Lower respiratory tract infection (LRTI) is a short-term illness, characterized primarily by cough and at least one other symptom such as fever, breathlessness, sputum production, or chest discomfort, without alternative explanations like sinusitis or asthma¹. Globally, LRTIs are the fourth leading cause of death, accounting for 34.6% of respiratory-related fatalities in the South-East Asia region^2.  Bacterial infections are the most common LRTIs in intensive care units (ICUs), affecting 10–25% of patients and contributing to high mortality rates of 22–71%. Among these, pneumonia stands out as the most prevalent and clinically significant LRTI³. This study focused exclusively on pneumonia cases, using the CURB-65 score to guide admission and treatment decisions⁴. Notably, microbiological profiles vary between community-acquired pneumonia (CAP) and healthcare-associated pneumonia (HCAP), particularly in patients hospitalized within 90 days prior.Lower respiratory tract infections (LRTIs) are a significant concern in neurological intensive care units (NICUs), affecting 10–25% of patients and contributing to mortality rates as high as 22–71%. The rise of antibiotic-resistant bacterial strains, both in hospitals and the community, poses a global public health challenge, especially in resource-limited settings⁵. Factors such as patient demographics, healthcare standards, inappropriate antibiotic use, and prevalence of resistant pathogens influence the incidence and mortality of LRTIs. Highly resistant Gram-negative bacilli (GNB) are particularly problematic in developing countries, where limited isolation facilities exacerbate therapeutic challenges. Acute respiratory infections remain a leading cause of death among critically ill patients in these regions. Empirical antimicrobial therapy is often initiated before culture results, but increasing resistance complicates treatment options. This study aims to analyze antimicrobial resistance patterns in ICU-acquired respiratory infections to guide effective antibiotic policies.

AIM

^{Clinical and Microbiological Profile of Patients with Pneumonia Admitted to the ICU of a Tertiary Care Hospital in Southern Rajasthan}

This study was conducted in the Medical and Respiratory ICUs of SPMC Bikaner, from January 2016 to October 2017, following approval by the Institutional Ethical Committee. Patients aged >18 years were included, excluding those on mechanical ventilation, HIV-positive individuals, and sputum-smear-positive tuberculosis cases. Upon ICU admission, clinical and radiographic evaluations were performed within 24 hours, with emphasis on prior hospitalizations within 90 days. Samples for investigation, including blood, sputum, and respiratory specimens, were collected before initiating antibiotics. Diagnosis of pneumonia in 94 patients followed NICE guidelines, with CURB-65 scores calculated and co-morbid conditions noted. Specimens underwent Gram staining and aerobic culture on standard media, with antimicrobial susceptibility testing performed using the Kirby-Bauer disc diffusion method as per CLSI guidelines. Final assessments were based on culture and sensitivity reports to guide treatment decisions.

Table 1: Gender Distribution

The data shows that males constitute the majority of the population, with 77 individuals (82%), while females make up a smaller portion, with 17 individuals (18%).

Table 2: Distribution Of Symptoms:

Among the 94 patients, cough (82%) and expectoration (78%) are the most common symptoms, followed by shortness of breath (54%), fever (56%), and chest pain (47%). These findings highlight the prevalent respiratory and systemic symptoms in the studied population.

Table 3:History of Hospitalisation and Associated Organisms in Patient

The data shows the presence of various organisms in hospitalized patients, with Pseudomonas spp being the most common, followed by Streptococcus pneumoniae, Klebsiella spp, and others, while 3 patients had a culture-negative result. These findings highlight the significance of hospital-acquired infections and the diversity of organisms involved.

Table 4:Patterns of Chest Radiographic Findings in Patients

The chest radiographic findings reveal that multilobar involvement is present in 31% of patients, while the right lower lobe (21%), left lower lobe (17%), and other lung areas show varying levels of involvement. These patterns highlight the diverse lung regions affected in the studied population.

Table 5:Antibiotic sensitivity pattern -gram negative isolates

Table shows antibiotic sensitivity patterns show varying resistance and susceptibility among gram-negative isolates, highlighting the importance of targeted therapy based on local antibiogram data.

Table 6: Antibiotic sensitivity pattern for gram positive isolates

The table shows varying antibiotic sensitivities in Gram-positive isolates, with high susceptibility to vancomycin and differing resistance patterns across other tested agents.

Our data presented in the table highlights the distribution of gender among the studied population, showing a notable disparity between males and females. Males constitute the majority, with 77 individuals accounting for 82% of the total population. This significant proportion suggests a predominance of males in the sample or study group. In contrast, females represent only 17 individuals, making up 18% of the total, indicating a relatively low representation compared to their male counterparts.

Our study shows that cough(82%) and expectoration (78%) are the most common symptoms among the 94 patients. Shortness of breath affects 54% of patients, while fever is present in 56% of the population. Chest pain is less frequent, affecting 47% of patients. These findings help clinicians identify key symptoms for diagnosis and treatment. Further research may explore symptom causes, severity correlations, and demographic variations.These findings are consistent with the other studies^6,7.

The data shows that hospital-associated infections in the 94 patients^8,9,10. involve multiple organisms, with Pseudomonas spp being the most prevalent. Other notable organisms include Streptococcus pneumoniae, Klebsiella spp, Acinetobacter spp, and Escherichia coli Additionally, Streptococcus aureus and Citrobacter spp are less common. Notably, 3 patients had culture-negative results, indicating no detectable organisms. Identifying these organisms is essential for effective infection control, treatment planning, and reducing hospital-acquired infections.Patients who did not have prior history of hospitalisation showed S. pneumonia as the most common pathogen isolated, which is in contrast with other studies Pseudomonas aeruginosa is a common pathogen in patients with severe COPD admitted to ICU¹¹.

The table shows the chest radiographic findings among the studied population, with multilobar involvement observed in 29 patients (31%). Right lower lobe involvement is seen in 20 patients (21%), while the left lower lobe is affected in 16 patients (17%). The right middle lobe is involved in 13 patients (14%), and the left upper lobe is affected in 9 patients (10%). Lastly, the right upper lobe is observed in 7 patients (7%). These findings highlight the distribution of lung involvement, which is critical for diagnosing and managing respiratory infections.Jain et al⁷ and Bansal et al¹² have reported involvement of the right lower lobe in most of the cases. This difference may be because Gram-negative pathogens were more common in our study, while Gram-positive pathogens were common in the previous studies. Most patients included in our study had a CURB-65 score of 3 or more which justifies their admission in ICU¹³.

Most of the Gram-negative isolates were susceptible to colistin (97%), and meropenem (91%) while the least effective antibiotic was ceftriaxone (58%). The pattern of antibiotic resistance recorded in the present study among P. aeruginosa, Acinetobacter spp., K. pneumonia and E. coli isolates is consistent with the results from other developing countries^14-16 Vancomycin showed highest activity (100%) against Gram-positive isolates followed by linezolid (92%) and gentamicin (79%) in the present study, which is in contrast with the results of earlier studies^17,18.

The rising antibiotic resistance in respiratory pathogens has made empirical treatment with traditional agents less reliable, necessitating a definitive bacteriological diagnosis and susceptibility testing for effective pneumonia management. Critically ill and elderly patients are particularly susceptible to Gram-negative pneumonia. Monitoring antimicrobial resistance is crucial in optimizing therapy, especially in ICUs where infection rates and antibiotic use are higher. Therefore, a locally developed antibiogram, along with bacteriological diagnosis and susceptibility testing, is essential to address the global challenge of antibiotic resistance in pneumonia treatment.

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