Background: Biofilm formation is an essential virulence factor that creates a highly protected growth mode for Staphylococcus aureus (S. aureus) to survive in any hostile environment. Antibiotic sub-minimal inhibitory concentration (sub-MIC) may modulate the biofilm formation ability of bacterial pathogens, thereby affecting bacterial pathogenesis and infection outcomes. Intense antimicrobial therapy to treat biofilm-associated infections can control the pathogenic infection aggravation but cannot guarantee its complete eradication. Objective: This study aimed to assess the sub-MICs effect of 5 different antimicrobial classes on biofilm-forming capacity among Staphylococcus aureus clinical isolates using three different biofilm quantitation techniques. Methods: In this study, the effects of 5 different antimicrobial agents, namely, azithromycin, gentamicin, ciprofloxacin, doxycycline, and imipenem, at sub-MICs of 12.5%, 25%, and 50% were tested on 5 different clinical isolates of S. aureus. The biofilms formed in the absence and presence of different antimicrobial sub-MICs were then assessed using the following three different techniques: the crystal violet (CV) staining method, the quantitative PCR (qPCR) method, and the spread plate method (SPM). Results: Biofilm formation was significantly induced in 64% of the tested conditions using the CV technique. On the other hand, the qPCR quantifying the total bacterial count and the SPM quantifying the viable bacterial count showed significant induction only in 24% and 17.3%, respectively (Fig. 1). The difference between CV and the other techniques indicates an increase in biofilm biomass without an increase in bacterial growth. As expected, sub-MICs did not reduce the viable cell count, as shown by the SPM. The CV staining method revealed that sub-MICs of imipenem and ciprofloxacin had the highest significance rate (80%) showing an inductive effect on the biofilm development. On the other hand, doxycycline, azithromycin, and gentamicin displayed lower significance rates of 73%, 53%, and 47%, respectively. Conclusion: Exposure to sub-MIC doses of antimicrobial agents induces the biofilm-forming capacity of S. aureus via increasing the total biomass without significantly affecting the bacterial growth of viable count.

Treatment of Proteus mirabilis infections is a challenge due to the high abundance of virulence factors and the high intrinsic resistance to antimicrobials. Multidrug resistance (MDR) and extensive drug resistance (XDR) further challenge the control of P. mirabilis infection. This study aimed to investigate the correlation between virulence determinants and multidrug resistance in 100 clinical isolates of P. mirabilis collected in Alexandria from December 2019 to June 2021. Susceptibility to antimicrobials was tested by the Kirby Bauer method. Detection of swarming, urease, protease, hemolysin, and biofilm formation was performed phenotypically and by PCR amplification of zapA, flaA, ureC, mrpA, atfA, ucaA, hpmA, and luxS. MDR and XDR were detected in 34% and 5%, respectively. All isolates were positive for motility, swarming, urease, and protease production. Ninety percent were positive for hemolysin production, while 73% formed biofilm. All isolates possessed the ureC and zapA genes. The luxS, flaA, ucaA, hpmA, mrpA, and atfA genes were detected in 99%, 98%, 96% 90%, 89%, and 84%, respectively. The presence of a single biofilm-related gene was statistically correlated with non-biofilm production (P= 0.018). It was concluded that P. mirabilis isolates from catheterized-urine samples were significantly associated with biofilm formation. MDR and virulence were not statistically correlated. A significant positive correlation was detected between some virulence genes in P. mirabilis. Non-MDR isolates of P. mirabilis had a high abundance of virulence factors with no statistically significant difference from MDR. Most of the MDR and all XDR isolates could produce biofilm.

Phytotherapeutics is widely used nowadays as an alternative to the current antifungal drugs to reduce their side effects. Curcumin, with its wide therapeutic array as antioxidant and anti-inflammatory agent, is one of the natural compounds that ha..s an antifungal effect, especially when being used at nanoscale to increase its bioavailability. Our research aimed to evaluate clinically and microbiologically the effect of using topical nanocurcumin suspension to treat oral candidiasis. After 4 days from induction of oral candidiasis (baseline), we randomly divided 39 female BALB/c mice into three groups of 13 animals; nanocurcumin, nystatin, and sham groups. All animals in nanocurcumin and nystatin groups received topical treatment twice daily for 10 days. Then, we performed clinical and microbiological evaluations at baseline, day 5, and day 10. By the end of treatment, our results revealed that nanocurcumin promoted a significant reduction in the number of candida colonies. There was no statistically significant difference neither clinically nor microbiologically between nanocurcumin and nystatin groups. In conclusion, nanocurcumin has a good antifungal effect as nystatin, however, its therapeutic efficacy takes a longer time to appear than nystatin. The enhanced bioavailability of curcumin at the nanoscale qualifies this nano-herb as a promising alternative therapy for oral candidiasis, evading nystatin-associated morbidity.

Background: Carbapenemase-producing Enterobacterales are increasingly spreading in healthcare facilities. Identifying the type of carbapenemase can help epidemiologic surveillance and proper selection of antimicrobials. Objective: This study assessed the sensitivity and specificity of carbapenem inactivation method (mCIM with eCIM) for identification of carbapenemase-production. Methodology: The study involved 150 isolates of Enterobacterales. Carbapenem-resistant isolates by Kirby Bauer method were further tested for carbapenemase production phenotypically by mCIM with eCIM, and genotypically by multiplex PCR using specific primers for blaKPC, blaOXA-48, blaNDM-1, blaVIM, and blaIMP. Results: Resistance to carbapenem was observed in 53/150 isolates. Phenotypically, 28/53 isolates produced metallo-β-lactamase, 16/53 produced serine carbapenemase, 5/53 isolates gave inconclusive results, and 4/53 were negative by mCIM with eCIM test. Genotypically, 30 isolates carried blaNDM-1, and 41 isolates carried blaOXA-48. Both genes co-existed in 18 Metallo-β-lactamase producers. The 9 isolates with negative or inconclusive results carried carbapenemase-encoding genes. For mCIM with eCIM test the sensitivity and specificity of detecting Metallo-β-lactamase production were higher (87% and 91%) than for serine carbapenemase detection (34% and 83%), respectively. Conclusion: It was concluded that the mCIM with eCIM test does not always lead to true conclusions about the existence and the type of carbapenemase produced by Enterobacterales.