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Aims: Methicillin-resistant Staphylococcus aureus (MRSA) is recognized as an important health problem worldwide. To counteract the human innate immunity, S. aureus produces a number of immune evasion cluster (IEC) including staphylokinase (SAK), staphylococcal enterotoxin P (SEP), staphylococcal enterotoxin A (SEA), staphylococcal complement inhibitor (SCIN), and chemotaxis inhibitory protein (CHIP) encoded by sak, sep, sea, scn, and chp genes, respectively. These genes are carried by β-hamolysin-converting bacteriophages. The present study was conducted to determine the IEC phage types and antibiotic resistance patterns in 145 clinical MRSA isolates from Khuzestan Province, Iran.
Methods: All the isolates were investigated by disc diffusion method and PCR assay of sak, sep, sea, scn, and chp genes.
Findings: The assessment of antibiotic resistance showed the highest rate of resistance towards penicillin (97.25%), followed by methicillin (95.8%), ceftazidime (81.4%), erythromycin (71.8%), clindamycin (61.4%), ciprofloxacin (60.7%), gentamycin (56%), imipenem (56.55%), and vancomycin (0%), respectively. Also, the frequency of IEC types was as follows: type A (4.8%), type B (9%), type C (13.1%), type D (12.4%), type E (27.6%), type F (1.4%), type G (0.7%), and type H (6.9%). On the other hand, 24.1% of the isolates did not show any of the IEC types.
Conclusion: The findings showed that IEC-carrying bacteriophages are highly prevalent among MRSA strains, resulting in the adaptation and counteraction of bacteria to the human immune system. Therefore, understanding the role of IEC in the virulence of bacteria can improve our knowledge about the evolution, vaccination, and treatment of S. aureus infection.

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Aims: Following the emergence of methicillin-resistant Staphylococcus aureus (MRSA) isolates, the use of other antibiotics especially vancomycin in S. aureus infections has become inevitable, leading to the emergence of vancomycin-resistant S. aureus (VRSA) strains, which is considered as a major public health concern. This study aimed to determine the vancomycin susceptibility patterns of S. aureus clinical isolates in order to evaluate the current status of vancomycin resistance in the southwest of Iran.
Materials & Methods: In this study, 100 S. aureus clinical strains were collected from the hospitals of Khuzestan province in the southwest of Iran. Next, antibiotic susceptibility, vancomycin resistance, and the presence of mecA, vanA, vanB, vanC, and vanD genes were investigated in these isolates.
Findings:  It was found that 1 and 2 isolates were vancomycin-intermediate S. aureus (VISA) and VRSA, respectively. All three strains showed methicillin-resistance pattern and carried mecA gene. vanA gene was detected in VRSA strains, whereas vanB, vanC, and vanD genes were detected in none of these isolates.
Conclusion: This study findings could be alarming regarding the emergence and spread of VRSA strains; therefore, the principles of infection control should be employed in the healthcare systems to prevent the spread of VRSA strains in healthcare facilities.
 

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Background: This study aimed to evaluate the frequency of extensively drug-resistant (XDR) uropathogenic Escherichia coli (UPEC) isolates and to detect their metallo-beta-lactamase (MBL) genes.
Materials & Methods: Three hundred urine samples collected from patients with suspected urinary tract infection (UTI) were evaluated for the presence of UPEC isolates. These isolates were subjected to antibiotic susceptibility testing to determine multidrug-resistance (MDR) and XDR profiles. Imipenem or meropenem-resistant isolates were evaluated for MBL production using modified carbapenem inactivation (mCIM) and EDTA-CIM (eCIM) methods. PCR was carried out to identify the presence of MBL genes, including bla_GIM, bla_SIM, bla_VIM-1, bla_VIM-2, bla_SPM-1, bla_IMP-1, bla_IMP-2, bla_NDM, and bla_KPC.
Findings: Out of 300 urine samples, 200 (66.66%) were positive for UTI. Among these, 150 were caused by UPEC. The highest antimicrobial resistance was against cefepime (88%) and ampicillin (85.3%), while the highest susceptibility was against imipenem (91.7%) and fosfomycin (84%). MDR and XDR profiles were detected in 145 (96.66%) and 5 (3.33%) isolates, respectively.  Overall, five UPEC isolates were XDR and resistant to imipenem and meropenem. All these isolates were positive for mCIM, while four were positive for eCIM. The bla_NDM gene was found in all five isolates, while the other MBL genes were not found.
Conclusion: The existence of MDR and XDR bacteria poses a significant risk to public health. bla_NDM is circulating in UPEC strains at least in Nasiriya province, Iraq. This could lead to increased resistance to carbapenems among Enterobacteriaceae, a serious threat to public health.