Zinc as a Predictor of Sepsis in Critically Ill Patients

INTRODUCTION

Sepsis in patients who were admitted to critical units would badly affect their prognosis [1]. Immune cells require sufficient minerals, vitamins, and energy to function properly. Zinc deficiency disrupts macrophages, and neutrophils and immunological function. Its shortage causes a range of alterations in DNA repair pathways, cytokine gene expression, and zinc transporters [2]. In the current study, we aimed to evaluate serum zinc as a predictor of sepsis.

PATIENTS/MATERIALS AND METHODS

Study setting & design:

This case-control study was carried out in the Critical Care Unit (CCU) of the Internal Medicine Department, Assiut University Hospital during the period from 1^st August 2022 to 30^th May 2023.

Selection criteria

Adult 60 (30 patients with sepsis and 30 patients without sepsis) patients with ages ranging between 18-70 years old with symptoms of systemic infection and with a clinical suspicion of sepsis as diagnosed by the CCU physician. Patients who received antibiotic therapy within three days before sample collection were excluded. Sepsis-related organ failure assessment (SOFA) score was used to define sepsis (patients required two points to be considered to have sepsis) [3].

Methodology

Each patient was subjected to, a full history and clinical examination including vital signs such as pulse, blood pressure, respiratory rate, and temperature. The following investigations were done; complete blood count, liver function tests, kidney function tests, and arterial Blood gases. Serum ferritin, C-reactive protein, and serum zinc.

Blood culture

Cultures were drawn before administration of antibiotics, if possible, and if not, a resin-containing bottle was used. Blood cultures were drawn via venepuncture, not from lines. Two samples were drawn via different sites per set to exclude contamination.  Collection of the sample as mentioned above and incubated in BacT/ALERT 3D system (bioMérieux, France).

Data analysis

Data was collected and analyzed by using SPSS (Statistical Package for the Social Science, version 20, IBM, and Armonk, New York). The Shapiro test was used to determine the compliance of the data to normal distribution. Quantitative data mean ± standard deviation (SD) and range. These data were compared with the Student t-test. Nominal data were given as number (n) and percentage (%). The Chi2 test was implemented on such data.

The receiver operator characteristic curve was used to determine the accuracy of serum zinc, CRP, and serum ferritin in the prediction of sepsis in critically ill patients. The level of confidence was kept at 95% and hence, the P value was considered significant if < 0.05.

RESULTS

Baseline data in the studied patients based on the development of sepsis (table 1):

Both groups had insignificant differences as regards baseline data (p> 0.05) except patients with sepsis had a significantly higher mean age (58.34 ± 14.69 vs. 46.75 ± 14.83 (age); p< 0.001). Baseline laboratory data in patients based on the development of sepsis (table 2, figures 1-3):

Patients with sepsis had significantly higher leucocytes, neutrophils, CRP, and ferritin with significantly lower serum albumin. Serum zinc (31.45 ± 6.78 vs.75.55 ± 12.45 (µg/dl); p < 0.001) was lower in patients with sepsis.Results of culture among patients with sepsis (table 3):

The most frequent isolated organisms were Staphylococcus hemolyticus (33.3%) and Klebsiella pneumonia (23.3%). Each of Staphylococcus epidermidis and Staphylococcus hominis was isolated in 4 (13.3%) patients.Correlation of zinc, CRP, and ferritin with other variables (table 4):

It was found that CRP had a positive correlation with leucocytes (r= 0.51), neutrophils (r= 0.46), ESR (r= 0.23), and ferritin (r= 0.21) with a negative correlation serum zinc (r= -0.53). Zinc level based on possible risk factors for sepsis and types of infection (table 5):

We found that different risk factors for sepsis showed no significant difference as regards zinc level. Also, zinc levels showed insignificant differences between types of infection either pneumonia or urinary tract infection.

Accuracy of serum zinc, CRP, and ferritin in the diagnosis of sepsis (table 6, figure 4):

For the prediction of sepsis in critically ill patients; serum zinc at cutoff < 28.90 µg/dl, had the best diagnostic accuracy in comparison to other markers (88%). Meanwhile, CRP at cutoff > 23.45 mg/dl had 67.5% accuracy while serum ferritin at cutoff > 997.67 mcg/l had 60% overall accuracy.

Outcome among the studied patients based on development of sepsis (table 7):

CCU’s stay was significantly longer among patients with sepsis (15.83 ± 1.87 vs. 9.14 ± 2.17 (days); p< 0.001). Also, a total of 6 (20%) patients with sepsis and only one patient without sepsis deteriorated and died.

 Table 1: Baseline data in the studied patients based on the development of sepsis

Table 7:  CCU's stay and outcome based on the development of sepsis in the current study

Data expressed as mean (SD), range, frequency (percentage). P value was significant if < 0.05. CCU: Critical care unit.

 DISCUSSION