Faecal indicator bacteria and antibiotic-resistant ß-lactamase producing Escherichia coli in blackwater: a pilot study.

The aim of this study was to identify and quantify faecal indicator bacteria in blackwater collected from a source separation unit and determine the amount of E. coli isolates resistant to antimicrobials and their potential to produce extended spectrum ß-lactamases (ESßLs) and metallo-ß-lactamases (MßLs), which hydrolyse the most important antibiotics used in clinical practice. Most of the isolates were resistant to amoxicillin with clavulanic acid (36.4 %), followed by ticarcillin with clavulanic acid (22.7 %) and tetracycline (18.2 %). ESßL-producing genes blaCTX-M and blaTEM were found in three (13.6 %) and four (18.2 %) E. coli strains, respectively, while MßL genes were found in two (9.1 %). By separating at source, this pilot study clearly shows that gastrointestinal bacteria of healthy people can be an important source of antibiotic resistance released into the environment through wastewaters. One way to prevent that is to treat wastewater with a combination of TiO2, UV light, or ozone, as successful methods to remove resistant bacteria and prevent their spread in the environment.

Biofouling of stainless steel surfaces by four common pathogens: the effects of glucose concentration, temperature and surface roughness.

There is a wide range of factors affecting bacterial adhesion and biofilm formation. However, in both food processing and medical settings, it is very hard to obtain suitably controlled conditions so that the factors that reduce surface colonisation and biofouling can be studied. The aim of this study was to evaluate the effect of glucose concentration, temperature and stainless steel (SS) surface roughness on biofouling by four common pathogens (Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and L. monocytogenes). Among the tested variables, the untreated SS surface (3C) was shown to be fouled more than 3D polished, brushed or electropolished SS surfaces. Although an array of parameters influenced biofouling, the most promising control measure was the influence of low temperature (4 °C) that reduced biofouling even in the case of the psychrophilic Listeria monocytogenes. The study findings could significantly contribute to the prevention of SS surface contamination and consequential biofouling by food and healthcare associated pathogens.

Antimicrobial susceptibility and characterization of metallo-ß-lactamases, extended-spectrum ß-lactamases, and carbapenemases of Bacillus cereus isolates.

The susceptibility of 66 clinical and environmental B. cereus isolates were tested to selected antimicrobials by a broth microdilution method. All strains were resistant to ß-lactams and susceptible to gentamicin and imipenem. Sixty-five (98.5%) isolates were susceptible to meropenem and ciprofloxacin and 74.2% to azithromycin. Significant differences in MIC values between environmental and clinical isolates were not demonstrated (p > 0.05). According to the disc diffusion method, 80.3%-98.5% of the strains were resistant to one or more of four cephalosporins. The presence of genes for B. cereus ß-lactamases BCI, BCII, BCIII, extended-spectrum ß-lactamases from the CTX and TEM family and the carbapenemases belonging to IMP and VIM family was studied. BlaII genes were expressed in all isolates; the PCR products for blaIII were also detected in two strains, but none of them was positive for blaI. The amplicon of the family blaCTX-M, mostly M-1 and M-15, was confirmed among 68.2% of the isolates, while were blaVIM-like genes determined in 21.2% of the samples.

Surveillance of bacterial colonisation on contact surfaces in different medical wards.

This study was conducted to determine the bacterial colonization of some bacterial groups, including extended-spectrum ß-lactamase (ESBLs) producers and methicillin-resistant Staphylococcus aureus (MRSA), on surfaces of the equipment and instruments in patient rooms and other workspaces in three different medical wards. The number of microorganisms on swabs was determined with the colony count method on selective microbiological mediums. The aerobic mesophylic microorganisms were found in 73.5 % out of 102 samples, with the average and maximum values of 2.6 × 102 and 4.6 × 103 colony forming units (CFU) 100 cm-2, respectively. Members of the family Enterobacteriaceae, coagulase positive staphylococci, coagulase-negative staphylococci, and enterococci were detected in 23.4, 31.4, 53.2, and 2.9 % of samples, respectively. The differences in bacterial counts on the surfaces of the psychiatric, oncology, and paediatric wards were statistically significant (P<0.001). About 40 % out of 19 isolates from the family Enterobacteriaceae showed multiple resistance to three or more different groups of tested antibiotics, while ESBL was confirmed for only one strain. Staphylococci isolates were mostly resistant to penicillin. MRSA was confirmed in 5.2 % of the tested S. aureus isolates. Greater attention should be paid to cleaning and the appropriate choice of disinfectants, especially in the psychiatric ward. Employees should be informed about the prevention of the spreading of nosocomial infections. Routine application of rapid methods for hygiene control of surfaces is highly recommended.

The influence of shear stress on the adhesion capacity of Legionella pneumophila.

Bacterial adhesion is a complex process influenced by many factors, including hydrodynamic conditions. They affect the transfer of oxygen, nutrients, and bacterial cells in a water supply and cooling systems. The aim of this study was to identify hydrodynamic effects on bacterial adhesion to and detachment from stainless steel surfaces. For this purpose we observed the behaviour of bacterium L. pneumophila in no-flow and laminar and turbulent flow conditions simulated in a fluid flow chamber. The bacterial growth in no-flow and laminar flow conditions was almost identical in the first 24 h, while at 48 and 72 h of incubation, the laminar flow stimulated bacterial growth. In the second part of this study we found that laminar flow accelerated bacterial adhesion in the first 48 h, but after 72 h the amount of bacterial cells exposed to the flow dropped, probably due to detachment. In the third part we found that the turbulent flow detached more bacterial cells than the laminar, which indicates that the strength of shear forces determines the rate of bacterial removal.

The impact of material surface roughness and temperature on the adhesion of Legionella pneumophila to contact surfaces.

The adhesion of bacterial cells to various surfaces is based on physical and chemical interactions between the micro-organisms and the surfaces. The main purpose of this research is to determine the effect of material roughness and incubation temperature on the adhesion of bacteria. To determine the adhesion of the bacterial strain of Legionella pneumophila ATCC 33153 to the glass coupons, a spectrophotometric method of measuring the optical density of crystal violet dye that is released from pre-stained bacterial cells attached to the test surface was used. The intensity of adhesion is in positive correlation to the increase in surface roughness (p < 0.05). The adhesion is the greatest at an optimal temperature of 36 °C, whereas the temperature of 15 °C has a bacteriostatic effect and the temperature of 55 °C a bactericidal effect.

High prevalence of enteric viruses in untreated individual drinking water sources and surface water in Slovenia.

Waterborne infections have been shown to be important in outbreaks of gastroenteritis throughout the world. Although improved sanitary conditions are being progressively applied, fecal contaminations remain an emerging problem also in developed countries. The aim of our study was to investigate the prevalence of fecal contaminated water sources in Slovenia, including surface waters and groundwater sources throughout the country. In total, 152 water samples were investigated, of which 72 samples represents groundwater from individual wells, 17 samples from public collection supplies and 63 samples from surface stream waters. Two liters of untreated water samples were collected and concentrated by the adsorption/elution technique with positively charged filters followed by an additional ultracentrifugation step. Group A rotaviruses, noroviruses (genogroups I and II) and astroviruses were detected with real-time RT-PCR method in 69 (45.4%) out of 152 samples collected, of which 31/89 (34.8%) drinking water and 38/63 (60.3%) surface water samples were positive for at least one virus tested. In 30.3% of drinking water samples group A rotaviruses were detected (27/89), followed by noroviruses GI (2.2%; 2/89) and astroviruses (2.2%; 2/89). In drinking groundwater samples group A rotaviruses were detected in 27 out of 72 tested samples (37.5%), genogroup I noroviruses in two (2.8%), and human astroviruses in one (1.4%) samples. In surface water samples norovirus genogroup GII was the most frequently detected (41.3%; 26/63), followed by norovirus GI (33.3%; 21/63), human astrovirus (27.0%; 17/63) and group A rotavirus (17.5%; 11/63). Our study demonstrates relatively high percentage of groundwater contamination in Slovenia and, suggests that raw groundwater used as individual drinking water supply may constitute a possible source of enteric virus infections. In the future, testing for enteric viruses should be applied for drinking water sources in waterborne outbreaks.