Clinicomicrobiological profile of the Indian elderly with sepsis

The study included 400 elderly patients (≥60 years of age) with clinically suspected sepsis. The maximum number of patients was in the age group of 60-69. Diabetes was the most prevalent comorbid condition. The most common site of infection was the urinary tract followed by the lungs atypical manifestations were quite prevalent with delirium being present in majority of patients. The most common organism isolated was Staphylococcus aureus followed by Escherichia coli. Introduction: Sepsis is one of the leading causes of morbidity and mortality in the elderly; despite great progress in antimicrobial treatment and intensive care medicine, the incidence of sepsis remains high while severe sepsis still has high mortality. Materials and Methods: The study included 400 consecutive elderly patients (≥60 years of age) with clinically suspected sepsis. Sepsis definition was based on the presence of infection and two or more of the systemic inflammatory response syndrome (SIRS) criteria. Blood and other site cultures were obtained on admission and during hospitalization when needed. Result: The total number of elderly patients with suspected septicemia who were enrolled in the study was 400. The maximum number of patients (68%) were in the age group of 60-69 years, whereas 32 patients (8%) were in the age group of >80 years. The age of the study population ranges from 60 years to a maximum of 95 years. The mean age of our study population was 67.52 ± 6.65 years with a male: female ratio of 1.68. The prevalence of SIRS criterion in the study population shows that tachycardia (89%) was the most common criteria followed by fever (84%) and leukocytosis (82.5%). All the four SIRS criteria were present in 42% of the patients, three in 37.5% of the patients and only two in 20.5% of the patients. The most common site of infection was the urinary tract (30.5%) followed by the lungs (21.25%) and skin infection (14%). Atypical manifestations were quite prevalent in the study population with delirium being the most common presentation. Conclusion: The present study was undertaken to study the clinicomicrobiological profile in Indian elderly patients presenting with sepsis. The mean age of the study population was 67.52 ± 6.65 years. Out of 400 cases, there were 115 (28.75%) blood culture positive cases. Gram-negative organisms (51.7%) were more commonly grown than gram-positive ones (48.30%). The most common organism isolated was Staphylococcus aureus (49 patients) followed by E. coli (36 patients). Diabetes was the most prevalent comorbid condition in our study population that was present in 28% of the population followed by BPH (17.75%) and hypertension (16%). Delirium was present in 112 (28%) patients not having CNS infection. In our study, 324 patients improved, whereas 76 died and the mortality was positively correlated with the stage of sepsis and it was statistically significant (P = 0.032).

Keywords: Blood culture, delirium, diabetes, elderly, sepsis

Sepsis is one of the leading causes of morbidity and mortality in the elderly; despite great progress in antimicrobial treatment and intensive care medicine, the incidence of sepsis remains high while severe sepsis still has high mortality. ^[1]

Compared with the younger population, the elderly have increased susceptibility to infections and are at a significantly increased risk for morbidity and mortality due to many common infections. Possible explanations for the observed higher morbidity and mortality rates among older patients include physiological decline due to aging and the frequent presence of comorbid illnesses. Each year, ~7 out of 50,000 patients in the USA develop severe sepsis. ^[2] More than 60% of these patients are ≥65 years of age. With the number of octogenarians expected to double by the year 2030, severe sepsis in the older patients is a major public health concern. ^[3]

Bacteremia in the elderly is a difficult diagnostic and therapeutic challenge due to many unusual presentations and associated comorbid conditions. ^{[4],[5],[6],[7]} Several studies have identified age as an independent predictor of mortality in patients with sepsis. ^[8],[9] Yet, analyses of bacteremia solely within an older population have been few. ^[10],[11]

The present study aims to characterize the clinical profile of the Indian elderly presenting with sepsis, associated comorbid conditions, presumed sites of infection, and factors associated with increased mortality.

The study took place at the Geriatric Division in the Department of General Medicine, Sir Sunder Lal Hospital, Banaras Hindu University (BHU), Varanasi, Uttar Pradesh, India with the collaboration of the Microbiology Department, Institute of Medical Sciences (IMS), BHU, Varanasi, Uttar Pradesh, India between July 2010 and June 2012.

Patients

The study included 400 consecutive elderly patients (≥60 years of age) with clinically suspected sepsis. Sepsis definition was based on the presence of infection and two or more of the systemic inflammatory response syndrome (SIRS) criteria. ^[12]

Blood and other site cultures were obtained on admission and during hospitalization when needed. Blood and other site cultures and routine biochemical and hematological tests were done as per standard protocol while several diagnostic procedures (chest x-rays, ultrasound, etc.) were performed to identify the source of infection. All the patients were treated with an empirical antibiotic regimen based on the protocols supervised by the treating consultants (e.g., third-generation cephalosporins plus an aminoglycoside while vancomycin, teicoplanin, meropenem, or clindamycin was used when necessary). Antimicrobial therapy was changed according to culture results when needed. Patients were closely monitored during hospitalization and severely ill patients were transferred to the intensive care unit (ICU). The study protocol was approved by the Hospital Ethics Committee and all subjects gave written consent for participation.

The total number of elderly patients with suspected septicemia who were enrolled in the study was 400. The maximum number of patients (68%) were in the age group of 60-69 years, whereas 32 patients (8%) were in the age group of >80 years. The age of the study population ranges from 60 years to a maximum of 95 years. The mean age of our study population was 67.52 ± 6.65 years with a male:female ratio of 1.68. The prevalence of SIRS criterion in the study population shows that tachycardia (89%) was the most common criteria followed by fever (84%) and leukocytosis (82.5%). All the four SIRS criteria were present in 42% of the patients, three in 37.5% of the patients and only two in 20.5% of the patients.

The most common site of infection was the urinary tract (30.5%) followed by the lungs (21.25%) and skin infection (14%) [Table 1].

Atypical manifestations were quite prevalent in the study population with delirium being the most common presentation [Table 2].

The data in [Table 3] show the prevalence of comorbid conditions in the study population. Diabetes was the most prevalent comorbid condition that was present in 28% of the population followed by benign prostatic hyperplasia (BPH) (17%), hypertension (16.5%), chronic obstructive pulmonary disease (COPD) (12.7%), and ischemic heart disease (IHD) (6%).

[Table 4] shows the outcome of sepsis in the study population. Among the patients, 81% improved while 19% died. There was a positive correlation between the severity of sepsis and mortality that was statistically significant (P = 0.032).

Blood culture was positive in 115 (28.75%) out of 400 patients. [Table 5] shows the blood culture isolates in the patients. Gram-negative ones (51.30%) were more commonly grown than gram-positive organisms (48.7%). The most common organism isolated was Staphylococcus aureus (in 49 cases) followed by E. coli (in 36 cases).

The present study was undertaken to evaluate the profile of elderly patients with sepsis. The study population included elderly patients with features of septicemia. In our study population, the mean age was 67.52 ± 6.65 years with the majority of patients (68%) in the age group of 60-69. Similarly in a study carried out by Leibovici et al. (1993), it was found that episodes of bacteremia were nearly double in the age group of 60-79 years (656) as compared to patients in the age group of 80 years and above (339). ^[13] In another study carried out by B.M.Greenberg et al. (2005), it was found that bacteremia was more common in the age group of 65-74 years (128) than in the age group of ≥75 years (110). ^[14] This difference was even more in our study as less number of people are in age group of ≥80 years in the developing world due to lower longevity.

The most common site of infection in our study was the urinary tract (30.5%) followed by the lungs (21.25%) and the skin (14%). A similar observation was made by B.M.Greenberg et al. (2005) in their study in which they found that the most common source of bacteremia was the urinary tract with 26% of the suspected cases having the disease at that site followed by the lungs (16.38%). ^[14] Leibovici et al. (1993) also found that the urinary tract was the most common source of bacteremia in the elderly. ^[13] They found that in patients who were aged 80 years and above, the source of 50% of the bacteremia cases was in the urinary tract compared with 34% of episodes in patients in the age group of 60-79 years. This study showed a higher percentage of patients having urinary tract infection (UTI). This may have been due to the fact that many patients were catheterized and were residents of a nursing home in the study. Marshall et al. (2001) also found that UTI (46%) was the most common presumptive source of septicemia in the elderly hospitalized for septicemia in the year 1997 in the USA. ^[15] Factors contributing to bacterial colonization and infection of the urinary tract of the elderly include mechanical changes (reduction in bladder capacity, uninhibited contractions, decreased urinary flow rate, and postvoid residual urine), urothelial change (enhanced bacterial adherence), prostatic hypertrophy in men, and hormonal changes (lack of estrogen in postmenopausal women).

The lungs (21.25%) and the skin (14%) were the next most common sites of infection in our study. These sites are more commonly involved in the elderly population as compared with the younger population. Mechanisms that are likely to contribute to increased risk of pneumonia in elderly are: Blunting of protective reflexes in the airway; decrease in mucociliary clearance; loss of local immunity (decreased T-cell subsets and immunoglobulin in respiratory secretions); and decreased acid production by the stomach.

Delirium is a common presenting manifestation in elderly patients with infection. In our study, 28% of the patients who had no evidence of central nervous system (CNS) infection presented with delirium. Similar to our study, B.M. Greenberg et al. (2005) found that on admission, 22% of the patients had a neurological chief complaint (including altered mental status). ^[14] Marshall et al. (2001) found that congestive heart failure (CHF) was present in 23.6% of the elderly patients admitted with the diagnosis of septicemia, ^[15] whereas in our study, 15% of the elderly had presented with CHF Atypical manifestations were quite prevalent in the study population with delirium being the most common presentation [Table 2].

Diabetes was the most prevalent comorbid condition that was present in 28% of the population followed by BPH (17%) and hypertension (16.5%). Similar to our study, B.M. Greenberg et al. (2005) also noted that diabetes was present in 31% of the bacteremic elderly patients; however, cardiovascular diseases were present in 37% of the patients. ^[14] Marshall et al. (2001) also noted that diabetes was present in 34.5% of the hospitalizations with sepsis ^[15] but the prevalence of hypertension was higher (23.1%) than our study (16%).

In our study, 19% of patients expired and a significant correlation was found between the outcome of sepsis and the stage of sepsis at the time of admission (P = 0.032). Similarly Leibovici et al. (1993) found that 35% of the patients aged 80 years and above and 30% of the patients aged 60-79 years died during hospital stay. ^[13] This can be explained by the fact that more patients were diagnosed as septic shock (13% in the age group of 60-79 years and 9% in the age group of ≥80 years) compared to our study where only 3.5% of the patients were in septic shock. This could also be due to selection bias as we selected patients from the medical wards with less serious complications. They also found a significant correlation of the shock [or low systolic blood pressure (SBP) at the time of admission] with a fatal outcome. C.A. Gogos et al. (2003) also concluded that the single best predictor of poor outcome was the presence of septic shock on admission. ^[16]

The blood culture positivity in our study was 28.75%. Christopher et al. (2001) observed blood culture positivity to be 40.3% in patients suspected of having septicemia ^[17] that is comparable to our study considering the fact that most of our patients were on antibiotic therapy at the time of blood collection for culture. In our study, among blood culture isolates gram-negative organisms (51.30%) were more commonly grown than gram-positive ones (48.7%). B.M.Greenberg et al. (2005) in their study reported that gram-positive organisms were present in 58% of the blood isolates and gram-negative organisms were present in 36% of the isolates. ^[14] In another study, Christopher et al. (2001) found that gram-positive organisms were isolated from 69.6% of the blood culture-positive cases and gram-negative organisms in 30.4%. ^[17] Martin et al. (2003) in their study observed that among the organisms reported to have caused sepsis in 2000 in USA, gram-positive bacteria accounted for 52.1% of cases, with gram-negative bacteria accounting for 37.6%. ^[18]

The most common organism isolated in our study was Staphylococcus aureus in 42.60% of blood culture positive cases and E. coli in 31.30% of cases. B.M. Greenberg et al. (2005) in their study also led to a similar observation with Staphyloccus aureus and E. coli being the two most common blood culture isolates present in 24% and 17% of the blood culture positive cases, respectively. ^[14] Christopher et al. (2001) in their study also found that Staphylococci (44.6%) were the most common blood culture isolates. ^[17]

The present study was undertaken to study the clinicomicrobiological profile in Indian elderly patients presenting with sepsis. The mean age of the study population was 67.52 ± 6.65 years. Out of 400 cases, there were 115 (28.75%) blood culture positive cases. Gram-negative organisms (51.7%) were more commonly grown than gram-positive ones (48.30%). The most common organism isolated was Staphylococcus aureus (49 patients) followed by E. coli (36 patients). Diabetes was the most prevalent comorbid condition in our study population that was present in 28% of the population followed by BPH (17.75%) and hypertension (16%). Delirium was present in 112 (28%) patients not having CNS infection. In our study, 324 patients improved, whereas 76 died and the mortality was positively correlated with the stage of sepsis and it was statistically significant (P = 0.032).

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/1755-6783.188525

[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]