The microbial colonization profile of respiratory devices and the significance of the role of disinfection: a blinded study.

Introduction: Approximately 10-40% of all the nosocomial infections are pulmonary, which lead to grave complications. Elderly, debilitated, or critically ill patients are at a high risk. The respiratory care equipments which include ventilators, humidifiers, nebulizers may have been identified as the potential vehicles which cause major nosocomial infections if they are colonized by fungi or bacteria.

Aim: To determine the rate of colonization by bacteria and fungi of the oxygen humidifier chambers of the portable cylinders and central lines at our hospital. The Hudson's chambers of nebulizers were also studied for the same.

Methods: Swab samples were obtained from the equipments by using sterile cotton swabs on a tuesday, as these chambers were usually cleaned on every Saturday. Spot samples were taken from the ICUs, wards, the casualty and OPDs on a single day. Air samples were also obtained on the same day to determine whether the fungal spore load in the inhaled room air was normal or high. We performed a disinfection with 70% ethanol after cleaning these devices.

Results: 53/70 (75.71%) samples showed fungal growth; out of which, 23/33 (69.70%) were from the ICU, 24/30(80%) were from the wards and 6/7 (85.71%) were from the OPDs. 23/30 (76.66%) swabs from the central line humidifiers, 18/23(78.26%) swabs from the O2 cylinder humidifiers and 8/17 (47.5%) swabs from the nebulizers grew bacteria. Of the total 61(87.14%) bacterial isolates, 42(68.85%) were gram negative bacteria and 19(31.14%) were gram positive cocci. Out of the 42 gram negative bacteria, 17 were multi-drug resistant like ESBL producers ie. Pseudomonas spp. (6) Acinetobacter spp.(4), Klebseilla pneumoniae (4), E.coli (2) and Stenotrophomonas maltophila (1). Our findings (before disinfection) showed that the colonization rate for fungi was 75% and that for bacteria, it was 87%. After the 70% ethanol disinfection and strict compliance with the hand hygiene, the colonization rates reduced significantly. The fungal colonization rate was reduced and only 15% fungi grew after the disinfection, while only 12% bacterial colonization rate was found.

Conclusion: This study indicates a potential in-hospital source of allergens and infections. The oxygen and nebulizer chambers need to be cleaned more frequently with disinfectants, to control the possible nosocomial infections.