4 DISCUSSION AND CONCLUSION
This retrospective study of 82 elderly patients with bacteremia,
compared with a control group of 69 patients, identified E. coli,
K. pneumoniae, and streptococcus as the most prevalent
gram-negative bacteria. These findings align with prior research
conducted by Guarno et al. [7]. Similarly, an
investigation by Daniela Dambroso et al. [8]indicated that 47.7% of bloodstream infections were due to
Gram-positive bacteria and 52.3% to Gram-negative bacteria, with the
Enterobacteriaceae family, particularly E. coli (26.5%) andK. pneumoniae (19.7%), being the most prevalent. Further support
for these results was offered by a study conducted in Japan[9], which identified E. coli (28/58, 48%)
as the leading causative bacteremia pathogen, followed by K.
pneumoniae (6/58, 10%), and Staphylococcus (5/58, 8%).
Our research also revealed a significant predominance of gram-negative
bacteria in elderly female patients with bacteremia (74.4%), compared
to their male counterparts (25.6%) (P = 0.021) (Table 5).
Interestingly, a higher positivity rate for E. coli was found in
the female patient population, making E. coli the most common
bacteremia pathogen among this demographic. This is in alignment with
existing literature that identifies E. coli as a predominant
human pathogen with the capability to colonize, infect, and invade
various human tissues, leading to severe E. coli disorders and
potential mortality [10]. E. coli is the
leading cause of bacteremia among adults in the world and is the common
frequent of sepsis and subsequent hospitalization or deaths in the
United States[11]. The risk of invasive E.
coli infections, which consisted of sepsis and bacteremia, and
increased with the growth of the age [12].
The comparative evaluation of blood cell parameters in our study
revealed a statistically significant increase in leukocyte count, NLR,
PLR, and RDW among bacteremia patients. From the ROC curves, NLR emerged
as the most effective predictor of bacteremia in geriatric patients.
While the total white blood cell count is traditionally used as an
indicator of bacterial infection, its efficacy is limited by the
influence of other conditions such as hematological diseases,
non-infectious inflammatory diseases, surgery, and trauma[13]. In our study, the sensitivity and
specificity of WBC in diagnosing bacteremia in elderly patients were
determined to be 74.4% and 87.0%, respectively. RDW, a measure of the
variation in red blood cell volume size, is primarily used for
diagnosing anemia. Elevated RDW may reflect better residual bone marrow
hematopoiesis during severe anemia [14]. In
conditions such as sepsis, oxidative stress and inflammation can disrupt
erythrocyte maturation, leading to an increased RDW[15]. A previous study by Professor Dogan P et al.
showed that an RDW cut-off of >19.50% was associated with
a sensitivity of 87% and a specificity of 81% for predicting
late-onset Gram-negative sepsis (P < 0.001)[16]. In our study, the diagnostic value of RDW
demonstrated an RDW cut-off of >13.0% with the sensitivity
of 78.0% and the specificity of 52.2% for predicting bacteremia. The
difference in the results of the two investigations were mainly due to
the difference in the enrolled subjects.
Finally, our study underscores the value of NLR as a reliable indicator
of systemic inflammatory response, which has potential predictive value
for bacteremia. While NLR can be influenced by several factors,
including age, obesity, and various diseases [5],
its efficacy in diagnosing bacteremia is supported by several studies,
including our own.
The insights provided by this study make a compelling case for utilizing
these routine blood parameters as cost-effective, straightforward, and
rapid indicators for bacteremia in the elderly. However, it’s important
to acknowledge the study’s limitations. Our focus was on bacterial
pathogens, excluding others such as fungi, mycoplasma, chlamydia,
parasites, and viruses. Moreover, the single-center nature of the study
limits the generalizability of our findings. Future studies should aim
for a multi-center approach with larger sample sizes to provide a more
comprehensive understanding of geriatric bacteremia infections. These
studies should also further investigate the distribution of
microorganisms and the predictive value of routine.