Helicobacter pylori antibiotic resistance data in Oman are limited yet crucial for effective treatment selection. The genetic diversity within H. pylori influences its pathogenicity and clinical outcomes. This study evaluates resistance patterns and genetic determinants to guide treatment strategies. This study assessed antibiotic susceptibility in 15 H. pylori isolates (from 169 clinical samples) from naïve and treatment-failed patients. Resistance to clarithromycin (CLA), amoxicillin (AMX), metronidazole (MTZ), tetracycline, rifampicin (RIF), and levofloxacin (LEV) was tested alongside genetic analysis of virulence and resistance-associated mutations by whole-genome sequencing (WGS). Among the 15 resistant isolates, 20% were resistant to one antibiotic, 33.3% to two, 20% to three, and 26.6% to four antibiotics. MTZ resistance was universal among single-drug resistant isolates (100%). AMX-MTZ dual resistance was present in 60%, while triple resistance (CLA-AMX-MTZ) was present in 66.7%. Quadruple resistance (CLA-AMX-MTZ-RIF) was present in 75%. WGS revealed 23S rRNA mutations in 33.3% of CLA-resistant strains and pbp-1 mutations in 66.6% of AMX-resistant strains. MTZ resistance was linked to rdxA/frxA mutations, while RIF and LEV resistance correlated with rpoB (65.7%) and gyrA (20%) mutations, respectively. The genotype–phenotype agreement was insignificant (p = 1). High mutation heterogeneity, virulence factors, and environmental influences contribute to resistance. Further studies on host–pathogen interactions are needed to understand resistance mechanisms.

Staphylococcus epidermidis has been recently recognized as an emerging nosocomial pathogen. There are concerns over the increasing virulence potential of this commensal due to the capabilities of transferring mobile genetic elements to Staphylococcus aureus through staphylococcal chromosomal cassette (SCCmec) and the closely related arginine catabolic mobile element (ACME) and the copper and mercury resistance island (COMER). The potential pathogenicity of S. epidermidis, particularly from blood stream infections, has been poorly investigated. In this study, 24 S. epidermidis isolated from blood stream infections from Oman were investigated using whole genome sequence analysis. Core genome phylogenetic trees revealed one third of the isolates belong to the multidrug resistance ST-2. Genomic analysis unraveled a common occurrence of SCCmec type IV and ACME element predominantly type I arranged in a composite island. The genetic composition of ACME was highly variable among isolates of same or different STs. The COMER-like island was absent in all of our isolates. Reduced copper susceptibility was observed among isolates of ST-2 and ACME type I, followed by ACME type V. In conclusion, in this work, we identify a prevalent occurrence of highly variable ACME elements in different hospital STs of S. epidermidis in Oman, thus strongly suggesting the hypothesis that ACME types evolved from closely related STs.

Introduction: Stenotrophomonas maltophilia (S. maltophilia) has emerged as an important opportunistic pathogen. It is resistant to most available antibiotics due to its intrinsic resistance, leaving only some antibacterial agents as possible therapeutic options, which is further complicated by acquired mechanisms of antimicrobial resistance. This study aimed to provide a comprehensive genomic characterization of clinical S. maltophilia complex (Smc) isolates, focusing on molecular characterization of its resistance and virulence, since studies tackling this are scarce in Oman. Methods: This study is a prospective cross-sectional study, in which a total of 21 clinical isolates of Smc were collected from different clinical samples and further characterized using Whole Genome Sequencing. Results: Besides S. maltophilia, the isolates included S. hibiscicola, S. pavanii, and S. muris for the first time in Oman. All isolates were found to be susceptible to cefiderocol, levofloxacin, and minocycline. Sequence types (STs) were diverse among the isolates, with more than half of the isolates showing new STs with novel alleles. Additionally, blaOXA-2, sul1, and the recently described aac(6′)-Iap and aph(9)-Ic were detected among the isolates. Moreover, virulence-associated genes (smf-1, pilT, pilQ, gpmA, rmlA, spgM, stmPr1, plcN, clpP, and katE) were highly conserved across all isolates. Mobile genetic elements were detected in most of the isolates (76.20%). Conclusions: The collected isolates showed high ST diversity and showed no specific pattern in terms of antibiotic susceptibility and resistance genes. More studies are needed to establish relationships between the different members of the Smc and the different molecular resistome and virulome.