The detection and evaluation of microbial contamination is the goal of many programs in the medical, food, pharmaceutical, and environmental monitoring/biothreat detection industries. Similarly, NASA's Planetary Protection program strives to assess, as well as prevent, microbial contamination in spacecraft assembly facilities and on spacecraft themselves. The development of improved methods and technologies designed to facilitate these common goals is therefore important. This review will focus on instrumentation and techniques currently being utilized or evaluated for use by the Planetary Protection program in the clean room environments of spacecraft assembly facilities. Current sampling technologies (novel sampling instrumentation and different collection materials) were compared with NASA standard protocols under field and controlled conditions. A brief literature review was presented to augment the comparisons. Additionally, as the integrity of sample analyses is directly dependent on both the efficiency of sample collection and the quality of sample processing, a novel nucleic acid extraction instrument was also evaluated. The impact of these new technologies will be discussed with respect to sample collection, processing, and analyses from the low biomass environments present in NASA clean rooms, although the findings may be applied in a broader context to other industries and programs as well as to the development of future integrated biosensors.
A total of 189 meat samples including 153 domestic and 36 imported meats were inspected for the isolation of Enterococcus faecalis and Enterococcus faecium. E. faecalis was detected from 113 samples (73.9%, 192 strains) of domestic meats and 26 samples (72.2%, 50 strains) of imported meats. E. faecium was detected from 13 samples (8.5%) of domestic meats and 3 samples (8.3%) of imported meats. To study the potential virulence factors of those isolates, the presence of certain genes, i.e. gelE, asa1, cylA, esp was investigated by PCR. E. faecalis possessing the virulence gene was detected from 97 (63.4%) domestic meats, and 26 (72.2%) imported meats. However, only one E. faecium strain (0.7%) from domestic meat posessed the virulence gene. The common virulence genes in E. faecalis isolated from domestic and imported meat were gelE (77.1% vs. 78.0%), followed by asa1 (50.5% vs. 76.0%), cylA (13.0% vs. 20.0%), and esp (5.2% vs. 12.0%). All strains of E. faecalis possessing either cylA or esp also possessed other virulence genes, and the same encoding combination of genes was found in strains from compromised hosts.
A total of 414 Staphylococcus aureus strains isolated from raw meat, humans, pigs and chickens between 2002 and 2005 were examined for susceptibility to 14 antimicrobial agents by the agar dilution method. In the isolates from dressed meat, the resistance rates were 54.4% (107/196), 66.7% (12/18) and 50.0% (9/18) in isolates from chicken, pork and beef, respectively. In the isolates from minced meat, the resistance rates were 78.1% (25/32), 83.3% (25/30) and 65.4% (17/26) in isolates from chicken, pork and beef, respectively. Most (86.7%) of the 195 resistant isolates showed multiple resistance to between two and eight antimicrobials. The most frequent anitimicrobial resistance profiles were PCG/ABPC (47.3%) and PCG/ABPC with other antimicrobials (one to six antimicrobials, 24.3%). Relatively high frequencies of resistance were observed with PCG (37.8%), ABPC (37.8%), OTC (20.9%), NFLX (17.5%) and EM (10.3%). The other 9 antimicrobials such as DSM, KM, LCM, BFLX, CP, MPIPC, CEZ, CEX or CET showed resistance levels below 10.0%. Only one MRSA isolate was isolated from minced pork. Commercial raw meat may contain resistant S. aureus posing a potential risk to consumers. In the isolates from the nares of humans, pigs and chickens, the resistance rates were 50.0% (17/34), 96.4% (53/55) and 100% (5/5) in isolates from humans, pigs and chickens, respectively. Resistance to PCG and ABPC was the most frequent in isolates from humans (38.2%) and pigs (65.5%). The pig isolates were also highly resistant to OTC (61.8%). A high frequency of restance to LCM (100%), OTC (80.0%) and EM (80.0%) was found in the isolates from chickens.