Pa ge 1 Pa ge 91 American Journal of Medical Science and Innovation (AJMSI) Gram-Negative Bacteremia: Epidemiology and Antimicrobial Resistance in Qatar Adila Shaukat1*, Masautso Chaponda1, Walid Al-Wali2, Farah Maher3, Sara Al-Balushi4, Abdulmajeed Maliyakkal5, Israa Elhakeem5 Tahani Al-Saadi2, Ali Omrani1, Muna Al Maslamani1 Volume 3 Issue 2, Year 2024 ISSN: 2836-8509 (Online) DOI: https://doi.org/10.54536/ajmsi.v3i2.3181 https://journals.e-palli.com/home/index.php/ajmsi Article Information ABSTRACT Received: September 05, 2024 Accepted: October 02, 2024 Published: October 05, 2024 One of the major causes of morbidity and mortality in hospitalised patients is the presence of gram-negative bacteremia (GNB) in blood. The developed resistance among the bacteria poses a significant challenge for treatment. The study aimed to identify the gram-negative patient’s epidemiological risk factors, antimicrobial susceptibility patterns, and clinical outcomes. A retrospective observational study of adult in-patients with gram- negative bacteremia was conducted between January 2019 and December 2020 in the 320-bed general hospital in Qatar. Data on demographics, antimicrobial resistance, source of infection, and treatment were collected. The primary outcomes were patients’ cure, death, or relapse. Total of 357 patients were identified with bacteremia, the most common sources being urinary tract infections (39.6%), intra-abdominal infections (28%), and lower respiratory tract infections (9%). The mean duration of the intravenous and oral antibiotics administration was 14 days. Surgical source control was performed in 35.7% of patients. Common pathogens were Escherichia-coli (47.2%), Klebsiella pneumoniae (16.4%), Salmonella enterica serotype Typhi (10.6%), and Pseudomonas aeruginosa (7.8%). 67.32% fully susceptible strains, 31.56% extended-spectrum beta-lactamase (ESBL) producing bacteria, and 1.11% multidrug-resistant organisms (MDROs) were among the isolates. Most infections (68%) were cured, but 5% had recurrence within 90 days of admission. Infection-related mortality was 8%, and death due to non-infectious causes was 2%. In conclusion, Gram-negative BSIs are severe infections with increasing antimicrobial resistance, primarily caused by ESBL- producing bacteria. High mortality rates are linked to diabetes, age, and hospitalisation, necessitating antibiotic treatment optimisation. Keywords Antimicrobial Resistance, Clinical Outcomes, Epidemiology, ESBL- Producing Bacteria, Gram- Negative Bacteremia 1 Infectious Disease Department, Hamad Medical Corporation, Qatar & Qatar University, College of Medicine, Qatar 2 Microbiology Department, Hamad Medical Corporation, Qatar 3 Pharmacy Department, Hamad Medical Corporation, Qatar 4 Epidemiology Department, CDC, Hamad Medical Corporation, Qatar 5 Medicine Department, Hamad Medical Corporation, Qatar * Corresponding author’s e-mail: adilazia44@gmail.com INTRODUCTION Gram-negative bacteria are known to cause a range of infections, including urinary tract infections, biliary infections, pneumonia, and primary and secondary bloodstream infections (Gajdács et al., 2019; Kim & Park, 2018; Kwiecińska-Piróg et al., 2018). Factors that predispose to these infections include extreme age, comorbidities such as diabetes mellitus, immunosuppression, prior use of antimicrobials, medical device usage, and invasive interventions such as surgery, nosocomial acquisition, and duration of stay, even though without a predisposing factor, the infection may also arise (Gajdács et al., 2019). One of the major factors contributing to the mortality and morbidity of hospitalised patients is gram-negative bacteremia (GNB). These patients require prompt diagnosis and appropriate antibiotic therapy. The initiation of appropriate antibiotics can reduce mortality, treatment failure, and length of stay, highlighting the importance of broad-spectrum empirical therapy, diagnostic stewardship, and rapid diagnostics for early and timely identification (Bassetti et al., 2020; Gajdács et al., 2019). Conflicting observations have resulted in uncertainty concerning the optimum duration of antibiotic therapy for bacteremia caused by gram-negative infections. Many believe gram-negative bacteremia patients should be treated with a 10-14-day intravenous antibiotics course to prevent serious sequelae, such as abscess formation and relapse (Turjeman et al., 2023). Recently, Lee et al. (2019) and Yahav et al. (2019) have suggested that short therapy courses are adequate for uncomplicated bacteremia (Lee et al., 2019; Yahav et al., 2019). The emerging resistance among these bacteria significantly challenges healthcare delivery (Iskandar et al., 2021). Infections by antimicrobial-resistant organisms, particularly multidrug- resistant organisms (De Waele et al., 2018), could result in treatment failure, increased morbidity and mortality, increased medical costs, prolonged hospital stays, and increased socioeconomic burden (Iskandar et al., 2021; Kitaya et al., 2023). In high resistance rates, selecting appropriate empiric antibiotic treatment for suspected gram- negative infections is difficult (Fitzpatrick et al., 2016). Inappropriate empirical antimicrobial therapy has been shown to predict death in critically ill patients (Turjeman et al., 2023). Furthermore, prolonged antimicrobial exposure is associated with adverse effects, increased rates of Clostridioides difficile infection, antimicrobial resistance, and longer hospital stays (Dyer et al., 2019). Pa ge 92 https://journals.e-palli.com/home/index.php/ajmsi Am. J. Med. Sci. Innov. 3(2) 91-102, 2024 Different centres vary depending on the patient population, immune status, infection control precautions, and antimicrobial use (Spellberg & Rice, 2019). Analysis of local trends and epidemiology is necessary to optimise empirical antibiotic treatment (Yahav et al., 2019). If indicated, appropriate antimicrobial therapy with source control is warranted to achieve optimal outcomes (Turjeman et al., 2023). The study aims to identify the local epidemiologically predisposing factors, antimicrobial susceptibility patterns, and clinical outcomes in adult patients with gram-negative bacteremia, focusing on factors associated with morbidity and mortality. MATERIALS AND METHODS Study Design and Selection Criteria A retrospective cohort study was conducted on in-patient adults with gram-negative bacteremia between January 2019 and December 2020 in a 320-bed general hospital in Qatar. All adult patients who presented with gram- negative bacteremia during the study period based on positive blood cultures were identified retrospectively from the Microbiology Lab through hospital electronic records. Pediatric patients (aged <14 years) and transit passengers were excluded from the study. Samples considered contaminants, as determined by the clinical picture and subsequent management, were also not included. A Microbiology database was used to record antimicrobial susceptibility testing current guidelines from the Clinical and Laboratory Standards Institute (CLSI) (Iskandar et al., 2021). The hospital’s electronic patient record system was used to capture all clinical data related to these patients. In contrast, the demographic details, including age, sex, comorbidities (immunosuppression, malignancy, pregnancy, renal disease, diabetes, and hypertension), and clinical presentation, were also recorded. A need for admission to the critical care unit was used to assess the severity of infection. The probable source of infection, persistence of bacteremia beyond the first blood culture, and therapeutic options with intravenous antibiotics alone or combined with source control (incision and drainage of abscesses, stent insertion) were examined. The choice of antibiotics and duration of treatment, including changes made according to sensitivity, were also recorded. Clinical outcomes were gauged as cure, death, or infection recurrence within 90 days of admission. Any subsequent development of alert organisms such as Clostridium difficile infection or the emergence of multidrug- resistant microorganisms 90 days after admission was also monitored. Multidrug resistance (MDR) was defined as resistance to at least one agent from three or more antimicrobial classes (Yezli et al., 2014). Ethical Approval This study was approved by the Institutional Review Board (IRB) and Medical Research and Ethics Committee Hamad Medical Corporation (Protocol ID MRC-01-21- 259). However, this retrospective cohort review did not obtain individual patient consent. Statistical Analysis Statistical analysis was conducted on 358 patients using the Sata/Se 14.2. The study analysed epidemiological data, including descriptive statistics and continuous and categorical variables. Categorical variables were presented as counts and percentages, whereas normal continuous variables are expressed as means and standard deviations, and non-normal variables are presented as medians and interquartile ranges (IQR). The Shapiro-Wilk test and visual inspection of histograms were employed to assess the normality of the data. The student’s t-test was applied to normal outcomes, the Mann-Whitney test was applied to non-normal outcomes, and the chi-square test was used for categorical variables. Survival analysis was performed using Kaplan-Meier survival curves and the log-rank test to assess the differences between the groups for variables associated with mortality based on univariate analysis. RESULTS AND DISCUSSIONS The demographic and clinical characteristics of the cohort with gram-negative bacteremia were analysed, with a total of 358 patients included in the study. Among these patients, the majority (218, 60.8%) were male, with a mean age of 51. Table 1 describes the comorbidities observed in the study population. Notably, diabetes mellitus emerged as a significant confounding factor. Patients’ demographic and clinical profiles were stratified based on their diabetes status, resulting in 197 non-diabetic patients (Non- DM) and 160 diabetes patients (DM). The non-diabetic group exhibited a significantly younger age than the diabetic group (median ages of 42.5 vs. 60, respectively, p < 0.001). Furthermore, hypertension, end-stage renal disease on hemodialysis, and chronic kidney disease were more prevalent in the diabetic group compared to the non-diabetic group (p < 0.001 for all). Although the length of hospital stay did not differ significantly between the two groups (p = 0.94), primary bacteremia was more common in the non-diabetic group (p = 0.038). Bacterial isolates also showed significant differences in prevalence, particularly with E. coli, Klebsiella, and Salmonella Typhi. Additionally, the source of bacteremia varied significantly between the groups, with urinary tract and intra-abdominal infections being prominent in both. Antibiotic resistance did not notably differ between the groups (p = 0.49), As shown in Table 1. Table 1: Baseline characteristics of the study population by diabetes status Non-DM (n = 197) DM (n = 160) Demographics Age (Wilcoxon rank) 42.00 (28.00-54.00) 60.00 (49.50-70.00) <0.001 Pa ge 93 https://journals.e-palli.com/home/index.php/ajmsi Am. J. Med. Sci. Innov. 3(2) 91-102, 2024 Male 128 (64.65%) 90 (56.25%) 0.093 Comorbidities HTN 37 (18.76%) 115 (71.88%) <0.001 ESRD HD 07 (3.55%) 25 (15.63%) <0.001 CKD 11 (5.58%) 33 (20.63%) <0.001 Malignancy 26 (13.20%) 9 (5.63%) 0.012 COPD/Asthma 12 (6.09%) 12 (7.50%) 0.59 HIV 0 (0.00%) 1 (0.63%) IHD 7 (3.55%) 38 (23.75%) <0.001 HF 10 (5.08%) 13 (8.13%) 0.24 Liver disease 9 (4.57%) 13 (8.13%) 0.16 Pregnant females (Fisher's exact) 7 (10.14 %) 1 (1.43 %) 0.063 Valvular disease (Fisher’s exact) 3 (1.52%) 10 (6.25%) 0.017 Cystic fibrosis 0 (0%) 0 (0%) Inflammatory bowel disease (Fisher's exact) 0 (0.00%) 1 (0.63%) 0.45 Tuberculosis 1 (0.51%) 0 (0.00%) 1 Immunosuppressive treatment 15 (7.61%) 9 (5.63%) 0.46 Long hospital stays 10 (5.08%) 12 (7.50%) 0.34 Complicated bacteremia 51 (25.89%) 53 (33.13%) 0.16 Persistence 13 (6.60%) 5 (3.13%) 0.15 Intubated 31 (15.74%) 29 (18.13%) 0.56 ICU 52 (26.40%) 39 (24.38%) 0.61 Readmission 25 (12.69%) 23 (14.37%) 0.88 Length of stay (Wilcoxon rank) 35.00 (16.00-44.00) 33.00 (12.00-46.00) 0.94 Emergence 7 (3.55%) 15 (9.38%) 0.05 C. diff 2 (1.02%) 0 (0.00%) 0.63 Source control 0.046 Yes 81 (41.12%) 47 (29.38%) Unknown 36 (18.27%) 42 (26.25%) Abs Previous 36 (18.27%) 63 (39.38%) <0.001 Completed IV 0.008 In-patient 128 (64.97%) 106 (66.25%) MHS 17 (8.63%) 29 (18.13%) OPAT 47 (23.86%) 24 (15.00%) Unknown 5 (2.54%) 1 (0.63%) Microbiology Primary bacteremia 75 (38.07%) 44 (27.50%) 0.038 Community-acquired bacteremia 157 (79.70%) 131 (81.88%) Bacterial isolates 0.004 Acinetobacter 3 (1.52%) 5 (3.13%) Brucella 6 (3.03%) 2 (1.25%) Citrobacter 1 (0.51%) 1 (0.63%) E. coli 90 (45.45%) 79 (49.38%) Enterobacter cloacae 6 (3.03%) 2 (1.25%) Klebsiella 28 (14.14%) 31 (19.38%) Non-typhoidal Salmonella 5 (2.53%) 0 (0.00%) Proteus 2 (1.01%) 4 (2.50%) Pseudomonas 12 (6.06%) 15 (9.38%) Pa ge 94 https://journals.e-palli.com/home/index.php/ajmsi Am. J. Med. Sci. Innov. 3(2) 91-102, 2024 Figure 1 shows that 68% of patients with gram-negative bloodstream infections (GNB) successfully recovered from sepsis, but 8% succumbed to sepsis, 5% experienced recurrence, and 6% died from unrelated causes. 5% showed multidrug-resistant organisms, indicating antimicrobial resistance. 2% experienced prolonged bacteremia, and 6% died from unknown causes. These findings highlight the complexity of GNB management and the need for comprehensive strategies to prevent adverse events. Salmonella Typhi 33 (16.67%) 5 (3.13%) Serratia 5 (2.53%) 6 (3.75%) Unidentified anaerobic Bacilli 0 (0.00%) 1 (0.63%) Pseudomonas 1 (0.51%) 0 (0.00%) Stenotrophomonas 0 (0.00%) 1 (0.63%) Missing 6 (3.03%) 8 (5.00%) Resistance 0.49 ESBL 57 (28.93%) 46 (28.75%) MDR 9 (4.57%) 12 (7.50%) None 131 (66.50%) 102 (63.75%) Source bacteremia (Fisher's exact) 0.004 Urinary tract infection 71 (36.04%) 71 (44.38%) Bone and soft tissue infection 7 (3.55%) 15 (9.38%) Burn wound infection 3 (1.52%) 0 (0.00%) Cardiovascular infection 1 (0.51%) 2 (1.25%) intra-abdominal infection 70 (35.53%) 31 (19.38%) Line related infection 4 (2.03%) 7 (4.38%) Lower respiratory tract infection 20 (10.15%) 17 (10.63%) Unknown 20 (10.15%) 17 (10.63%) Surgical site infection 1 (0.51%) 0 (0.00%) Figure 1: The primary clinical outcomes of this study are shown in chart The duration of treatment with intravenous antibiotics revealed that most patients underwent a short course of intravenous therapy. Specifically, more than 70% of patients received treatment lasting less than 10 days, which suggests a trend towards shorter intravenous antibiotic therapy durations in managing gram-negative bacteremia cases, as shown in Table 2. Pa ge 95 https://journals.e-palli.com/home/index.php/ajmsi Am. J. Med. Sci. Innov. 3(2) 91-102, 2024 Table 2: Intravenous (IV) treatment duration – intervals Duration of IV treatment (days) Counts Percentages % <7 161 44.97 7 to 10 100 27.93 11 to 14 54 15.08 >14 43 12.01 Sum 358 100 Figure 2 shows the distribution of gram-negative bacteremia by infection site. Urinary tract infections are most common (45%), followed by intra-abdominal infections (40%) and lower respiratory tract infections (15%). A notable proportion (10%) has an unknown infection site. Other sites include bone and soft tissue infections (5%), line-related infections (2.5%), cardiovascular infections (1%), and miscellaneous sources (2.5%). This breakdown underscores the varied origins of gram-negative bacteremia, emphasising the need for tailored treatment strategies based on infection site specificity. Figure 2: Epidemiology of gram-negative bacteremia Escherichia coli was the most frequently identified organism, accounting for 47.2% of cases, followed by Klebsiella pneumoniae (16.4%), Salmonella enterica serotype Typhi (10.6%), and Pseudomonas aeruginosa (7.8%). Other less common organisms included Serratia marcescens (3%), Acinetobacter baumannii (2.2%), Brucella sp. (2.2%), non-typhoidal Salmonella (1.3%), Citrobacter sp. (0.5%), and various others (8.3%). These findings detail the characteristics of gram-negative bacteria isolated in the study, highlighting the prevalence of different species contributing to persistent bacteremia cases. Additionally, the mean duration of antimicrobial treatment, including intravenous and oral administration, was 14.6 days, with intravenous antibiotics specifically administered for an average duration of 5.4 days, as shown in Table 3. Table 3: Organisms isolated in persistent bacteremia Organism Count (out of 18) Percentage % E. coli 4 22.22 Klebsiella sp. 5 27.77 Enterobacter cloacae 1 5.55 Pseudomonas sp. 2 11.11 Salmonella typhi 3 16.66 Proteus sp. 1 5.55 Stenotrophomonas maltophilia 1 5.55 Achromobacter sp. 1 5.55 As illustrated in Figure 3, gram-negative bacteremia arises from various sources within the body. The most prevalent infection sites of cases originating in the urinary tract are evident. Intra-abdominal infections and lower respiratory tract infections follow this. It is crucial to note that these percentages may not match the original figure exactly due to potential rounding errors. Pa ge 96 https://journals.e-palli.com/home/index.php/ajmsi Am. J. Med. Sci. Innov. 3(2) 91-102, 2024 There were four cases of multidrug-resistant organisms (MDROs), two Klebsiella pneumoniae carbapenemase- producing Enterobacteriaceae (KPC), and two New Delhi metallo-beta-lactamase-1 (NMD-1). Extended- spectrum beta-lactamase-producing organisms (ESBL) constituted 31.56% (113) cases. Antibiotic collateral damage was noted as the emergence of MDRO in 90 days in 22 patients (6.1%) and Clostridium difficile in two patients (0.5%). Persistent bacteremia was reported in 18 patients (5%), out of which nine (50%) had intra-abdominal infections, three had soft tissue infections (16.7%), two had lower respiratory tract infections (11.1%), two had urinary tract infections (11.1%), one had cardiovascular infection (5.5%), and one had line-related infection (5.5%), as shown in Table 4. Figure 3: Common sites of infection in gram-negative bacteremia cases Table 4: Description of bacterial isolates Organisms Count Percentage (%) Multidrug-resistant organisms (MDROs) 4 1.11 Extended-spectrum beta-lactamase-producing organisms (ESBL) 113 31.56 Sensitive strains 241 67.32 Single microbe 336 93.85 Polymicrobial 22 6.14 Figure 4 illustrates the distribution of gram-negative bacteremia cases by different bacterial types. The listed bacteria include Escherichia coli, Klebsiella pneumoniae, Salmonella typhi, Pseudomonas, Serratia, Acinetobacter, non-typhoidal Salmonella, and Citrobacter. The X-axis represents the percentage of cases for each bacterial type. This graph provides insights into the prevalence of various bacterial species causing gram-negative bacteremia, which is essential for understanding the epidemiology and guiding treatment approaches for these infections. Figure 4: Comorbidities in gram-negative bacteremia cases Pa ge 97 https://journals.e-palli.com/home/index.php/ajmsi Am. J. Med. Sci. Innov. 3(2) 91-102, 2024 Table 5 illustrates the management of source control in patients with persistent bacteremia. Among 18 patients with persistent bacteremia, source control was performed in seven cases, accounting for 38.9% of the cohort. Conversely, five patients (27.8%) did not require source control. In contrast, source control was deemed necessary in six cases (33.3%) but was not carried out due to factors such as the patient’s unstable condition or inaccessible sites. Table 5: Comorbidities of Study Population Comorbidity Number Percentage (%) Diabetes mellitus 160 44.69 Hypertension 152 42.45 The end-stage renal disease of dialysis 32 8.93 Chronic kidney disease 44 12.29 Malignancy 36 10.05 Asthma/Chronic Obstructive Pulmonary Disease 24 6.70 Human Immunodeficiency Virus 1 0.27 Ischemic heart disease 45 12.56 Heart failure 23 6.42 Chronic liver disease 22 6.14 Pregnancy 8 2.23 Valvular disease 13 3.63 Cystic fibrosis 0 0 Inflammatory bowel disease 1 0.27 Tuberculosis 1 0.27 Immunosuppressive treatment 24 6.70 Figure 5 presents the survival probability comparison between diabetic and nOn-diabetic patients following a positive culture. According to the graph, patients without diabetes have a better chance of surviving than those with the disease. This observation underscores the potential impact of diabetes as a comorbidity on patient outcomes in cases of gram-negative bacteremia. Understanding such differences in survival probabilities can inform clinical decision-making and highlight the importance of tailored management strategies for patients with diabetes who develop gram-negative bacteremia. Figure 5: Kaplan-Meier survival analysis denoting survival probability of diabetic and non-diabetic groups Table 6 presents the duration of antibiotic treatment in diabetic (DM) and non-diabetic (non-DM) patient groups with gram-negative bacteremia. Statistical analysis revealed no significant difference in the duration of antibiotic treatment between the two groups (p=0.617). Most patients in both groups received antibiotics for more than 14 days, with 63 (31.98%) in the DM group and 52 (32.5%) in the non-DM group. Interestingly, a Pa ge 98 https://journals.e-palli.com/home/index.php/ajmsi Am. J. Med. Sci. Innov. 3(2) 91-102, 2024 slightly higher percentage of diabetic patients (10.63%) received antibiotics for less than 7 days compared to non-diabetic patients (8.63%). Moreover, a somewhat higher proportion of diabetic patients (35.63%) received antibiotics for 11 to 14 days compared to non-diabetic patients (32.49%). Table 6: Total duration of antibiotic treatment in diabetic and non-diabetic patients Total duration of treatment (days) Non-DM (n=197) DM (n=160) Count Percentages % Count Percentages % Less than 7 days 17 8.63 17 10.63 7 to 10 days 53 26.90 34 21.25 11 to 14 days 64 32.49 57 35.63 More than 14 days 63 31.98 52 32.5 P-value = 0.617 Univariate analysis of recurrence at 90 days, cure rate, and death due to sepsis showed a significant difference between the groups (p=0.037, p=0.09, p=0.052, respectively. The sepsis outcomes comparison revealed that diabetic patients had a higher death risk due to sepsis (11.88%) and recurrence within 90 days (8.75%) compared to non-diabetic patients. Additionally, the cure rate is less (69.38%) in diabetic patients than in non- diabetic patients (81.73%), as shown in Table 7. Table 7: Univariate analysis of outcomes in diabetic and non-diabetic patients Outcome (Fisher's exact) Non-DM (n=197) DM (n=160) P-value Death due to sepsis 11 (5.58%) 19 (11.88%) 0.052 Recurrence in 90 days 7 (3.55%) 14 (8.75%) 0.037 Cured 161 (81.73%) 111 (69.38%) 0.009 Age, treatment duration of fewer than seven days, and hospital-acquired infections showed a significant association with higher mortality in gram-negative bacteremia in the multivariate analysis (OR=1.040, p=0.014), (OR=20.030, p=0.001), (OR=3.517, p=0.020) respectively. Conversely, the presence of E. coli and UTI as sources of infection was not significantly associated with mortality due to sepsis. Kaplan-Meier survival analysis was used to assess the survival probability of the diabetic and non-diabetic groups. The log-rank test result was insignificant (p=0.934), as shown in Table 8. Table 8: Multivariate analysis of factors associated with mortality in gram-negative bacteremia patients adjusting for baseline characteristics Variable OR p-value 95% Confidence Interval Age 1.040 0.014 1.008 1.072 Male 1.609 0.448 0.471 5.496 DM 1.008 0.990 0.314 5.496 HTN 4.060 0.056 0.967 17.049 ESRD/HD 1.237 0.756 0.324 4.716 Less than 7 days of treatment 20.030 <0.001 5.454 75.038 Hospital-acquired 3.517 0.020 1.217 10.168 Secondary 1.394 0.559 0.457 4.253 MDR 0.588 0.547 0.104 3.309 E. coli 0.457 0.192 0.141 1.482 UTI - a source of infection 0.043 0.007 0.004 0.040 Discussion GNB bloodstream infections pose a serious health problem globally and in the Middle East, where antimicrobial resistance is rising (Inam et al., 2023). Several studies have been conducted in this region to understand this condition’s epidemiology and risk factors. The emergence of antimicrobial resistance (AMR) has been the top agenda item for the past four years for the Gulf Cooperation Council Centre for Infection Control (GCC-IC) (Al Muhairi et al., 2019). A previous study on the epidemiology of all bacteremia patients in Qatar found 452 cases of bacteremia with 63% gram- Pa ge 99 https://journals.e-palli.com/home/index.php/ajmsi Am. J. Med. Sci. Innov. 3(2) 91-102, 2024 negative organisms (Borgio et al., 2021), with Escherichia coli as the most common isolate. The present study also found E. coli to be the predominant bacterium (47.2%), followed by Klebsiella pneumoniae (16.4%). Many cases of Salmonella bloodstream infections (10.6%) in our centre were identified mainly as travellers or immigrants from Southeast Asia. Salmonella typhi was 10.6%, and non-typhoidal Salmonella constituted 1.3% of cases. An earlier study by Qatar found that 97% of patients had a history of travel to endemic areas (Ahmedullah et al., 2018). Salmonella typhi isolates from the present study centre demonstrated high levels of resistance to ciprofloxacin (40%) but were susceptible to ceftriaxone. Among the cases, the Brucella sp. was identified in eight patients (2.2 %). In the Middle East and North Africa (MENA) region, brucellosis is not uncommon as a blood culture isolate (Wareth et al., 2022). Usually, there is a history of exposure to cattle and camels, either through occupational exposure or consumption of dairy products. MDROs and ESBL-producing isolates comprised 34% of the samples, while the rest were sensitive strains (66%). Previous studies also found a higher prevalence of ESBL-producing E. coli and Klebsiella pneumoniae (55.7%) than present findings (Sid Ahmed et al., 2023), which indicates the implementation of antimicrobial stewardship practices and monitoring the appropriateness of antimicrobials and their consumption. In addition, previous studies from Qatar reported 4.4 % MDR isolates of Pseudomonas aeruginosa (P. aeruginosa) (Ahmed et al., 2019); however, out of 28 patients with P. aeruginosa bloodstream infection (7.8%), only 2 patients (0.56%) were multidrug-resistant, which is in contrast to studies from Saudi Arabia with a high prevalence of multidrug- resistant (MDR) bacteria, with more than 50% of the isolates resistant to at least one antimicrobial agent (Yezli et al., 2014). Although P. aeruginosa remains susceptible to carbapenems, quinolones, and aminoglycosides in most centres in Saudi Arabia, its resistance is still on the rise. Similarly, Enterobacteriaceae, Escherichia coli, Klebsiella pneumoniae, and Enterobacter sp. AMR is increasing, especially in gram-negative infections in the Middle East (Sid Ahmed et al., 2023). Prior use of antimicrobials is an established independent risk factor for the emergence of MDROs (Ahmed et al., 2019). In Qatar, about half of the cases of Klebsiella pneumonia are reported as extended- spectrum β-lactamase (ESBL) producers (Alsamawi et al., 2022). A survey from Oman found Escherichia coli (32.39%), P.aeroginosa (22.16%), Klebsiella pneumoniae (19.97%), and Acinetobacter baumannii (5.22%), with growing resistance against ciprofloxacin and meropenem (Sathya Kumar et al., 2023). The factors included prolonged hospital stay, intravenous cannulation, multiple co-morbid conditions, and previous antibiotic exposure, which are attributed to the resistance in the present study. A study in Iran demonstrated that the most common gram-negative infections included Klebsiella pneumoniae, Escherichia coli, Serratia marcescens, and Pseudomonas aeruginosa (Mahmoudi et al., 2023). The study also found a high prevalence of carbapenem-resistant isolates, with more than 70% Klebsiella pneumoniae carbapenem- resistant; therefore, the implementation of antimicrobial stewardship and infection prevention measures is necessary to control the emergence and subsequent spread of AMR, as they are two facets of the same coin. In Sub-Saharan Africa, the levels of third-generation cephalosporins resistance in the bloodstream are reported to be high in Escherichia coli (18.4%), Klebsiella sp. (54.4%), non-typhoidal Salmonellae (1.9% ) (Lester et al., 2020). Studies from Finland, Australia, Sweden, and Canada have shown increased overall resistant Escherichia coli BSI rates (Buetti et al., 2017). Persistent bacteremia was reported in 18 patients (5 %), with the most common pathogens being Klebsiella sp. and Escherichia coli. Source control was performed in only one-third of the patients; out of 30 patients, 13 (43.3%) have died due to persistent bacteremia; source control was performed for eight of them. Persistent bacteremia is a serious condition that can lead to significant morbidity and mortality and increased healthcare costs (Iskandar et al., 2021). The epidemiology of persistent GNB is complex and is influenced by factors such as prior antibiotic use, exposure to healthcare facilities, and comorbidities. Several studies have identified risk factors such as end-stage renal disease (ESRD) during hemodialysis, intravascular devices, bacteremia due to MDRO organisms, and ineffective antibiotic therapy as independent predictors of persistent GNB bacteremia (De Waele et al., 2018). The incidence of persistent GNB is increasing, with higher rates observed in older adults and patients with comorbidities (De Waele et al., 2018). Persistent GNBs are often seen in patients with weakened immune systems, such as malignancies, HIV, or organ transplants (Tumbarello et al., 2012). The main contributing factors to GNB bacteremia were DM- 2, hypertension, ischemic heart disease, and chronic kidney disease in the present study. Approximately 10% of patients had malignancy, and 6.7% were on immunosuppressive drugs. The management of persistent bacteremia can be challenging and requires a multidisciplinary approach. The first step in management includes identifying the source of the infection. Appropriate antimicrobial therapy should be initiated with proper source control, including removing infected intravascular devices, such as central venous catheters, or surgical intervention to remove infected tissue. A reasonable approach for source control was observed in the patient population. Fortunately, there were only a handful of cases where it was indicated but not performed. Appropriate antibiotic therapy should be used based on the organism’s susceptibility pattern to manage persistent GNB effectively. Chu et al. found that inappropriate initial antimicrobial treatment increases mortality risk (Chu et al., 2020). All GNB bacteremia in patients are reported directly to the infectious disease physician on call by the Clinical Microbiology Department as a part of the antimicrobial stewardship Pa ge 10 0 https://journals.e-palli.com/home/index.php/ajmsi Am. J. Med. Sci. Innov. 3(2) 91-102, 2024 program. As part of the same stewardship, broad- spectrum antimicrobials are authorised by infectious disease physicians within 48 hours of initiation. A combination therapy may be necessary to achieve adequate bacterial clearance (Kalelkar et al., 2022); the empirical antimicrobials were started according to study hospital guidelines and subsequently tailored to narrow- spectrum agents as soon as sensitivities were available. Local epidemiology of infective organisms, antibiograms, immune status, previous antimicrobial exposure, possible source of infection, and colonisation with MDR bacteria and other alert microorganisms such as Clostridium difficile and Candida auris must be considered before initiating empirical therapy. Initial broad-spectrum antibiotics should be administered empirically in severely ill patients, followed by source identification and control as soon as possible (Timsit et al., 2020). De-escalation from a broad- spectrum to a narrow-spectrum antimicrobial when culture and sensitivity results are available effectively reduces AMR (Lester et al., 2020) and is rigorously followed in our hospital. On average, the duration of Intravenous (IV) antibiotics was 5-8 days, although longer durations were used when the underlying illness and source of infection were present. Another important intervention was the close teamwork relationship and clinical discussions between our infectious disease physicians and medical microbiologists in decision- making (De Waele et al., 2018). In South Korea, extended-spectrum beta-lactamase- producing Enterobacterales have emerged as a significant cause of community-acquired bacteremia after the prior use of antimicrobials (Timsit et al., 2020). The present study did not look for previous use of antimicrobials but noted that last hospitalisation and prolonged hospital stay were associated with a higher emergence of resistance. Similarly, a study from Lebanon reported that infections caused by resistant bacteria were associated with a significant increase in hospital stays compared to those with susceptible bacteria, leading to higher costs (Iskandar et al., 2021). The duration of antibiotic therapy for gram-negative bacteremia depends on several factors, such as the site of infection, severity of illness, and the type of causative organism. In this study, many patients received IV antibiotics for less than 7 days, while only 12% received treatment for more than 14 days (either due to persistent bacteremia or complicated bacteremia). Several studies have determined the optimal duration of antibiotic therapy for gram-negative bacteremia (Dyer et al., 2019; Lee et al., 2019). Yahav et al. found that a short course of antibiotic therapy (7 days) was as effective as a longer course (14 days) in the treatment of gram-negative bacteremia (Yahav et al., 2019). A meta-analysis of three randomised controlled trials (RCTs) with 1121 patients with Enterobacterale bacteremia showed no significant difference in 90 days of mortality between 7 and 14 days of treatment (Turjeman et al., 2023). Shorter durations of antimicrobials are advocated as a goal for many antimicrobial stewardship programs to treat community-acquired pneumonia, urinary tract infections, intra-abdominal infections, and skin and soft- tissue infections. Batlas et al. reported an overall mortality at 1 year of 36.2 %, with 18% within the first 30 days (Baltas et al., 2021). Similarly, a study from Calgary found that 28-day, 90-day, and 365-day all-cause case-fatality rates after bloodstream infection were 12%, 17%, and 25%, respectively (Laupland et al., 2011). A study by Qatar showed a hospital mortality rate of 29.7 % for all bacteremia cases (Khan et al., 2010). A larger study examined the epidemiology of bloodstream infections in 51 countries across six continents in critically ill patients, including COVID-19 patients (Buetti et al., 2017), found that gram-negative bacteria were the most common cause of bloodstream infections and the overall mortality for bloodstream infections was 45%, with higher rates reported in Covid-19 patients (Buetti et al., 2017). Mortality due to gram-negative bacteremia can vary depending on various factors, such as the specific bacterial species involved, age and overall health of the patient, presence of underlying medical conditions, and promptness and effectiveness of treatment. The mortality from gram-negative bacteremia is higher than that from gram-positive bacteremia, with some studies suggesting mortality ranging between 20 and 50%. However, mortality rates can vary widely based on individual circumstances, and it is important to note that timely and appropriate antibiotic treatment can greatly improve outcomes in patients with gram-negative bacteremia. The incidence and mortality rates of gram-negative bacteremia can vary globally, depending on healthcare practices, antibiotic resistance patterns, and population demographics. The study centre has an antimicrobial stewardship program with formulary restriction and preauthorisation of restricted antimicrobials that aid in appropriately starting antimicrobials, particularly in bacteremia cases, and is followed by the infectious disease team in collaboration with the medical microbiologist, which could be one reason why the MDRO rate was not significantly high. However, cephalosporins are not restricted in clinical practice, which might explain the higher numbers of ESBL-producing Enterobacterales. CONCLUSION In conclusion, gram-negative BSIs are serious infections with increasing antimicrobial resistance (AMR). Extended- spectrum beta-lactamase (ESBL) producing bacteria are our centre’s most common cause of AMR. Diabetes Mellitus-2, old age and hospital-acquired infections are risk factors leading to higher mortality. Healthcare professionals should be aware of the risk factors associated with this condition and initiate empirically effective antibiotic therapy to achieve optimal treatment outcomes and prevent collateral damage. Further research is needed to understand better the epidemiology and pathophysiology of gram-negative bacteremia in Qatar and formulate effective targeted treatment strategies. Pa ge 10 1 https://journals.e-palli.com/home/index.php/ajmsi Am. J. Med. Sci. Innov. 3(2) 91-102, 2024 LIMITATIONS The limitations of our study include the need for more data on the prior use of antimicrobials and health care costs. The long-term impact of GNB beyond 3 months has yet to be investigated. The retrospective nature of this study and the single-center data are other limitations. Further analysis with a larger sample size is recommended to enhance the understanding of these findings in clinical practice. In this study, we only looked at long-term mortality within 90 days. Still, collateral damage was determined, such as the emergence of MDRO in 90 days at 6.1%, while infection with Clostridioides difficile occurred only in 2 patients (0.5%). Acknowledgement Clinical Microbiology Department and Pharmacy Department Data Availability Statement The data used to support the findings of this study were restricted by the Institutional Review Board (IRB) medical research centre at Hamad Medical Corporation to protect patients’ privacy. Data can be obtained after IRB approval for researchers who meet the criteria for access to confidential data. REFERENCES Ahmed, M. S., Hassan, A., Jarir, S. A., Hadi, H. 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