Cockroaches [Periplaneta americana (L.), Dictyoptera; Blattidae] as Carriers of Bacterial Pathogens, Khorramshahr County, Iran

Headnote

ABSTRACT

Background: American cockroaches are found in association with human dwellings and hospitals. They have a worldwide distribution. These domestic pests affect human health in several ways. Their habits make them ideal mechanical carriers of different pathogenic microorganisms. Numerous bacteria of medical importance have been isolated from cockroaches.

Objectives: The objective of this research was to determine the role of American cockroaches as carriers of pathogenic bacteria. This was accomplished through the isolation and identification of these microorganisms from the external surfaces of cockroaches captured in Health and Medical Services Centers and their surroundings.

Materials and Methods: Seventy-three cockroaches were caught in Health and Medical Services Centers in Khorramshahr County, southwestern Iran, in 2006. The fluid used to wash the external surfaces of cockroaches was cultured to isolate and identify bacterial pathogens.

Results: Pathogenic bacteria were isolated from the external surfaces of ioo% of the American cockroaches examined. The following bacterial pathogens were recovered from their body surface:ide5sie//a (47.9%), Pseudomonas (37%), Escherichia coli (30.1%), Staphylococcus (24.6%), Enterobacter (19.2%), Streptococcus (15.1%), Serratia (8.2%), Bacillus (4.1%), and Proteus (2.7%).

Conclusions: The bacterial pathogenic flora isolated from this cockroach species indicate that domestic pests could pose a health problem to humans. Thus, we must control cockroaches, particularly in indoors, sewage and solid wastes.

©2012, AJUMS. Published by Kowsar M.P.Co. All rights reserved.

Keywords:

Bacterial Pathogen

Cockroach

1. Background

Hospital-acquired infections have emerged as a cause of death and illness in people over recent years (1). Insects, hospital care staff, or medical equipments could transport etiologic agents to patients in medical environments. Cockroaches are highly prevalent in residential homes, restaurants, and medical and financial institutions. During the daytime, these insects remain concealed in secluded locations or gaps in walls, but become active at night (2).

In hospitals, cockroaches have been detected inside sick rooms, the intensive therapy zone, surgical section, kitchen, and medicine part (3). The hospital provides them with suitable temperature, food, water, and protective cover(4). Cockroaches can derive nourishment from vomit, spit, phlegm, excrement, human entrails, and on other diverse food sources. They are able to transfer viruses, bacteria, fungi, and other medically significant pathogenic agents in infectious regions (5). They have been proposed as likely transmitters of drug-resistant pathogens. Up to 98% of cockroaches found in a clinical setting can bear pathogenic agents on their teguments or in their intestines (6). The American cockroach [Periplaneta americana (L)] is one possible vector of bacteria. Over 100 species of bacteria have been isolated from domestic cockroaches (7). They have been found to carry Escherichia coli, Enterobacter spp., Klebsiella spp., Pseudomonas aeruginosa, Acinetobacter baumannii, Serratia marcescens, Shigella spp., Staphylococcus aureus, Enterococcus spp., and Bacillus spp. (8, 9).

2. Objectives

The aim of this study was to assess the presence of medically important bacteria on the external surfaces of American cockroaches collected from health and medicalcenters.

3. Materials and Methods

This study was carried out in Khorramshahr, southwestern Iran. The locality is situated at an elevation of approximately 3m above sea level. Its geographical coordinates are 30°26"21' North, 48°10"45' East. It has long, hot summers and mild, short winters. The mean temperature in summer is 55°C and the annual rainfall is 200 mm. The annual relative humidity of the area ranges from 50% to 80%. Khorramshahr has an estimated total population of 164,797. Health and Medical Services Centers, and their surroundings, were considered in this study. Cockroaches were collected randomly from five health and medicalcenters (Emam Reza, Taleghani, Emam Hossein, Behbahanian, and Kofeishe) in 2006. Identification of cockroaches was performed in accordance with a standard taxonomic key (10).

Seventy-three P. americana cockroaches were caught using sterile test tubes and sterile hand gloves. Each cockroach was collected in a sterile test tube, transported to the laboratory, and anesthetized by freezing at O0C for 5min. Two milliliters of sterile normal saline (0.9%) was then added to each test tube and the cockroaches were thoroughly shaken for 2 min. A fixed volume (O.OlmL) of the saline washing was inoculated onto blood agar (Hi Media, India), MacConkey agar (Merck, Germany), and desoxycholate citrate agar (Merck) plates. The plates were incubated overnight at 37°C and the colonies identified by standard bacteriological procedures (11, 12). Briefly, a representative colony was identified by its macroscopic morphology, Gram stain, various biochemicals, and other specific characteristics.

In addition, 0.5-mLaliquots of the saline washings were inoculated into thioglycollate (Merck) and selenitebroths (Merck), incubated for 24 h at 37°C, and subcultured on the same media. After overnight incubation at 37°C, the media were examinedand colonies identified.

4. Results

A total of 73 cockroaches (captured mostly at night) and their microbial flora were studied. All cockroaches were identified as P. americana. Medically important microorganisms were isolated from the external surfaces of 100% of the cockroaches examined. Examination of the external body washes of cockroaches revealed that cockroaches are carriers of Klebsiella, Pseudomonas, E. coli, Staphylococcus, Enterobacter, Streptococcus, Serratia, Bacillus, and Proteus. Klebsiella spp. (47.9%), Pseudomonas spp. (37%), and E. coli (30.1%) were the most frequently identified organisms. The frequencies of the bacterial species carried on the external surfaces of cockroaches are given in Table.

5. Discussion

Nosocomial infections are considered important causes of morbidity in immuno compromised patients, particularly in those who have prolonged hospital stays (13). In this study, a high percentage of cockroaches (100%) were found to carry various bacteria of medical importance. This finding suggests the probability that almost all cockroaches in Health and Medical Services Centers carry pathogenic bacteria. We therefore consider that these insects could represent a risk to patients, although the involvement of cockroaches in diseases transmission is difficult to demonstrate.

Isolation of pathogenic bacteria from 83% of cockroaches trapped in different areas of a hospital has been reported (14). Bacterial species, such as Klebsiella spp., E. coli, Staphylococcus spp., Enterobacter spp., Streptococcus spp., Pseudomonas spp., Proteus spp., Bacillus spp., Neisseria spp., Shigella spp., and Salmonella spp., have also been isolated fromP. americana, Blatella germanica, and Polyphaga aegyptica cockroaches by other researchers (15-20). The findings of the present study confirm that cockroaches in health and medical centers can play an important role as mechanical vectors of pathogenic bacteria. Therefore, it is suggested that suitable control measures are taken specifically to make medical centers free from cockroaches.

Acknowledgments

We are grateful to E Izadpor from the microbiology laboratory, Khorramshahr Vali-e-Asr Hospital, for helping us in carrying out this research.

Financial Disclosure

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

Funding/Support

None declared.

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ARTICLE INFO

Article type:

Original Article

Article history:

Received: Ol Jan 2011

Revised: 20 Mar 2011

Accepted: Ol May 2011

* Implication for health policy/practice/research/medical education:

The results displayed medically significant bacteria segregated from Periplaneta americana in health and medically centres. This is important data that reveal cockroaches may transmit nosocomial bacterial infections in such environments.

* Please cite this paper as:

Kassiri H, Kazemi S. Cockroaches [Periplaneta americana (L.), Dictyoptera; Blattidae] as Carriers of Bacterial Pathogens, Khorramshahr County, han.Jundishapur J Microbiol. 20i2;5(l):320-2. DOI:lo.58i2/kowsar.20083645.2434

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