Serological and molecular identification of Legionella spp. isolated from water and surrounding air samples in Italian healthcare facilities.

BACKGROUND: Legionella is an intracellular microorganism living in natural and artificial aquatic environments. Although its transmission to humans is linked to the inhalation of contaminated aerosols, there is no validated air sampling method for the control and prevention of the disease. The aim of the present study was to provide more information on the distribution of Legionella spp. in indoor environments and to determine whether the same Legionella strains are isolated from air and water samples. METHODS: Ten healthcare facilities located in seven regions of Italy were enrolled. The serological typing of Legionella spp. from water samples and the surrounding air by active and passive sampling was assessed using polyvalent and monovalent antisera. Subsequently, the strains identified as Legionella pneumophila (Lpn) underwent molecular typing by sequence-based typing (SBT) using seven genes (flaA, pilE, asd, mip, mompS, proA, and neuA). The allelic profile number was assigned using the European Working Group for Legionella Infections-SBT database. RESULTS: Lpn serogroup 6 was the most prevalent serogroup; it was found simultaneously in the air and water samples of three different healthcare facilities. In the remaining seven hospitals, Lpn serogroups 1, 6, 7, 9, and 12 were isolated exclusively from water samples. The molecular investigation showed that Lpn strains in the water and air samples of each positive healthcare facility had the same allelic profile. Strains, identified as sequence types (STs) 728 and ST 1638+ST 1324, were isolated in two respective healthcare facilities, and a new strain, identified as ST 1989, was obtained in one healthcare facility. CONCLUSION: The application of the SBT method allowed to verify the homology among Legionella strains from water samples and the surrounding air. The results showed that the same Lpn strains were present in the air and water samples, and a new Legionella strain was identified.

Analytical performance issues: comparison of ATP bioluminescence and aerobic bacterial count for evaluating surface cleanliness in an Italian hospital.

Contaminated hospital surfaces have been demonstrated to be an important environmental reservoir of microorganisms that can increase the risk of nosocomial infection in exposed patients. As a consequence, cleaning and disinfecting hospital environments play an important role among strategies for preventing healthcare-associated colonization and infections. The aim of the present study was to evaluate whether adenosine triphosphate (ATP) presence, measured by bioluminescence methods, can predict microbiological contamination of hospital surfaces. The study was carried out between September and December 2012 at the University Hospital "P. Giaccone" of Palermo. A total of 193 randomly selected surfaces (tables, lockers, furnishings) were sampled and analyzed in order to assess ATP levels (expressed as relative light units or RLU) and aerobic colony count (ACC) or presence of S. aureus. ACC had median values of 1.85 cfu/cm(2)(interquartile range = 4.16) whereas ATP median was 44.6 RLU/cm(2)(interquartile range = 92.3). Overall, 85 (44.0%) surfaces exceeded the established microbial benchmark: 73 (37.8%) exceeded the 2.5 cfu/cm(2)ACC standard, 5 (2.6%) surfaces were positive for S. aureus and 7 (3.6%) showed both the presence of S. aureus and an ACC of more than 2.5 cfu/cm(2). ACC and bioluminescence showed significant differences in the different surface sites (p < 0.001). A significant correlation was found between ACC and RLU values (p-value < 0.001; R(2)= 0.29) and increasing RLU values were significantly associated with a higher risk of failing the benchmark (p < 0.001). Our data suggest that bioluminescence could help in measuring hygienic quality of hospital surfaces using a quick and sensitive test that can be an useful proxy of microbial contamination; however, further analysis will be necessary to assess the cost-efficacy of this methodology before requiring incorporation in hospital procedures.

[Legionella spp. contamination in indoor air: preliminary results of an Italian multicenter study]. / La contaminazione indoor da Legionella spp: risultati preliminari di una indagine multicentrica italiana.

OBJECTIVE: To propose a standardized protocol for the evaluation of Legionella contamination in air. DESIGN: A bathroom having a Legionella contamination in water >1,000 cfu/l was selected in 10 different healthcare facilities. Air contamination was assessed by active (Surface Air System, SAS) and passive (Index of Microbial Air, IMA) sampling for 8 hours, about 1 m away from the floor and 50 cm from the tap water. Two hundred liters of air were sampled by SAS every 12 min, after flushing water for 2 min. The IMA value was calculated as the mean value of colony forming units/16 plates exposed during sampling (2 plates/hour). Water contamination was evaluated at T0, after 4 and 8 hours, according to the standard methods. RESULTS: Air contamination by Legionella was found in three healthcare facilities (one with active and two with passive sampling), showing a concomitant tap water contamination (median=40,000; range 1,100-43,000 cfu/l). The remaining seven hospitals isolated Legionella spp. exclusively from water samples (median=8,000; range 1,200-70,000 cfu/l). CONCLUSIONS: Our data suggest that environmental Legionella contamination cannot be assessed only through the air sampling, even in the presence of an important water contamination.

Air microbial contamination in dental clinics: comparison between active and passive methods.

The aim of this study was to evaluate the correlation between the microbial air contamination values obtained by active sampling (colony-forming units per cubic metre, CFU/m3) and by passive sampling (Index of microbial air contamination, IMA) and to calculate the corresponding equations. Air sampling was performed in ten dental clinics (DC), before (T0), during (T1) and after (T2) the clinical activity, for five consecutive days, once a month for a period of three months, for a total of 450 air samplings. The correlation was evaluated using the Spearman test, and a p value below 0.05 was considered statistically significant. A statistically significant correlation was found considering both the results obtained from the total observations and from the single sampling times, T0, T1 and T2. Different correlation patterns were observed stratifying by DC. Both methods were able to evaluate the microbial air quality and highlight critical situations; therefore, both can be used with this aim. However, in particular during the activity, passive sampling resulted more sensitive, and for its simplicity, economy and standardization by IMA, as suggested by several authors, can be suggested for routine monitoring.

[Surveillance of nosocomial infections in a cardiac surgery unit in Palermo (Italy)]. / Sorveglianza delle infezioni nosocomiali in una unità di cardiochirurgia di Palermo.

A study was performed to assess the incidence of hospital acquired infections at the Cardiac Surgey/Intensive Care Unit of the university teaching hospital "Paolo Gaccione" in Palermo (Italy), their associated risk factors and mortality. The unit consists of 31 beds, including 7 intensive care beds. One hundred patients admitted to the unit between 1 March 2008 and 30 June 2008 and hospitalised for > 48 hours were enrolled in the study. Active surveillance of hospital acquired infections was performed for these patients and overall, 18 cases of infection were diagnosed (9.3 infections per 1.000 day-patient). Infections acquired in hospital were found to be associated with several risk factors (duration of stay, duration of the surgical procedure and number of persons in the operating theatre during the procedure) and with a higher mortality rate (OR=5.9). Knowledge of the factors associated with hospital infections is essential to reducing human and social costs related to such infections while simultaneously improving the quality of health care.

Hygienic-sanitary quality of ready-to-eat salad vegetables on sale in the city of Palermo (Sicily).

In recent years there has been an increase in the consumption of bagged prepared salad vegetables. The aim of this study was to evaluate the microbiological quality of such vegetables in the city of Palermo (Italy). Forty samples of different salad vegetables were examined for the presence of mesophilic germs, E. coli, Salmonella, Listeria, E. coli O157, S. aureus, Giardia, Cryptosporidium. Variables considered included the presence of carrots, the atmospheric temperature of the day of purchase and of the two previous days, the expiry date, and the production site. The presence of carrots and of an atmospheric temperature above 20 degrees C (average of the three days considered) were found to be significantly associated with a high mesophilic germ count. This study highlights the need to implement good hygiene practices in order to prevent contamination and/or bacterial growth in ready-to-eat salad vegetables. Maintaining the cold chain and using vegetables of good microbiological quality were found to be especially relevant.

Microbial environmental contamination in Italian dental clinics: A multicenter study yielding recommendations for standardized sampling methods and threshold values.

A microbiological environmental investigation was carried out in ten dental clinics in Italy. Microbial contamination of water, air and surfaces was assessed in each clinic during the five working days, for one week per month, for a three-month period. Water and surfaces were sampled before and after clinical activity; air was sampled before, after, and during clinical activity. A wide variation was found in microbial environmental contamination, both within the participating clinics and for the different sampling times. Before clinical activity, microbial water contamination in tap water reached 51,200cfu/mL (colony forming units per milliliter), and that in Dental Unit Water Systems (DUWSs) reached 872,000cfu/mL. After clinical activity, there was a significant decrease in the Total Viable Count (TVC) in tap water and in DUWSs. Pseudomonas aeruginosa was found in 2.38% (7/294) of tap water samples and in 20.06% (59/294) of DUWS samples; Legionella spp. was found in 29.96% (89/297) of tap water samples and 15.82% (47/297) of DUWS samples, with no significant difference between pre- and post-clinical activity. Microbial air contamination was highest during dental treatments, and decreased significantly at the end of the working activity (p<0.05). The microbial buildup on surfaces increased significantly during the working hours. This study provides data for the establishment of standardized sampling methods, and threshold values for contamination monitoring in dentistry. Some very critical situations have been observed which require urgent intervention. Furthermore, the study emphasizes the need for research aimed at defining effective managing strategies for dental clinics.

Can technical, functional and structural characteristics of dental units predict Legionella pneumophila and Pseudomonas aeruginosa contamination?

Legionella pneumophila and Pseudomonas aeruginosa are common colonizers of water environments, particularly dental unit waterlines. The aim of this study was to assess whether the technical, functional and structural characteristics of dental units can influence the presence and the levels of opportunistic pathogens. Overall, 42 water samples were collected from dental units in a teaching hospital in Palermo, Italy, including 21 samples from the 21 taps supplied by the municipal water distribution system and 21 samples from oral rinsing cups at 21 dental units. L. pneumophila was present in 16 out of 21 water samples (76.2%) from dental units, and the median concentration was higher in samples from oral rinsing cups than in those from taps (P < 0.001). P. aeruginosa was equally distributed in water samples collected from oral rinsing cups and from taps. Some characteristics of dental units (age, number of chairs per room, number of patients per day and water temperature) were slightly associated with the presence of P. aeruginosa, but not with contamination by L. pneumophila. Our experience suggests that L. pneumophila is frequently detected in dental units, as reported in previous studies, whereas P. aeruginosa is not a frequent contaminant. As a consequence, microbiological control of water quality should be routinely performed, and should include the detection of opportunistic pathogens when bacterial contamination is expected.