Antibiotic resistance is a major public health concern worldwide. In 2017, the World Health Organization (WHO) identified bacteria with urgent needs for new antibiotics, categorizing Klebsiella as a critical priority [1] . Klebsiella pneumoniae is a gram-negative pathogen that poses a significant threat to public health due to its ability to cause a wide range of infections, particularly in healthcare settings. Found in water, soil, and dust, it is also present on human skin, mucous membranes, and especially the upper respiratory tract and digestive tract [2] . It causes infections that are often challenging to treat due to antibiotic resistance.

The emergence of Klebsiella pneumoniae strains resistant to antibiotics has become a critical issue, as it limits the effectiveness of therapeutic options. This antibiotic resistance affects certain families of antibiotics, including aminoglycosides, third-generation cephalosporins [3] , and more recently, carbapenems [4] , which are last-resort antibiotics. Carbapenems are used to treat multi-resistant strains and represent the last resort in antibiotic therapy against extended-spectrum beta-lactamase-producing Enterobacteriaceae. To date, their spectrum of activity is progressively narrowing with the emergence of several resistance mechanisms [5] [6] . Infections with extended-spectrum beta-lactamase-producing Klebsiella pneumoniae are a significant cause of hospital morbidity and mortality [7] .

Since the early 2000s, carbapenem resistance has spread to all regions of the world, raising serious concerns [8] and posing a significant public health problem. According to the European Antibiotic Resistance Surveillance System (EARSS) in 2014, the resistance rate of Klebsiella pneumoniae to carbapenems was 31.5% in Romania, 62.3% in Greece, and 0.9% in Croatia [9] . According to the antibiotic resistance surveillance network, out of 5922 multi-resistant bacteria (all species combined) isolated in hospitals, 57% of Klebsiella pneumoniae strains were resistant to beta-lactams through the production of extended-spectrum beta-lactamases [8] .

Due to the challenges of treatment, we deemed it necessary to conduct this study with the aim of contributing to the control and prevention of Klebsiella pneumoniae antibiotic resistance. In this article, we focus on the distribution and resistance profile of Klebsiella pneumoniae strains isolated at the Central Hospital of Yaoundé, with the goal of providing information on the prevalence and resistance patterns of this pathogen in a hospital setting.

Following the applied method, we were able to collect and identify 32 strains of Klebsiella pneumoniae. The results are presented as follows.

Klebsiella pneumoniae isolates were predominantly recovered from hospitalized patients, with a range of infections, including urinary tract infections, bacteremia, and pus infections. Our findings are consistent with a 2014 Lebanese study by Obeid Charrouf et al. [10] , which reported a higher prevalence of Klebsiella pneumoniae in urine and pus samples. This mirrors global trends, where urine and pus are commonly identified as high-yield samples for pathogenic bacteria.

We observed significant antibiotic resistance. However, increased resistance to penicillins is expected due to natural penicillinase production. A French study by F. Guillard et al. reported a lower ofloxacin resistance rate (16.4%) compared to our findings, possibly due to geographical differences [11] . Our results exceeded the ESBL production rate found by Fissou Henry in Chad (56.52%), likely due to widespread and unchecked cephalosporin use [12] . A Togolese study also showed urine samples had the highest ESBL production (57.94%) [13] . In Asia, Clement Yaw et al. identified cefotaxime (79.2%), ceftazidime (75.7%), ciprofloxacin (59.8%), and amikacin (40.8%) as antibiotics with high resistance rates [11] , contrasting with our findings where ofloxacin (81.25%), cefotaxime (78.13%), tobramycin (71.88%), and cefoxitin (62.50%) showed highest resistance. These disparities may be attributed to geographical and antibiotic testing differences. Notably, NDM carbapenemase was the only detected enzyme. NDM dissemination poses a public health concern transcending borders [14] .

Antimicrobial resistance is a growing public health concern. High resistance rates to commonly used antibiotics in Cameroonian hospitals, such as Yaoundé Central Hospital, highlight the complexity of patient treatment via antibiotic therapy. The presence of New Delhi metallo-β-lactamase (NDM) carbapenemase exacerbates this issue. Alan P. Johnson et al. (2013) noted that NDM dissemination involves complex epidemiology, including transmission of diverse NDM-positive bacterial species and inter-strain, inter-species, and inter-genus transfer of blaNDM-containing plasmids [14] . This mechanism underscores the evolving resistance of bacterial species via NDM carbapenemase. Our study identified NDM-producing bacteria in a hospitalized patient, raising concerns about potential dissemination within the ward and uncontrolled spread of clones. Faryal Yumus et al. (2019) emphasized that NDM-mediated resistance is alarming, as carbapenems are considered last-resort antibiotics against multidrug-resistant (MDR) bacteria, particularly in intensive care units and high-risk services [15] . The escalating and persistent threat of antimicrobial resistance in Cameroonian healthcare facilities, particularly at Yaoundé Central Hospital, underscores the need for vigilant monitoring and control of resistance enzymes. Cameroon’s Antimicrobial Resistance (AMR) program includes surveillance of resistance mechanisms. This study aims to contribute to this program by highlighting resistance patterns in healthcare settings and improving patient care. Our findings emphasize the importance of monitoring the spread of resistant strains, enhancing healthcare personnel education on nosocomial infection risks, and patient education on hygiene practices.

This study has some limitations. Conducted in a single institution, its findings may not be representative of the NDM situation in other hospitals or regions of the country. However, our sample included both inpatients and outpatients, providing a basis for potential extrapolation in larger-scale studies.

Klebsiella pneumoniae strains isolated from various samples exhibited increased resistance to antibiotics, producing ESBL, penicillinase, cephalosporinase, and carbapenemase. Continuous surveillance of antibiotic resistance in Klebsiella pneumoniae is crucial for guiding treatment strategies and preventing the spread of multidrug-resistant strains. Strict control measures must be implemented to minimize the impact of this pathogenic bacterium in healthcare settings.