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Background: Macrolides inhibit the growth of bacterial cells by preventing the elongation of polypeptides during protein biosynthesis and include natural, synthetic, and semi-synthetic products. Elongation prevention occurs by blocking the passage of the polypeptide chain as the macrolides bind at the nascent peptide exit tunnel. Objective: Recent data of ribosome profiling via ribo-seq further proves that, other than blocking the polypeptide chain, macrolides are also able to affect the synthesis of individual proteins. Thus, this shows that the mode of action of macrolides is more complex than we initially thought. Since the discovery of macrolides in the 1950s, they have been widely used in veterinary practice, agriculture, and medicine. Due to misuse and overuse of antibiotics, bacteria have acquired resistance against them. Hence, it is of utmost importance for us to fully understand the mode of action of macrolides as well as the mechanisms of resistance against macrolides in order to mitigate antibiotic-resistance issues. Results: Chemical modifications can be performed to improve macrolide potency if we have a better understanding of their mode of action. Furthermore, a complete and detailed understanding of the mode of action of macrolides has remained vague, as new findings have challenged theories that are already in existence—due to this obscurity, research into macrolide modes of action continues to this day. Conclusion: In this review, we present an overview of macrolide antibiotics, with an emphasis on the latest knowledge regarding the mode of action of macrolides as well as the mechanisms of resistance employed by bacteria against macrolides.

Background: Many studies reported the effects of antibiotic exposure on E. coli bacterial growth and cell modification. However, scarce descriptive information on ultrastructural effects upon exposure of commercial antibiotics. Methods: This study described the morphological and ultrastructural alterations caused by selected antibiotics (amoxicillin-clavulanate, ceftriaxone, polymyxin B, colistin, gentamicin, and amikacin) that targeted cell wall, plasma membrane, and cytoplasmic density, and also proteins synthesis. We determined extracellular morphological changes of exposure through scanning electron microscopy (FESEM) and intracellular activities through transmission electron microscopy (TEM) investigation. Results: FESEM and TEM micrograph of E. coli exposed with selected antibiotics shows ultrastructural changes in beta-lactam class (amoxicillin-clavulanate, ceftriaxone) elongated the cells as the cell wall was altered as it inhibits bacterial cell wall synthesis, polymyxin class (polymyxin B, colistin) had plasmid and curli-fimbriae as it breaking down the plasma/cytoplasmic membrane, and aminoglycoside class (gentamicin, and amikacin) reduced ribosome concentration as it inhibits bacterial protein synthesis by binding to 30 s ribosomes. Conclusion: Morphological and ultrastructural alterations of E. coli’s mechanism of actions were translated and depicted. This study could be reference for characterization studies for morphological and ultrastructural of E. coli upon exposure to antimicrobial agents.

Background. The noncholera Vibrio spp. which cause vibriosis are abundantly found in our water ecosystem. These bacteria could negatively affect both humans and animals. To date, there is a paucity of information available on the existence and pathogenicity of this particular noncholera Vibrio spp. in Malaysia in comparison to their counterpart, Vibrio cholera. Methods. In this study, we extracted retrospective data from Malaysian surveillance database. Analysis was carried out using WHONET software focusing noncholera Vibrio spp. including Vibrio parahaemolyticus, Vibrio vulnificus, Vibrio fluvialis, Vibrio alginolyticus, Vibrio hollisae (Grimontia hollisae), Vibrio mimicus, Vibrio metschnikovii, and Vibrio furnissii. Results. Here, we report the first distribution and prevalence of these species isolated in Malaysia together with the antibiotic sensitivity profile based on the species. We found that V. parahaemolyticus is the predominant species isolated in Malaysia. Noticeably, across the study period, V. fluvialis is becoming more prevalent, as compared to V. parahaemolyticus. In addition, this study also reports the first isolation of pathogenic V. furnissii from stool in Malaysia. Conclusion. These data represent an important step toward understanding the potential emergence of noncholera Vibrio spp. outbreaks.

Bacterial and fungal secondary and co-infections are commonly identified with viral respiratory infections. This study was undertaken to determine the incidence and factors associated with bacterial and fungal infections in patients with COVID-19 as well as antibiotics prescription patterns within the first and second waves of the outbreak in Malaysia. Clinical records of 3532 COVID-19 patients admitted to hospitals in Malaysia between 4 February and 4 August 2020 were analyzed. Co-morbidities, clinical features, investigations, treatment, and complications were captured using the REDCap database. Culture and sensitivity test results were retrieved from the WHONET database. Univariate and multivariate regression analyses were used to identify associated determinants. A total of 161 types of bacterial and fungal infections were found in 81 patients, i.e., 2.3%. The most common bacterial cultures were Gram-negative, i.e., Pseudomonas aeruginosa (15.3%) and Klebsiella pneumoniae (13.9%). The most common fungal isolate was Candida albicans (41.2%). Augmentin, ceftriaxone, tazocin, meropenem, and azithromycin were the five most frequently prescribed antibiotics. The latter four were classified under the “Watch” category in the WHO AwaRe list. Our data showed that bacterial and fungal secondary and co-infections were frequently found in severely ill COVID-19 patients and were associated with a higher mortality rate.