• Provide local baseline epidemiological data that reveals the scope of our tertiary care hospital's ICU infection problem and can be used to track trends via the construction of cumulative antibiograms and evaluate the effectiveness of preventive measures in the near future.
• Help building efficient antimicrobial stewardship. For instance, the use of carbapenem sparing strategies is highlighted by the high resistance of gram-negative bacteria to the drug.
• Additional prospective multicenter epidemiological studies in multidisciplinary ICUs are needed to appropriately employ antimicrobial stewardship as a strategy for reducing antibiotic resistance in intensive care units across the nation.

Table (1): Positive samples prevalence in emergency and surgical ICUs.

ICU: intensive care unit, EICU: Emergency intensive care unit, SICU: surgical intensive care unit, BAL: bronchoalveolar lavage, CSF: cerebrospinal fluid.

The data were presented in the form of a number and a percentage. ^aPositive sputum isolates was the most prevalent infection.

Table (2): The incidence of pathogens isolated from emergency and surgical ICUs

The data were presented in the form of a number and a percentage. The most commonly encountered Gram-negative bacteria was the Klebsiella pneumoniae

Table (3): The incidence of different pathogens in various clinical samples.

 Table 3 (continue): The incidence of different pathogens in various clinical samples            

DISCUSSION

Antibiograms are frequently used to help choosing the best empirical antibiotic treatment for a suspected microbial infection. This is the first study to provide antibiogram analysis and offer epidemiological data on microorganisms and drugs that are available for surgical and emergency ICUs at Zagazig University Hospitals.

Our findings revealed that sputum specimens showed the most common infection (31.7%) in our surgical and emergency ICUs at Zagazig University Hospitals during the study period, despite the fact that the commonest nosocomial infection globally is the catheter-associated urinary tract infection (CAUTI) which constitutes 40% of all HAIs [9]. This may be elucidated through the fact that our study only included ICU patients and not all hospitalized patients, in addition to the well-known high use of mechanical ventilation, which is frequently used in patients with critical illnesses [10]. Furthermore, some research results found that teaching hospitals had a higher incidence of device-associated infections (DAI) as compared to nonteaching hospitals [11, 12].

Negm et al. also discovered that positive sputum isolates were the most common in different intensive care units, such as emergency, pulmonary, and pediatric units. Based on clinical, radiological, and laboratory results; local observation of these units revealed that ventilator associated pneumonia was found to be the most prevalent [13]. In the study by Shao et al. 64.75% of all nosocomial infections were respiratory tract infections, with urinary tract infections accounting for 9.4% and bloodstream infections accounting for 7.96% [14].

In contrast to our findings, Shebl et al. discovered in their analysis of 554 bacterial isolates that specimens of urine had the greatest prevalence of all isolates (41.5%, n = 230), followed by blood (23.1%, n = 128), whereas sputum samples had the lowest occurrence (17%, n = 94) [15]. According to Klevens et al., over 30% of all infections treated in intensive care units, are due to urinary tract infections [16]. This highlights the importance of reviewing clinical practices for infection localization. It is mandatory to focus more on lowering the frequency of invasive procedures as much as possible or attempting to restrict duration of these procedures when possible [17].

Infections caused by gram-negative micro-organisms have recently been found to be on the rise around the world. Our findings revealed that the most prevalent pathogens recovered were Gram-negative pathogens (84.27%), this could be attributed to their widespread presence in the hospital environment. Furthermore, their antibiotic resistance may contribute to their survival and spread. K. pneumoniae, gram-negative bacteria, was the most often identified (39.01%). 

This was consistent with Harbade et al. who discovered that gram-negative bacilli caused the vast majority of ICU-acquired illnesses, with Klebsiella pneumonia being the most commonly isolated pathogen [19]. Our findings were also consistent with Tabah et al.'s study, which found that gram-negative bacteria were the most commonly encountered pathogens (59.0%) [17], as well as that of Wang et al [20] which stated that Gram-negative bacteria were determined to be the most abundant isolates (68.4%) but the last two studies disagreed with our results regarding the most prevalent microorganism; Klebsiella spp. being the most prevalent gram-negative bacillus according to Tabah et al.[18] and Acinetobacter (31.6%) dominating, followed by Pseudomonas aeruginosa (13.4%), according to Wang et al.[20]. This discrepancy may be attributed to differences in the source of infection. 

Antibiotics are among the primary cornerstones of modern medicine, and they serve a crucial role in the prevention as well as the treatment of infectious diseases. Identifying bacterial infections and selecting an antibiotic that is effective against that specific organism are crucial for successful bacterial infection treatment [21]. Unreasonable antimicrobial usage is the most significant contributor to the rising risk of resistance, particularly in developing nations [22]. It is important to note that antimicrobial treatment needs to consider information on the local incidence of pathogenic microorganisms and their antibiotic resistance pattern, contrary to global standards.

K. pneumoniae was the most frequent microbe in our study (39.01%)and showed a significant level of resistance to carbapenem (86% to meropenem and 87% to imipenem), whereas a study by Qadeer et al. discovered a lower level of resistance (56% to meropenem and 55% to imipenem) [23]. However Sheth et al. discovered 100% carbapenem sensitivity [24], and Rajan et al. found 28.13% carbapenem resistance [25]. In the current investigation, there was a strong pattern of resistance to third-generation cephalosporins (95% for ceftriaxone) and fourth-generation cephalosporins (96% for cefepime). Aminoglycosides also demonstrated 88% and 78% for gentamicin and amikacin, respectively. In accordance with our results, 3rd-generation cephalosporins (94% to ceftazidime, 82% to ceftriaxone, and 70% to cefoperazone/sulbactam) and aminoglycosides (61% to gentamicin, 48% to amikacin) also exhibited a significant pattern of resistance in Qadeer et al.'s study[23]. In Gunjal et al.'s study also, there was 60% amikacin resistance and 80% gentamicin resistance [26]. In our investigation, colistin was the most efficient antibiotic, which had 5% resistance then followed by tigecycline, which had 25% resistance. In Qadeer et al.'s investigation, the antibiotic discovered to be the most efficient against multidrug-resistant Klebsiella was tigecycline, with 100% sensitivity [23].

E. coli, the second most prevalent bacterium in our study (14.56%), demonstrated 11% and 13% resistance to colistin and tigecycline, respectively, as well as substantial resistance to the cephalosporins with 91.5% for ceftriaxone (third-generation) and 94% for cefepime (fourth-generation). This is consistent with Qadeer et al.'s study results of 33% tigecycline resistance in E. coli, as well as significant resistance to 3rd-generation cephalosporins (93% for ceftazidime and 90% for ceftriaxone). Furthermore, Al Mohammady et al. found more than 90% E. coli resistance to third-generation cephalosporins [27]. Resistance to carbapenem was 52% with imipenem and 58% with meropenem. According to this study results but Qadeer et al. revealed that carbapenem resistance is just 10%. [23]. This might be due to different isolates among these studies. According to Gunjal et al. 28.10% of E. coli isolates were amikacin-resistant and 48.20% were gentamicin-resistant, which are near to our results; resistance to both amikacin and gentamicin being 42% and 48%, respectively. [26]. Colistin demonstrated 11% resistance to E. coli in this investigation.

Our findings demonstrated that carbapenem resistance is quite common among Acinetobacter (third most common bacteria 11.18%); 90% for imipenem, and 91% for meropenem. The investigation by Qadeer et al. revealed complete carbapenems resistance [23]. Another study conducted by Negm et al. found that carbapenem resistance was prevalent among Acinetobacter, with 79.9% imipenem resistance and 79.7% meropenem resistance [13]. In contrast, Rajan et al.discovered 52% carbapenem resistance in Acinetobacter. [25]. This difference can be due to the small number of patients in Rajan et al. study which included 501 from medical ICUs and 195patients from surgical ICUs.

Acinetobacter was resistant to cephalosporins with 95% for ceftriaxone (third-generation) and 6 % for cefepime (fourth-generation), amino-glycosides with gentamycim and amikan resistance of 84%, 78% respectively and quinolones resistance of 91% for ciprofloxacin and 95% for levofloxacin in our investigation. In accordance with our results, Acinetobacter was found to be extremely resistant to 3rd-generation cephalosporins (100% for ceftazidime), aminoglycosides with 97% for gentamicin and 95% for amikacin, and fluoroquinolones (100% for ciprofloxacin) in Qadeer et al.'sstudy [23].

In this study, Colistin was the most effective medication, with 15% resistance, followed by tigecycline (24%). Colistin was the most successful medicine in Qadeer et al.'s research, in agreement with our research results, with only 3% resistance [23]. Similarly, Rajan et al. [25] found colistin to be efficient against Acinetobacter, whereas the antibiotic tigecycline was discovered to be most efficient against Acinetobacter by Hasan et al. [28].

In our study, Pseudomonas, the fourth most common gram-negative bacteria (10.32%), demonstrated carbapenem`s resistance with 87% for imipenem and 84% for meropenem. Pseudomonas resistance to carbapenems was found to be significantly substantial, as our results, in a study conducted by Negm et al [13] (82.7% for Imipenem and 84.7% meropenem). Our results were disagreeing with those of Qadeer et al.'s investigation which stated that Pseudomonas demonstrated decreased carbapenems resistance (59% imipenem/ meropenem) [23]. Rakheeet al. [28] whose results discovered 20.8% imipenem resistance to Pseudomonas and Rajan et al. [25] who identified 12.9% resistance to carbapenems among Pseudomonas. Which are also discordant with our results. Differences in the number of the patients and sources of the infection may explain such discrepancy.   

Pseudomonas demonstrated also substantial resistance to cephalosporins with 100% for ceftriaxone and 87% for cefepime whereas aminoglycosides demonstrated resistance with 79% for gentamicin and 76% for amikacin. In accordance with our results Negm et al.'s study [13], demonstrated strong Pseudomonas resistance to cephalosporins with 100%for ceftriaxone and 86.2% for cefepime whereas aminoglycosides shown resistance with 80.4% to gentamicin and 78.2% to amikacin. On the other hand, Radji et al. discovered that ceftriaxone had a resistance rate of 60.9% and that amikacin, with a resistance rate of 15.6%, as the highly efficient antibiotic against Pseudomonas [30]. Colistin was determined to be the highly efficient antibiotic against Pseudomonas in our study, with a resistance rate of only 8%.

Staph. hominis (coagulase-negative staphylococci) was the most frequent gram-positive organism, which accounted for 43.2% of all gram-positive organisms and having 95% and 98% sensitivity to vancomycin and linezolid, respectively. Staph. aureus (coagulase-positive Staphylococci) accounted for 19.1% of the total organism, whereas MRSA accounted for 90.5%, and showing 87% and 100% susceptibility to vancomycin and linezolid respectively. Vancomycin resistance in MRSA may be attributed to its extended and subsequent use in empirical therapy. Negm et al. agreed to our results stating that coagulase-negative Staphylococcus (CoNS) (26.43%) was the most frequently isolated gram-positive organism, followed by Staph. aureus (19.24%) [13], whereas Chidambaram et al. found that among gram-positive isolates, Enterococcus (4.79%) was the most commonly isolated, followed by Staphylococcus aureus (3.7%) [31].

In our study, fungal growth accounted for less than 1% of the total. In contrast, Savanur et al. discovered fungal development in 15.1% of the cases [32]. This disparity may be attributable to false-negative reports in our institution, which may be connected to a lack of information regarding the importance of fungal investigations in surgical and emergency ICUs.

Because our hospital is a referral tertiary care facility, the high frequency of resistance found in our investigation could be attributed to prior antibiotic use, prior gram-negative bacterial infections, an unsuitable antibiotic treatment, and patients arriving with severe sepsis and this enhances the chance of the development of multidrug-resistant organisms. This high frequency of resistance is concerning since it necessitates constant surveillance to analyze the sensitivity and resistance pattern at certain levels, which could aid in the selection of the optimal antimicrobial treatment.

Given the large, dangerous, and alarming occurrence of antimicrobial resistance as well as the limited options for empirical antibiotics, a comprehensive antimicrobial resistance campaign should be made a national priority. This programme includes carrying out infection-control policies, the antimicrobial stewardship programme, quality, and education. Using existing antibiogram data, antibiotics will be the only solution for our intensive care units. Combinations and the provision of newly accessible antibiotic generations in our facility until the antimicrobial stewardship programme is fully implemented, not only within our hospital ICUs but in all Egyptian healthcare institutions.

Our research was hampered by a lack of clinical information to discriminate between infections acquired in hospitals and in the community, as well as the data needed to distinguish between actual infection and colonisation.

CONCLUSION

In conclusion, the current study provided local baseline epidemiological data that reveals the scope of our tertiary care hospital's ICU infection problem and can be used to track trends via the construction of cumulative antibiograms and evaluate the effectiveness of preventive measures in the near future. It also showed the problem of high ICU infection rates in Zagazig University Hospitals. To protect the potential of the existing antimicrobial drugs, this local prevalence analysis will help build efficient antimicrobial stewardship. For instance, the use of carbapenem sparing strategies is highlighted by the high resistance of gram-negative bacteria to the drug. Additional prospective multicenter epidemiological studies in multidisciplinary ICUs are needed to appropriately employ antimicrobial stewardship as a strategy for reducing antibiotic resistance in intensive care units across the nation.

Funding: None.

Conflict of interest: None.

Ethical approval : The Medical Research Ethics Committee at Zagazig University approved the study (No. ZU-IRB # 10367-24-1-2023)