Microbial Agents in Ventilation Associated Pneumonia (VAP) and their Resistance Pattern in Patients of ICU of Square Hospital, Bangladesh: An Observation for Two and a Half Year

Background Ventilator-associated pneumonia (VAP) is a major cause of higher morbidity and mortality among hospitalized patients especially in the intensive care unit (ICU) despite of recent advances in diagnosis and treatment. VAP is usually complicated by infection with multidrug-resistant (MDR) difficult-to-treat microorganisms. This study was conducted to evaluate the microbial agents, their antimicrobial characteristics, presence of MDR biomarkers such as ESBL, CRE and MRSA in VAP related infections. Methods This study reviewed the records of admitted patients in the ICU of Square Hospital Ltd (SHL) who developed VAP between January 2015 and 30 June 2017. Evaluation included microbial isolates, their resistant pattern and the biomarkers detected in Microbiology laboratory following standard methods and analyzed information on VAP associated morbidity and mortality. Results Of 2758 patients, 16 % (442 of 2758) patients died. Among deaths, 50 % (222 of 442) developed ventilator-associated pneumonia, more in males over 60 years. With regard to microbial isolates, Acinatobacter species (29 %) was the most frequently isolated gram-negative pathogens followed by Klebsiella pneumoniae (26 %), Pseudomonas (10 %) and E. coli (5 %). Acinatobacter had 86 % resistance to meropenem, 17 % resistance to collistin, but Klebsiella still 100 % sensitive to both collistin and polymyxin B. Of gram-positive isolates, Staphylococcus aureus (9 %) predominated over coagulase-negative Staphylococcus species (6 %). Antimicrobials such as Amikacin, Meropenem, Collistin and Polymyxin B were more sensitive against gram-negative bacteria, while Linezolid and Vancomycin were the drugs of choice for other Staphylococcal species. Candia was associated 4.5 % cases. Of MDR biomarkers, ESBL producer E. coli and Klebsiella were associated in VAP cases by 45 % and 16 % respectively, CRE producing Klebsiella and Acinatobacter in 61 % and 86 % cases, while MRSA producer S. aureus was in 55 % cases. Thus for VAP patients, collistin, polymyxin B and minocycline are the treatment option for CRE, meropenem for ESBL and vancomycin for MRSA cases. Conclusion Ventilator-associated pneumonia complicates the prognosis of patients receiving mechanical ventilation. Challenges remain with ESBL, CRE, MRSA and emerging collistin resistant Acinatobacter cases. Higher prevalence of VAP with MDR infections in ICU warrant early management plan using appropriate antibiotics followed by de-escalation based on culture-sensitivity and clinical response of the patient.