Variance in Microbiology in Double Lumen Catheters Related Sepsis in Diabetic Patients

Catheter related blood stream infections (CRBSIs) are a challenge in healthcare in the world, as they increase morbidity, the number of days of hospitalization, and the cost of healthcare. The central venous catheters (especially the double lumen ones) are extensively utilized in the clinical setting in order to deliver medications, total parenteral nutrition, and hemodynamic. Their application, however, is often linked to infectious complications as a result of microbial colonization and biofilm development on the surface of catheters [1-3].

Diabetic patients are more prone to infections because of compromised immunity, lack of glycemic control, and due to greater exposure to invasive procedures. Hyperglycemia negatively influences the neutrophil activity, decreases chemotaxis and impairs phagocytosis and, in this way, predisposes diabetic patients to severe and repeated infections. Catheter-related infections are more common, virulent, and linked with multidrug-resistant organisms in this population [4-6].

 Historically, the most frequently reported pathogens in CRBSIs have been Gram-positive organisms, including Staphylococcus aureus and coagulase-negative Staphylococci. Nevertheless, as recent research reports, there seems to be a trend toward Gram-negative bacteria, especially in hospitalized and immunocompromised patients. This dynamic microbial trend combined with the growing resistance to antimicrobials is a significant obstacle in treating these infections [7-9].

 Inappropriate use of antibiotics, lengthy hospital stay, and the use of invasive devices have increased global antibiotic resistance in both Gram-positive and Gram-negative species. Methicillin-resistant Staphylococcus aureus (MRSA) and extended-spectrum beta-lactamase (ESBL) producing Gram-negative bacteria are multidrug-resistant organisms that severely reduce the therapeutic choices and are linked to adverse clinical outcomes [10].

 Although, CRBSIs are clinically important, the microbiological spectrum and resistance patterns of diabetic patients with the double-lumen catheters is not widely documented locally, especially in the Pakistani healthcare context. Knowledge of the local epidemiology is critical in the process of informing empirical antibiotic therapy and effective infection control measures [11].

 Therefore, the present study was conducted to determine the frequency of microorganisms causing double-lumen catheter-related bloodstream infections and to evaluate their antibiotic resistance patterns among diabetic patients.

This cross-sectional study was conducted in the Department of Internal Medicine at Islamabad Medical and Dental College, Akbar Niazi Teaching Hospital (ANTH), Bharakahu, Islamabad, Pakistan, over a period of five months from May 2025 to September 2025. The study aimed to determine the frequency of microorganisms causing double-lumen catheter-related bloodstream infections (CRBSIs) and to evaluate the antibiotic resistance patterns of isolates among diabetic patients.

 Prior to the commencement of the study, ethical approval was obtained from the College of Physicians and Surgeons Pakistan (CPSP), Research Evaluation Unit, vide reference number CPSP/REU/MED-2020-135-16688, dated June 25, 2025. Written informed consent was obtained from all participants in accordance with the principles of the Declaration of Helsinki.

 The sample size of 168 patients was calculated using a 95% confidence level, a population proportion of 30.9%, and an absolute precision of 7%, employing a non-probability consecutive sampling technique. The study included adult diabetic patients aged 18–70 years, of either gender, diagnosed with diabetes mellitus (Type 1 or Type 2), who had double-lumen catheters inserted for at least 48 hours, exhibited clinical signs suggestive of sepsis (such as fever >38°C, chills, or hypotension), and had laboratory-confirmed CRBSI based on blood cultures obtained from both the catheter and peripheral vein, and/or catheter tip cultures.

 Patients were excluded if they had non-catheter-related infections as the primary source of sepsis, were immunocompromised (including those on chemotherapy or post-transplant), or were receiving long-term antibiotic or antifungal therapy prior to catheter insertion.

Clinical indications such as total parenteral nutrition (TPN), administration of crystalloids and colloids, blood transfusion, medication delivery, and central venous pressure (CVP) were the clinical indications of inserting double-lumen catheters. Catheters were usually kept 7 -10 days and were taken off in case of any suspicion of infection.

 In microbiological assessment, the semi-quantitative culture technique was used. Segment of catheters were swabbed on blood agar plates 3-4 times with sterile forceps then inoculated into nutrient broth. The media were both incubated aerobically and at 37 C and observed after 24 hours. In case turbidity was formed in the broth, subcultures were carried out on blood agar and incubated overnight. Standard bacteriological methods were used to identify microorganisms and counts of colonies were counted.

Moreover, histopathological analysis of the segments of catheters was conducted in order to identify fungal or bacterial invasion. When there was a suspicion of fungal infection, special staining techniques were used, such as Periodic Acid-Schiff (PAS) and Gomori methenamine silver stain. The resistance pattern of bacterial and fungal isolates to commonly used antimicrobial agents was determined by performing standard antibiogram test such as Kirby-Bauer disk diffusion method and Minimum Inhibitory Concentration (MIC) testing.

 Consistency was used by applying operational definitions. Catheter-related bloodstream infection (CRBSI) was considered to be the occurrence of the identical microorganism found in the tip of the catheter and in at least one peripheral blood culture in a patient with clinical evidence of sepsis. Infection occurring in the catheter was considered catheter-related infection and was determined by a growth of more than 15 colony-forming units (CFU) in a segment of the catheter related to local infection at the site of insertion. Microbial variation was taken to be the differences in the types and proportions of the organisms isolated, such as Gram positive bacteria, Gram negative bacteria, and fungi. Antibiotic resistance was determined as a ratio of the number of isolates resistant to the commonly used antimicrobial agents on the susceptibility test.

IBM SPSS version 27 was used to enter and analyze the data. The continuous variables, which included age, BMI, HbA1c, blood glucose levels, and catheter dwell time, were represented as mean and standard deviation and the categorical variables, including gender, catheter site, indications, clinical features, microbial isolates and resistance patterns as frequencies and percentages. Stratification was used to control effect modifiers which included age, gender, BMI, comorbidities, catheter site, duration of diabetes and catheter dwell time. Chi-square test or Fisher exact test was used to determine associations between variables, p-value of 0.05 was considered to be statistically significant.

The present study evaluated the microbiological spectrum and antibiotic resistance patterns in double-lumen catheter-related bloodstream infections (CRBSIs) among diabetic patients. The findings revealed that Gram-negative organisms were the predominant pathogens, followed by Gram-positive bacteria and a smaller proportion of fungal isolates. This predominance of Gram-negative organisms aligns with recent trends observed in hospital-acquired infections, particularly in developing countries, where increased use of invasive devices and prolonged hospital stays contribute to a shift from traditionally Gram-positive to Gram-negative dominance [12-14].

The most commonly identified pathogens among the isolated ones were Klebsiella pneumoniae and Staphylococcus aureus, which underscores the duality of both a community-associated and a hospital-acquired infection. The use of a large percentage of coagulase-negative Staphylococci (CONS) also highlights the importance of skin flora and catheter handling practices in the pathogenesis of CRBSIs. These results concur with up-to-date research that has recorded such kind of microbial patterns in catheter-related infections, especially in patients with a chronic illness like diabetes mellitus [15-17].

 One of the major findings in this work was the extensive antimicrobial resistance, particularly Gram-negative microbes. The level of resistance to widely used antibiotics like ceftriaxone and ciprofloxacin is remarkably high, but comparatively lower resistance to carbapenems and colistin was observed, which means that they could be still regarded as the last-resort therapy. Multidrug-resistant organisms (MDROs) are becoming increasingly more problematic as evidenced by the increasing proportion of Gram-positive isolates resistant to methicillin-resistant Staphylococcus aureus (MRSA). Such results are indicative of the international issue of antimicrobial resistance and the importance of stringent antibiotic stewardship initiatives [18].

 It was also revealed in the study that there is a strong relationship between poor glycemic control (HbA1c levels) and higher rate of Gram-negative infections, indicating that uncontrolled diabetes can dispose a patient to more severe and opportunistic infections. Moreover, there was a significant relationship between the length of catheter dwell time and increased infection rates especially of Gram-negative organisms. These results support the significance of the best glycemic control and the appropriate management of catheters in terms of minimizing the risk of CRBSIs [19].

 Fungal infections were less common but mostly Candida species with a significant percentage being resistant to fluconazole. Clinical implications of this finding are seen in the fact that it shows the emergence of non-albicans Candida and antifungal resistance, especially in immunocompromised and critically ill diabetic patients [20].

 This study has some limitations although it has its strengths. As a single-centre cross-sectional study, the results might not be applicable in other healthcare environments. Also, there was no molecular characterization of resistant strains or long-term clinical follow-up. The research however offers useful data regarding the local microbial profile and resistance trends that play a vital role in informing the empirical therapy.

In conclusion, this study demonstrates that Gram-negative organisms are the leading cause of double-lumen catheter-related bloodstream infections in diabetic patients, with Klebsiella pneumoniae and Staphylococcus aureus being the most commonly isolated pathogens. A high prevalence of antimicrobial resistance, including MRSA and multidrug-resistant Gram-negative organisms, was observed, posing a significant clinical challenge.

Poor glycemic control and prolonged catheter duration were identified as important risk factors associated with infection. These findings highlight the need for strict infection control measures, early catheter removal when indicated, optimized glycemic management, and rational use of antibiotics to reduce the burden of CRBSIs.

 Further multicenter studies with advanced microbiological techniques are recommended to better understand evolving resistance patterns and to develop targeted therapeutic strategies.

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