Study of Imipenem Resistant Metallo- Beta-Lactamase Positive Pseudomonas aeruginosa from Burns Wound Infections, Environmental Sources and Impact of Infection Control Measures in a Burns Care Center

Imipenem resistant Metallo -Beta-lactamase producing Pseudomonas aeruginosa (IR-MBLP-PA) is an emerging threat causing burns wound infections with increased mortality and morbidity and with a potential to spread rapidly resulting in outbreaks and epidemics. Very limited data is available after review of literature on detection of IR-MBLP-PA from burns wound infections, environmental sources, their role as source and/or reservoir of nosocomial infections and impact of strict infection control measures on incidence of IR-MBLP-PA infections from burn care centers. Present study was conducted to detect IR-MBLP-PA from burns wound infections, different hospital environmental sources, their antibiogram typing, to assess the role of environmental source and /or reservoir on nosocomial infections and study the impact of Infection control measures on environmental sources of IR-MBLP-PA. During two years study period, 226 clinical and 62 environmental and 20 hand specimens of health care workers, collected and processed by standard laboratory procedures. IR-MBLP-PA detection was done by IMIPENEM+EDTA combined disc test. Antibiogram typing done. Association with clinical cases done by isolation of strain with identical antibiogram type of IR-MBLP-PA isolate from environmental source and clinical case. Impact of Infection control measures were assessed by percentage reduction in incidence of IR-MBLP-PA isolates from respective environmental sources. Study reported an overall incidence of 10.2%(23/226) for IR-MBLP-PA with 16.4% and 6.9% for IR-MBLP-PA before and after infection control measures respectively. Incidence of 34.78% from environmental sources and 10% (2/20) hands of HCWs was observed. Six of the eight IR-MBLP-PA antibiogram types from environmental sources and patients could be associated with 23 burns wound infections with two strains with no association. Strain 1 (Resistant to all antibiotics used) was most common strain (26.08%) associated with seven burns wound infections during the study period. Infection control measures reduced the incidence of P aeruginosa among patients but was not successful in eradicating this organism from various environmental sources. With a high incidence of IR-MBLP-PA (10.2%), present study underscores the role of environmental source in burn care centre (sinks, suction apparatus, water of hydrotherapy tanks and mask of AMBU bags) as a source/or reservoir of infections by temporospatial association and by antibiogram typing. Although met with partial success, implementation of CDC recommended infection control measures resulted in decreased incidence of IR-MBLP-PA burns wound infections necessitating periodic environmental sampling for their detection. Aprons and gowns of health care workers, curtains, beddings and linen were not found to be important source/or reservoirs of IR-MBLP-PA. Resistance profile of predominant IR-MBLP-PA isolates helps in choosing initial empirical antibiotic therapy.