Integrons are genetic units characterized by the ability to capture and incorporate gene cassettes, thus can contribute to the emergence and transfer of antibiotic resistance. The objectives of this study were: (1) to investigate the presence and distribution of class I and class II integrons and the characteristics of the gene cassettes they carry in Enterobacteriaceae isolated from nosocomial infections at Zagzig University Hospital in Egypt, (2) to determine their impact on resistance, and (3) to identify risk factors for the existence of integrons. Relevant samples and full clinical history were collected from 118 inpatients. Samples were processed; isolated microbes were identified and tested for antibiotic susceptibilities. Integrons were detected by polymerase chain reaction (PCR) and were characterized into class I or II by restriction fragment length polymorphism (RFLP). Integron-positive isolates were subjected to another PCR to detect gene cassette, followed by gene cassette sequencing. Risk factors were analyzed by logistic regression analysis. Seventy-six Enterobacteriaceae isolates were recognized, 41 of them (53.9%) were integron-positive; 39 strains carried class I and 2 strains carried class II integrons. Integrons had gene cassettes encoding different combinations and types of resistance determinants. Interestingly, blaOXA129 gene was found and ereA gene was carried on class I integrons. The same determinants were carried within isolates of the same species as well as isolates of different species. The presence of integrons was significantly associated with multidrug resistance (MDR). No risk factors were associated for integron carriage. We conclude that integrons carrying gene cassettes encoding antibiotic resistance are significantly present among Enterobacteriaceae causing nosocomial infection in our hospital. Risk factors for acquisition remain to be identified.

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Regulatory T (Treg) cells are the chief player in induction of autotolerance and the transcription factor, Forkhead Box P3 (Foxp3), is the master regulator of their development and function. Polymorphisms in Foxp3 locus affect Foxp3 expression and can influence Treg cell function. This study aimed to determine the frequency of -3279C/A and -924A/G polymorphisms in the promoter region of the Foxp3 gene in Egyptian rheumatoid arthritis (RA) patients in comparison to apparently healthy controls, to test their association with Foxp3 serum levels as well as with patients’ clinical and laboratory features. Also, to evaluate Foxp3 serum level as a putative measure of Foxp3+ Treg cells-mediated immune regulation and disease activity. A total of 136 subjects (68 RA patients and 68 controls) were studied for determining the frequency of both -3279 C/A and -924 A/G polymorphisms in the Foxp3 promoter region by PCR-RFLP and measuring their Foxp3 protein serum levels by ELISA. Our results indicated that; -3279 Foxp3 CA and AA genotypes were significantly higher in patients than controls (OR (95% CI) = 2.86 (1.31-6.26) and 2.79 (1.11-7.07), P= 0.008 and p = 0.03, respectively). Similarly, -924 AG genotype was significantly higher in patients than controls (OR (95% CI) = 2.92 (1.35-6.34); P=0.006). A significantly higher risk of RA was associated with the Foxp3 polymorphic variants -3279 A and -924 G. There was a statistically significant elevation in Foxp3 serum levels among patients, which was positively correlated to disease activity score and disease grade. In conclusion, Foxp3 polymorphisms influenced the risk of developing RA, but did not influence disease severity or activity. Serum level of Foxp3 is not a reliable indicator of Treg-mediated immune regulation in RA patients.

Background: Infection of burn wounds by multidrug-resistant (MDR) Pseudomonas aeruginosa (P. aeruginosa) is a leading cause of morbidity and mortality and remains one of the most challenging concerns for the burns unit. The aim of this study is purify and characterize the haemolysin produced by multidrug resistant P. aeruginosa PAO1 isolated from burn wounds. Methods: Isolation and identification of P. aeruginosa from burns was done by standard bacteriological methods. P. aeruginosa PAO1 was identified by PCR amplification and sequencing of the 16S rRNA gene. The haemolysin of P. aeruginosa PAO1 was purified by 70% ammonium sulphate precipitation followed by gel filtration on Sephadex G-100, and separation by SDS-Poly Acrylamide Gel Electrophoresis. In vivo toxicity of the purified haemolysin was determined by intraperitoneal injection of Swiss albino mice, and in vitro toxin-antitoxin neutralization test was performed as previously described. Results: The pure haemolysin had a molecular weight of 37 kDa, with maximum activity at 25°C for 30 minutes and stable within pH range of 4-9 (maximum activity at pH 7). The haemolysin was activated by Ca2+, Fe3+ and Cu2+. Intraperitoneal injection of mice with 0.5ml of haemolysin (128 HU/ml) caused 100% mortality while 0.5 and 0.1 ml of haemolytic titer (64 HU/ml) of the heated haemolysin (toxoid) caused 50% and 0% mortality respectively. In vitro toxin-antitoxin neutralization test revealed that anti-haemolysin antitoxin was present in the serum of the mice that were previously vaccinated with heated toxin. Conclusion: This study concluded that haemolysin can be a potential vaccine component for prevention of haemolysis caused by multidrug resistant P. aeruginosa in burn patients.Keywords: haemolysin, Pseudomonas aeruginosa, multidrug resistant organism

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