Spectrum of microbial infection in an Intensive Care Unit: a single centre tertiary care experience in Southern Indian state of Karnataka


  • Shruthi S. Department of Medicine, Yenepoya medical college hospital, Deralakatte, Mangalore, Karnataka, India
  • Balachandra S. Bhat Department of Medicine, Yenepoya medical college hospital, Deralakatte, Mangalore, Karnataka, India




Hospital-acquired pneumonia, Intensive care unit acquired pneumonia, Multi Organ Dysfunction, Ventilator-acquired pneumonia


Background: There is an increased incidence of hospital acquired infection, especially in ICU setting, the most common being ICU acquired pneumonia which increases the morbidity, mortality, prolongs hospital stay and consuming more resources. Microbial etiology of intensive care unit (ICU)-acquired pneumonia (ICUAP) determines antibiotic treatment and outcomes which vary from centre to centre. Hence, a study of risk factors, clinical profile of patient, microorganisms and their resistance patterns to antibiotics are important for the diagnosis, prognosis of patient with ICU acquired pneumonia and also in the prevention of the same.

Methods: Patients with ICUAP confirmed microbiologically were prospectively compared according to identification of 1 (monomicrobial) or more (polymicrobial) potentially pathogenic microorganism. Patients without microbiological confirmation were excluded from the study. We assessed clinical characteristics, microbiology and outcome variables.

Results: In the present study 60 patients with ICU Pneumonia were included out of which 50 (83%) had mono-microbial infection. Most common organism isolated in mono microbial infection was Klebsiella species (26%), followed by Acinetobacter species (25%), out of which 20 percent was multidrug resistant. Multi-drug resistance was similarly frequent in both groups.  Outcome variables like initial response to the empiric treatment, length of stay and mortality were similar in both monomicrobial and polymicrobial pneumonia. Mortality rates were higher with higher pneumonia scores (p value <0.002) and with multi organ dysfunction (p <0.008) irrespective of mono microbial or poly microbial infection.

Conclusions: In this study mono microbial infection was more than polymicrobial, the most common organism being Kliebsiella species followed by Acinetobacter species. When empiric treatment is frequently appropriate, mortality rates were higher with higher pneumonia scores and MODS. In our study polymicrobial aetiology did not influence the outcome of ICUAP.


Leone M, Bouadma L, Bouhemad B, Brissaud O, Dauger et al. Hospital acquired pneumonia in ICU. Anaesth Crit Care Pain Med. 2018 Feb;37(1):83-98.

American Thoracic Society, Infectious Diseases Society of America. Guidelines for the management of adults with hospital-acquired, ventilator-associated, and healthcare-associated pneumonia. Am J Respir Crit Care Med. 2005;171:388-416.

Melsen WG, Rovers MM, Groenwold RH, Bergmans DC, Camus C, Bauer TT, et al. Attributable mortality of ventilator-associated pneumonia: a meta-analysis of individual patient data from randomised prevention studies. Lancet Infect Dis.2013; 13 (8):665-71.

Rosenthal VD, Maki DG, Jamulitrat S, Medeiros EA, Todi SK, Gomez DY, et al. International Nosocomial Infection Control Consortium (INICC) report, data summary for 2003‑2008, issued June 2009. Am J Infect Control. 2010;38:95‑104.

Koulenti D, Tsigou E, Rello J. Nosocomial pneumonia in 27 ICUs in Europe: perspectives from the EU-VAP/CAP study. Europ J Clini Microbiol Infectious Dis. 2017 Nov 1;36(11):1999-2006.

Branch-Elliman W, Wright SB, Howell MD. Determining the ideal strategy for ventilator-associated pneumonia prevention. Cost–benefit analysis. Am J Respirator Crit Care Med. 2015 Jul 1;192(1):57-63.

Alvarez-Lerma F, ICU-acquired Pneumonia Study Group. Modification of empiric antibiotic treatment in patients with pneumonia acquired in the intensive care unit. Intensive Care Med. 1996 May 1;22(5):387-94.

Kumar A, Zarychanski R, Light B, Parrillo J, Maki D, Simon D, et al. Early combination antibiotic therapy yields improved survival compared with monotherapy in septic shock: a propensity-matched analysis. Crit Care Med. 2010 Sep 1;38(9):1773-85.

Heyland DK, Dodek P, Muscedere J, Day A, Cook D. Canadian Critical Care Trials G. Randomized trial of combination versus monotherapy for the empiric treatment of suspected ventilator-associated pneumonia. Crit Care Med. 2008;36(3):737-44.

Di Pasquale M, Ferrer M, Esperatti M, Crisafulli E, Giunta V, Li Bassi G, et al. Assessment of severity of ICU-acquired pneumonia and association with etiology. Crit Care Med. 2014;42:303-12.

Blot S, Koulenti D, Dimopoulos G, Martin C, Komnos A, Krueger WA, et al. Prevalence, risk factors, and mortality for ventilator-associated pneumonia in middle-aged, old, and very old critically ill patients. Crit Care Med. 2014;42:601-9.

Combes A, Figliolini C, Trouillet JL, Kassis N, Wolff M, Gibert C, et al. Incidence and outcome of polymicrobial ventilator-associated pneumonia. Chest. 2002;121:1618-23.

Kohlenberg A, Schwab F, Behnke M, Geffers C, Gastmeier P. Pneumonia associated with invasive and noninvasive ventilation: an analysis of the german nosocomial infection surveillance system database. Intensive Care Med. 2010;36:971-8.

Karhu J, Ala-Kokko TI, Ylipalosaari P, Ohtonen P, Laurila JJ, Syrjala H. Hospital and long-term outcomes of ICU-treated severe community- and hospitalacquired, and ventilator-associated pneumonia patients. Acta Anaesthesiol Scand. 2011;55:1254-60.

Giunta V, Ferrer M, Esperatti M, Ranzani O, Saucedo LM, Bassi GL, et al. ICU-acquired pneumonia with or without etiologic diagnosis: a comparison of outcomes. Crit Care Med. 2013;41:2133-43.

Fabregas N, Ewig S, Torres A, El Ebiary M, Ramirez J, De La Bellacasa JP, et al. Clinical diagnosis of ventilator associated pneumonia revisited: comparative validation using immediate post-mortem lung biopsies. Thorax. 1999;54:867-73.

Charles PG, Wolfe R, Whitby M, Fine MJ, Fuller AJ, Stirling R, et al. SMART-COP: a tool for predicting the need for intensive respiratory or vasopressor support in community-acquired pneumonia. Clini Infect Dis. 2008 Aug 1;47(3):375-84.

Woodhead MA, Torres A. Definition and Classification of Community-Acquired and Nosocomial Pneumonias. In: Torres A, Woodhead M, editors. Pneumonia. Sheffield: Europ Respirator Soc J Ltd. 1997:1-12.

Charles MP, Kali A, Easow JM, Joseph NM, Ravishankar M, Srinivasan S, et al. Ventilator-associated pneumonia. Austr Med J. 2014;7(8):334.

Ferrer M, Difrancesco LF, Liapikou A, Rinaudo M, Carbonara M, Bassi GL, et al. Polymicrobial intensive care unit-acquired pneumonia: prevalence, microbiology and outcome. Crit Care. 2015 Dec 1;19(1):450.

Jj R, Jy F, Chastre J, Domart Y, Trouillet JL, Pierre J, et al. Nosocomial pneumonia in patients receiving continuous mechanical ventilation. Prospective analysis of 52 episodes with use of a protected specimen brush and quantitative culture techniques. Am Rev Respir Dis. 1989;139:877-84

Rouby JJ, Martin de Lassales E, Poete P. Nosocomial bronchopneumonia in the critically III. Am Rev Respir Dis. 1992;146:1059-66.

Jimenez P, Torres A, Rodriguez RR, De-La-Bellacasa JP, Aznar R, Gatell JM, et al. Incidence and etiology of pneumonia acquired during mechanical ventilation. Crit Care Med. 1989;17:882-5

Jl T, Chastre J, Vuagnat A, Joly-Guillou ML, Combaux D, Dombret MC, et al.Ventilator-associated pneumonia caused by potentially drug-resistant bacteria. Am J Respir Crit Care Med. 1998;157:531-9.

Burgmann H, Hiesmayr JM, Savey A, Bauer P, Metnitz B, Metnitz PP. Impact of nosocomial infections on clinical outcome and resource consumption in critically ill patients. Intensive Care Med. 2010;36:1597-601

Ioanas M, Cavalcanti M, Ferrer M, Valencia M, Agusti C, Puig De La Bellacasa J, et al. Hospital-acquired pneumonia: coverage and treatment adequacy of current guidelines. Eur Respir J. 2003;22:876-82

Kollef MH. Appropriate antibiotic therapy for ventilator-associated pneumonia and sepsis: a necessity, not an issue for debate. Intensive Care Med. February 2003;29(2):147-9.

Namias N, Samiian L, Nino D, Shirazi E, O'Neill K, Kett DH, et al. Incidence and susceptibility of pathogenic bacteria vary between intensive care units within a single hospital: implications for empiric antibiotic strategies. J Trauma Injury Infect Crit Care.2000;49:638-64

Rello J, Sa Borges M, Correa H, Leal SR, Baraibar J. Variations in etiology of ventilator-associated pneumonia across four treatment sites: implications for antimicrobial prescribing practices. Am J Respir Crit Care Med. 1999;160:608-13.

Trouillet JL, Chastre J, Vuagnat A, Joly-Guillou ML, Combaux D, Dombret MC, et al. Ventilator-associated pneumonia caused by potentially drug-resistant bacteria. Am J Respir Crit Care Med.1998; 157:531-9

Pawar M, Mehta Y, Khurana P, Chaudhary A, Kulkarni V, Trehan N. Ventilator-associated pneumonia: Incidence, risk factors, outcome, and microbiology. J Cardiothorac Vasc Anes. 2003 Feb;17(1):22-8.

Kornum JB, Thomsen RW, Riis A, Lervang HH, Schønheyder HC, Sorenson HT. Diabetes, Glycemic Control, and Risk of Hospitalization With Pneumonia. Diab Care. 2008 Aug; 31(8):1541-5.

Koziel H, Koziel MJ. Pulmonary complications of diabetes mellitus. Pneumonia. Infectious disease clinics of North America. 1995 Mar;9(1):65-96.






Original Research Articles