E Premalatha

G Jayalakshmi

T K V Sharavanan

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Copyright © August, 2014; IJPAB                                       161 
 
 
 
 
 
A Study on Bacterial Profile of Lower Respiratory Tract Infections in 
Geriatric Population 
E. Premalatha1*, T. K.V. Sharavanan2 and G. Jayalakshmi.3 
1Assistant Professor, Department of Microbiology, Melmaruvathur Adhiparasakthi Institute of Medical 
Sciences and Research. Melmaruvathur-603319 
2Associate Professor, Department of General Medicine, Melmaruvathur Adhiparasakthi Institute of Medical 
Sciences and Research. Melmaruvathur-603319 
3Professor and Head of Department, Institute of Microbiology, Madras Medical College and Rajiv Gandhi 
Government General Hospital, Chennai 
*Corresponding Author E-mail: drpremalathae@yahoo.c.in 
 
            ABSTRACT                                                                                                       
Background: The Geriatric population refers to persons who are 65 years of age and above. Lower 
Respiratory Tract Infections are among the most common diseases encountered in elderly people.  This 
study was conducted to determine the bacterial pathogens causing lower respiratory tract infections in 
geriatric population, and their antibiotic susceptibility pattern. Materials & Methods: The present study 
for a period of one year included 110 patients with lower respiratory tract infections, 65 years of age and 
above, admitted in Geriatric Medical ward, Rajiv Gandhi Government General Hospital, Chennai.  The 
study population included 110 geriatric patients admitted in Geriatric Medical ward for lower 
respiratory tract infections. The respiratory samples and blood were collected and processed according 
to standard methods. Results: In this study, data showed that majority of patients with lower respiratory 
tract infections were in the age group of 65-74 years (82.0%) and predominantly males (62.7%) Among 
the 110 patients, significant bacterial growth was exhibited by 68 (61.8%) cases.  Out of the 76 isolates, 
Klebsiella pneumoniae (36.8%) was the commonest pathogen. A total of 26 (34.2%) and 5 (6.6%) isolates 
were Extended Spectrum Beta-Lactamase and AmpC Beta-Lactamase producing organisms, respectively. 
About 7.9% of the total isolates were Methicillin-Resistant Staphylococcus aureus . Blood samples 
yielded growth in 2.7% cases. Conclusion: Due to the evolving nature of the epidemiology of lower 
respiratory tract infections in older persons, continued research and surveillance are essential to 
optimize the prevention and therapy of lower respiratory tract infections in the Geriatric population. 
Key words: Lower Respiratory Tract Infections, Geriatrics, Klebsiella pneumoniae. 
 
INTRODUCTION  
The term geriatric refers to the aging human population1. Geriatric population is defined as persons 65 
years of age and older. 2 The number of people older than 65 will double to 14 percent from 7 percent of 
the world’s population in the next 30 years, rising to 1.4 billion by 2040 from about 506 million in the 
middle of last year, said the report, “An Aging World: 2008,” commissioned by the U.S. National  
Institute on Aging3. The older persons have age-related immunological chnges, chronic cognitive and 
physical impairments, and diseases that alter host resistance. Therefore, they are highly susceptible o 
infections and their complications4. The elderly are more likely than younger patients to have nonspecific 
signs and symptoms of infection, more severe disease, and resistant microorganisms. Lower Respiratory 
Tract Infections [LRTI] remains the most important cause of hospitalization in the elderly people. It 
consisted of episodes of pneumonia, acute bronchitis and exacerbations of chronic obstructive pulmonary 
disease (COPD).  
Available online at www.ijpab.com  
 
   ISSN: 2320 – 7051   
Int. J. Pure App. Biosci. 2 (4): 161-165 (2014) 
INTERNATIONAL JOURNAL OF PURE & APPLIED BIOSCIENCE 
Research Article 
Copyright © August, 2014; IJPAB                                       162 
 
Premalatha, E. et al                      Int. J. Pure App. Biosci. 2 (4): 161-165 (2014)                          ISSN: 2320 – 7051 
These patients were allowed to have more than one episode of LRTI with at least a 3-week symptom-free 
interval between each episode5. This study was conducted to determine the etiologcal agents causing 
lower respiratory tract infections in geriatric population attending tertiary care hospital. Antibiotic 
susceptibility patterns of the pathogens and the predisposing factors for LRTI were also evaluated, which 
would provide information to optimize accurate timely diagnosis, treatment and care of the elderly. 
MATERIALS AND METHODS 
This prospective study was conducted in the Institute of Microbiology in association with the Department 
of Geriatric Medicine, Madras Medical College and Rajiv Gandhi Government General Hospital, 
Chennai, over a period of one year from October 2010 to September 2011. The study population included 
110 geriatric patients admitted in Geriatric Medical w rd for lower respiratory tract infections. The study 
was approved by the Institutional Ethics Committee, Madras Medical College and Rajiv Gandhi 
Government General Hospital, Chennai.  Patients below 65 years of age, and those who were being 
started on antibiotic therapy for lower respiratory t act infections in Geriatric medical ward, before 
collection of samples, and also patients admitted in Geriatric medical ward for diseases other than lower 
respiratory tract infections were not included in this study. The respiratory samples collected were sputum 
(93 samples), bronchial wash (11 samples), bronchoalve l r lavage (4 samples), and pleural fluid (2 
samples). 
Laboratory Assay: Blood was also collected from the 110 patients. The samples were processed 
according to the standard methods. The respiratory specimens were plated out on MacConkey agar, blood 
agar, and chocolate agar and incubated at 370 C for 24 hours. Blood was inoculated into the Brain-heart 
infusion biphasic medium bottle in the ratio of 1:5, and incubated at 350 C. Routine subcultures were 
performed after 48 hours of incubation at 350 C in 10% CO2. Incubation was continued up to 14 days in 
the absence of negative subcultures6.   Bacterial growth was identified by the colony morphology, Gram 
staining, motility, biochemical reactions. Antibacterial sensitivity tests [Disc Diffusion Method - Kirby 
Bauer’s] was performed by standard microbiological techniques as recommended by Clinical and 
Laboratory Standards Institute (CLSI).  Production of (ESBL) Extended  spectrum β-Lactamases in 
Gram- negative bacilli was detected by screening test, Double disk diffusion synergy test (DDST) and 
CLSI phenotypic confirmatory disc diffusion test (PCDDT) . AmpC  β-Lactamases producing Gram- 
negative bacilli were identified by screening methods.Imipenem-EDTA combined disk method was 
employed to determine Metallo  β-Lactamases ( MBL) production in Gram- negative bacilli.Disc 
diffusion method and Oxacillin agar method were used to isolate methicillin resistant Staphylococcus 
aureus (MRSA). 
RESULTS 
Majority of the patients were in the age group of 65 to 74 years (82%). Males (62.7%) were found to be 
predominantly affected than females (37.3%). AECOPD (55.5%) was the commonest lower respiratory 
tract infection, observed in our study. [Table 1] The older persons most often presents with atypical 
clinical features, which interferes with rapid diagnosis and treatment. In this study, patients present d 
with non-specific symptoms  like myalgia (68.2%), chills (21.8%), confusion (18.2%), vomiting (10%) 
and diarrhea (1.8%). The respiratory symptoms noticed were cough (82.7%), dyspnea (71.8%), sputum 
production (67.3%) and pleuritic chest pain (35.5%). The risk factors that   increases the morbidity and
mortality of lower respiratory tract infections like hypertension (53.6%), smoking (50.9%), Diabetes 
Mellitus (49.1%), alcohol intake (44.5%), previous exacerbations of COPD (36.4%), poor oral hygiene 
(29.1%), dysphagia (24.5%), cardiac disease (17.3%), cognitive impairment (10.0%), malnutrition 
(6.4%), tumour (1.8%), renal disease (1.8%) and hemiparesis (1.8%)  were observed in the study 
population. Among the 110 patients, significant bacterial growth was exhibited by 68 (61.8%) cases. 
[Table 2]. Polybacterial growth was observed in 8 (7.3%) cases. Of the 76 isolates, Klebsiella 
pneumoniae (36.8%) was the commonest pathogen, followed by Pseudomonas aeruginosa (22.3%), 
Acinetobacter baumannii (11.8%), Staphylococcus aureus (10.5%) Proteus mirabilis (5.3%), Escherichia 
coli (3.9%), Streptococcus pneumoniae (2.6%)  and Citrobacter koseri (2.6%). A total of 26 (34.2%) and 
Copyright © August, 2014; IJPAB                                       163 
 
Premalatha, E. et al                      Int. J. Pure App. Biosci. 2 (4): 161-165 (2014)                          ISSN: 2320 – 7051 
5 (6.6%) isolates were  ESBL and AmpC Beta-Lactamases producing organisms, respectively. 7.9% of 
the total isolates were Methicillin-Resistant Staphylococcus aureus (MRSA) . Blood samples yielded 
growth in 2.7% cases. 
TABLE 1: AGE, SEX AND DISEASE DISTRIBUTION OF PATIE NTS N=110 
Age in years 65-74 yrs 75-84 yrs 
 
> 85yrs 
 
Total 
AECOPD=61 
(55.5%) 
M 28 (25.5%) 9 (8.1%) 1 (0.9%) 38 (34.5%) 
F 20 (18.2%) 2 (1.8%) 1 (0.9%) 23 (20.9%) 
Pneumonia=40 
(36.4%) 
M 23 (20.9%) 3 (2.7%) - 26 (23.6%) 
F 13 (11.8%) 1 (0.9%) - 14 (12.7%) 
Acute 
Bronchitis=9 
(8.2%) 
M 5 (4.5%) - - 5 (4.5%) 
Total 
F 2 (1.8%) 1 (0.9%) 1 (0.9%) 4 (3.6%) 
 91 (82.7%) 16 (14.5%) 3 (2.7%) 110 
 
TABLE 2:   CULTURE POSITIVITY OF RESPIRATORY SAMPLE S  N=110 
Type of Sample No. of samples collected 
No. of  culture 
positive samples 
Sputum 93 (84.5%) 65 (59.1%) 
Bronchial wash 11 (10.0%) 2 (1.8%) 
Bronchoalveolar Lavage 4 (3.6%) 1 (0.9%) 
Pleural Fluid 2 (1.8%) - 
                                                   
DISCUSSION 
Lower Respiratory Tract Infections are among the most c mmon diseases encountered in elderly people. 
In most studies carried out, age is a major risk factor for both occurrence and severity of lower respiratory 
tract infections.    Majority of the patients were in the age group of 65 to 74 years (82%). The p-value 
obtained is 0.04, which is statistically significant. The number of patients with LRTI decreased as age 
advanced. Jackson ML et al 7 showed an increase in the incidence of lower respiatory tract infections 
with increasing age, in their study of USA seniors. The low life expectancy at birth in India contributes to 
the decrease in population of oldest people.Among the 110 patients, admitted in Geriatric Medical ward 
for lower respiratory tract infections, males (62.7%) were found to be predominantly affected than 
females (37.3%). The male predilection seen in this study could be explained by the increase in frequency 
of co morbidities and the risk factors  present in male patients.  Similar finding was also observed in the 
study by E Hak et al from Netherlands, in which 63% of patients with LRTI were males.8History of 
smoking was presented by 56 male (50.9%) patients. The p-value obtained for smoking was <0.01. This 
shows significant association of smoking with LRTI. In the Leiden 85-plus study of  A.Sliedrecht et al, 9 
smoking was mentioned as the greatest contributor of LRTI with a population attributable risk of 32%.  A  
total  of  66  isolates  (60%)  of  aerobic  Gram  negative  bacilli  and 10(9.1%)  isolates  of  Gram  
positive  cocci  were  cultured  from  110  samples. Similar  result was also seen  in the randomized study 
by Phillip K. Peterson et al,10  in which  about 81% of  the 123  cases  yielded Gram negative bacteri . 
Belousov IuB et al, 11 in his study from Moscow, showed isolation of Gram positive cocci from 70% of 
the patients. In the current study, Klebsiella  pneumoniae (25.5%) was the most frequent pathogen 
isolated from the  respiratory samples. The study by Christopher Aye Egbe et al from Nigeria  also 
showed the predominance of Klebsiella pneumoniae (30.16%) in lower  respiratory tract infections. 12 The 
susceptibilities of the bacterial isolates towards the various antibiotics were determined by disc diffus on 
method and broth macrodilution method. Among the  76 pathogens isolated, 26 (34.2%) were Extended 
Spectrum Beta-Lactamase (ESBL) producers.  
Copyright © August, 2014; IJPAB                                       164 
 
Premalatha, E. et al                      Int. J. Pure App. Biosci. 2 (4): 161-165 (2014)                          ISSN: 2320 – 7051 
Klebsiella pneumoniae was the  predominant ESBL producing organism. 12 (42.8%) strains of the 28 
isolates of Klebsiella pneumoniae were confirmed to be ESBL producers. This result is in accordance 
with the study by MU Xin-lin et al13 in which 39 strains (30.9%) out of the total 126 isolates of Klebsiella 
pneumoniae  were ESBL producers. About 5(6.6%) AmpC  Beta-Lactamase producing Gram negative 
bacteria were determined in this study by screening test. In he study conducted by Singhal S et al,14 the 
occurrence of AmpC β-lactamases was found to be 8% of the total isolates.In the study under discussion, 
7.9% of the total isolates were found to be M thicillin-Resistant Staphylococcus aureus (MRSA). Out of 
the 8 isolates of Staphylococcus aureus, 6 (75%) isolates were MRSA. All the strains of Staphylococcus 
aureus  were sensitive to Vancomycin. Adel Khattab et al 15 isolated 8.1% of MRSA among the total 
isolates. Blood cultures from the 110 patients yielded 3 pathogens (2.7%) including 2 strains of Klebsiella 
pneumoniae and 1 isolate of Streptococcus pneumoniae. The sputum from the patients showing positive 
blood culture also reported the same pathogens with similar antibiogram. This finding was supported by 
the Nima Afshar et al16 in their systematic review, in which  they reported  0% to 14%  of  cases  of 
community-acquired pneumonia showing true positive blood culture results. 
 
CONCLUSION  
From this prospective study, it is quite clear that t e elderly patients are at high risk for contracting lower 
respiratory tract infections due to Gram negative bacteria. The emergence of resistant strains in the 
patients of the present study emphasize the need of prudent use of antibiotics. Due to the evolving nature 
of the epidemiology of lower respiratory tract infections in older persons, continued research and 
surveillance are essential to optimize the prevention and therapy of lower respiratory tract infections i  
the Geriatric population. 
Acknowledgement 
The authors express their thanks to the Dean, Madras Medical College and Rajiv Gandhi Government 
General Hospital, Chennai for granting permission to conduct this study and Dr. V. S. Natarajan, Retired  
Professor of Geriatric Medicine, Madras Medical College for his excellent guidance and assistance in 
preparing this study material. 
  
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A Study on Bacterial Profile of Lower Respiratory Tract Infections in Geriatric Population

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A Study on Bacterial Profile of Lower Respiratory Tract Infections in Geriatric Population

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