Amira El-Far

Methicillin resistant Staphylococcus aureus (MRSA) is a pathogen to humans causing life-threatening infections. MRSA have the capability to grow resistance to many antibiotics, and phage therapy is one treatment option for this infection. The aim of the present study was to isolate and characterize the lytic bacteriophages specific to MRSA from domestic sewage water at a tertiary care hospital in Egypt. Thirty MRSA strains were isolated from different clinical samples admitted to the microbiology lab at Theodor Bilharz Research institute (TBRI) hospital, Giza, Egypt. They were confirmed to be MRSA through phenotypic detection and conventional PCR for mecA gene. They were used for the isolation of phages from sewage water of TBRI hospital. Plaque assay was applied to purify and quantify the titer of the isolated phages. The host range of the isolated phages was detected using the spot test assay. The morphology of phages was confirmed using transmission electron microscope (TEM). Digestion of DNA extracted from phages with endonuclease enzymes including EcoRI and SmaI was performed. SDS-PAGE was performed to analyze MRSA specific phage proteins. As a positive control prophages were isolated from a mitomycin C (MitC) treated culture of S. aureus strain ATCC25923. Further characterization using conventional polymerase chain reaction (PCR) was used to select three known Staphylophages by detecting the endolysin gene of phage K, the polymerase gene of phage 44AHJD, and the minor tail gene of phage P68. Isolated phages in this research displayed a wide host range against MRSA using the spot test, out of thirty tested MRSA isolates 24 were sensitive and got lysed (80%). The titer of the phages was estimated to be 1.04 × 106 pfu/ml using plaque test. Identification of head and tail morphology of the phages was achieved using TEM and they were designated to tailed phages of order Caudovirales, they composed an icosahedral capsid. Prophages were isolated through MitC induction. DNA of phages was digested by endonuclease enzymes. Conventional PCR yielded 341 bp of phage K endolysin gene and phage P68 minor tail protein gene 501 bp. Protein analysis using SDS-PAGE showed 4 proteins of sizes between 42 kDa and 140 kDa. Phages isolated here are alike to others mentioned in previous studies. The high broad host range of the isolated phages is promising to control MRSA and can be in the future commercially suitable for treatment as lysate preparations. Animal models of phage-bacterial interaction will be our next step that may help in resolving the multidrug resistant crisis of MRSA in Egypt.

Background: Multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains of Pseudomonas aeruginosa are the leading cause of healthcare-associated infections worldwide. Objective: The aim was to identify the resistant phenotypes among P. aeruginosa and to characterize different aminoglycosides and carbapenem resistance genes as major mechanisms of resistance in these isolates, in Theodor Bilharz Research Institute (TBRI), a tertiary care hospital in Cairo, Egypt. Methods: During a period of 11 months, 42 P. aeruginosa clinical isolates were collected from the microbiology laboratory by routine culture. Antimicrobial sensitivity testing to the aminoglycosides gentamicin and amikacin, and other classes of antibiotics, was performed by a disk diffusion method. Isolates were tested for aminoglycoside resistance genes, aac(6ʹ)-lb , aac-(3)-lla , rmtB , rmtC , armA , rmtD , and rmtF , and carbapenemase resistance genes bla NDM , bla VIM , and bla IMP , using conventional PCR. Results: Thirty-three (78.5%) of the clinical P. aeruginosa isolates showed MDR and XDR phenotypes at 42.4% and 57.65%, respectively, and these were included in the study. Aminoglycoside resistance was found in 97%, whereas carbapenem resistance was found in 81% of the isolates phenotypically. Only 59.4% (19/26) of the aminoglycoside-resistant isolates harbored resistance genes; none of the amikacin-susceptible isolates harbored any of the tested aminoglycoside resistance genes. Aminoglycoside resistance genes rmtB , armA , aac(6ʹ)-lb , and rmtF were found at rates of 17/33 (51.5%), 3/33 (9%), 2/33 (6%), and 2/33 (6%), respectively, whereas rmtD , acc(3)-II , and rmtC were not detected. Only 40.7% (11/27) of the carbapenem-resistant isolates harbored resistance genes. Carbapenem resistance genes, bla NDM and bla VIM , were found at rates of 7/33 (21.2%) and 6/33 (18.1%), respectively, and bla IMP was not detected. Conclusion: Rates of MDR and XDR P. aeruginosa and resistance to aminoglycosides and carbapenems in our setting are high. Methyltransferases and metallo-beta-lactamases are the main mechanisms of resistance to aminoglycosides and carbapenems, respectively. The presence of bla NDM and rmtF in the strains confirms their rapid dissemination in the Egyptian environment. Keywords: aminoglycosides, carbapenems, antibiotic resistance, Pseudomonas aeruginosa , MDR, XDR, rmtB , rmtF , NDM

Abstract Background Enterococci are intrinsically resistant to clinically achievable concentrations of aminoglycosides. However, high-level resistance to aminoglycosides (HLAR) is primarily due to the acquisition of genes encoding aminoglycoside-modifying enzymes (AMEs). Aminoglycosides along with cell wall inhibitors are given clinically for treating enterococcal infections. The current study was conducted to investigate the rate of HLAR and to determine aminoglycoside resistance encoding genes profile in enterococcal isolates from different clinical specimens. Results From 120 Enterococcus species, 50 (41.7%) enterococcal isolates were proven to have HLAR, 78% (39/50) have high-level gentamicin resistance (HLGR), and 74% (37/50) were high-level streptomycin-resistant (HLSR). HLGR isolates carried aminoglycoside modifying gene aac (6′)-Ie-aph (2 ′ )-Ia in 26/39 (66.7%) of isolates, whereas 32/37 (86.5%) of HLSR carried aph (3 ′ )-IIIa gene and were observed in E. faecalis , E. faecium , E. gallinarum , and E. casseliflavus . The aph (2 ′ )-Ib , aph (2 ′ )-Ic , and aph (2 ′ )-Id that encode HLGR could not be detected. Conclusions The high detection rate of HLAR among the studied Enterococcus species and the coexistence of HLGR and HLSR strains provide crucial insights to the necessity of routine testing for HLAR in the microbiology lab. The main AME genes among HLGR and HLSR enterococci were aac (6′)-Ie-aph (2″)-Ia and aph (3′)-IIIa , respectively.

Candida species resistant to fluconazole and voriconazole were screened for the presence of ERG11gene by polymerase chain reaction (PCR). Also, the association of this gene with the demonstration of Candida virulence factors; biofilm formation, phospholipase and proteinases activities were studied. A total of 61 Candida isolates were collected from urine specimens. Candida species were identified by API 20 C Aux test. Extracellular phospholipase, secretory aspartyl proteinase and biofilm formation were determined. ERG11 gene was detected by PCR. C. albicans was identified in 34.5%, C. glabrata in 29.5% and C. tropicalis and C. krusei in 18% each. Candida species was resistant to fluconazole and voriconazole in 55.7% and 27.9%, respectively. Seventeen (50%) of fluconazole resistant Candida isolates were sensitive to voriconazole. The most frequently Candida species revealed fluconazole resistance were C. glabrata (47.1%), C. krusei (29.4%), and C. tropicalis and C. albicans (11.8% each). Biofilm formation, phospholipase and proteinase activity were determined in 41.2%, 67.6% and 35.3% of fluconazole resistant Candida isolates, respectively. Erg 11 gene was determined in 82.4% of fluconazole resistant Candida isolates and prominent in C. glabrata (93.75%), followed by C. krusei (90%), C. tropicalis (75%) and C. albicans (25%). Erg 11 gene was detected in 64.7% (11/17) of fluconazole resistant-voriconazole sensitive Candida isolates. Regarding, correlation of Erg11 gene positivity and virulence factors among fluconazole resistant Candida isolates, 34.5% exhibited biofilm formation and 62.1% and 31% showed phospholipase and proteinase activities, respectively. There were statistically significant difference concerning the association of proteinase activities and Erg 11 gene expression among fluconazole resistance Candida isolates (P=0.04). The study emphasizes the high prevalence of Erg11 gene among fluconazole resistant Candida species. There was association between the proteinase activity, fluconazole resistance and the presence of Erg11 among Candida species. Voriconazole maintains better activity towards Candida species and represent an alternative therapy.