The research team, led by clinical laboratory scientists at the Ministry of Defense hospital alongside collaborators from Umm Al Qura University and Taif University, compiled antibiogram data from 5,626 specimens that yielded significant bacterial growth. These included 3,022 urine samples, 1,438 blood cultures, 875 lower respiratory tract samples such as sputum and tracheal aspirates, and 291 wound swabs. All organisms were identified using standard microbiological techniques, and antibiotic susceptibility testing followed the guidelines of the Clinical and Laboratory Standards Institute. The team tested dozens of antibiotics, spanning old workhorses like ampicillin and gentamicin to modern combinations like ceftazidime-avibactam, designed specifically to defeat bacteria armed with destructive beta-lactamase enzymes.

To move beyond simple snapshots of resistance, the researchers applied binary logistic regression models to each antibiotic individually, treating resistance as a binary outcome and year as a continuous predictor. This approach yielded an odds ratio for each drug, quantifying how the odds of resistance changed with each passing year, along with confidence intervals that indicate whether a trend is statistically reliable. The team also used multinomial logistic regression to track shifts in the composition of bacterial species and the distribution of infection sites over time. The result is one of the more granular pictures of resistance dynamics available for the region, capturing not just which drugs are failing but how quickly, and against which pathogens.

The statistical analysis identified a cluster of antibiotics with statistically significant and rising resistance. Tigecycline, a glycylcycline often deployed against carbapenem-resistant bacteria, showed an odds ratio of 1.442 per year, meaning the odds of resistance climbed roughly 44 percent annually. Ceftazidime-avibactam, a flagship cephalosporin-betalactamase inhibitor combination reserved for multidrug-resistant Gram-negative infections, showed an odds ratio of 1.395. Fosfomycin, aztreonam, cefoxitin, and piperacillin-tazobactam all showed significant year-on-year increases as well. What makes these numbers especially troubling is the identity of the drugs involved: ceftazidime-avibactam and tigecycline are frequently counted among the final therapeutic options against carbapenem-resistant Enterobacterales, a group of bacteria that the World Health Organization regards as one of the gravest threats in modern medicine.

Paradoxically, the news was not uniformly bleak. The carbapenems imipenem and meropenem, long considered benchmark drugs for serious Gram-negative infections, showed stable resistance patterns throughout the study, with odds ratios hovering near one. Resistance to amikacin actually declined significantly, with an odds ratio of 0.798, and trimethoprim-sulfamethoxazole also registered a modest but statistically significant decrease. The authors interpret this split pattern as evidence that the problem is not a uniform drift toward resistance across the entire antibiotic arsenal, but rather a targeted erosion of the newer, broader agents that are pressed into service against the hardest infections, often under intense selective pressure.

Perhaps the most striking finding concerned extended-spectrum beta-lactamase, or ESBL, production among Escherichia coli. Of 2,033 isolates examined for this phenotype, 29 percent, or 607 isolates, were ESBL producers, enzymes that hydrolyze penicillins and most cephalosporins and render first-line treatments ineffective. E. coli dominated the pathogen landscape throughout the study, accounting for 1,540 of the non-duplicate isolates, and its share of infections actually grew over time, rising from 58.5 percent of isolates in 2020 to 66.9 percent in 2024. Meanwhile, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus aureus all declined in relative frequency. The dataset included 614 K. pneumoniae isolates, 172 Acinetobacter isolates, 151 P. aeruginosa isolates, and 105 S. aureus isolates.

The geography of infection also shifted in ways that carry clinical consequences. Urinary tract infections expanded steadily, from 66 percent of specimen sources in 2020 to 79.1 percent in 2024, while lower respiratory tract infections collapsed from 18.3 percent to just 8.9 percent over the same period. Bloodstream and wound infections declined slightly. Combined with the rising dominance of E. coli, these numbers sketch a scenario in which resistant urinary pathogens are becoming the region’s central clinical challenge, a pattern consistent with global surveillance showing ESBL prevalence in some regions climbing from 44 percent to 59 percent over the past decade. For clinicians, this means empirical treatment of urinary infections, one of the most common reasons for antibiotic prescriptions, is increasingly likely to fail without susceptibility confirmation.

The study’s timeframe points to an uncomfortable suspect: the COVID-19 pandemic. During the early waves, large proportions of patients received broad-spectrum antibiotics empirically, despite the disease being viral and bacterial co-infection being uncommon. This practice, combined with the reallocation of healthcare resources and the suspension or weakening of antimicrobial stewardship programs, imposed intense selective pressure on hospital and community bacterial populations. The authors note that recent research has established resistance to tigecycline and ceftazidime-avibactam can emerge in some settings within a single month under such pressure, with non-susceptibility to tigecycline rising from virtually zero percent in 2019 to 71 percent in 2022 in certain clinical contexts, and ceftazidime-avibactam resistance climbing from 27 percent to 70 percent.

The concept of therapeutic exhaustion captures what happens when each successive line of defense erodes faster than new agents can be developed. When carbapenems remain stable but the drugs reserved for carbapenem-resistant infections begin to fail, the effective treatment window narrows from both sides. Previous studies in Saudi Arabia had already documented concerning resistance levels, including reports of 30 percent ESBL positivity and 74 percent multidrug resistance among isolates in some settings. The new data extend that picture longitudinally, showing that the problem is not static but accelerating for precisely the drugs where acceleration matters most.

The authors argue that their findings make a strong case for revitalizing antimicrobial stewardship programs and reassessing empirical treatment guidelines in the region, particularly for urinary tract infections, where presumptive therapy without susceptibility testing may soon become untenable for some patients. They emphasize that resistance patterns differed across bacterial species and infection sites, underscoring the need for site-specific, pathogen-targeted treatment strategies rather than one-size-fits-all protocols. Without strict intervention and careful antibiotic use, they warn, the medical community may soon face infections for which no viable therapeutic options remain. For a region where many tertiary care hospitals historically lacked systematic resistance data, this five-year antibiogram represents both a warning and a template: continuous, statistically rigorous local surveillance is not an academic luxury, but the foundation on which every rational prescribing decision now depends.

Subject of Research: Antimicrobial resistance trends in pathogenic bacteria isolated from clinical specimens at a Saudi hospital from 2020 to 2024

Article Title: Antibiogram of pathogenic bacterial isolates from various samples in Prince Sultan Hospital, Western Region, Saudi Arabia. Retrospective study from 2020 to 2024

Article References: Alqurashi, E. H., Obaid, N. A., Alzahrani, A., Alshareef, F. S., Mohandes, N. M., Althyabi, A. M., Albugami, S., & Almammari, S. (2026). Antibiogram of pathogenic bacterial isolates from various samples in Prince Sultan Hospital, Western Region, Saudi Arabia. Retrospective study from 2020 to 2024. Frontiers in Antibiotics, 5, Article 1872911. https://doi.org/10.3389/frabi.2026.1872911

Image Credits: AI Generated

DOI: 10.3389/frabi.2026.1872911

Keywords: antimicrobial resistance, antibiogram, ESBL, Escherichia coli, tigecycline, ceftazidime-avibactam, carbapenem-resistant Enterobacterales, COVID-19, antimicrobial stewardship, urinary tract infections, Saudi Arabia, clinical microbiology