Introduction

Health care-associated infections (HCAIs) are the infections which occur in hospitals during health care. HCAIs are usually developed in hospitals and appear after 48 hours of hospital admission, or within 30 days after getting health care services.^[1] The US Center for Disease Control and Prevention identifies that nearly 1.7 million hospitalized patients annually acquire HCAIs and more than 98,000 patients (1 in 17) die worldwide due HCAIs.^[2] Commonly acquired HCAIs are infections of surgical wounds, urinary tract infections and respiratory tract infections like Hospital Acquired Pneumonia (HAP).^[3] HAP is second most common HCAIs that occur in 27% critically ill patients.^[4] HAP can be defined as pneumonia that occurs after 48 hour or more after admission to the hospital but did not appear to be incubating at time of admission.^[5]

These ICUs are equipment with mechanical ventilators to assist breathing through an endotracheal tube (ETT) or by a tracheotomy tube. Eighty-six percent of HAP are associated with mechanical ventilation (MV) and are termed as ventilator associated pneumonia (VAP).^[6] VAP is defined as bacterial pneumonia developing in patients after at least 48 hours of Mechanical ventilation but not present at the time of intubation or admission in hospital.^[7] Early onset VAP (EOVAP) is defined as VAP occurring within 0-4 days of endotracheal intubation while Late onset VAP (LOVAP) is defined as VAP occurring after 5 or more days of intubation. VAP is commonest complication in ICUs patients reported at the rate of 1-3% per day of Mechanical Ventilation(MV) and prevalence rate ranges from 10% to 65% in tertiary care hospitals.^[8]

Risk of VAP increases with increase in duration of mechanical ventilation, so accelerate weaning and by using non-invasive ventilation can reduce the risk.^[9] Supine (0°)patient positioning also facilitates aspiration, which can be decreased by changing position to semirecombent (45°) position.^[10] Enterally feeding has been considered as a risk factor for development of VAP because of an increase risk of aspiration. Non-modifiable risk factors includesmale gender, head trauma, preexisting pulmonary disease, AIDS, coma and multi-organ system failure. Other risk factors for the development of VAP includes- tracheostomy, dialysis, reintubation, tube thoracostomy, sedatives, corticostcroids, inotropic drugs, presence and duration of central venous and arterial catheters.^[11]

Microorganisms causing pneumonia can be endogenous (digestive system or nose and throat), or exogenous from contaminated respiratory equipment which colonizes in the upper airway and bronchi and can cause infection in the lungs (pneumonia). Both Gram-positive and Gram-negative bacteria are implicated in VAPs, but most commonly found are Acinetobacter baumannii, Pseudomonas aeruginosa followed by Klebsiella pneumoniae, Enterococcus faecalis, Staphylococcus aureus, and Enterobacter species.^[12] Studies highlighted that frequent and unselective usage of broad spectrum antibiotics without consideration of culture and Susceptibility reporting leads to the development of multidrug resistant microorganisms (MDRs).^[13] These MDRs are frequently colonized through endogenous or exogenous sources on life saving instruments such as Mechanical Ventilators in ICUs.^[14] Bacteriological examination of respiratory secretions offer helping hand to clinician in diagnosing VAP and also helps him to initiate early antibiotic regimen. The rapid availability of cytological data including inflammatory cells and gram stain are useful in initial therapeutic decisions. Every possible effort should therefore be made to obtain reliable pulmonary specimens for direct microscopic examination and cultures from each patient clinically suspected of having developed VAP before new antibiotics are administered.

Aims and Objective

To isolate and identify the bacterial pathogens in endotracheal tubes aspirates of ICUs patients and study their antimicrobial susceptibility pattern.

Materials and Methods

A prospective longitudinal study was conducted in the Microbiology laboratory of a tertiary care hospital over a period of six months. All the samples of ETT secretions received in Clinical Microbiology lab from ICU patients and fulfilling the criteria for VAP were included in this study. This present study was carried out for 06 months after clearance from institutional Research Committee and Ethical Committee.

Direct smear staining was performed for each sample and organisms were identified on the basis of morphology, arrangement and Gram’s reaction. The samples were inoculated on Blood agar and MacConkey agar plates. The plates were then incubated overnight at 37°C for 24 hours. The growth of the organisms were observed on Blood agar medium and MacConkey agar medium. The colonies were identified from colony characters like size, shape, surface, edges, margin, consistency, emulsifiability, opacity, colour and any odour. Further growth was confirmed by Gram staining, biochemical reactions and other specific confirmatory tests. Antimicrobial susceptibility testing was performed on Mueller Hinton Agar (MHA) by Kirby Bauer disc diffusion method as per CLSI guidelines.^[15]

Different antibiotics disks of HIMEDIA were used according to bacterial isolate. Sensitivity was recorded by measuring the diameter of zone of inhibition in reference to CLSI. Clinical data was collected from patient’s file by visiting ICU.

Results

Total 100 samples were enrolled in the present study of which 67(67.0%) were of male and 33(33.0%) of female patients ([Table 1]). The age wise distribution showed 13 (13.0%)ETT secretions samples were received from 0-20 year’s age group, 14(14%) from 21-40 year age group, 29(29.0%) from 41-60 years age group and 44(44.0%) from >60 years age group ([Table 2]). Total 20(20.0%) samples of ETT had the history of early onset of VAP and 80(80.0%) samples belong to late onset of VAP. Total 70(70.0%) patients has the prior history of antibiotics, 44(44.0%) has the clinical representation to Prior Hospitalization, 15(15.0%) were belong to Aspiration, 18(18.0%) patients has clinical history of Re-Intubation, 34(34.0%) samples patients has prior history of Diabetes Mellitus, 30(30.0%) patients has clinical picture of Hypertension and 07(7.0%) were on immunosuppressant therapy ([Table 3]). In our study, 76 (76.0%) ET samples were showing the significant bacterial growth with a total 80 isolates obtained. Among these 80 bacterial isolates, 05(6.26%) were gram positive and 75(93.7%) were gram negative. The most frequent isolates were Acinetobacter baumannii 35(43.7%) followed by Klebsiella pneumoniae 25(31.2%) Pseudomonas aeruginosa 7(8.75%), Escherichia coli 6 (7.5%), Staphylococcus aureus 3(3.7%), Enterococcus faecalis 2 (2.5%) and other gram negative isolates 02 (2.5%) ([Table 4]). Antibiotic susceptibility pattern of isolated bacteria was as shown in [Table 5], [Table 6].

Discussion

The risk for development of VAP depends upon several factors such as Host immunity, duration of stay in hospitals, exposure to potential pathogens, re-intubation and Diabetes mellitus.^[16] In our study among 100 samples 67(67%) were from male ([Table 1]) patients which were similar to study by Neha Samal et al. This may be due to more admission of male patients and also male are more prone to accidental trauma.^[17] In this study maximum patients were belong to the age group >60 years. Similar finding was also reported by Mukesh Dube et al. in his study in 2018.^[18] This indicates that patients with higher age group are highly prone to VAP. This is because of the fact that patients with higher age groups were having lower immunity, decrease mucocillary clearance of secretions and co-morbid conditions like diabetes mellitus and hypertension. In our study maximum cases of VAP were late onset compare to early onset this is because of prolonged hospital stay increases cross infection and HAIS among patients. Our results were similar to that of ElipsGiantsou while a study by cook et al. found higher incidence of early onset VAP.^[19] Major risk factors associated with VAP in our study were history of prior antibiotics, prior hospital admission, re-intubation, diabetes and hypertension ([Table 3]). In a similar study Tedja R hasanalysed 107 samples out of which 49 were having the history of home antibiotics.^[20] The reason behind this is production of MDRs by unselective use of antibiotics. These MDRs are potential risk of VAP. The prevalence of VAP in our study was 76%. Similar high prevalence 53% of VAP was also noted by Pooja Gupta et al. In our study Gram negative isolates were predominate over Gram positive isolates.^[21] Our study results indicate Acinetobacter baumannii is major pathogenic bacteria followed by Klebsiella pneumonia and Pseudomonasaeruginosa ([Table 4]). A study conducted by Zorgani A et al. also found major pathogens as Acinetobacter baumanni and Klebsiella pneumonae. All Acinetobacter baumannii isolates were sensitive to colistin while resistant to ampicillin and amoxiclav ([Table 5]). Sensitivity to tigecyclin was 82.2%, imipenem and meropenem 11.4% and piperacillin tazobactem 5.7% ([Table 5]). All Klesiella pneumonia isolates were sensitive to colisitin and resistant to ampicillin, amoxiclav, ciprofloxacin, cefixime, piperacillin tazobactam. Sensitivity to tigecyclin was 44% amikacin 28%, imipenem and meropenem 16% and gentamicin 12% ([Table 5]). All Pseudomonas aeruginosa isolates were sensitive to colistin while resistant to ampicillin, amoxiclav,ceftizidime and piperacillin tazobactam. Sensitivity to amikacin and gentamicin was 42.8%, ciprofloxacin, imipenem and meropenem is 28.5% each.([Table 5]) In our study antimicrobial pattern of isolated bacteria shows multidrug resistant pathogens are associated with VAP. Similar type of Multidrug resistance among VAP pathogen was also noted by another studies.^[17], ^[22] The detection of Multi Drug Resistant isolates in VAP patients further limit therapeutic options and necessitating the role of culture and sensitivity. A combined clinical, microbiological, infection control strategies which include proper diagnosis and appropriate antibiotic can lead to proper patient management. Every hospital should have appropriate antibiogram to start the imperical antibiotic treatment.

Conclusion

The presence of devices in airway, prevents the cough, impairs mucocilliary clearance, permit micro aspiration of contaminated sub-glottic secretions around the cuff and allow the formation of intraluminal biofilms by bacteria. These Gram negative and Gram Positive bacteria are major source of Ventilator associated pneumonia. Every hospital should have appropriate antibiogram to start the imperical antibiotic treatment. Appropriate training of health care staff regarding different measures to prevent spread of multidrug resistance should be done time to time decrease the incidence of VAP and to fight MDR pathogens.

Source of Funding

Nil.

Conflict of Interest

Nil.