Broad-Spectrum Antibiotic Pressure Dominated a Quito Tertiary Hospital
A retrospective evaluation from a 610-bed tertiary hospital in Quito, Ecuador, shows how deeply entrenched broad-spectrum antibiotic use can become when formal antibiotic stewardship has not yet been fully embedded into routine care. Over eight years, the hospital analyzed a staggering 16,984,355 prescriptions representing 8,191,418.57 g of antibiotics, or 5,760,479.37 defined daily doses. The numbers point to a steady institutional pattern rather than an isolated prescribing spike: antimicrobial exposure was high across the hospital, and the intensive care unit carried the heaviest burden.
Mean inpatient antibiotic prescribing reached 148.8 ± 14.8 DDD per 100 occupied bed-days. In the ICU, the mean climbed to 293.5 ± 65.3 DDD per 100 occupied bed-days. Those figures matter because they describe a clinical environment in which microbial selection pressure is constant, especially in high-acuity settings where broad empiric therapy is often started early and adjusted late. In that setting, resistance is not a theoretical concern; it becomes a predictable ecological consequence of repeated exposure to powerful agents.
Carba penem Use Stayed Central to the Stewardship Problem
The hospital’s prescribing pattern was dominated by broad-spectrum agents. First-line antibiotics accounted for 38% of use, second-line agents for 52%, and third-line drugs for 10%. Even without a line-by-line formulary audit, the distribution makes the clinical direction of travel clear: more than half of all antibiotic use sat in the second-line category, with a non-trivial share already pushed into third-line therapy. In practical terms, this is the profile of a hospital where escalation has become common and reserve agents are carrying too much of the treatment load.
Carbapenems sat at the center of the stewardship intervention. Restrictive measures were introduced in 2016, requiring pre-authorisation and expert audit before dispensing. This is a classic stewardship approach for a drug class that is often used when clinicians fear resistant gram-negative infection, yet it can also accelerate resistance if used indiscriminately. By limiting access and inserting a review step, the hospital aimed to slow unnecessary exposure and preserve activity against organisms that would otherwise be driven toward further resistance.
Imipenem Fell After Restriction, While Meropenem Did Not
The interrupted time series analysis captured a striking asymmetry in the post-intervention response. Immediately after introduction of the stewardship programme, imipenem showed a change in outcome level of -3.97, with a 95% confidence interval from -5.31 to -2.61. Meropenem did not show the same immediate reduction; its change in level was 0.66, with a 95% confidence interval from -0.37 to 1.71.
One carbapenem moved; the other did not.
That divergence suggests the intervention altered prescribing behavior in a selective way rather than uniformly suppressing all carbapenem exposure. In a hospital setting, that can happen when prescribers substitute one reserve agent for another, preserve a preferred agent for certain services, or route patients toward the drug that is easier to justify under pre-authorisation rules. The microbiological consequence is important: partial restriction can shift pressure across agents without fully reducing the selective environment that sustains carbapenem resistance.
Resistance Trends Need a Broader Containment Strategy
The study linked antibiotic consumption with carbapenem resistance data from the microbiology laboratory, reinforcing a central stewardship principle: prescribing volume and susceptibility patterns are biologically connected. Heavy broad-spectrum use creates a competitive advantage for organisms that can survive exposure, especially in units where colonized and infected patients mix with frequent device use, invasive procedures, and high antimicrobial turnover. In that environment, even well-intentioned empiric therapy can become a driver of resistance if it is not rapidly narrowed.
The hospital’s findings also show why defining stewardship success narrowly around one drug can be misleading. Reducing imipenem alone does not guarantee a meaningful reduction in the total carbapenem burden, especially if meropenem use remains stable or rises in compensation. A stewardship programme that focuses only on access control may produce a visible signal in one agent while leaving the broader prescribing culture unchanged. For that reason, the most durable interventions usually pair restriction with audit, feedback, guideline reinforcement, service-specific oversight, and repeated measurement of both consumption and resistance outcomes.
What the Quito Data Mean for Resource-Constrained Hospitals
This analysis carries particular weight because Ecuador was described as not yet adherent to WHO antibiotic stewardship strategies, and baseline data on basic metrics were limited. In that context, even a single tertiary hospital dataset can help define the local starting point for policy. The prescription density was high, broad-spectrum use predominated, and the ICU showed the most intense antimicrobial pressure. Those are exactly the conditions under which stewardship programs need to be sustained rather than symbolic.
The clinical implication is not simply that carbapenem access should be restricted. It is that stewardship must be designed as a system-level intervention capable of changing prescribing habits across services, not just at the point of dispensing. When a hospital depends heavily on second-line and third-line agents, any effective program has to anticipate substitution effects, monitor both individual drugs and total class use, and align infectious diseases expertise with front-line prescribing behavior.
The data also argue for better feedback loops between the microbiology laboratory and prescribers. Resistance does not emerge in a vacuum; it tracks antibiotic pressure over time. A hospital that tracks only aggregate dispensing without tying it to organism susceptibility misses the opportunity to see where ecological pressure is rising fastest and where restriction is merely redistributing the problem.
Stewardship Worked, but the Signal Was Partial
The program succeeded in reducing imipenem consumption. It did not produce an equally clear effect for meropenem, and that uneven response is the central lesson from the analysis.
For hospitals considering similar interventions, the most important question is not whether one carbapenem can be constrained. The real challenge is whether the entire prescribing system can be shifted away from broad-spectrum dependence without creating a new imbalance elsewhere. In this cohort, the answer was incomplete, which is why the authors called for a more embracing plan to prevent unexpected effects and support further intervention.