Pseudo-outbreak of Mycobacterium gordonae in a teaching hospital: importance of strictly following decontamination procedures and emerging issues concerning sterilization.

Aim of this study was to investigate a pseudo-outbreak of Mycobacterium gordonae analyzing isolates detected from clinical and environmental samples. Mycobacterium gordonae was detected in 7 out of 497 broncho-alveolar lavage (BAL) samples after bronchoscopy procedure in patients admitted to a teaching hospital between January and April 2013. During this pseudo-outbreak clinical, epidemiological, environmental and molecular investigations were performed. None of the patients met the criteria for non-tuberculous mycobacterial (NTM) lung disease and were treated for M. gordonae lung disease. Environmental investigation revealed M. gordonae in 3 samples: in tap water and in the water supply channel of the washer disinfector. All the isolates were subjected to genotyping by pulsed-field gel electrophoresis (PFGE). The PFGE revealed that only patients' isolates presented the same band pattern but no correlation with the environmental strain was detected. Surveillance of the outbreak and the strict adherence to the reprocessing procedure and its supplies resulted afterwards in no detection of M. gordonae in clinical respiratory samples. Clinical surveillance of patients was crucial to establish the start of NTM treatment. Regular screening of tap water and endoscopic equipment should be adopted to compare the clinical strains with the environmental ones when an outbreak occurs.

Microbiological safety of glasses dispensed at 3D movie theatres.

Recent popularity of three-dimensional movies raised some concern about microbiological safety of glasses dispensed into movie theatres. In this study, we analysed the level of microbiological contamination on them before and after use and between theatres adopting manual and automatic sanitation systems. The manual sanitation system was more effective in reducing the total mesophilic count levels compared with the automatic system (P < 0.05), but no differences were found for coagulase-positive staphylococci levels (P = 0.22). No differences were found for mould and yeast between before and after levels (P = 0.21) and between sanitation systems (P = 0.44). We conclude that more evidences are needed to support microbiological risk evaluation.

Factors influencing persistence of Legionella pneumophila serogroup 1 in laboratory cocultures.

BACKGROUND: Risk for infections from Legionella pneumophila for immunocompromised individuals increases greatly when this species is present within the biofilm of the water distribution systems of hospitals or other health facilities. Multiplication and persistence of Legionella may dependent also upon planktonic growth in alternative to sessile growth. Here we compared the persistence of L. pneumophila serogroup 1 in experimental planktonic co-cultures subsided with iron, Pseudomonas aeruginosa and other non Legionella bacteria (quantified as Heterotrophic Plate Count, HPC at 37°C), isolated from drinking water sources of a large hospital. RESULTS: Concentrations of L. pneumophila showed a decreasing pattern with incubation time in all co-cultures, the degree of reduction depending on the experimental treatment. In co-cultures with added P. aeruginosa, no L. pneumophila was detectable already after 4 days of incubation. In contrast in co-cultures without P. aeruginosa, HPC but not iron were significant factors in explaining the pattern of L. pneumophila, although the HPC effect was different according to the incubation time (HPC x time interaction, p < 0.01). CONCLUSIONS: Our results highlight the need of controlling for both HPC and metal constituents of the water systems of buildings used by individuals at particular risk to the effects of Legionella exposure.

Legionella control in the water system of antiquated hospital buildings by shock and continuous hyperchlorination: 5 years experience.

BACKGROUND: To control the presence of Legionella in an old hospital water system, an integrated strategy of water disinfection-filtration was implemented in the university hospital Umberto I in Rome. METHODS: Due to antiquated buildings, hospital water system design and hospital extension (38 buildings), shock hyperchlorination (sodium hypochlorite, 20-50 ppm of free chlorine at distal points for 1-2 h) followed by continuous hyperchlorination (0.5-1.0 mg/L at distal points) were adopted, and microbiological and chemical monitoring of the water supply was carried out in the university hospital (December 2006-December 2011). RESULTS: Overall, 1308 samples of cold <20°C (44.5%), mixed ≥20°C ≤ 45°C (37.7%) and hot >45°C (17.8%) water were collected, determining residual free chlorine (0.43 ± 0.44 mg/L), pH (7.43 ± 0.29) and trihalomethanes (8.97 ± 18.56 µg/L). Legionella was isolated in 102 (9.8%) out of 1.041 water samples without filters (L. pneumophila sg 1 17.6%, L. pneumophila sg 2-14 28.4%, L. non pneumophila 53.9%), and in none of the 267 samples with filters. Legionella was recovered in 23 buildings out of 38 and 29 samples (28.4%) exceeded 103 cfu/L. When considering the disinfection treatment Legionella was isolated: before shock hyperchlorination (21.1%), 15 days after shock hyperchlorination (7.8%), 30 days after shock hyperchlorination (3.5%), during continuous hyperchlorination (5.5%) and without continuous hyperchlorination (27.3%). Continuous hyperchlorination following the shock treatment achieved >70% reduction of positive samples, whereas no continuous hyperchlorination after shock treatment was more frequently associated to Legionella isolation (OR 6.41; 95% CI 3.10-13.26; p <0.001). Independent risk factors for Legionella isolation were: residual free chlorine <0.5 mg/L (OR 13.0; 95% CI 1.37 - 123.2; p <0.03), water T° ≥20°C ≤ 45°C (OR 12.0; 95% CI 1.28 - 111.48; p <0.03) and no continuous hyperchlorination after shock treatment (OR 10.3; 95% CI 1.06 - 100.05; p <0.05). CONCLUSIONS: Shock and continuous hyperchlorination achieved significant Legionella reduction, but effective chlorine levels (>0.5 < 1.0 mg/L) deteriorated water quality (organoleptic and chemical). However, shock and continuous hyperchlorination remains a valid-term option in old buildings with no water system rational design, managing problems due to hospital extension and absence of a proper hot water recirculation system.

Temporal pattern of microbial indicators of ready-to-eat rocket salads during shelf life.

INTRODUCTION: From 2001-2009 there have been numerous community alerts and notifications about the rocket salad produced in Italy and distributed in Europe. Our study describes the evolution of the microbial quality of ready to eat rocket salad during shelf life among three different Italian producers. MATERIAL AND METHODS: Total Mesophilic Count (TMC) and Escherichia coli (EC) count were measured in 248 samples. We used Wilcoxon test to compare the median values of TMC and EC counts and Kruskal Wallis test to compare the producers. RESULTS: The TMC and EC values differed among producers at the stages of raw material and in the finished product (Kruskall Wallis test, p < 0.05). The evolution of bacterial charges had significant differences among producers at expiration date (Wilcoxon test, p < 0.05). More than half of the samples (54.8%) exceed reference standard for TMC after 48 h from packaging. CONCLUSION: Differences among producers may linked to the different minimal processing technologies adopted after harvesting.

Ready-to-eat vegetables production with low-level water chlorination. An evaluation of water quality, and of its impact on end products.

INTRODUCTION: We evaluated the microbiological impact of low-level chlorination (1 ppm free chlorine) on the production of ready-to-eat (RTE) vegetables by monitoring the microbiological quality of irrigation and processing water in two production plants over a 4-season period, as well as the microbiological quality of unprocessed vegetables and RTE product. Water samples were also characterized in terms of some chemical and physico-chemical parameters of relevance in chlorination management. MATERIALS AND METHODS: Both producers use water with maximum 1 ppm free chlorine for vegetables rinsing, while the two processes differ by the number of washing cycles. RESULTS AND CONCLUSIONS: Salmonella spp and Campylobacter spp were detected once in two different irrigation water samples out of nine from one producer. No pathogens were found in the vegetable samples. As expected, the procedure encompassing more washing cycles performed slightly better in terms of total mesophilic count (TMC) when comparing unprocessed and RTE vegetables of the same batch. However, data suggest that low-level chlorination may be insufficient in preventing microbial build-up in the washing equipment and/or batch-to batch cross-contamination.