Flies and water as reservoirs for bacterial enteropathogens in urban and rural areas in and around Lahore, Pakistan

Sachet water quality and Vendors’ practices in Damongo, northern Ghana during the emergence of SARS-CoV-2 using multivariate statistics, water quality and pollution indices, and panel assessment

The emergence of the SARS-CoV-2 has affected several production services including the water production and delivery processes. This study considered sachet water quality during the advent of the SARS-CoV-2 pandemic using multivariate statistics and Water Quality Index, Water Pollution Index and, hygienic and sanitation practices of sixty-two (62) sachet water vendors using a panel assessment approach. The findings showed that vendors did not adhere to proper hygienic practices as ninety-four (94%) of them did not have health clearance, ninety (90%) did not frequently wash their receptacles for selling daily, and most of them stored and sold in unhygienic environments. Majority of the producers violated Food and Drugs Authority Regulations. The Empirical Orthogonal Function analysis showed that total iron, Total Heterotrophic Bacteria, Salmonella, Cl⁻, E. coli, and fecal and total coliforms were the controlling elements in the water. All the brands were below threshold limits based on the physical water assessment. However, enteric bacteria were observed in all the brands. Water Quality and Water Pollution Indices (WQI and WPI) described all the sachet water brands (vendors and production sites) as excellent for drinking. The WQI computations for samples from the production and vending sites respectively ranged from 0.12 to 0.36 and 0.27–0.42 whereas WPI presented 0.22–0.31 and 0.23–0.32. Comparatively, samples from vendors had elevated elemental concentrations and loads. This suggests that besides sachet water contamination during production and transportation, vendors significantly impacted the quality of sachet water. Sensitization on proper hygienic practices for sachet water production and vending and routine assessment of the quality of sachet water produced or sold is recommended.

Microbial Quality of Sliced Pawpaw (Carica papaya) and Watermelon (Citrullus lanatus) Sold on Some Streets of Accra Metropolis, Ghana

In most African countries, street vending of fruits is prevalent and the likelihood of predisposing consumers to microbial contamination is very high. This study aimed to determine various bacteria and risk factors that are associated with fruits sold by street vendors in Accra. Sliced watermelons and pawpaws were randomly purchased from selected suburbs in Greater Accra Region of Ghana. One gram (1 g) of each watermelon and pawpaw was homogenized in 9 ml of sterile peptone water, and 0.1 ml from each serial dilutions of each fruit was spread on plate count agar, blood agar, and MacConkey agar plates for total aerobic counts and coliform counts. Agar plates were incubated at 33–37°C for 18–24 h. Bacterial identification was done by standard bacteriological methods. Additionally, questionnaires were administered to the vendors to gather data on food hygiene and knowledge on foodborne illness. The study revealed that although some of the fruit vendors were educated on food hygiene, most sold fruits were contaminated with mean total aerobic plate counts of 2.6 × 10⁵–8.1 × 10⁵ CFU g⁻¹ and 3.7 × 10⁴–7.1 × 10⁴ CFU g⁻¹ for watermelon and pawpaw. The mean coliform counts for pawpaw and watermelon ranged between 1.2 × 10³–8.1 × 10³ CFU g⁻¹ and 1.6 × 10⁴–3.1 × 10⁴ CFU g⁻¹, respectively. Overall, mean aerobic counts and mean coliform counts were not significantly different among vendors in selected locations (p > 0.05). However, predominant bacteria isolated included Enterobacter species (33.3%), Citrobacter sp. (20.0%), and Klebsiella sp. (15.9%). The study revealed that watermelon and pawpaw sold on the streets in Accra could be possible source of foodborne illness. Therefore, street food vendors must be educated on food hygiene protocols and measures to improve microbial quality of street vended fruits.

A systematic review of human pathogens carried by the housefly (Musca domestica L.)

BACKGROUND

The synanthropic house fly, Musca domestica (Diptera: Muscidae), is a mechanical vector of pathogens (bacteria, fungi, viruses, and parasites), some of which cause serious diseases in humans and domestic animals. In the present study, a systematic review was done on the types and prevalence of human pathogens carried by the house fly.

METHODS

Major health-related electronic databases including PubMed, PubMed Central, Google Scholar, and Science Direct were searched (Last update 31/11/2017) for relevant literature on pathogens that have been isolated from the house fly.

RESULTS

Of the 1718 titles produced by bibliographic search, 99 were included in the review. Among the titles included, 69, 15, 3, 4, 1 and 7 described bacterial, fungi, bacteria+fungi, parasites, parasite+bacteria, and viral pathogens, respectively. Most of the house flies were captured in/around human habitation and animal farms. Pathogens were frequently isolated from body surfaces of the flies. Over 130 pathogens, predominantly bacteria (including some serious and life-threatening species) were identified from the house flies. Numerous publications also reported antimicrobial resistant bacteria and fungi isolated from house flies.

CONCLUSIONS

This review showed that house flies carry a large number of pathogens which can cause serious infections in humans and animals. More studies are needed to identify new pathogens carried by the house fly.

Prevalence and Association of Escherichia coli and Diarrheagenic Escherichia coli in Stored Foods for Young Children and Flies Caught in the Same Households in Rural Bangladesh

Consumption of contaminated stored food can cause childhood diarrhea. Flies carry enteropathogens, although their contribution to food contamination remains unclear. We investigated the role of flies in contaminating stored food by collecting food and flies from the same households in rural Bangladesh. We selected 182 households with children ≤ 24 months old that had stored foods for later feeding at room temperature for ≥ 3 hours. We collected food samples and captured flies with fly tapes hung by the kitchen. We used the IDEXX Quanti-Tray System (Colilert-18 media; IDEXX Laboratories, Inc., Westbrook, ME) to enumerate Escherichia coli with the most probable number (MPN) method. Escherichia coli–positive IDEXX wells were analyzed by polymerase chain reaction for pathogenic E. coli genes (eae, ial, bfp, ipaH, st, lt, aat, aaiC, stx₁, and stx₂). Escherichia coli was detected in 61% (111/182) of food samples, with a mean of 1.1 log₁₀ MPN/dry g. Fifteen samples (8%) contained pathogenic E. coli; seven (4%) had enteropathogenic E. coli (EPEC) genes (eae and/or bfp); and 10 (5%) had enteroaggregative E. coli genes (aat and/or aaiC). Of flies captured in 68 (37%) households, E. coli was detected in 41 (60%, mean 2.9 log₁₀ MPN/fly), and one fly (1%) had an EPEC gene (eae). For paired fly-food samples, each log₁₀ MPN E. coli increase in flies was associated with a 0.31 log₁₀ MPN E. coli increase in stored food (95% confidence interval: 0.07, 0.55). In rural Bangladesh, flies possibly a likely route for fecal contamination of stored food. Controlling fly populations may reduce contamination of food stored for young children.

Microbiological Safety of Street Vended Foods in Jigjiga City, Eastern Ethiopia

Background

Food safety problems are particularly becoming an increasingly serious threat to public health in developing countries. This study was conducted to assess microbiological safety of street vended foods from May to November, 2014 in Jigjiga City.

Methods

A cross-sectional design was used to answer questions concerning the current status of food hygiene and sanitation practire of street food vending sites. Interview and observational assessments were used to collect socio-demographic data about street food venders. One hundred thirty-two samples of street foods were aseptically collected from four ‘kebeles’ of Jigjiga City. Both descriptive and analytical statistical methods were applied.

Results

The majority of the street food vendors were women, 120(90.9%), with the average age group of 23–49 years, (42.85%), and 99(66.7%) them were illiterate. The study revealed that 95(72%) of the food samples had pathogenic bacterial contaminations. Three different bacterial species were isolated: E. coli 68(51.5%), S. aureus 85(64.4%) and 26(19.7%) Salmonella species. The highest incidence of S. aureus 23/33(69%) was seen in ‘Sambusa’; the highest incidence of E. coli 24/33(73.5%) was observed in ‘Pasta’, while the highest Salmonella incidence was observed in ‘Ades’

Conclusion

This study revealed that there is a reasonable gap on food safety knowledge among street food venders. The microbial profile was also higher compared to standards set by the World Health Organization. Due attention should be given by the government to improve knowledge about food safety and the quality standard of street foods sold in the City.

Escherichia coli contamination of child complementary foods and association with domestic hygiene in rural Bangladesh

OBJECTIVE

To determine the frequency and concentration of Escherichia coli in child complementary food and its association with domestic hygiene practices in rural Bangladesh.

METHOD

A total of 608 households with children <2 years were enrolled. We collected stored complementary food samples, performed spot checks on domestic hygiene and measured ambient temperature in the food storage area. Food samples were analysed using the IDEXX most probable number (MPN) method with Colilert-18 media to enumerate E. coli. We calculated adjusted prevalence ratios (APR) to assess the relationship between E. coli and domestic hygiene practices using modified Poisson regression, adjusting for clustering and confounders.

RESULT

Fifty-eight percentage of stored complementary food was contaminated with E. coli, and high levels of contamination (≥100 MPN/dry g food) were found in 12% of samples. High levels of food contamination were more prevalent in compounds where the food was stored uncovered (APR: 2.0, 95% CI: 1.2-3.2), transferred from the storage pot to the serving dish using hands (APR: 2.0, 95% CI: 1.3-3.2) or stored for >4 h (APR: 2.5, 95% CI: 1.5, 4.2), in compounds where water was unavailable in the food preparation area (APR: 2.6, 95% CI: 1.6, 4.2), where ≥1 fly was captured in the food preparation area (APR: 1.6, 95% CI: 1.0, 2.6), or where the ambient temperature was high (>25-40 °C) in the food storage area (APR: 2.7, 95% CI: 1.5, 4.4).

CONCLUSION

Interventions to keep stored food covered and ensure water availability in the food preparation area would be expected to reduce faecal contamination of complementary foods.

Environmental transmission of diarrheal pathogens in low and middle income countries

Every year, more than half a million children die due to diarrheal diseases. Recent studies have identified the most important etiologies of diarrheal disease are enterotoxigenic and enteropathogenic E. coli, Shigella spp., rotavirus, norovirus and Cryptosporidium spp. These etiologies are unsurprisingly characterized by a combination of high shedding, high infectivity, and transmissibility through multiple environmental reservoirs. The relative importance of the transmission routes is likely site-specific. So the impact of interventions, which typically target only one or two environmental reservoirs, is likely also site-specific. The factors influencing the transmission routes most important for diarrheal disease are complex, including - at a minimum - etiology of endemic disease; and water, sanitation, and hygiene infrastructure and practices. The site-specific nature - and complexity of transmission - helps explain the observed variation in impacts of water, sanitation, and hygiene interventions. It may also render efforts to estimate or quantify global means for interventions' impacts irrelevant. The theme of this Perspective is that greater reductions in diarrheal disease transmission in LMICs can be achieved by designing interventions to interrupt the most important environmental transmission pathways. Intervention choice should be informed by site-specific conditions, most notably: diarrheal etiology and existing water, sanitation, and hygiene infrastructure and practices. The theme is discussed through the lens of the characteristics of the most important diarrheal diseases (shedding, infectivity, growth, and persistence) and the general characteristics of environmental reservoirs (exposure pathways and fecal contamination). The discussion highlights when interventions - and combinations of interventions - will be most effective at reducing diarrheal disease burden.

Dose-dependent fate of GFP-expressing Escherichia coli in the alimentary canal of adult house flies

The adult house fly Musca domestica (L.) (Diptera: Muscidae) can disseminate bacteria from microbe-rich substrates to areas in which humans and domesticated animals reside. Because bacterial abundance fluctuates widely across substrates, flies encounter and ingest varying amounts of bacteria. This study investigated the dose-dependent survival of bacteria in house flies. Flies were fed four different 'doses' of green fluorescent protein (GFP)-expressing Escherichia coli (GFP E. coli) (very low, low, medium, high) and survival was determined at 1, 4, 10 and 22 h post-ingestion by culture and epifluorescent microscopy. Over 22 h, the decline in GFP E. coli was significant in all treatments (P < 0.04) except the very low dose treatment (P = 0.235). Change in survival (ΔS) did not differ between flies fed low and very low doses of bacteria across all time-points, although ΔS in both treatments differed from that in flies fed high and medium doses of bacteria at several time-points. At 4, 10 and 22 h, GFP E. coli ΔS significantly differed between medium and high dose-fed flies. A threshold dose, above which bacteria are detected and destroyed by house flies, may exist and is likely to be immune-mediated. Understanding dose-dependent bacterial survival in flies can help in predicting bacteria transmission potential.

Early-life enteric infections: relation between chronic systemic inflammation and poor cognition in children

The intestinal microbiota undergoes active remodeling in the first 6 to 18 months of life, during which time the characteristics of the adult microbiota are developed. This process is strongly influenced by the early diet and enteric pathogens. Enteric infections and malnutrition early in life may favor microbiota dysbiosis and small intestinal bacterial overgrowth, resulting in intestinal barrier dysfunction and translocation of intestinal bacterial products, ultimately leading to low-grade, chronic, subclinical systemic inflammation. The leaky gut-derived low-grade systemic inflammation may have profound consequences on the gut-liver-brain axis, compromising normal growth, metabolism, and cognitive development. This review examines recent data suggesting that early-life enteric infections that lead to intestinal barrier disruption may shift the intestinal microbiota toward chronic systemic inflammation and subsequent impaired cognitive development.

Environmental Factors Associated with High Fly Densities and Diarrhea in Vellore, India

Diarrhea causes significant morbidity and mortality in Indian children under 5 years of age. Flies carry enteric pathogens and may mediate foodborne infections. In this study, we characterized fly densities as a determinant of infectious diarrhea in a longitudinal cohort of 160 urban and 80 rural households with 1,274 individuals (27% under 5 years of age) in Vellore, India. Household questionnaires on living conditions were completed at enrollment. Fly abundance was measured during the wet and dry seasons using fly ribbons placed in kitchens. PCRs for enteric bacteria, viruses, and protozoa were performed on 60 fly samples. Forty-three (72%) fly samples were positive for the following pathogens: norovirus (50%), Salmonella spp. (46.7%), rotavirus (6.7%), and Escherichia coli (6.7%). Ninety-one episodes of diarrhea occurred (89% in children under 5 years of age). Stool pathogens isolated in 24 of 77 (31%) samples included E. coli, Shigella spp., Vibrio spp., Giardia, Cryptosporidium, and rotavirus. Multivariate log-linear models were used to explore the relationships between diarrhea and fly densities, controlling for demographics, hygiene, and human-animal interactions. Fly abundance was 6 times higher in rural than urban sites (P < 0.0001). Disposal of garbage close to homes and rural living were significant risk factors for high fly densities. The presence of latrines was protective against high fly densities and diarrhea. The adjusted relative risks of diarrheal episodes and duration of diarrhea, associated with fly density at the 75th percentile, were 1.18 (95% confidence interval [CI], 1.03 to 1.34) and 1.15 (95% CI, 1.02 to 1.29), respectively. Flies harbored enteric pathogens, including norovirus, a poorly documented pathogen on flies.

Assessment of microbiological quality of some drinks sold in the streets of Dhaka University Campus in Bangladesh

Background

Various kinds of fruit juices and sherbets sold by the street vendors are widely consumed in Dhaka city. These street vended fruit juices and sherbets are usually high in microbial loads. So, the present study was undertaken to assess the microbiological load, possible risk factors and identity of freshly squeezed juices and sherbets and their safety for human consumption in terms of pathogens.

Result

For the study purpose papaya juice, sugarcane juice, tukmaria sherbet, lemon sherbet and wood apple sherbet were taken as samples. The study showed a high microbial load in the drinks. The range of average total viable count (microbial load) and total coliforms were 7.7 × 103 - 9 × 108 cfu/ml and 210–1100 cfu/100 ml, indicated the heavy presence of microorganisms in all the drinks analyzed in this study. The study revealed that tukmaria sherbet was most contaminated with a count of 9 × 108 cfu/ml. The least contamination was observed in lemon sherbet. A count of 1.98 × 106 cfu/ml was observed in papaya juice and 3.4 × 105 cfu/ml was in wood apple sherbet. Total coliforms were present in all samples and average count for total coliforms was high in tukmaria sherbets than others. Various pathogenic species of bacteria such as Proteus sp., Enterobacter sp, E. coli, Shigella sp, Citrobacter sp, Vibrio sp, Yersinia sp and Hafnia sp were isolated from the juices and sherbets. Unhygienic water for dilution, dressing with ice, prolonged use without refrigeration, insanitary surroundings, raw materials, chemical properties, equipment, fruit flies and airborne dust are the risk factors of contamination.

Conclusion

It was revealed that consumption of these street drinks were harmful for people. These drinks can cause various food borne illnesses. People should avoid these drinks.

Prevalence and antibiotic susceptibility of thermophilic Campylobacters from sources implicated in horizontal transmission of flock colonisation

Thermophilic Campylobacter are commonly associated with poultry as commensals of the avian gut and are the causative agent responsible for human Campylobacteriosis. This study aimed to establish the prevalence of Campylobacter spp. from environmental sources that have previously been implicated as sources of horizontal transmission. The highest prevalence of thermophilic Campylobacter was found in water samples (87.5%) and lowest from flies (7.2%). Only C. jejuni was isolated from all sources. A secondary aim was to provide a baseline of resistance profiles of Campylobacter spp. isolates obtained. Alarmingly all the C. jejuni isolates from environmental sources as well as humans were multi-drug resistant.

Microbiological Quality of Salads Served along with Street Foods of Hyderabad, India

A study has been done to analyse the microbiological quality of salads served along with street foods of Hyderabad. A total of 163 salad samples, 53 of carrot and 110 of onion samples, were collected from four different zones of Hyderabad. About 74% and 56% had Staphylococcus aureus in carrots and onions, respectively. Fifty-eight percent of carrots and forty-five percent of onions samples contained Salmonella, 68% of carrots and 24% of onions had Yersinia. HACCP study was carried out with 6 street food vendors to identify the source of Salmonella contamination in salads. Food handlers were found to be responsible for Salmonella contamination in salads. The present study revealed the potential hazards of street vended salad vegetables, considering the handling practice usually carried out by vendors. Ninety-eight percent of the vendors did not wash the vegetables before processing and serving while about 56.6% of the vendors did not peel the vegetables. Majority of street vendors' nails were uncut. A significant difference (P < 0.01) was observed in Yersinia spp. and Salmonella spp. in wet-dirty chopping board when compared to clean-dry chopping board. A significant difference (P < 0.05) of Staphylococcus spp. was observed when the status of cleaning cloth was neat/untidy.

Comparison of time series models for predicting campylobacteriosis risk in New Zealand

Predicting campylobacteriosis cases is a matter of considerable concern in New Zealand, after the number of the notified cases was the highest among the developed countries in 2006. Thus, there is a need to develop a model or a tool to predict accurately the number of campylobacteriosis cases as the Microbial Risk Assessment Model used to predict the number of campylobacteriosis cases failed to predict accurately the number of actual cases. We explore the appropriateness of classical time series modelling approaches for predicting campylobacteriosis. Finding the most appropriate time series model for New Zealand data has additional practical considerations given a possible structural change, that is, a specific and sudden change in response to the implemented interventions. A univariate methodological approach was used to predict monthly disease cases using New Zealand surveillance data of campylobacteriosis incidence from 1998 to 2009. The data from the years 1998 to 2008 were used to model the time series with the year 2009 held out of the data set for model validation. The best two models were then fitted to the full 1998-2009 data and used to predict for each month of 2010. The Holt-Winters (multiplicative) and ARIMA (additive) intervention models were considered the best models for predicting campylobacteriosis in New Zealand. It was noticed that the prediction by an additive ARIMA with intervention was slightly better than the prediction by a Holt-Winter multiplicative method for the annual total in year 2010, the former predicting only 23 cases less than the actual reported cases. It is confirmed that classical time series techniques such as ARIMA with intervention and Holt-Winters can provide a good prediction performance for campylobacteriosis risk in New Zealand. The results reported by this study are useful to the New Zealand Health and Safety Authority's efforts in addressing the problem of the campylobacteriosis epidemic.

The bacteriological safety and antimicrobial susceptibility of bacteria isolated from street-vended white lupin (Lupinus albus) in Bahir Dar, Ethiopia

BACKGROUND

Whereas street vended foods are readily available sources of meals for many people across the world, the microbial safety of such food is always uncertain. In developing countries the major sources of food-borne illnesses are street vended foods. The aim of this study was thus to assess the prevalence and antibiogram of bacteria from white lupin in Bahir Dar Town.

METHODS

A total of 40 samples were processed for detection of indicator bacteria and pathogens from December, 2011 to February, 2012 using standard bacteriological techniques. Antimicrobial susceptibility test was performed using the Kirby-Bauer disk diffusion method.

RESULTS

The total coliform counts were 954.2±385 and 756.2±447.3 at the surface and the core of white lupin, respectively. On the other hand, the fecal coliform counts were 880.9±396.6 and 662.1±461.9 at surface and the core, respectively. There was a statistically significant difference in total colifoms and fecal coliform counts between the surface and core of white lupin (p <0.05). Escherichia coli 29 (72.5%), Salmonella spp. 23 (57.5%) and Shigella spp. 8 (20%) were the pathogens isolated. Most bacterial isolates were resistant to tetracycline, cotriamoxazole and erythromycin whereas many of them were sensitive to chloramphenicol, nalidixic acid, gentamicin and ciprofloxacin. The overall multiple antimicrobial resistances rate was 75%.

CONCLUSION

This study revealed contamination of white lupin and a potential health to consumers, and the bacteria isolated showed high rates of multiple drug resistance. Surveillance of antimicrobial resistance should be done on food borne pathogens. In addition, further studies should be conducted on the bacteriological quality of waters used for soaking white lupin.

A comparison of disease caused by Shigella and Campylobacter species: 24 months community based surveillance in 4 slums of Karachi, Pakistan

Despite the efforts of the international community diarrheal diseases still pose a major threat to children in children less than five years of age. Bacterial diarrhea has also emerged as a public health concern due to the proliferation of drug resistant species in many parts of the world. There is a paucity of population-based data about the incidence of shigellosis and Campylobacter infections in Pakistan. We report country specific results for Shigella diarrhea that were derived from a multicenter study conducted in six Asian countries. Disease surveillance was conducted over a 24 month period in urban slums of Karachi, Pakistan, a city with a population of 59,584. Cases were detected through passive detection in study treatment centers. Stool specimens or rectal swabs were collected from all consenting patients. Between January 2002 and December 2003 10,540 enteric infection cases were detected. The incidence rate of treated diarrhea in children under 5 was 488/1000/year. In children, 5 years and older, the diarrhea rate was 22/1000/year. 576 (7%) Campylobacter isolates were detected. The pre-dominant Campylobacter species was C. jenuni with an increase of 29/1000 year in children under 5 years. Shigella species were isolated from 394 of 8032 children under 5 years of age. Shigella flexneri was the dominant species (10/1000/year in children under 5 years) followed by Shigella sonnei (3.9/1000/year), Shigella boydii (2.0/1000/year) and Shigella dysenteriae (1.3/1000/year). Shigellosis and Campylobacter infection rates peaked during the second year of life. The incidence rate of shigellosis increased in old age but such a trend was not observed in Campylobacter infections. Of 394 shigellosis patients 123 (31%) presented with dysentery in contrast to only 54 (9%) of 576 patients with Campylobacter infections (p<0.001). Both Campylobacter infections and shigellosis are common in community settings of Pakistan but shigellosis presented more frequently with abdominal pain and dysentery than Campylobacter infections indicating that shigellosis may be a more severe illness than Campylobacter infections. Due to the increased and disease severity, drug resistant shigella have become a significant health problem; moreover it is a disease of poor and impoverished people who do not have the access to standard water and sanitary conditions, health care services or optimal treatment. In the face of these facts it is empirically important to develop a low cost effective vaccine that can protect these populations for a longer duration.

Frequency of resistance and susceptible bacteria isolated from houseflies

BACKGROUND

In this study, we determine the vector competence of Musca domestica with reference to the transmission of susceptible and resistance bacterial strains in hospitals and slaughter house in Sanandaj City, west Iran.

METHODS

Totally 908 houseflies were collected to isolate bacteria from their external body based on standard procedures.Antibiotic susceptibility testing was performed by Kirby-Bauer disc diffusion method on Mueller Hinton agar based on recommendations of CLSI (formerly the National Committee for Clinical Laboratory Standards).

RESULTS

From collected houseflies, 366 bacteria species were isolated. The most common isolated bacterium at hospitals was Klebsiella pneumoniae 43.3% (n= 90) followed by Pseudomonas aeruginosa 37% (n= 77), while that of slaughterhouse was Proteus mirabilis. 29.1% (n= 46) followed by Citrobacter freundii 28.4% (n= 45). Among all the isolates from hospitals, cephalexin, chloramphenicol, ampicillin, and tetracycline, resistance rates were above 32.5% and gentamicin expressed the highest susceptibility among all the isolates from hospitals. It is worth to note that K. pneumoniae showed 61% and 44.5% resistance to cephalexin and chloramphenicol respectively. Similarly, all isolates from slaughterhouse were more than 28% and 30% resistant to cephalexin and chloramphenicol respectively. Surprisingly, among all the isolates, Citrobacter freundii were highly resistant to gentamicin.

CONCLUSION

Houseflies collected from hospitals and slaughterhouse may be involved in the spread of drug resistant bacteria and may increase the potential of human exposure to drug resistant bacteria.

Some aspects of epidemiology of filth flies: Musca domestica, Musca domestica vicina, Drosophilia melanogaster and associated bacteria pathogens in Ekpoma, Nigeria

Between January 2005 and December 2005, including the wet and dry seasons, 1,358 filth flies (Musca domestica, 737 [54.3%]; M. domestica vicina 556 [41%]; and Drosophilia melanogaster 65 [5%]) were caught by quadrant samplings using nets twice each month (early and later) in each of the various sites with varying sanitary conditions in Ekpoma, Nigeria. These sites were markets, hospitals, houses/human habitations, pit latrines, stalls of local food vendors, abattoirs/slaughterhouses, and dairy farms. These filth flies were studied for their potential to carry bacterial species. The identified filth flies were found to carry bacterial pathogens, with each harboring 2-10 bacteria. Seven bacterial species and their load namely, Escherichia coli (189 x 10(10) organisms per milliliter), Proteus species (210 x 10(10) organisms per milliliter), Streptococcus species (192 x 10(10) organisms per milliliter), Klebsiella species (213 x 10(10) organisms per milliliter), Salmonella species (386 x 10(10) organisms per milliliter), Staphylococcus species (163 x 10(10) organisms per milliliter), and Serratia macenscens (5.0 x 10(10) organisms per milliliter) were isolated. The highest mean bacterial load for all bacteria isolated from pooled flies was 200 x 10(10) organisms per milliliter. The mean bacterial loads of 150, 90, and 10 x 10(10) organisms per milliliter were recorded for M. domestica, M. domestica vicina, and D. melanogaster, respectively. Approximately 15(4)-23(6) bacterial colonies per fly were recorded. The total number of bacteria isolated from flies caught in the dairy farms were higher than those isolated from flies caught in any other studied sites. Lower prevalence of associated bacterial pathogens was established from flies caught in areas where hygienic conditions prevailed. Salmonella species was the most prevalent bacterial pathogen isolated amongst the flies that perched on dairy products sampled. Bacterial load was most prevalent during the wet season. Resistances of some bacterial pathogens to common available antibiotic drugs shown by zone of inhibition (<or=10 mm) include: E. coli (penicillin G and erythromycin), Streptococcus species(tetracycline, erythromycin, and cloxacillin), Serratia species (streptomycin, erythromycin, and ampicillin), Proteus species(cloxacillin and clindamycin), and Klebsiella species (cloxacillin). Indeterminate results were observed with Serratia species using gentamycin and clindamycin.

Correlations between Campylobacter spp. prevalence in the environment and broiler flocks

AIMS

To investigate (i) possible correlations between the presence of Campylobacter spp. in the surroundings of broiler farms and their incidence in flocks, and (ii) possible associations between weather conditions and the occurrence of Campylobacter spp.

METHODS AND RESULTS

Farms were selected according to previous results from the Swedish Campylobacter programme. Samples were collected in and around broiler houses during the rearing period from 131 flocks on 31 farms, including sock samples from the ground outside, from the floor in the broiler houses and anterooms, and samples from insects, water, feed and ventilation shafts.

CONCLUSIONS

As expected, there was a difference in Campylobacter isolation rates for different categories of farms regarding samples taken in the houses. However, there were no differences regarding the presence of Campylobacter spp. in the environment between producers that often deliver Campylobacter-positive slaughter batches and those that rarely deliver positive batches. Campylobacter spp. were more frequently found in the surroundings on rainy days when compared with sunny days.

SIGNIFICANCE AND IMPACT OF THE STUDY

Physical barriers between outside and inside the houses appeared to be important for preventing Campylobacter spp. in the environment to be transferred into the broiler houses.

Carriage of bacteria by proboscises, legs, and feces of two species of flies in street food vending sites in Ouagadougou, Burkina Faso

Flies are widely recognized as potential reservoirs and vectors of bacteria. In the present study, an attempt was made to assess meat-poultry and local fruit juice processing and vending sites for their hygienic status and the presence of houseflies, Musca domestica, and blow flies, Lucilia caesar, for bacterial carriage. The hygienic status results revealed the presence of waste and sewage nearby which provided food and harborage for flies. On the two sites, the M. domestica population was dominant ranging from 76.48 to 91.30%, while the L. caesar population rate ranged from 8.70 to 23.52%. Using specific growth media for bacteria and biochemical tests, bacterial carriage of pooled fly proboscises, legs, and feces were assessed. For both flies, 66.67 to 100% of feces pools were positive for Shigella, Salmonella, and streptococci, while 35.41 to 82.05% of leg and proboscis pools were positive for the same bacteria. In assessment, 0 to 2.56% of feces pools and 8.33 to 28.20% of leg and proboscis pools were staphylococci positive. Coliforms were detected in 100% of pooled organs, while 10 x 10(3) to 1.1 x 10(3) CFU with predominance of coliforms, streptococci, and Shigella were counted on legs and feces of houseflies captured on the two vending sites. Blow flies from the same vending site had an organ bacterial load in the range of 3 x 10(2) to 2.7 x 10(3) CFU per organ. Coliforms, Shigella, and streptococci were present in high numbers. Staphylococci was noticed in low numbers in all parts tested of both flies. Captured housefly and blow fly bacteria-releasing frequency through feces was estimated at 5 to 35 CFU per feces sample for Salmonella and 85 to 495 CFU per feces sample for Shigella.

Horizontal transfer of Shiga toxin and antibiotic resistance genes among Escherichia coli strains in house fly (Diptera: Muscidae) gut

Whether the house fly, Musca domestica L., gut is a permissive environment for horizontal transfer of antibiotic resistance and virulence genes between strains of Escherichia coli is not known. House flies were immobilized and force fed suspensions of defined, donor strains of E. coli containing chloramphenicol resistance genes on a plasmid, or lysogenic, bacteriophage-born Shiga toxin gene stx1 (bacteriophage H-19B::Ap1). Recipient strains were E. coli lacking these mobile elements and genes but having rifampicin as a selectable marker. Plasmid transfer occurred at rates of 10(-2) per donor cell in the fly midgut and 10(-3) in the fly crop after 1 h of incubation postfeeding. Bacteriophage transfer rate was approximately 10(-6) per donor cell without induction, but induction with mitomycin C increased rates of transfer to 10(-2) per donor cell. These findings show that genes encoding antibiotic resistance or toxins will transfer horizontally among bacteria in the house fly gut via plasmid transfer or phage transduction. The house fly gut may provide a favorable environment for the evolution and emergence of pathogenic bacterial strains through acquisition of antibiotic resistance genes or virulence factors.

Carriage by the housefly (Musca domestica) of multiple-antibiotic-resistant bacteria that are potentially pathogenic to humans, in hospital and other urban environments in Misurata, Libya

Using standard microbiological procedures, bacteria that are potentially pathogenic to humans were isolated from 150 houseflies collected in the Libyan city of Misurata (50 flies each from the Central Hospital, streets and abattoir). Salmonella spp., Yersinia enterocolitica and Edwardsiella tarda were isolated from flies collected on the streets and in the abattoir but not from those collected in the hospital. Shigella sonnei was detected in just one fly, which was collected in the abattoir. Of the flies collected in the hospital, streets and abattor, 42%, 42% and 32% were positive for Escherichia coli, 70%, 50% and 62% for Klebsiella spp., 2%, 20% and 10% for Aeromonas spp., 96%, 36% and 34% for Pseudomonas spp., 20%, 12% and 16% for Staphylococcus spp., and 24%, 22% and 18% for Streptococcus spp., respectively. When the antibiotic susceptibilities of the fly isolates were investigated, the Enterobacteria isolated from the houseflies collected in the hospital were found to be resistant to significantly more of the commonly used antibiotics that were tested than the Enterobacteria isolated from the flies caught in the streets or abattoir. Whatever the source of the flies from which they were collected, the Pseudomonas isolates frequently showed resistance to multiple antibiotics, with >50% each being resistant to at least 10 antimicrobial agents. Two isolates of Sta. aureus (both from flies collected in the hospital) were resistant to methicillin. The present study supports the belief that the housefly is a potential vector of multiple-antibiotic-resistant, pathogenic bacteria, including methicillin-resistant Sta. aureus, in the hospital environment. Given their mobility, it seems likely that houseflies carry such pathogens from hospitals to surrounding communities, and vice versa.

Could flies explain the elusive epidemiology of campylobacteriosis?

Background

Unlike salmonellosis with well-known routes of transmission, the epidemiology of campylobacteriosis is still largely unclear. Known risk factors such as ingestion of contaminated food and water, direct contact with infected animals and outdoor swimming could at most only explain half the recorded cases.

Discussion

We put forward the hypothesis that flies play a more important role in the transmission of the bacteria, than has previously been recognized. Factors supporting this hypothesis are: 1) the low infective dose of Campylobacter; 2) the ability of flies to function as mechanical vectors; 3) a ubiquitous presence of the bacteria in the environment; 4) a seasonality of the disease with summer peaks in temperate regions and a more evenly distribution over the year in the tropics; 5) an age pattern for campylobacteriosis in western travellers to the tropics suggesting other routes of transmission than food or water; and finally 6) very few family clusters.

Summary

All the evidence in favour of the fly hypothesis is circumstantial and there may be alternative explanations to each of the findings supporting the hypothesis. However, in the absence of alternative explanations that could give better clues to the evasive epidemiology of Campylobacter infection, we believe it would be unwise to rule out flies as important mechanical vectors also of this disease.

Fly transmission of Campylobacter

An annual increase in Campylobacter infection in England and Wales begins in May and reaches a maximum in early June. This increase occurs in all age groups and is seen in all geographic areas. Examination of risk factors that might explain this seasonal increase identifies flies as a potential source of infection. The observed pattern of infection is hypothesized to reflect an annual epidemic caused by direct or indirect contamination of people by small quantities of infected material carried by flies that have been in contact with feces. The local pattern of human illness appears random, while having a defined geographic and temporal distribution that is a function of the growth kinetics of one or more fly species. The hypothesis provides an explanation for the seasonal distribution of Campylobacter infections seen around the world.

Detection of Campylobacter and Escherichia coli O157:H7 from filth flies by polymerase chain reaction

Flies (Diptera: Muscidae) that breed in faeces and other organic refuse (filth flies) have been implicated as vectors of pathogenic bacteria including Escherichia coli O157:H7, which cause haemorrhagic colitis in humans, and Campylobacter, which is the principal causative agent of human enteritis. The potential role of filth flies in the epidemiology of these pathogens in the United States was investigated by examining the prevalence of Campylobacter spp. and E. coli O157:H7 from two Arkansas turkey facilities. Polymerase chain reaction was conducted on DNA extractions of individual Musca domestica Linnaeus, Stomoxys calcitrans (Linnaeus), Hydrotaea aenescens (Wiedemann), Adia cinerella Fallen and turkey faecal samples using primers specific for E. coli H7, O157 and Campylobacter spp. Culturing verified that the flies were carrying viable Campylobacter spp. and E. coli O157:H7. Results from this study indicated that M. domestica, S. calcitrans, H. aenescens and Anthomyids are capable of carrying Campylobacter in North American poultry facilities and that the E. coli O157:H7 is carried by house flies and black dump flies associated with poultry. This PCR method provided a rapid and effective method to identify Campylobacter spp. and E. coli O157:H7 directly from individual filth flies.

A comparison of Campylobacter jejuni enteritis incidence rates in high- and low-poultry-density counties: Michigan 1992-1999

To compare the incidence of Campylobacter jejuni enteritis in high- and low-poultry-density counties in Michigan between the years 1992 and 1999, an ecological study was conducted in the state of Michigan. A log-linear model was used to compare yearly, seasonal, age, and gender-specific incidence rates between county groupings. Counties with a high poultry density had a higher overall incidence of C. jejuni enteritis, particularly among children and young adults, compared with counties with low poultry density. The findings suggest that living in high-poultry-density counties is associated with higher odds for C. jejuni enteritis. This may be due to occupational exposure among poultry workers in these counties, but the findings in children suggest that indirect or environmental exposures may also play a role. Future studies should be conducted to investigate these issues.

The role of non-biting flies in the epidemiology of human infectious diseases

The feeding and reproductive habits of non-biting synanthropic flies make them important mechanical vectors of human pathogens. Synanthropic flies are major epidemiologic factors responsible for the spread of acute gastroenteritis and trachoma among infants and young children in (predominantly) developing countries. House flies are involved in mechanical transmission of nosocomial infections with multiple antibiotic-resistant bacteria in hospital environments.

Regulatory action criteria for filth and other extraneous materials. III. Review of flies and foodborne enteric disease

Forty-seven species of flies have been reliably associated with filthy conditions that might allow the spread of foodborne pathogens. These are categorized as "filth flies." Of that 47, only 21 species represent a potential threat to human health as scientifically proven causative agents of foodborne myiasis or as carriers of enteropathogenic Escherichia coli, Salmonella, Shigella, and other foodborne pathogens. These 21 species are categorized as "disease-causing flies" based on strict scientific criteria. The criteria are association with E. coli, Salmonella, AND Shigella; synanthropy; endophily; communicative behavior; attraction to both excrement and food products; and recognition by authorities as a potential health hazard. Within Hazard Analysis and Critical Control Point and other U.S. Food and Drug Administration regulatory frameworks, disease-causing flies are contributing factors to the spread of foodborne disease that require preventive and corrective actions as appropriate under Sanitation Standard Operating Procedures, Good Manufacturing Practices, or pest control programs.

Occurrence of Escherichia coli in Wildlife from Different Habitats of Sarawak, Malaysia

This study was carried out to assess the occurrence of Escherichia coli (E. coli) in the bats, birds and rodents asrepresentative of wildlife from different habitats in Sibu and Kapit, Sarawak, Malaysia. A total of 682 swabsamples were collected from wildlife hosts and screened for the bacteria E. coli and E. coli O157:H7 usingstandard microbiological methods and molecular techniques. The overall occurrence rates of E. coli among thesehosts were 14%, 17% and 54% for bats, birds and rodents, respectively. The occurrence of E. coli was thehighest in rodents regardless of the habitats. Isolated E. coli were then screened for E. coli O157:H7 by using amultiplex PCR with four primer pairs targeting for Shiga toxin producing genes (slt-I and slt-II), and the genesinvolved in biosynthesis of O157 antigen (rfbE) and H7 antigen (fliCH7 ). slt-I, slt-II and rfbE genes were notdetected in any of the E. coli isolates. However, the gene encoding for H7 antigen was detected in 23 E. coliisolates. This indicated that E. coli O157:H7 strain was not detected in the wildlife studied. Absence of E. coliO157:H7 in the wildlife studied indicated these wild animals do not serve as an important reservoir of E. coliO157:H7. However, precautions have to be taken as other group of pathogenic E. coli may pose a zoonotic riskfor humans and other animals.