The Challenging Diagnosis of Non-Community-Acquired Pneumonia in Non-Mechanically Ventilated Subjects: Value of Microbiological Investigation

Abstract

Background: Early recognition and an attempt at obtaining microbiological documentation are recommended in patients with non-community-acquired pneumonia (NCAP), whether hospital-acquired (HAP) or health care-associated (HCAP). We aimed to characterize the clinical features and microbial etiologies of NCAP to assess the impact of microbiological investigation on their management.

Methods: This was a prospective 1-y study in a university hospital with 141 non-mechanically ventilated subjects suspected of having HAP (n = 110) or HCAP (n = 31).

Results: Clinical criteria alone poorly identified pneumonia (misdiagnosis in 50% of cases). Microbiological confirmation was achievable in 80 subjects (57%). Among 79 microorganisms isolated, 28 were multidrug-resistant aerobic Gram-negative bacilli and group III Enterobacteriaceae and 6 were methicillin-resistant Staphylococcus aureus. Multidrug-resistant aerobic Gram-negative bacilli accounted for one third of the microorganisms in early-onset HAP and for 50% in late-onset HAP. Methicillin-resistant S. aureus was most often recovered from subjects with HCAP. Inappropriate empirical antibiotics were administered to 36% of subjects with confirmed pneumonia. Forty subjects were admitted to the ICU, 13 (33%) of whom died. Overall, 39 subjects (28%) died in the hospital.

Conclusions: Integrating the microbiological investigation in the complex clinical diagnostic workup of patients suspected of having NCAP is mandatory. Respiratory tract specimens should be obtained whenever possible for appropriate management.

Keywords: antibiotics; diagnosis; hospital-acquired pneumonia; multidrug-resistant microorganisms; nosocomial infection.