Burden of Resistant Gram Negative Bacteria in Lower Respiratory Tract Infections in ICU patients

Background

Lower respiratory infections (LRTIs) represent the world’s deadliest infectious disease, responsible for approximately 2.5 million deaths worldwide. LRTIs are the most frequent infections among patients in the ICU (intensive care unit), often involving multidrug-resistant (MDR) pathogens.

Methods

We retrospectively analyzed 2582 clinical samples (479 sputum and 2103 endotracheal aspirates) from 2150 patients with LRTI admitted to the ICU of the Emergency Clinical County Hospital of Craiova, Romania, between 2022 and 2024.

Results

Gram-negative bacteria were responsible for 77.49% (3233) of the total of 4,172 bacterial isolates. The most frequently isolated pathogens were Klebsiella spp. (1168-36.13%), Acinetobacter spp. (935-28.92%), Pseudomonas spp. (414-12.81%), and Escherichia coli (332-10.27%). During the three-year period, the resistance rate of Acinetobacter spp. significantly increased for cefepime (from 74.09% to 94.25%, p < 0.001), imipenem (from 79.15% to 94.83%, p < 0.001), meropenem (from 88.63% to 94.95%, p < 0.05), piperacillin-tazobactam (from 86.67% to 94.39%, p = 0.001), and tigecycline (from 33.17% to 45.15%, p = 0.01). From 2022 to 2024, the resistance rate of Klebsiella spp. significantly increased for cefepime (from 47.70% to 55.71%, p < 0.05), imipenem (from 33.09% to 51.39%, p < 0.001), meropenem (from 33.09% to 52%, p < 0.001), ciprofloxacin (from 49.46% to 58.15%, p < 0.05), and levofloxacin (from 40% to 59.76%, p < 0.001). A significant decrease in resistance was found against tigecycline (from 34.91% to 13.88%, p < 0.001) and colistin (from 3.46% to 0.67%, p = 0.01). The rate of carbapenem-resistant Pseudomonas spp. strains significantly increased between 2022 and 2024 (from 41.72% to 56.93%, p = 0.01).

Conclusions

The data indicate an alarming increase in resistance to several first-line and last-resort antibiotics among Klebsiella spp. and Acinetobacter spp. strains, with progressive limitation of effective therapeutic options for ICU-LRTIs.

Key messages

• The emergence of resistant Gram-negative strains is an alarm signal regarding the therapeutic options available in the future for critically ill patients with lower repiratory tract infections.

• There is an urgent need to implement strategies aimed at reducing the prevalence of multidrug-resistant Gram-negative pathogens causing lower respiratory tract infections.