Ultrastructural and morphological studies on variables affecting Escherichia coli with selected commercial antibiotics

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.

Secondary and Co-Infections in Hospitalized COVID-19 Patients: A Multicenter Cross-Sectional Study in Malaysia

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.

Distribution, Prevalence, and Antibiotic Susceptibility Profiles of Infectious Noncholera Vibrio Species in Malaysia

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.

Potential Applications of Conducting Polymers to Reduce Secondary Bacterial Infections among COVID-19 Patients: a Review

The COVID-19 pandemic is a motivation for material scientists to search for functional materials with valuable properties to alleviate the risks associated with the coronavirus. The formulation of functional materials requires synergistic understanding on the properties of materials and mechanisms of virus transmission and disease progression, including secondary bacterial infections that are prevalent in COVID-19 patients. A viable candidate in the struggle against the pandemic is antimicrobial polymer, due to their favorable properties of flexibility, lightweight, and ease of synthesis. Polymers are the base material for personal protective equipment (PPE), such as gloves, face mask, face shield, and coverall suit for frontliners. Conducting polymers (CPs) are polymers with electrical properties due to the addition of dopant in the polymer structure. The conductivity of polymers augments their antiviral and antibacterial properties. This review discusses the types of CPs and how their properties could be exploited to ward off bacterial infections in hospital settings, specifically in cases involving COVID-19 patients. This review also covers common CPs fabrication techniques. The key components to produce CPs at several possibilities to fit the current needs in fighting secondary bacterial infections are also discussed.

Development of monoclonal antibodies against recombinant LipL21 protein of pathogenic Leptospira through phage display technology

Leptospirosis is a potentially fatal zoonosis that is caused by spirochete Leptospira. The signs and symptoms of leptospirosis are usually varied, allowing it to be mistaken for other causes of acute febrile syndromes. Thus, early diagnosis and identification of a specific agent in clinical samples is crucial for effective treatment. This study was aimed to develop specific monoclonal antibodies against LipL21 antigen for future use in leptospirosis rapid and accurate immunoassay. A recombinant LipL21 (rLipL21) antigen was optimized for expression and evaluated for immunogenicity. Then, a naïve phage antibody library was utilized to identify single chain fragment variable (scFv) clones against the rLipL21 antigen. A total of 47 clones were analysed through monoclonal phage ELISA. However, after taking into consideration the background OD₄₀₅ values, only 4 clones were sent for sequencing to determine human germline sequences. The sequence analysis showed that all 4 clones are identical. The in silico analysis of scFv-lip-1 complex indicated that the charged residues of scFv CDRs are responsible for the recognition with rLipL21 epitopes. The generated monoclonal antibody against rLipL21 will be evaluated as a detection reagent for the diagnosis of human leptospirosis in a future study.