Neck - 13 cm2 below hairline at the base of the neck
Ears - Right and left external auditory canals with two revolutions of each swab in each ear canal
Axillae - 6.5 cm2 below hair area on each side
Hands - 6.5 cm2 on right and left palms
Navel - The internal area of the umbilicus, and a surrounding 13 cm2 area with at least two revolutions made with each swab
Groin - 5 cm strip from rear to front on right and left inguinal area between the legs
Toes - Area between the two smallest toes of each foot
Nares - Both nostrils
Throat swab - Surfaces of tonsils and posterior pharyngeal vault swabbed with each of two dry calcium alginate swabs
Gargle - 60 ml phosphate buffer used as gargle and washed through oral cavity three times
Urine - 60 ml midstream sample
Feces - Two samples of 100 mg each taken from center of the fecal specimen
Two calcium alginate swabs, wetted in phosphate buffer, were used to sample the nostrils and each external body surface area. A single, dry alginate swab for virological analysis was used to sample the throat. Phosphate buffer was used to wash the oropharyngeal cavity. Additionally, a midstream urine sample was collected from the first void of the day and fecal specimens were collected at the convenience of the subject. In-flight crew samples were collected 16 days before the end of each Skylab mission and returned under chilled conditions for analysis on Earth.
Spacecraft samples were collected before, during and after each Skylab mission from the command module, orbital workshop hardware and orbital workshop air. The orbital workshop was sampled up to 10 times, including one preflight sample set. In-flight air samples were collected two days before the end of each mission. The command module was sampled on launch and recovery days for each mission. In all cases, samples collected in-flight were stored differently, and for a longer time than were preflight and postflight samples. Therefore, direct correlation of the resulting data is not always applicable.
In excess of ten thousand selected microbial isolates were analyzed by quantification, identification and characterization. For this study, the effects of space flight conditions on microbial populations was studied only to the first level of complexity. That is, only alterations affecting the total autoflora was evaluated. (More detailed analyses conducted at increasing degrees of complexity were published elsewhere).
Crew Microbiology - A summary of the numerical means of recovered isolates of medically important microorganisms from all nine prime crewmembers indicated that the incidence of these species on the body decreased during the preflight quarantine period, establishing a low point the morning of launch. This event no doubt reflected decreased contact with these species during the quarantine period. The largest number of medically important microorganisms was recovered from the immediate postflight sample set after which the value returned to its near normal pre-quarantine value.
Returning space travelers were feared to experience a microbial shock, responding negatively to renewed contact with potentially pathogenic microorganisms that were absent in the space flight environment. This fear was based on the assumption that contact with potential pathogens during space flight would be limited, resulting in a reduction of immunocompetence. Data collected during the Skylab 2, 3 and 4 missions showed an increase in the distribution of potential pathogens immediately following space flight. However, as with the Apollo missions, no clinical or microbiological evidence of any microbial shock was present following any of the Skylab missions.
Transfer of pathogenic microorganisms between crewmembers during space flight has previously been documented in missions up to 18 days. During the Skylab series, in-flight cross-contamination, colonization, and infection with Staphylococcus aureus was demonstrated. Most strains of this species, which is one of the most infectious of the common inhabitants of man's autoflora, may be distinguished by their reaction with specific bacteriophages. Bacteriophage typing provides the ability to monitor the exchange of S. aureus with greater resolution. Data showed that the same S. aureus strain was recovered repeatedly from the nasal passages of one subject during Skylab 2, indicating that this crewmember was a carrier. Although spread to the orbital workshop was demonstrated, there was apparently no transfer to other crewmembers during the mission. Therefore, being restricted to a confined space for 28 days with an S. aureus carrier does not necessarily result in cross infection.
Skylab 3 data indicated that two crewmembers were nasal carriers, carrying phage types 3A and 29/79, respectively. Prior to flight, S. aureus was not recovered from any samples from the third crewmember. Analysis of in-flight samples show that the workshop became contaminated with both phage types and that type 29/79 was temporarily transferred to the third crewmember. Postflight analysis indicated that type 3A had spread to the subject carrying 29/79 but, as could be expected, did not colonize as he was a carrier of another phage type. Phage type 3A was repeatedly isolated from the postflight samples of the third, previously uninfected, crewmember, indicating actual colonization. This was a clear demonstration of in-flight intercrew transfer of a pathogenic species where the contaminant could be shown to have established itself as a member of the autoflora of the new host.
It was important to relate these observations to the incidence of in-flight crew illness during the Skylab 3 mission. The carrier of type 29/79 developed a sty that was successfully treated with Neosporin. The 3A carrier developed a boil that was treated with warm compresses. As neither of these infections was draining, in-flight contingency samples were not taken, so the causative agent could not be identified. However, S. aureus is the usual causative agent of both maladies, and both individuals were carriers. Therefore, the development of a pathogenic microorganism was traced from its preflight carrier state in two crewmembers through in-flight contamination of the orbital workshop, and colonization on the third crewmember. Also, this species was probably responsible for the active in-flight infections of the two S. aureus carriers.
Environmental Microbiology -
Air - Low levels of in-flight bacterial contamination were observed on the first two missions, whereas the recovery from Skylab 4 was considerable higher. These higher counts were due entirely to an influx of Serratia marcescens, a microorganism that has been shown to produce various infections in man. Whereas this species was not recovered from any preflight crew sample analysis, it was recovered from multiple sites from all three Skylab 4 astronauts upon recovery. Further, this species persisted in the nasal cavity of one Skylab 4 crewmember throughout the postflight quarantine period. Subsequent investigation demonstrated several potential sources of this microorganism in the Skylab environment. However, these potential sources could not be sampled in-flight and, therefore, a direct correlation could not be made. By active microbial monitoring, the release of this microbial contamination into the orbital workshop was traced from possible sources, detected in the Skylab air, subsequently recovered as a new species from all three crewmembers, and was ultimately shown to colonize the nasal passages of one astronaut.
Spacecraft - In-flight samples were collected to evaluate the level of microbial contamination occurring in the orbital workshop. The results of analyses of samples collected prior to launch were typical of a clean (although obviously not sterile) environment. The reduction of aerobic bacteria recovered from the Skylab 2 in-flight samples was probably a reflection of the thermal problems experienced in the orbital workshop after launch. Although there was a simultaneous tenfold increase in the presence of anaerobic bacteria, the Skylab 2 crew apparently entered a very clean environment, which remained clean during the mission.
The recovery of both aerobic and anaerobic bacteria from the Skylab 3 mission increased with no apparent reason except for increased length of habitation by the crewmembers. During the 84-day Skylab 4 mission, the total concentration of aerobic bacteria remained nearly constant although anaerobe recovery decreased significantly. This drop was due to the loss of Propionibacterium acnes, which contributed strongly to the anaerobe population of the other two Skylab missions. This loss of P. acnes reflected a similar loss of anaerobic bacteria from the skin surfaces of the astronauts. Therefore, this decrease in anaerobic bacterial contamination of the Skylab environment was shown to directly reflect a decrease in these same microbes in the skin of the astronauts.
Sampled immediately before and after each Skylab mission, aerobic bacteria were recovered from 15 sites within the command modules. Whereas there was some variation in the contamination level of the different command modules, there were no major differences between preflight and postflight values for a particular command module. Therefore, the variations noted in the orbital workshop could not be shown to affect population levels of bacteria in the command modules.
Suggestions have been made that molds would present problems on long-term space flights, especially if high humidity was experienced. Numbers of fungal isolations from the Skylab vehicle before and during launch were low until the Skylab 4 mission. Although overall humidity was low on the Skylab 4 mission, local areas of high humidity could not be entirely eliminated. The reasons for the large increase in fungal isolations on Skylab 4 have been well established. Early in the Skylab 4 mission, it was discovered that mildew was present on the liquid-cooled garments that had been previously stowed aboard. A sample was taken off this growth, and one liquid cooled garment was returned for additional sampling. In general, the species of fungi isolated from surface samples and air samples were the same species isolated from the liquid cooled garment. These same microorganisms also contaminated the Petri dishes of the ED31 experiment flown on Skylab 4. The liquid-cooled garments were apparently the source of spore contamination since some of these garments had not previously been removed from their original containers, but were subsequently found to harbor these microorganisms.
This contamination was also reflected in the recovery of fungi from the crew samples collected 16 days before return from Skylab. For Skylab 2 and Skylab 3, a total of two and zero filamentous fungi, respectively, were isolated from the crew during flight. On Skylab 4, a total of 11 fungi were isolated, including a significant contamination to the astronauts. This contamination to the crew was demonstrated 62 days after the first exposure to the liquid-cooled garments, indicating either continued contamination from inanimate sources, abnormally slow return to normal levels, or both.
Data show that the fungal contamination of the orbital workshop during Skylab 4 did not affect the command module samples collected on recovery day. Although the command module was attached to the orbital workshop during this period of contamination, it was a separate entity, out of the area of heavy use, and away from the contaminating space suits. This relatively clean command module probably contributed to the low level of fungal contamination of the crew postflight.
In conclusion, microbiological data collected during the Skylab 2, 3, and 4 missions show that, while gross contamination of the Skylab environment was demonstrated and there were several in-flight disease events (presumably of microbial origin), such events were not shown to be limiting hazards for long-duration space flight. Evaluation of the major groups of microorganisms comprising the microbial populations tested, tended to support the theory of microbial simplification for anaerobic bacteria, but not for other microbes. Intercrew transfer of pathogens was demonstrated. The data mediate against the theory of postflight microbial shock. The question of in-flight autoinfection remains unanswered because none of the in-flight disease events were evaluated microbiologically.