Fatthy Mohamed Morsy

Background: The colonization of preterm neonates by multidrug-resistant Enterobacteriaceae, especially in neonatal intensive care units (NICUs), remains poorly understood despite its potential role in healthcare-associated transmission. This study addresses this gap by characterizing gut colonization by Enterobacteriaceae, focusing on carbapenem-resistant Klebsiella pneumoniae in preterm neonates. Results: Samples of preterm neonates’ stool were cultured on eosin methylene blue (EMB) agar, followed by biochemical identification, 16S rRNA gene sequencing, and antibiotic susceptibility testing using the VITEK 2 system. All preterm neonates aged 2 weeks or older exhibited colonization by enterobacteria. K. pneumoniae was the most prevalent species, identified in 56.2% (9/16) of samples, with K. quasipneumoniae present in an additional 6.3% (1/16). Two K. pneumoniae isolates were multidrug-resistant; one exhibited carbapenem resistance, and one showed intermediate susceptibility. These strains were also resistant to multiple other antibiotics. Escherichia coli was detected in 50% (8/16) of cases but exhibited no carbapenem resistance. Conclusions: This study demonstrates that preterm neonates in NICUs can harbor multidrug-resistant K. pneumoniae in their gut, highlighting the gut as a potential reservoir and source of CRE (carbapenem-resistant Enterobacteriaceae) dissemination. These findings stress the need for enhanced surveillance, strict infection control practices, and strategies to prevent gut colonization and fecal–oral transmission of multidrug-resistant bacteria in vulnerable neonatal populations. All strains of K. pneumoniae , including those resistant or with intermediate resistance to carbapenems, displayed widespread sensitivity to gentamicin (GM) and tigecycline (TGC) in vitro , suggesting potential clinical utility, though further evaluation is warranted.

Carbapenems-resistant enterobacteria are considered multidrug-resistant, making the control of their nosocomial infections a major challenge in healthcare settings. It is important to know the incubation site and source of the spread of these strains, especially in neonatal intensive care units (NICU). Colonization of the colon of preterm neonates per se by multidrug-resistant bacterial strains could be the source of dissemination of these multidrug-resistant strains and their site of incubation. In this study, colonization of the colon of preterm neonates with enterobacteria and their multidrug-resistant strains was investigated. The presence of enterobacteria in the stool of preterm neonates was investigated on EMB (eosin-methylene blue) agar, followed by morphological and biochemical characterization and phylogenetic analysis of the 16S rRNA-encoding gene sequences. Antibiotic susceptibility of all isolated strains was tested using VITEK 2 technology. All cases examined at two weeks of age and older showed bacterial colonization of the colon. Klebsiella pneumoniae colonized the colon in 56.2% of the preterm neonates and Klebsiella quasipneumoniae was found in 6.3%, corresponding to 62.5% in total. The colonizing Klebsiella pneumoniae was multidrug-resistant in 2 of 9 cases. One strain of Klebsiella pneumoniae was resistant to carbapenems and another showed intermediate resistance to these antibiotics. These Klebsiella pneumoniae strains showed resistance to most of the other antibiotics tested. Some cases contained more than one genus, with Escherichia coli found in 50% of cases in preterm neonates. In contrast to Klebsiella pneumoniae, none of the E. coli strains colonizing the colon of preterm neonates in this study showed resistance to carbapenems. The results of this study suggest that Klebsiella pneumoniae and its carbapenems multidrug-resistant strains are well marked in preterm neonates colonizing their colon, which is the incubation site and source of such multidrug-resistant bacterial strains in NICU. This study highlights the importance of careful management of preterm neonates in the NICU and possible contamination with multidrug-resistant Klebsiella pneumoniae incubated in their colon. Further studies would be of interest to avoid the possibility of fecal-oral transmission and infection by these multidrug-resistant bacteria and their treatment in the colon, where their incubation site is located.

The results of this study suggest that the initial postnatal colonization of neonates’ colon by beneficial bacteria is a naturally controlled process in which the prenatal colon’s meconium might play a role in protecting against infection of the babies’ gut during delivery.

Cellulosic biowastes are one of the cheapest and most abundant renewable organic materials on earth that can be, subsequent to hydrolysis, utilized as an organic carbon source for several fermentation biotechnologies. This study was devoted to explore a semidry acid hydrolysis of cellulose for decreasing the cost and ionic strength of the hydrolysate. For semidry acid hydrolysis, cellulose was just wetted with HCl (0 to 7 M) and subjected to autoclaving. The optimum molar concentration of HCl and period of autoclaving for semidry acid hydrolysis of cellulose were 6 M and 50 min respectively. Subsequent to the semidry acid hydrolysis with a minimum volume of 6 M HCl sustained by autoclaving, the hydrolysate was diluted with distilled water and neutralized with NaOH (0.5 M). The reducing sugars produced from the semidry acid hydrolysis of cellulose was further used for dark fermentation biohydrogen production by Escherichia coli as a representative of most hydrogen producing eubacteria which cannot utilize non-hydrolyzed cellulose. An isolated E. coli TFYM was used where this bacterium was morphologically and biochemically characterized and further identified by phylogenetic 16S rRNA encoding gene sequence analysis. The reducing sugars produced by semidry acid hydrolysis could be efficiently utilized by E. coli producing 0.4 mol H₂ mol⁻¹ hexose with a maximum rate of hydrogen gas production of 23.3 ml H₂ h⁻¹ L⁻¹ and an estimated hydrogen yield of 20.5 (L H₂ kg⁻¹ dry biomass). The cheap cellulosic biowastes of wheat bran, sawdust and sugarcane bagasse could be hydrolyzed by semidry acid hydrolysis where the estimated hydrogen yield per kg of its dry biomass were 36, 18 and 32 (L H₂ kg⁻¹ dry biomass) respectively indicating a good feasibility of hydrogen production from reducing sugars prepared by semidry acid hydrolysis of these cellulosic biowastes. Semidry acid hydrolysis could also be effectively used for hydrolyzing non-cellulosic polysaccharides of dry cyanobacterial biomass. The described semidry acid hydrolysis of cellulosic biowastes in this study might be applicable not only for bacterial biohydrogen production but also for various hydrolyzed cellulose-based fermentation biotechnologies.

Background Human colon is a microbial ecosystem where its initial bacterial colonization in neonates is important step for establishing a beneficial microbiota for the body health. This study investigated occurrence of viable culturable Escherichia coli in first day meconium versus subsequent days stool to explore the prenatal versus postnatal initial colonization of colon by Escherichia coli in healthy neonates. Methods E. coli occurrence was conducted on eosin methylene blue agar followed by morphological and biochemical characterizations and phylogenetic analysis of 16S rRNA encoding gene. Results Viable culturable E. coli was not detected in meconium of healthy male and female neonates of normal birth or cesarean section surgical delivery. Neonates of surgical delivery showed no E. coli colonization at also 2nd and 3rd day confirming a postnatal colonization of colon by this enterobacterium. E. coli initial colonization in colon of normal birth neonates occur at 2nd day which can be attributed to inoculation from vaginal canal during delivery which in comparison to neonates of surgical delivery infers that the bacterium is not originally found in meconium. Conclusions This study suggests no viability of meconium microbiome in healthy neonates possibly due to antimicrobial action in the prenatal colon’s meconium protecting babies’ gut from infection during delivery.

Initial colonization of human gut by bacteria is an important step in controlling its microbiota and health status. This study followed the initial colonization by lactic acid bacteria (LAB) in colon of new born babies through following its occurrence in their stool at first week of their life. The LAB occurrence in the neonates’ stool was followed on MRS agar medium. The isolated LAB from male and female newborn babies of normal birth and cesarean section surgical delivery were molecular biologically identified by phylogenetic analysis of 16S rRNA gene sequence. From the 24 investigated newborn babies, three LAB taxa, Lactobacillaceae, Enterococcus, and Streptococcus, were detected in their stool at first week of their life. Lactobacillaceae represented 20.8% of total colonized LAB in newborn babies in the culture-dependent approach used in this study and included three species namely Limosilactobacillus reuteri (previously known as Lactobacillus reuteri), Lacticaseibacillus rhamnosus (previously known as Lactobacillus rhamnosus) and Ligilactobacillus agilis (previously known as Lactobacillus agilis). Enterococcus faecalis and E. faecium were detected where E. faecalis was the highest dominant, representing 62.5% of total LAB colonizing newborn babies. This result suggests that this bacterium has high potency for colonization and might be important for controlling the initial settlement of microbiota in healthy newborn babies. Only one species of Streptococcus namely Streptococcus agalactiae was detected in 8.33% total of the investigated newborn babies indicating high competency by other LAB for colonization and that this bacteria, in spite of its pathogenicity, is commensal in its low existence in healthy babies. The explored potency of natural initial colonization of the LAB species E. faecalis, E. faecium, L. reuteri, L. rhamnosus, and L. agilis of which many health beneficial strains were previously reported, would be important for future applications. Despite the controversy in evaluating its health benefits, E. faecalis as a potent competitor to other LAB refers to its importance in initial colonization of healthy babies colon at first week of their life. Further future studies, with more number of samples and characterization, would be of importance for evaluating the potential use of beneficial Enterococcus strains which could improve intestinal ecosystem.

In the last two decades, a large number of literature had focused on the biosynthesis of silver nanoparticles (AgNPs) from silver ions by bacteria and other microorganisms. This study infers that bacteria and other microorganisms do not per se synthesize AgNPs. All tested auto- and heterotrophic microorganisms in this study were killed by silver ions and could not as viable cells produce AgNPs. Microbial cell viability represented in colony-forming units and metabolic viability represented in aerobic respiration in all investigated microorganisms as well as photosynthesis in photoautotrophic microorganisms ceased by silver ions too early before AgNPs formation. The time required for AgNPs synthesis inversely related to the incubation temperature of the investigated microorganisms with silver ions where it requires only few minutes for nanoparticles formation at high temperature or autoclaving. The minimum inhibitory and minimum bactericidal and fungicidal concentrations of silver ions were significantly lower than AgNPs, indicating that silver ions are more efficient antimicrobial. The results presented in this study indicate that formation of AgNPs by eubacteria, cyanobacteria and fungi is not a vitally regulated cellular metabolic process and the mechanism occurs via bioreduction of silver ions to nanoparticles by organics released from the dead cells.