Prevalence of bacterial contaminants in domestic kitchen sinks and laundry machines in houses of Mosul, and the effect of common disinfectants

A total of (107) samples, (54) from kitchen sinks, and (53) from laundry machines were obtained from houses in the city of Mosul . Samples were analyzed for the Presence of Mesophilic aerobic bacteria, Pseudomonas, Staphylococci, and enterobacteriaceae. Results showed that 94.4 % of sink samples were contaminated with one or more microorganisms. Pseudomonas Prevalence of bacterial contaminants .... 24 and Klebsiella were the two dominant bacteria in addition to coagulase negative micrococcaceae, E. coli, Citrobacter, Enterobacter, Proteus and Salmonella. Also, 69% of laundry machines were contaminated mostly with pseudomonas, and coagulase negative micrococcaceae , in addition to Enterobacter and Citrobacter . disinfectant were evaluated against Pseudomonas aeroginosa and Klebsiella :Lenol, Fenetol, Hexavlon, Aredol, Chloroxylenol, and Nahypochlorite. The latter was the most effective shortly after its addition . Introduction Previous studies in many countries have drawn attention to the high prevalence of bacterial contamination in the domestic environment .The current attention on bacterial contamination in the kitchen was started in the late 1970s. The first comprehensive study (1) who isolated bacteria from numerous surfaces in homes. The most noted finding was that the kitchen sink was found to harbor large number of bacteria, whereas, toilet areas showed little evidence of contamination with faecal bacteria. A larger investigation was also done by (2) where samples were taken from 201 houses. They found that more than 80 % of the houses examined contained one or more Enterobacterial spp. Furthermore, they reported in a study in 1984, that cleaning with detergents and hot water produced no reduction in microbial contamination, while using disinfectants under controlled condition produced substantial but brief reduction in microbial contamination. Kitchen sinks have been found to be rapidly colonized with large number of coliforms within one week of the occupancy of a new house (1) . It was suggested that the coliform are derived from food production brought into the home. Contamination levels in kitchens of U.K. homes over a 24-hour period was studied by (3). They sampled many sites inside the kitchen like refrigerator handles , kettle handle , work surfaces , ...cutting boards .They found that enterobacterial spp. Contamination level varied during the day , peaking after meal preparation and generally falling overnight . Studies of the domestic environments by (1, 2, 3, 4, 5, and 6) indicate that microorganisms including some potentially pathogenic species are commonly found in all areas of the home environment. The results of these studies indicate that wet sites such as kitchen sinks areas ( particularly sink surfaces , draining boards , U-tubes) ,toilet are most commonly associated with heavy contamination and occurrence of potentially harmful species . These results suggest that, in the kitchen, although raw food is probably the main source of contamination, the sink, can also act as semi-permanent source of reservoirs which harbor and encourage the establishment of free living bacterial and fungal population. Another breeding grounds for bacteria are the laundry machines (basin) where there is always accumulated water .(7 , 8 ,9 ). Although many different detergents wash cycles and commercial and home type machines have been used, the general consensus is that appreciable number of contamination survive and probably recontaminate the next washing load. Shababa A. Bahjet , Sahar S. B. Al-Naqqar Ghada A. M. Al-Taee 25 It should be mentioned here, that the kitchen is the most germ-infested spot in the house, according to a university of Arizona study led by Charles Gerba (microbiologist). Bacteria thrive in warm, dark, moist environments. Trapped food particles in the sink, along with moisture, create an ideal environment for bacterial growth. Sink may harbor microscopic germs that can ultimately cause colds, diarrhea, food poisoning and even hepatitis and cancer. Results of these studies , along with the lack of conventional detergents and disinfectants over the past decade or more due to the sanctions imposed on our country has generated increased interest in bacterial contamination in the home in general and kitchens in particular . Materials and methods Early morning swab samples were taken from (54) sink basins and (53) laundry machines in (107) homes in Mosul city. Household samples were randomly selected from (>20) different vicinities. Most of the occupants belonged to college staff members Samples were obtained using sterile swabs moistened with sterile saline solution (0.85 %) and transferred to the laboratory and processed immediately by inoculating each sample on blood and MacConkey's agar plates. Inverted plates were incubated aerobically at 37 c for 24 hr. The following criteria were taken into consideration for the identification of bacterial isolates : colony morphology , odor , pigmentation , gram stain , oxidase test , IMViC tests , H2S production (TSI) ,Motility (SIM) and urease test (10 ,11 ,12) . Two bacterial isolates were then chosen to evaluate six disinfectant products purchased from local markets. The disinfectants used are summarized in table (1). Prevalence of bacterial contaminants .... 26 Table (1) : Names and composition of disinfectants Name Company Chemical composition concentration Lenol Spartan (Jordan) Chloroxylenol , pine oil , caster oil , soap and alcohol Concentrated Fenetol Syria 1% 2-hydroxyβ-phenyl ,2benzyl 4chlorophenyl(product of german bayer company) , soap and alcohol . Concentrated Aredol Al-Amal (Jordan) Dichlorometaxylenal (demx) 1-5 % , edta , isopropyl alcohol , pine oil castor oil caustic potash .D.W. Concentrated Hexavlon Al-Arabia (Syria) Chlorohexidene d-gluconate 0.2% cetrimide 2% Concentrated 5chloroxylenol B.p 5% SDI (Iraq) Chlroxylenol B.p 5% 2 % 6-Bleach (Fas) Iraq Na-hypochlorite concentrated As a first step evaluation of disinfectant was done sing the disk diffusion method. Bacterial isolate were activated on styptic soy broth and incubated at 37 c for 18 hr. Nutrient agar plates were seeded with the overnight bacterial culture, left for 5 minutes. Sterile filter papers impregnated with disinfectant (concentrated) were applied on the seeded agar. All plates were incubated at 37 c for 24 hr. The disinfectant that gave inhibition regardless of the size of inhibition zone was chosen to determine the optimum time for killing . An overnight culture of each bacterial strain was diluted with sterile saline solution to 1/l0 concentration . Equal volumes of bacterial diluted suspension and the disinfectant (Concentration as recommended on the bottle) were mixed in a sterile test tube . At time intervals of 0, 15, and 30 minutes a sample of 0.1 ml was spread on duplicate nutrient agar plates are incubated for 24 hr . Control plates with diluted bacteria only ( without disinfectants) were also inoculated in the same manner. RESULTS AND DISCUSSION Within the home, the primary sources by which pathogenic microorganisms are continually and inevitably introduced into this setting are people, food, pets, water, in sects and air. Additionally, sites where stagnant Shababa A. Bahjet , Sahar S. B. Al-Naqqar Ghada A. M. Al-Taee 27 water accumulates, such as in sinks and laundry machines can support growth and become a primary reservoir of known or opportunistic pathogens and bad odors. Once contaminants are introduced and attached to surfaces, particularly in biofilms , it becomes very difficult to remove . They may then grow potentially reaching infectious dose levels and, in the presence of moisture and/or food debris survive to contaminate any thing that comes in contact (hands, utensils, laundry ...). (13) suggested that kitchen surfaces and hands may contaminate each other in a cyclic pattern .The goal of the present study was to determine bacterial contamination in our home setting. Most of the papers published (if not all) investigated the homes of western countries which differs in many ways in respect to cultural , economical , and traditional behavior from the eastern part of the world. Results of this study are summarized in table (2) : Site Total no. of samples +ve samples -ve samples