Page 81 - JSOM Spring 2024

TABLE 1 Characteristics of Microorganisms Isolated After 6 Weeks packaging method for sterilized instruments. Furthermore, ste-
by Group rility was evaluated after only short-term storage of 30 days.
Organism Group
Aerobic gram-positive cocci* ,† 3 (sterile peel packaging) Another study evaluated two methods of packaging sterilized
Aerobic gram-positive rods ‡ 4 (unsterilized control) screws stored in a clean operating room with no reported
8
*Staphylococcus haemolyticus. moisture or excessive dust. No microbial growth was found
† Staphylococus epidermidis. after 96 weeks in the double-wrapped linen group or the sterile
8
‡ Species not identified. peel-pack envelope group. Although the study evaluated two
common methods used for packaging sterilized instruments, it
TABLE 2 Characteristics of Microorganisms Isolated After 12 Weeks did not evaluate the effects of high temperature and humidity
by Group thought to compromise instrument sterility.
Organism Group
Aerobic gram-positive rods* 3 (sterile peel packaging), The organisms cultured and isolated in this study are similar
4 (unsterilized control) to those in the literature. Bhumisirikul et al. found Bacillus
Anaerobic gram-positive rods* 4 (unsterilized control) species, a gram-positive rod, and coagulase-negative Staphylo-
*Species not identified. cocci were the most common organisms cultured in long-term
9
storage of small surgical instruments in autoclaved packages.
The isolates from the positive cultures were aerobic gram- These findings are similar to ours, which found gram- positive
positive cocci (S. haemolyticus and S. epidermidis) and un- rods and coagulase-negative Staphylococci to be the most
identified aerobic and anaerobic gram-positive rods. No fungi common culture isolates.
were identified from the cultures.
Overall mean temperature and humidity values in the pres-
ent study fell below recommended thresholds. However, there
Discussion were multiple instances where temperature and humidity val-
Higher temperature and humidity are believed to promote bac- ues exceeded these thresholds (Figures 1 and 2). It is possible
terial growth despite limited evidence from controlled studies. that exposing surgical instruments to varying temperatures
In addition, recommendations for optimal temperature and and humidity led to instrument sterility compromise in the
humidity vary according to different sources. This study pro- present study. Previous authors have shown fluctuations in
vided data that support the hypothesis that higher temperature temperature and humidity can lead to condensation, which
10
and humidity can promote bacterial growth in sterilely pack- can compromise sterile packaging. In the present study, there
aged and stored instruments. In addition, this study also found were more days where humidity values exceeded thresholds
a difference in the maintenance of sterility when comparing than when temperatures exceeded thresholds (Figures 1 and
two commonly used methods for sterile packaging. More spe- 2). However, the contribution of excessive temperature or hu-
cifically, bacterial growth was demonstrated when sterile peel midity to instrument sterility maintenance is unclear. Another
packaging was used for sterile instrument storage for 6 and possible explanation for the findings of the present study could
12 weeks in a high-temperature and high-humidity environ- have been differences between the layers of sterile packaging
ment. No growth was observed in any specimen sterilized and in the comparison groups. For example, the method used for
stored with cellulose wrapping. The most common organisms wrapping the screws in group 2 (sterile cellulose wrapping)
cultured were gram-positive rods and two species of Staph- resulted in at least two layers of sterile cellulose wrapping. In
ylococcus, which represent common nosocomial pathogens. 8 contrast, group 3 (sterile peel packaging) had just a one-layer
barrier. It has been suggested that using two layers of sterile
Recommendations for temperature and humidity thresholds packaging rather than one is more effective for instrument ste-
for sterile instrument storage vary according to different rility maintenance. 11
sources. The Association of Perioperative Registered Nurses
has recommended temperatures ≤24°C and humidity ≤70%. Another interesting finding of the present study was the lack of
3
In contrast, the Joint Commission recommends a temperature growth observed in group 1 (time-zero control). This suggests
range of 22°C–26°C and humidity <60%. Other authors have that while initial sterility can be achieved using single-layer
4
recommended temperature ranges of 18°C–22°C and humid- sterile peel packaging, maintenance of sterility is limited in
ity between 35% and 50%. By comparison, the present study high-temperature and high-humidity environments. The time
5
selected temperature and humidity levels (>24°C and >60%) that lapsed from autoclave sterilization to microbial culture
to define high temperature and humidity. Therefore, it is pos- in group 1 was around 1.5 weeks. Therefore, it would be rea-
sible sterility compromise would occur at higher thresholds. sonable to suggest sterility compromise occurred sometime
However, previous work has not demonstrated this. between 1.5 and 6 weeks in group 3 (sterile peel packing).
Exploration of this occurrence in future studies would help to
Bruna et al. compared two groups of surgical sterilized instru- clarify these temporal differences.
ments stored at different temperature and humidity conditions
following intentional contamination with Serratia marcescens. In the present study, the timing and bacterial growth varied at
1
The high-temperature and high-humidity group was stored at 6 and 12 weeks in group 3 (sterile peel packing). At 6 weeks,
35°C and 75% humidity, and the low-temperature and low- group 3 demonstrated bacterial growth on day 1 that was
1
humidity group was stored at 20°C and 60% humidity. No characterized as very heavy. At 12 weeks, bacterial growth was
bacterial growth was detected in either group after 30 days of demonstrated on day 8 and was characterized as moderate.
1
storage. However, the authors only evaluated packaging tech- There are multiple possible explanations for these findings.
niques that wrapped sterile instruments. No evaluation was One possibility is unintentional contamination. This explana-
performed of sterile peel-pack envelopes—another common tion could be supported by the fact that the bacteria cultured
Sterile Instrument Storage in Austere Environments | 79