxifen citrate. The coating of chitosan nanoparticles decreased their degradation in the acidic pH.