European Journal of Cardiovascular Medicine

Community-acquired pneumonia can cause considerable morbidity and mortality due to respiratory illness and affects individuals of all ages regardless of severity, however, older adults and people with chronic medical conditions have a higher incidence of severity and complications [1]. The disease burden in India will continue to remain high due to delay in diagnosis and treatment, limited access to healthcare, and factors associated with India's environment such as air pollution and the use of biomass fuels for cooking [2].

The most common cause of community-acquired pneumonia is bacteria. The identification of the responsible organism is important because the use of inaccurate or late antibiotic therapy will increase morbidity, length of hospitalization, and cost. However, the identification of the responsible organism is often a challenge, since clinical symptoms overlap and microbiological identification is not always available [3].

Streptococcus pneumoniae has traditionally been identified as the most common cause of bacterial pneumonia around the world. Other common pathogens include Haemophilus influenzae, Staphylococcus aureus, and various Gram-negative organisms [4]. The relative prevalence of these organisms may differ based on geographic region, population age, vaccination coverage, and the presence of comorbid illness. In recent years, infections due to drug-resistant organisms have increased, making it more difficult to select empiric therapy that is effective [5].

Growing concern surrounds antibiotic resistance. The overuse and misuse of antimicrobials, in both outpatient and inpatient settings, have contributed to the evolution of resistance, which includes resistance to commonly prescribed antimicrobial treatment modalities, such as macrolides, fluoroquinolones, and third-generation cephalosporins. Regular monitoring of antimicrobial susceptibility patterns at the local level is critical for informing treatment guidelines, improving overall patient care, and advancing antimicrobial stewardship [6,7].

Data from India suggest variations in pathogen distribution and resistance patterns between hospitals and regions. Local microbiological surveillance helps clinicians choose antibiotics that are more likely to be effective at the time of initial treatment, before laboratory results are available. This is particularly important in resource-limited settings where treatment delay can significantly worsen outcomes.

Therefore, it is of interest to study the bacteriological profile and antibiotic sensitivity pattern in patients with community-acquired pneumonia admitted to a tertiary care hospital in India.

Study design and duration

This was a prospective cross-sectional observational study conducted over a period of twelve months, from January 2024 to December 2024.

Study setting

The study was carried out in the Department of Respiratory Medicine at a tertiary care hospital in India that manages a wide range of respiratory illnesses, including community-acquired pneumonia.

Sample size

A total of 130 patients were enrolled based on predefined eligibility criteria, representing a practical and statistically adequate sample for assessing bacteriological profiles in community-acquired pneumonia.

Inclusion criteria

• Patients aged 18 years and above
• Clinical features suggestive of community-acquired pneumonia such as cough, sputum production, fever, breathlessness, or chest pain
• Radiological evidence of new infiltrates on chest imaging
• Onset of symptoms in the community or within 48 hours of hospital admission

Exclusion criteria

• Hospital-acquired pneumonia or ventilator-associated pneumonia
• Immunocompromised patients such as those with HIV/AIDS, those receiving chemotherapy, or chronic immunosuppressive therapy
• Patients already on antibiotics for more than 48 hours prior to admission
• Patients unwilling or unable to provide adequate respiratory samples

Specimen collection and microbiological analysis

When feasible, sputum samples were obtained prior to the commencement of antibiotic therapy. All samples were evaluated for acceptability based on the number of epithelial cells and leukocytes seen on microscopic examination. Acceptable samples were analyzed according to standard bacteriological techniques for Gram stain and culture. Blood cultures and bronchoalveolar lavage samples were collected when clinically indicated. For organism identification, biochemical tests were done when automated methods were not available. Antibiotic susceptibility testing was done using the Kirby-Bauer disc diffusion method in accordance with the Clinical and Laboratory Standards Institute (CLSI) guidelines; antifungal susceptibility testing if performed was determined via the E-test method. Antimicrobial agents included those which are commonly prescribed to manage pneumonia: beta-lactams, cephalosporins, macrolides, fluoroquinolones, and aminoglycosides.

Data collection

Demographic information, clinical symptoms, laboratory findings, radiological findings, pathogen type and identification, and antibiotic resistance patterns were documented using a structured proforma on admission.

Ethical considerations: The institutional ethics committee approved the study, and informed consent was obtained from all patients prior to enrollment in the study. All information related to patients was kept confidential.

Statistical analysis

Data was collected and analyzed using descriptive statistics. Frequency and percentages were used to display organism distribution and antibiotic susceptibility patterns

A total of 130 patients diagnosed with community-acquired pneumonia were included in this study. Most patients were in the middle-aged to elderly population, and males made up a larger proportion of cases. Smoking and chronic lung disease were the most frequently reported risk factors. Cough and fever were the predominant presenting symptoms, followed by breathlessness and sputum production. A positive bacterial culture was obtained in approximately three-fourths of the study population, indicating a good rate of microbiological yield from specimens collected prior to antibiotic initiation. Streptococcus pneumoniae was identified as the most common organism, followed by Haemophilus influenzae and Klebsiella pneumoniae. Antibiotic resistance patterns varied among the isolates, with Gram-negative organisms demonstrating higher levels of resistance compared to pneumococcal isolates. Hospital stay duration reflected favorable recovery in most patients with appropriate management.

Table 1: Age distribution of study participants

Table 1 shows that most patients belonged to the age group of 51–70 years.

Table 2: Gender distribution

Table 2 shows a higher proportion of males compared to females.

Table 3: Common risk factors

Table 3 indicates smoking and chronic lung disease as the most common associated risks.

Table 4: Presenting symptoms

Table 4 highlights cough and fever as the most frequent symptoms.

Table 5: Culture positivity

Table 5 shows that 74.6% of samples grew a bacterial pathogen.

Table 6: Bacterial organisms isolated

Table 6 shows Streptococcus pneumoniae as the leading pathogen.

Table 7: Antibiotic sensitivity pattern of Streptococcus pneumonia

Table 7 shows high sensitivity to β-lactams and macrolides.

Table 8: Antibiotic sensitivity pattern of Haemophilus influenza

Table 8 reflects good sensitivity to cephalosporins but lower to penicillins.

Table 9: Antibiotic sensitivity pattern of Klebsiella pneumonia

Table 9 demonstrates notable resistance to multiple agents.

Table 10: Antibiotic sensitivity pattern of Staphylococcus aureus

Table 10 highlights the presence of methicillin resistance.

Table 11: Hospital stay duration

Table 11 shows most patients recovered within 7–10 days.

Table 1 shows that the majority of patients were aged 51–70 years. Table 2 indicates that males were more commonly affected. Table 3 demonstrates smoking as the predominant risk factor. Table 4 highlights cough and fever as the most common symptoms. Table 5 shows a culture positivity rate of 74.6 percent. Table 6 confirms Streptococcus pneumoniae as the leading isolate. Table 7 indicates high sensitivity of pneumococcal strains to beta-lactams and macrolides. Table 8 shows good sensitivity of Haemophilus influenzae to cephalosporins. Table 9 reveals higher resistance among Klebsiella pneumoniae isolates, with carbapenems remaining effective. Table 10 indicates methicillin resistance in a subset of Staphylococcus aureus isolates but full sensitivity to vancomycin and linezolid. Table 11 shows recovery within 5–10 days for most patients.

This study examined the bacteriological profile and antibiotic sensitivity pattern in patients with community-acquired pneumonia admitted to a tertiary care hospital in India. The data show that most affected individuals were middle-aged to elderly, and males were more frequently involved [8]. Smoking and pre-existing chronic lung diseases were the most common risk factors, which aligns with the well-known contribution of airway damage and impaired mucociliary clearance to lower respiratory tract infections [9].

Streptococcus pneumoniae was the main organism found, which supports both global and national data that classify it as the most common bacterial organism involved in community-acquired pneumonia [10]. Haemophilus influenzae was also isolated frequently, mainly in chronic lung disease patients, who are more likely to have colonization. Notably, the presence of multiple Gram-negatives, such as Klebsiella pneumoniae, suggests a shift possibly due to comorbid conditions, risk of aspiration, and previous healthcare exposures [11].

Staphylococcus aureus, including methicillin-resistant types, was found in a small but clinically significant number of cases. These infections are uncommon, but the clinical presentation may be more severe with complications, especially in specific populations. The isolation of Pseudomonas aeruginosa, while infrequent, supports broad spectrum anti-microbial coverage in some populations at higher risk for this specific pathogen [12,13].

Antibiotic susceptibility testing provided useful information to empirically guide the treatment of these infections. Streptococcus pneumoniae showed universal sensitivity to beta-lactams and macrolides, which supports recommendations for first-line therapy and therapy that has been successfully used in some of the previously evaluated studies [14]. Both pneumococcal and Haemophilus influenzae isolate resistance profiles highlight the need for continued monitoring. The most concerning finding was the higher resistance observed in the Klebsiella pneumoniae isolates, particularly with fluoroquinolones and some cephalosporins. Carbapenems and aminoglycosides are still of value; however, stewardship considerations should lead to these agents being reserved for resistant types of infections or in with cases that are severe [15]

These results underscore the importance of empirical therapy being based on local susceptibility trends rather than generalized guidelines. Indiscriminately prescribing antibiotics or selecting the wrong antibiotic contributes to the increased resistance, limiting treatment options in the future. Antimicrobial stewardship initiatives as well as updated local antibiograms can provide opportunities to modify prescribing behavior and enhance patient outcomes. Most patients experienced resolution to their infection within 1 week of appropriate therapy, indicating a potentially favorable response when the choice of antibiotic aligns with the sensitivity results. The small subset of patients who required prolonged hospitalization were likely representing patients who were either very ill/presented late in the course of their illness, or infected with resistant organisms.

Clinical implications

Knowing the local bacterial causes and resistance patterns in a particular clinical setting is critical in developing effective treatment strategies. Involving routine local surveillance into clinical practice helps inform optimal empirical therapy, improves ability to respond to new resistance patterns, and allows for rational antibiotic use.

Future research directions

Viral and atypical organisms should be included in larger multicenter studies to gain a more complete understanding of the etiology of community-acquired pneumonia in India. In addition, molecular diagnostics and risk stratification via biomarkers may improve early diagnosis of infections with resistance patterns and allow for more precise treatment decisions.

In this cross-sectional study, a significant association between persistent high levels of high-density lipoprotein (HDL) and higher rates of persistent high vascular occlusion was demonstrated. The patients with low HDL levels had a greater risk of prolonged occlusion suggesting a determinant of poor cardiovascular outcomes if not diagnosed and treated in some timely fashion. These results suggest that using HDL levels as a continuous clinical variable and not just a standard risk stratification variable may provide earlier indications of vascular risk. Although the present study does not provide any information about treatment effectiveness, it points to the value of early, proactive, and intentional assessment of lipids during standard day-to-day practice in cardiology. Future studies should examine larger multicenter cohorts and longer follow-up to determine whether targeted lipid optimization affects long-term vascular patency and overall patient survival in the event of obstructive vascular disease.

1. Mohapatra S, Pathi BK, Mohapatra I, Singh N, Sahoo JP, Das NK, Pattnaik D. Bacteriological Profile of Patients With Stroke-Associated Pneumonia and Antimicrobial Susceptibility of Pathogens: A Cross-Sectional Study. Cureus. 2024 Nov 21;16(11):e74150. doi: 10.7759/cureus.74150. PMID: 39712707; PMCID: PMC11663042.
2. El-Nawawy A, Ramadan MA, Antonios MA, Arafa SA, Hamza E. Bacteriologic profile and susceptibility pattern of mechanically ventilated paediatric patients with pneumonia. J Glob Antimicrob Resist. 2019 Sep;18:88-94. doi: 10.1016/j.jgar.2019.01.028. Epub 2019 Jan 30. PMID: 30710648.
3. Chapman TM, Perry CM. Cefepime: a review of its use in the management of hospitalized patients with pneumonia. Am J Respir Med. 2003;2(1):75-107. doi: 10.1007/BF03256641. PMID: 14720024.
4. Yuan J, Mo B, Ma Z, Lv Y, Cheng SL, Yang Y, Tong Z, Wu R, Sun S, Cao Z, Wu J, Zhu D, Chang L, Zhang Y; Investigator Group of the Phase 3 Study on Oral Nemonoxacin. Safety and efficacy of oral nemonoxacin versus levofloxacin in treatment of community-acquired pneumonia: A phase 3, multicenter, randomized, double-blind, double-dummy, active-controlled, non-inferiority trial. J Microbiol Immunol Infect. 2019 Feb;52(1):35-44. doi: 10.1016/j.jmii.2017.07.011. Epub 2017 Aug 2. PMID: 30181096.
5. Hoeffken G, Meyer HP, Winter J, Verhoef L; CAP1 Study Group. The efficacy and safety of two oral moxifloxacin regimens compared to oral clarithromycin in the treatment of community-acquired pneumonia. Respir Med. 2001 Jul;95(7):553-64. doi: 10.1053/rmed.2001.1113. PMID: 11453311.
6. Paganin F, Chanez P, Brousse C, Lilienthal F, Darbas H, Jonquet O, Godard P, Michel FB. Pneumonies communautaires dans la région de Montpellier. Augmentation des pneumocoques de sensibilité diminuée aux pénicillines [Community acquired pneumonias in the region of Montpellier. Increase of pneumococci with reduced sensitivity to penicillins]. Presse Med. 1995 Oct 7;24(29):1341-4. French. PMID: 7494845.
7. Vanlalruati RS, Mamta Devi KS, Singh NB, Singh NT. A study of bacteriological profile (aerobic) and antimicrobial susceptibility of community acquired pneumonia cases in the RIMS hospital. J Commun Dis. 2012 Mar;44(1):47-9. PMID: 24455915.
8. Meyer Sauteur PM. Childhood community-acquired pneumonia. Eur J Pediatr. 2024 Mar;183(3):1129-1136. doi: 10.1007/s00431-023-05366-6. Epub 2023 Dec 19. PMID: 38112800; PMCID: PMC10950989.
9. Chen YC, Hsu WY, Chang TH. Macrolide-Resistant Mycoplasma pneumoniae Infections in Pediatric Community-Acquired Pneumonia. Emerg Infect Dis. 2020 Jul;26(7):1382-1391. doi: 10.3201/eid2607.200017. PMID: 32568052; PMCID: PMC7323531.
10. Wei J, Walker AS, Eyre DW. Addition of Macrolide Antibiotics for Hospital Treatment of Community-Acquired Pneumonia. J Infect Dis. 2025 Apr 15;231(4):e713-e722. doi: 10.1093/infdis/jiae639. PMID: 39718980; PMCID: PMC11998547.
11. Andrews J, Nadjm B, Gant V, Shetty N. Community-acquired pneumonia. Curr Opin Pulm Med. 2003 May;9(3):175-80. doi: 10.1097/00063198-200305000-00004. PMID: 12682561.
12. Gil R, Webb BJ. Strategies for prediction of drug-resistant pathogens and empiric antibiotic selection in community-acquired pneumonia. Curr Opin Pulm Med. 2020 May;26(3):249-259. doi: 10.1097/MCP.0000000000000670. PMID: 32101906.
13. Bessat C, Boillat-Blanco N, Albrich WC. The potential clinical value of pairing procalcitonin and lung ultrasonography to guide antibiotic therapy in patients with community-acquired pneumonia: a narrative review. Expert Rev Respir Med. 2023 Jul-Dec;17(10):919-927. doi: 10.1080/17476348.2023.2254232. Epub 2023 Nov 24. PMID: 37766614.
14. Teng GL, Chi JY, Zhang HM, Li XP, Jin F. Oral vs. parenteral antibiotic therapy in adult patients with community-acquired pneumonia: a systematic review and meta-analysis of randomized controlled trials. J Glob Antimicrob Resist. 2023 Mar;32:88-97. doi: 10.1016/j.jgar.2022.12.010. Epub 2023 Jan 18. PMID: 36669558.
15. Ruuskanen O, Mertsola J. Childhood community-acquired pneumonia. Semin Respir Infect. 1999 Jun;14(2):163-72. PMID: 10391410.