Assessment of antibiotic-resistant organism transmission among rooms of hospitalized patients, healthcare personnel, and the hospital environment utilizing surrogate markers and selective bacterial cultures.

OBJECTIVE: To assess potential transmission of antibiotic-resistant organisms (AROs) using surrogate markers and bacterial cultures. DESIGN: Pilot study. SETTING: A 1,260-bed tertiary-care academic medical center. PARTICIPANTS: The study included 25 patients (17 of whom were on contact precautions for AROs) and 77 healthcare personnel (HCP). METHODS: Fluorescent powder (FP) and MS2 bacteriophage were applied in patient rooms. HCP visits to each room were observed for 2-4 hours; hand hygiene (HH) compliance was recorded. Surfaces inside and outside the room and HCP skin and clothing were assessed for fluorescence, and swabs were collected for MS2 detection by polymerase chain reaction (PCR) and selective bacterial cultures. RESULTS: Transfer of FP was observed for 20 rooms (80%) and 26 HCP (34%). Transfer of MS2 was detected for 10 rooms (40%) and 15 HCP (19%). Bacterial cultures were positive for 1 room and 8 HCP (10%). Interactions with patients on contact precautions resulted in fewer FP detections than interactions with patients not on precautions (P < .001); MS2 detections did not differ by patient isolation status. Fluorescent powder detections did not differ by HCP type, but MS2 was recovered more frequently from physicians than from nurses (P = .03). Overall, HH compliance was better among HCP caring for patients on contact precautions than among HCP caring for patients not on precautions (P = .003), among nurses than among other nonphysician HCP at room entry (P = .002), and among nurses than among physicians at room exit (P = .03). Moreover, HCP who performed HH prior to assessment had fewer fluorescence detections (P = .008). CONCLUSIONS: Contact precautions were associated with greater HCP HH compliance and reduced detection of FP and MS2.

Biogeographic study of human gut-associated crAssphage suggests impacts from industrialization and recent expansion.

CrAssphage (cross-assembly phage) is a bacteriophage that was first discovered in human gut metagenomic data. CrAssphage belongs to a diverse family of crAss-like bacteriophages thought to infect gut commensal bacteria belonging to Bacteroides species. However, not much is known about the biogeography of crAssphage and whether certain strains are associated with specific human populations. In this study, we screened publicly available human gut metagenomic data from 3,341 samples for the presence of crAssphage sensu stricto (NC_024711.1). We found that crAssphage prevalence is low in traditional, hunter-gatherer populations, such as the Hadza from Tanzania and Matses from Peru, as compared to industrialized, urban populations. Statistical comparisons showed no association of crAssphage prevalence with variables such as age, sex, body mass index, and health status of individuals. Phylogenetic analyses show that crAssphage strains reconstructed from the same individual over multiple time-points, cluster together. CrAssphage strains from individuals from the same study population do not always cluster together. Some evidence of clustering is seen at the level of broadly defined geographic regions, however, the relative positions of these clusters within the crAssphage phylogeny are not well-supported. We hypothesize that this lack of strong biogeographic structuring is suggestive of an expansion event within crAssphage. Using a Bayesian dating approach, we estimate that this expansion has occurred fairly recently. Overall, we determine that crAssphage presence is associated with an industrialized lifestyle and the absence of strong biogeographic structuring within global crAssphage strains is likely due to a recent population expansion within this bacteriophage.

A simple, reproducible and cost-effective procedure to analyse gut phageome: from phage isolation to bioinformatic approach.

The microbiota of the human gut is a complex and rich community where bacteria and their viruses, the bacteriophages, are dominant. There are few studies on the phage community and no clear standard for isolating them, sequencing and analysing their genomes. Since this makes comparisons between studies difficult, we aimed at defining an easy, low-cost, and reproducible methodology. We analysed five different techniques to isolate phages from human adult faeces and developed an approach to analyse their genomes in order to quantify contamination and classify phage contigs in terms of taxonomy and lifestyle. We chose the polyethylene glycol concentration method to isolate phages because of its simplicity, low cost, reproducibility, and of the high number and diversity of phage sequences that we obtained. We also tested the reproducibility of this method with multiple displacement amplification (MDA) and showed that MDA severely decreases the phage genetic diversity of the samples and the reproducibility of the method. Lastly, we studied the influence of sequencing depth on the analysis of phage diversity and observed the beginning of a plateau for phage contigs at 20,000,000 reads. This work contributes to the development of methods for the isolation of phages in faeces and for their comparative analysis.

Efficacy and safety assessment of two enterococci phages in an in vitro biofilm wound model.

Chronic wounds affect thousands of people worldwide, causing pain and discomfort to patients and represent significant economical burdens to health care systems. The treatment of chronic wounds is very difficult and complex, particularly when wounds are colonized by bacterial biofilms which are highly tolerant to antibiotics. Enterococcus faecium and Enterococcus faecalis are within the most frequent bacteria present in chronic wounds. Bacteriophages (phages) have been proposed as an efficient and alternative against antibiotic-resistant infections, as those found in chronic wounds. We have isolated and characterized two novel enterococci phages, the siphovirus vB_EfaS-Zip (Zip) and the podovirus vB_EfaP-Max (Max) to be applied during wound treatment. Both phages demonstrated lytic behavior against E. faecalis and E. faecium. Genome analysis of both phages suggests the absence of genes associated with lysogeny. A phage cocktail containing both phages was tested against biofilms formed in wound simulated conditions at a multiplicity of infection of 1.0 and a 2.5 log CFU.mL-1 reduction in the bacterial load after at 3 h of treatment was observed. Phages were also tested in epithelial cells colonized by these bacterial species and a 3 log CFU.mL-1 reduction was observed using both phages. The high efficacy of these new isolated phages against multi-species biofilms, their stability at different temperatures and pH ranges, short latent periods and non-cytotoxicity to epithelial cells suggest their therapeutic use to control infectious biofilms present in chronic wounds.

Bacteriophage production processes.

High quantities of bacteriophages are currently used in the food industry and agriculture. However, growing antibiotic resistance of bacteria has recently awakened the interest to use bacteriophages for the treatment of bacterial infections in humans indicating that even higher quantities will be required in the future. High demand combined with a wide range of applications requires also efficient bacteriophage production processes operating at low production costs and with high productivity. To achieve this goal, different approaches were introduced and extensive studies of various parameters affecting bacteriophage formation were investigated. In this mini-review, we provide a short overview about different operation modes of bacteriophage production such as batch, semi-continuous and especially continuous with the pros and cons of each. We present factors affecting bacterial physiological state, its effect on phage formation and provide a description of methods for determination of bacteriophage growth parameters, through which bacteriophage formation is obtained. Understanding of described phenomena and inclusion of potential occurrence of mutations and selection in continuous systems enables evaluation of continuous process productivity and its optimization.

Simple drop cast method for enumeration of bacteriophages.

Phage enumeration is a basic prerequisite for application of phages in industrial, medical and other processes. Double layer agar (DLA) plaque assay is the classical method employed for isolation, detection as well as enumeration of phage particles in a solution. However, DLA method is considered cumbersome due to its specific temperature requirements and need for one petriplate with two agar layers for each phage sample. We are proposing a drop cast method for enumeration of phages which is comparatively easier and cost effective than classical DLA method as single layer of agar without any specific temperature condition is required. Added advantage of this method is that 7-10 dilutions of phage suspension can be enumerated on a single agar plate in contrast to one dilution per plate as required in DLA method. Although standard deviation in phage count was higher in the proposed method than DLA method, still drop cast method provided first-approximation phage titer which can be further validated by DLA method for more accuracy. Hence, the present method can be considered reliable, easy and cost effective for determining approximate phage count in an unknown phage suspension.

Assessment of swine-specific bacteriophages of Bacteroides fragilis in swine farms with different antibiotic practices.

We assessed the occurrence and specificity of bacteriophages of Bacteroides fragilis in swine farms for their potential application in microbial source tracking. A local B. fragilis host strain, SP25 (DSM29413), was isolated from a pooled swine feces sample taken from a non-antibiotic farm. This strain was highly specific to swine fecal materials because it did not detect bacteriophages in any samples from human sewage, sheep, goats, cattle, dogs, and cats. The reference B. fragilis strain, RYC2056, could detect phages in swine samples but also detected phages in most human sewage and polluted urban canal samples. Phages of SP25 exist in the proximity of certain swine farms, regardless of their antibiotic use (p > 0.05). B. fragilis strain SP25 exhibited relatively high resistance to most of the veterinary antimicrobial agents tested. Interestingly, most farms that were positive for SP25 phages were also positive for RYC2056 phages. In conclusion, the swine-specific SP25 strain has the potential to indicate swine fecal contamination in certain bodies of water. Bacterial isolates with larger distributions are being studied and validated. This study highlights the importance of assessing the abundance of phages in local swine populations before determining their potential applicability for source tracking in local surface waters.

Numbers of coliforms, Escherichia coli, F-RNA phage, rotavirus, bovine enteric calicivirus and presence of non-O157 STEC on commercial vacuum packaged beef.

The numbers of coliforms, Escherichia coli, F-RNA coliphages, bovine enteric calicivirus (BEC) and rotavirus (RV) and presence of non-O157 shiga toxigenic E. coli (STEC) were determined on commercial vacuum packaged beef subprimals at the retail level from swabs obtained from the entire surfaces of 150 cuts that originated from federally and provincially registered plants. The prevalence and log mean numbers of E. coli were higher in provincially registered plants than in federally registered plants; 64% vs 20%, respectively, and -0.3 vs -1.22 log cfu/100 cm(2), respectively. In contrast, the prevalence and mean log numbers of F-RNA coliphages were lower for the provincially registered plants than for the federally registered plants; 31% vs 68% and -0.86 vs -0.13 log cfu/100 cm(2), respectively. One E. coli sample tested positive for stx2 and eae. F-RNA coliphages associated with human origin (GII/GIII) were detected in 12% and 30% of samples that originated from provincially and federally registered plants, respectively. RV RNA was detected in 4% of samples while BEC RNA was not detected. Although the infectivity of RV is unknown, the presence of viable F-RNA coliphages suggests that consumers could potentially be at risk when consuming undercooked meat that is contaminated with RV.

A bacteriophage detection tool for viability assessment of Salmonella cells.

Salmonellosis, one of the most common food and water-borne diseases, has a major global health and economic impact. Salmonella cells present high infection rates, persistence over inauspicious conditions and the potential to preserve virulence in dormant states when cells are viable but non-culturable (VBNC). These facts are challenging for current detection methods. Culture methods lack the capacity to detect VBNC cells, while biomolecular methods (e.g. DNA- or protein-based) hardly distinguish between dead innocuous cells and their viable lethal counterparts. This work presents and validates a novel bacteriophage (phage)-based microbial detection tool to detect and assess Salmonella viability. Salmonella Enteritidis cells in a VBNC physiological state were evaluated by cell culture, flow-cytometry and epifluorescence microscopy, and further assayed with a biosensor platform. Free PVP-SE1 phages in solution showed the ability to recognize VBNC cells, with no lysis induction, in contrast to the minor recognition of heat-killed cells. This ability was confirmed for immobilized phages on gold surfaces, where the phage detection signal follows the same trend of the concentration of viable plus VBNC cells in the sample. The phage probe was then tested in a magnetoresistive biosensor platform allowing the quantitative detection and discrimination of viable and VBNC cells from dead cells, with high sensitivity. Signals arising from 3 to 4 cells per sensor were recorded. In comparison to a polyclonal antibody that does not distinguish viable from dead cells, the phage selectivity in cell recognition minimizes false-negative and false-positive results often associated with most detection methods.

Surface plasmon resonance detection of E. coli and methicillin-resistant S. aureus using bacteriophages.

Early diagnosis and appropriate treatment of Escherichia coli (E. coli) O157:H7 and methicillin-resistant Staphylococcus aureus (MRSA) are key elements in preventing resultant life-threatening illnesses, such as hemorrhagic colitis, hemolytic uremic syndrome, and septicemia. In this report, we describe the use of surface plasmon resonance (SPR) for the biodetection of pathogenic bacteria, using bacteriophages as the recognition elements. T4 bacteriophages were used to detect E. coli, while a novel, highly specific phage was used to detect MRSA. We found that the system permits label-free, real-time, specific, rapid and cost-effective detection of pathogens, for concentrations of 10(3) colony forming units/milliliter, in less than 20 min. This system promises to become a diagnostic tool for bacteria that cause major public concern for food safety, bioterrorism, and nosocomial infections.

A new rapid and cost-effective method for detection of phages, ICEs and virulence factors encoded by Streptococcus pyogenes.

Streptococcus pyogenes (group A Streptococcus, GAS) is a human pathogen that causes diseases of various intensity, from mild strep throat to life threatening invasive infections and postinfectional sequelae. S. pyogenes encodes multiple, often phage encoded, virulence factors and their presence is related to severity of the disease. Acquisition of mobile genetic elements, carrying virulence factors, as phages or ICEs (integrative and cojugative elements) has been shown previously to promote selection of virulent clones. We designed the system of eight low volume multi- and one singleplex PCR reactions to detect genes encoding twenty virulence factors (spd3, sdc, sdaB, sdaD, speB, spyCEP, scpA, mac, sic, speL, K, M, C, I, A, H, G, J, smeZ and ssa) and twenty one phage and ICE integration sites described so far for S. pyogenes. Classification of strains based on the phage and virulence factors absence or presence, correlates with PFGE MLST and emm typing results. We developed a novel, fast and cost effective system that can be used to detect GAS virulence factors. Moreover, this system may become an alternative and effective system to differentiate between GAS strains.

Sustainable microbial water quality monitoring programme design using phage-lysis and multivariate techniques.

Contamination of surface waters is a pervasive threat to human health, hence, the need to better understand the sources and spatio-temporal variations of contaminants within river catchments. River catchment managers are required to sustainably monitor and manage the quality of surface waters. Catchment managers therefore need cost-effective low-cost long-term sustainable water quality monitoring and management designs to proactively protect public health and aquatic ecosystems. Multivariate and phage-lysis techniques were used to investigate spatio-temporal variations of water quality, main polluting chemophysical and microbial parameters, faecal micro-organisms sources, and to establish 'sentry' sampling sites in the Ouse River catchment, southeast England, UK. 350 river water samples were analysed for fourteen chemophysical and microbial water quality parameters in conjunction with the novel human-specific phages of Bacteroides GB-124 (Bacteroides GB-124). Annual, autumn, spring, summer, and winter principal components (PCs) explained approximately 54%, 75%, 62%, 48%, and 60%, respectively, of the total variance present in the datasets. Significant loadings of Escherichia coli, intestinal enterococci, turbidity, and human-specific Bacteroides GB-124 were observed in all datasets. Cluster analysis successfully grouped sampling sites into five clusters. Importantly, multivariate and phage-lysis techniques were useful in determining the sources and spatial extent of water contamination in the catchment. Though human faecal contamination was significant during dry periods, the main source of contamination was non-human. Bacteroides GB-124 could potentially be used for catchment routine microbial water quality monitoring. For a cost-effective low-cost long-term sustainable water quality monitoring design, E. coli or intestinal enterococci, turbidity, and Bacteroides GB-124 should be monitored all-year round in this river catchment.

Is there a cost of virus resistance in marine cyanobacteria?

Owing to their abundance and diversity, it is generally perceived that viruses are important for structuring microbial communities and regulating biogeochemical cycles. The ecological impact of viruses on microbial food webs, however, may be influenced by evolutionary processes, including the ability of bacteria to evolve resistance to viruses and the theoretical prediction that this resistance should be accompanied by a fitness cost. We conducted experiments using phylogenetically distinct strains of marine Synechococcus (Cyanobacteria) to test for a cost of resistance (COR) to viral isolates collected from Mount Hope Bay, Rhode Island. In addition, we examined whether fitness costs (1) increased proportionally with 'total resistance', the number of viruses for which a strain had evolved resistance, or (2) were determined more by 'compositional resistance', the identity of the viruses to which it evolved resistance. A COR was only found in half of our experiments, which may be attributed to compensatory mutations or the inability to detect a small COR. When detected, the COR resulted in a approximately 20% reduction in relative fitness compared to ancestral strains. The COR was unaffected by total resistance, suggesting a pleiotropic fitness response. Under competitive conditions, however, the COR was dependent on compositional resistance, suggesting that fitness costs were associated with the identity of a few particular viruses. Our study provides the first evidence for a COR in marine bacteria, and suggests that Synechococcus production may be influenced by the composition of co-occurring viruses.

Microbiological assessment of ambient waters and proposed water sources for restoration of a Florida wetland.

This study evaluated the microbial quality of reclaimed and storm water as proposed sources for restoration of a Florida wetland. Bacterial indicators, bacteriophages and waterborne pathogenic microorganisms (Cryptosporidium, Giardia and infectious enteric viruses) were analysed during a 1-year period in order to determine potential public health risks associated with exposure to the proposed water sources for restoration. Ambient waters within the wetland (four active water wells and four major lakes) were included in the study in order to determine the microbial water quality before restoration. Storm water and lakes had the highest level of microbial contamination. Much lower levels of microbial indicators and waterborne pathogens were found in reclaimed water and groundwater. Pathogen occurrence in groundwater was intermittent. Owing to the small percentage of source waters (3.3%) migrating to the water wells, ambient concentration of microbial constituents in surface and groundwater could dominate microbial risk. The results of this study indicate that, in the light of the uncertainties involved in computing average Cryptosporidium concentrations, additional characterization of the current ambient water quality should be ongoing prior to restoration.

An assessment of water quality and microbial risk in Rio Grande Basin in the United States-Mexican border region.

Increased reliance of urban populations on Rio Grande water has necessitated an expanded microbial surveillance of the river to help identify and evaluate sources of human pathogens, which could pose a public health risk. The objectives of this study were to investigate microbial and chemical water quality in Rio Grande water and to perform risk assessment analyses for Cryptosporidium. No oocysts in any of the ten-litre samples were detected. However, the limit of detection in the water samples ranged between 20 and 200 oocysts/100 L. The limits of detection obtained in this study would result in one to two orders of magnitude higher risk of infection for Cryptosporidium than the U.S.EPA annual acceptable risk level of 10(-4). The bacterial data showed the significance of animal farming and raw sewage as sources of fecal pollution. Male specific and somatic coliphages were detected in 52% (11/21) and 62% (24/39) of the samples, respectively. Somatic coliphages were greater by one order of magnitude, and were better correlated with total (r2 = 0.6801; p < or = 0.05) and fecal coliform bacteria (r2 = 0.7366; p < or = 0.05) than male specific coliphages. The dissolved organic carbon (DOC) and specific ultraviolet absorbance (SUVA) values ranged 2.58-5.59mg/L and 1.23-2.29 m(-1) (mg/I)(-1), respectively. Low SUVA values of raw water condition make it difficult to remove DOC during physical and chemical treatment processes. The microbial and chemical data provided from this study can help drinking water utilities to maintain balance between greater microbial inactivation and reduced disinfection by-products (DBPs) formation.

Assessment of drinking water quality using indicator bacteria and bacteriophages.

Bacterial indicators and bacteriophages suggested as potential indicators of water quality were determined by public laboratories in water from springs, household water wells, and rural and metropolitan water supplies in north-eastern Spain. Indicator bacteria were detected more frequently than bacteriophages in springs, household water wells and rural water supplies. In contrast, positive bacteriophage detections were more numerous than those of bacteria in metropolitan water supplies. Most of the metropolitan water supply samples containing indicators had concentrations of chlorine below 0.1 mg l(-1), their indicator loads resembling more closely those of rural water supplies than any other samples taken from metropolitan water supplies. The number of samples from metropolitan water supplies containing more than 0.1 mg l(-1) of chlorine that contained phages clearly outnumbered those containing indicator bacteria. Some association was observed between rainfall and the presence of indicators. Sediments from service reservoirs and water from dead ends in the distribution network of one of the metropolitan water supplies were also tested. Bacterial indicators and phages were detected in a higher percentage than in samples of tap water from the same network. Additionally, indicator bacteria were detected more frequently than bacteriophages in sediments of service reservoirs and water from dead end samples. We conclude that naturally occurring indicator bacteria and bacteriophages respond differently to chlorination and behave differently in drinking water distribution networks. Moreover, this study has shown that testing for the three groups of phages in routine laboratories is easy to implement and feasible without the requirement for additional material resources for the laboratories.

Occurrence and densities of bacteriophages proposed as indicators and bacterial indicators in river waters from Europe and South America.

AIMS: To evaluate the feasibility of bacteriophages as a complementary tool for water quality assessment in surface waters from different parts of the globe. METHODS AND RESULTS: Faecal coliform bacteria, enterococci, spores of sulphite-reducing clostridia, somatic coliphages, F-specific RNA bacteriophages and bacteriophages infecting Bacteroides fragilis were determined by standardized methods in raw sewage and in 392 samples of river water from 22 sampling sites in 10 rivers in Argentina, Colombia, France and Spain, which represent very different climatic and socio-economic conditions. The results showed that the indicators studied maintained the same relative densities in the raw sewage from the different areas. Classifying the river water samples according to the content of faecal coliform bacteria, it can be observed that the relative densities of the different bacterial indicators and bacteriophages changed according to the concentration of faecal coliform bacteria. There was a relative increase in the densities of all groups of bacteriophages and sulphite-reducing clostridia with respect to faecal coliforms and enterococci in the samples with low counts of faecal coliform bacteria. CONCLUSIONS: The numbers of bacterial indicators and bacteriophages were similar in the different geographical areas studied. Once released in rivers, the persistence of the different micro-organisms differed significantly. Bacteriophages and spores of sulphite-reducing clostridia persisted longer than faecal coliforms and enterococci. SIGNIFICANCE AND IMPACT OF THE STUDY: Bacteriophages in river water samples provide additional information to that provided by bacteria about the fate of faecal micro-organisms in river water. The easy, fast and cheap methods for phage determination are feasible both in industrialized and developing countries.

[Prevention of epidemiological consequences during an extreme situation caused by the natural disaster in the Republic of North Ossetia-Alania]. / Preduprezhdenie épidemiologicheskikh posledstvii vo vremia ékstremal'noi obstanovki, vyzvannoi stikhiinym bedstviem v Respublike Severnaia Osetiia-Alaniia.

Information on the organization of interaction between different services responsible for restoration works, sanitary cleaning, disinfection under the conditions of the emergency situation is presented. The activity of the sanitary and epidemiological services in the areas in the Republic of North Ossetia-Alania, affected by high flood, is described. Measures aimed at the epidemiological surveillance of acute enteric infections, the control of the quality of drinking water and foodstuffs, the bacteriological study of material samples taken from humans, vaccinal and phage prophylaxis have taken an important place in the work of the institutions of sanitary and epidemiological surveillance. As the result of all these measures the sanitary and epidemiological service has managed to prevent the aggravation of the sanitary and epidemiological situation in the republic.

Isolation and characterization of five Erwinia amylovora bacteriophages and assessment of phage resistance in strains of Erwinia amylovora.

Phages able to infect the fire blight pathogen Erwinia amylovora were isolated from apple, pear, and raspberry tissues and from soil samples collected at sites displaying fire blight symptoms. Among a collection of 50 phage isolates, 5 distinct phages, including relatives of the previously described phages phiEa1 and phiEa7 and 3 novel phages named phiEa100, phiEa125, and phiEa116C, were identified based on differences in genome size and restriction fragment pattern. phiEa1, the phage distributed most widely, had an approximately 46-kb genome which exhibited some restriction site variability between isolates. Phages phiEa100, phiEa7, and phiEa125 each had genomes of approximately 35 kb and could be distinguished by their EcoRI restriction fragment patterns. phiEa116C contained an approximately 75-kb genome. phiEa1, phiEa7, phiEa100, phiEa125, and phiEa116C were able to infect 39, 36, 16, 20, and 40, respectively, of 40 E. amylovora strains isolated from apple orchards in Michigan and 8, 12, 10, 10, and 12, respectively, of 12 E. amylovora strains isolated from raspberry fields (Rubus spp.) in Michigan. Only 22 of 52 strains were sensitive to all five phages, and 23 strains exhibited resistance to more than one phage. phiEa116C was more effective than the other phages at lysing E. amylovora strain Ea110 in liquid culture, reducing the final titer of Ea110 by >95% when added at a ratio of 1 PFU per 10 CFU and by 58 to 90% at 1 PFU per 10(5) CFU.

Distribution of indicator bacteria and bacteriophages in shellfish and shellfish-growing waters.

Shellfish (mussels and clams) and shellfish-growing waters were examined for indicator bacteria according to the EC regulations, Salmonella spp., coliphages and anti-Salmonella phages. Samples were collected both from natural-growing areas along the coast and from authorized shellfish-harvesting beds. The coastal area was affected by organic pollution and extensive faecal contamination and, according to the legal requirements, was unsuitable for shellfish farming. The shellfish collected along the coast also showed faecal contamination at levels which did not conform to legal standards. No significant differences were observed between the frequency of isolation of somatic coliphages and indicator bacteria from sea water. In contrast, both the authorized and wild coastal shellfish were contaminated by coliphages at a significantly higher level than the corresponding bacterial indicators for faecal contamination (chi 2 test, P < 0.01). Coliphage concentrations were significantly correlated with faecal indicators in marine waters (P < 0.001) and sediments (P < 0.05), but no correlation was found in shellfish, thus showing their low specificity as indicators of faecal pollution of human origin in shellfish of economic importance.