Are cockroaches carriers of fungi that cause nosocomial infections?
Opportunistic fungal infections target high-risk patients, including immunocompromised hosts, critically-ill cases, and debilitated surgical patients. While
Candida and
Aspergillus are the most common causes of invasive fungal infections, the virtual spectrum of fungi causing these infections appears to be very wide. Due primarily to the high mortality rates of nosocomial fungal infections, understanding the mechanisms of transmission of these pathogens and development of preventive strategies are of special significance.
Air, medical instrumentations, and hands of hospital staff have been identified as the major sources of nosocomial fungal infections. Vectors, such as rodents and insects, on the other hand, may play role as carriers for fungi. Among these, cockroaches are of particular concern, since they can be found everywhere in the hospital environment.
The fungal flora on the external surface of 103 cockroaches (
Periplaneta americana) has been explored in an interesting study from Goiania, Brazil. In this study, alive and intact cockroaches were collected from the intensive care unit of an hospital during three consecutive weeks.
Each collected cockroach was first immobilized by freezing at 0°C and then mixed strongly with sterilized saline. Aliquot of the saline was finally cultivated on Sabouraud dextrose agar supplemented with chloramphenicol. The agar plates were incubated at 25°C for 3 weeks.
The fungi recovered on culture media were identified by using conventional methods. Interestingly and importantly, 93.2% of the cockroaches were found to carry medically important fungi.
Candida (38.6%),
Aspergillus (30.7%) and
Penicillium (8.9%) were the most commonly isolated fungi. The whole list of growing fungi included 13 different fungal genera.
Whether cockroaches are involved in transmission of nosocomial fungal infections remains difficult-to-demonstrate. However, the results of this study suggest that existence of cockroaches in the hospital environment may potentially contribute to the development of nosocomial mycoses.
Related reading
-
Lemos et al. Cockroaches as carriers of fungi of medical importance. Mycoses 2006; 49: 23.
- Munoz et al. Environmental surveillance and other control measures in the prevention of nosocomial fungal infections. Clin Microbiol Infect 2001; 7(Suppl. 2): 38.
