- Email: [email protected]
Microbial contamination of ‘sterile water’ used in Japanese hospitals
Microbial
contamination Japanese
of ‘sterile hospitals
water’
used
S. Oie”, M. Oomakij-, K. Yoriokat, T. Tatsumig, M. Amasakiyl, T. Fukudall, H. Hakuno **, K. Naganof-f-, M. Matsuda$$, N. Hirata@, N. Miyanoll, A. Kamiya”
in
62
S. Oie et al.
Figure
1. Japanese
ultra
filtration
system.
or a reverse osmosis system (RO water) set up in the operating room (Figure 1). Manufacturers advertise UF water or RO water as sterile but surveys of microbial contamination of such waters have not been performed. Therefore, we evaluated the microbial contamination of UF and RO waters used for preoperative handwashing and also that of water from a water distillation system set up in the hospital dispensary for the preparation of drugs. Materials
and
methods
Waters were examined from 10 hospitals in Yamaguchi Prefecture between February and April 1996. Nineteen samples of UF water were obtained from 19 machines (five types, five manufacturers), 17 samples of RO water from 17 machines (six types, six manufacturers) and 19 samples of distilled water from 19 machines (eight types, five manufacturers). One sample of tap water was obtained from each of the 10 hospitals. Each sample was collected after leaving the tap on for 3 min. Each sample was diluted IO’and 102-fold in nutrient broth; 0.2 mL of each dilution and of an undiluted sample were spread onto trypticase soy agar and Sabouraud’s dextrose agar. The plates were incubated at 30°C for 24-72 h (trypticase soy agar) or 25°C
Microbial Prefilter
contamination
of water
Ultra filteration
Water Ion-exhange resin
(b)
63
Active
carbon filter
tap
Reverse osmosis
Water tap Active
carbon filter
Ion-exchange resin
Distillation
Water
tank
I
I
Water I:igure
distillation
2(a)
;\lodel svstcrn.
tlo\v
of an ultra
tiltration
system;
(b)
re\‘erse
osmosis
system;
tap (c)
watcl
for two to seven days (Sabouraud’s dextrose agar). Colonies \vere counted and organisms identified by Gram-stain, morphology, OF test, cytochromc oxidase test and the ‘API’ system. I:igures 2(a)-(c) show model flows of the ultra filtration, reverse osmosis and water distillation systems respectively. :I\\;ailable chlorine was detcrmincd using a pH/ion meter F-24 (Horiba Co., ‘l’okyo) with Orion”’ rcs. chlorine electrode 977ORK (,4nalytical ‘I’echnology, Inc., Tokyo). Results
‘l‘ablc I shows the available chlorine content, degree of microbial contamination and most common micro-organisms isolated from each \vater type. Available chlorine content lvas 0.17-0.42 ppm in the 10 samples of tap Lvater and the concentration of micro-organisms \vas < 10 cfu/mL. Available chlorine content of UF lvater u-as 0-0~06 ppm and zero in RO and distilled water. The micro-organism concentration was lO’-10’ cfu/ mL in 13 (68%) of the 19 samples of IJI: water, nine (53%) of the 17 samples of RO \\:atcr and 15 (79%) of the 19 samples of distilled \vater. ‘I’he majority of micro-organisms xvere non-fermentative bacteria such as Sphin,gomonas paucinzohilis and CDC g1-.1\~ C-2.
S. Oie et al.
64 Table
I.
Chlorine
content
Type of water (No. of sample tested)
arzd culture Chl orine bpm)
results
,No. of samples microorganisms (cfu/ml)
\‘ater from ultra-filtration system (19) Water reverse system
an
from a osmosis (17)
\Vater from distillation (19)
a water system
Tap
(10)
water
* Glucose
non-fermentative,
of various
10-100
types
of water
in
containing at a density of: 101-999
lo’-10’
2
9
2
0
8
6
1
2
0
4
3
10
2
0.17-0.42 Gram-negative
hospitals
Microorganisms
6
O-0.06
ten Japanese
Sphingomonas paucimohilis CDC gr.IV C-2 GNGB* Sphingomonas paucimobilis Moraxella spp GNGB Sphingomonus paucimobilis Burkholderia cepacia CDC gr.IV C-2 Acinetobactev junii/johnsonii
10 bacilli
Discussion
Previous work has shown that distilled water and deionized water produced in hospitals are susceptible to microbial contamination.‘*2 Infections have been described following their use.3-” Other reports have demonstrated contamination of disinfectants and water.‘-12 Microbial contamination of water used in hospitals, therefore, is an important cause of nosocomial infection. Many Japanese hospitals use UF or RO water instead of tap water for preoperative handwashing, despite the absence of studies showing the usefulness of such waters for this purpose. This study describes microbial contamination in these types of water. The micro-organism concentration in tap water (used as a control) was ~10 cfu/mL. Conversely, more than 50% of the samples of both UF and RO waters were contaminated with IO’-10’ cfu/mL. The ultra filtration system and the reverse osmosis system theoretically produce sterile water. All the systems examined in this study had an ultraviolet sterilization apparatus or anti-microbial beads containing iodine for preventing microbial contamination at the water collection site. Nevertheless, more than 50% of the samples produced using these systems showed microbial contamination. In Japan, health regulations state that tap water should contain 0.1 ppm or more available chlorine at the end of the water pipe. In this survey, all samples of tap water examined complied with this regulation and there was no microbial contamination observed. UF and RO waters produced from
Microbial
contamination
of water
65
this tap water contained little or no a\-ailable chlorine. ‘I‘his ma\- lx the main reason for the microbial contamination of L:F and RC) waters. ‘I’hcse results suggest that tap \wter is cleaner than I!I; or RO Lvaters as \vwtcr for preoperative handwashing, and far more economical. I>istilled \vater from ii water distillation system \vas also frcquentl~ contaminated with micro-organisms. In this system, vxter lucking a\~ailal>le chlorine after distillation is stored in the tank and thus becomes contaminated. This system should he LISC'~ \\-ith periodical disinfection and microbial csamination. References I
tierman
I,(;.
SO~I-ces
of the
slo\\
-grooving
plgmcnted
\vater
hactcria.
ffc,tr/tlr
IA/)
Sr-i
1076; 13: S-10. 2. I’ublic Health I,aboratory Service ctorking party. 1Iicrobial contamination of mcdicincs administered to hospital patients. I'~7lrcr~77r~c,lrti~~7/ J IO7 I ; July I B: ‘K-00. 3. Schaffner \\‘, Reisig (;. Vcrrall RX. Outbreak of Psrrrdo77rontrs c~ptrcitr infection duv to contaminated anaesthetics. I,trrrc.et1073; I: lOSO-1051. 4. Redding I’J. LIc\Talter I’\\‘. /‘.ssp~~do~~~o~~~~sfE~owsct~~/s cross-infection clue to c.ontamin;~tc.d hunlidifer \vatcr. fir !TIrtr’.y 1080; 280: 2.75. 5. (;oodison RR. I’.sr,r/tior//orltr.s cl-oss-infection clue to contalninatcd humidilicr \\II~CI-. ljr Alzrtl J 19x0; 281: 12xX. 0. Revcrdy RlI<, T;rencx J, I;lrurrttc J, C‘oulct 11, SuI-got \I, AIwrmct I), I’loton C‘. Nosocomial coloniz;ktic,n and infection t,! .-I[./7ro7rrohtrc.t(,~ \~~/oso.~itlrrr/s. J C’lirr .I/ic~r~d~io/ 10x-c; 19: 140-143.
contamination Japanese
of ‘sterile hospitals
water’
used
S. Oie”, M. Oomakij-, K. Yoriokat, T. Tatsumig, M. Amasakiyl, T. Fukudall, H. Hakuno **, K. Naganof-f-, M. Matsuda$$, N. Hirata@, N. Miyanoll, A. Kamiya”
in
62
S. Oie et al.
Figure
1. Japanese
ultra
filtration
system.
or a reverse osmosis system (RO water) set up in the operating room (Figure 1). Manufacturers advertise UF water or RO water as sterile but surveys of microbial contamination of such waters have not been performed. Therefore, we evaluated the microbial contamination of UF and RO waters used for preoperative handwashing and also that of water from a water distillation system set up in the hospital dispensary for the preparation of drugs. Materials
and
methods
Waters were examined from 10 hospitals in Yamaguchi Prefecture between February and April 1996. Nineteen samples of UF water were obtained from 19 machines (five types, five manufacturers), 17 samples of RO water from 17 machines (six types, six manufacturers) and 19 samples of distilled water from 19 machines (eight types, five manufacturers). One sample of tap water was obtained from each of the 10 hospitals. Each sample was collected after leaving the tap on for 3 min. Each sample was diluted IO’and 102-fold in nutrient broth; 0.2 mL of each dilution and of an undiluted sample were spread onto trypticase soy agar and Sabouraud’s dextrose agar. The plates were incubated at 30°C for 24-72 h (trypticase soy agar) or 25°C
Microbial Prefilter
contamination
of water
Ultra filteration
Water Ion-exhange resin
(b)
63
Active
carbon filter
tap
Reverse osmosis
Water tap Active
carbon filter
Ion-exchange resin
Distillation
Water
tank
I
I
Water I:igure
distillation
2(a)
;\lodel svstcrn.
tlo\v
of an ultra
tiltration
system;
(b)
re\‘erse
osmosis
system;
tap (c)
watcl
for two to seven days (Sabouraud’s dextrose agar). Colonies \vere counted and organisms identified by Gram-stain, morphology, OF test, cytochromc oxidase test and the ‘API’ system. I:igures 2(a)-(c) show model flows of the ultra filtration, reverse osmosis and water distillation systems respectively. :I\\;ailable chlorine was detcrmincd using a pH/ion meter F-24 (Horiba Co., ‘l’okyo) with Orion”’ rcs. chlorine electrode 977ORK (,4nalytical ‘I’echnology, Inc., Tokyo). Results
‘l‘ablc I shows the available chlorine content, degree of microbial contamination and most common micro-organisms isolated from each \vater type. Available chlorine content lvas 0.17-0.42 ppm in the 10 samples of tap Lvater and the concentration of micro-organisms \vas < 10 cfu/mL. Available chlorine content of UF lvater u-as 0-0~06 ppm and zero in RO and distilled water. The micro-organism concentration was lO’-10’ cfu/ mL in 13 (68%) of the 19 samples of IJI: water, nine (53%) of the 17 samples of RO \\:atcr and 15 (79%) of the 19 samples of distilled \vater. ‘I’he majority of micro-organisms xvere non-fermentative bacteria such as Sphin,gomonas paucinzohilis and CDC g1-.1\~ C-2.
S. Oie et al.
64 Table
I.
Chlorine
content
Type of water (No. of sample tested)
arzd culture Chl orine bpm)
results
,No. of samples microorganisms (cfu/ml)
\‘ater from ultra-filtration system (19) Water reverse system
an
from a osmosis (17)
\Vater from distillation (19)
a water system
Tap
(10)
water
* Glucose
non-fermentative,
of various
10-100
types
of water
in
containing at a density of: 101-999
lo’-10’
2
9
2
0
8
6
1
2
0
4
3
10
2
0.17-0.42 Gram-negative
hospitals
Microorganisms
6
O-0.06
ten Japanese
Sphingomonas paucimohilis CDC gr.IV C-2 GNGB* Sphingomonas paucimobilis Moraxella spp GNGB Sphingomonus paucimobilis Burkholderia cepacia CDC gr.IV C-2 Acinetobactev junii/johnsonii
10 bacilli
Discussion
Previous work has shown that distilled water and deionized water produced in hospitals are susceptible to microbial contamination.‘*2 Infections have been described following their use.3-” Other reports have demonstrated contamination of disinfectants and water.‘-12 Microbial contamination of water used in hospitals, therefore, is an important cause of nosocomial infection. Many Japanese hospitals use UF or RO water instead of tap water for preoperative handwashing, despite the absence of studies showing the usefulness of such waters for this purpose. This study describes microbial contamination in these types of water. The micro-organism concentration in tap water (used as a control) was ~10 cfu/mL. Conversely, more than 50% of the samples of both UF and RO waters were contaminated with IO’-10’ cfu/mL. The ultra filtration system and the reverse osmosis system theoretically produce sterile water. All the systems examined in this study had an ultraviolet sterilization apparatus or anti-microbial beads containing iodine for preventing microbial contamination at the water collection site. Nevertheless, more than 50% of the samples produced using these systems showed microbial contamination. In Japan, health regulations state that tap water should contain 0.1 ppm or more available chlorine at the end of the water pipe. In this survey, all samples of tap water examined complied with this regulation and there was no microbial contamination observed. UF and RO waters produced from
Microbial
contamination
of water
65
this tap water contained little or no a\-ailable chlorine. ‘I‘his ma\- lx the main reason for the microbial contamination of L:F and RC) waters. ‘I’hcse results suggest that tap \wter is cleaner than I!I; or RO Lvaters as \vwtcr for preoperative handwashing, and far more economical. I>istilled \vater from ii water distillation system \vas also frcquentl~ contaminated with micro-organisms. In this system, vxter lucking a\~ailal>le chlorine after distillation is stored in the tank and thus becomes contaminated. This system should he LISC'~ \\-ith periodical disinfection and microbial csamination. References I
tierman
I,(;.
SO~I-ces
of the
slo\\
-grooving
plgmcnted
\vater
hactcria.
ffc,tr/tlr
IA/)
Sr-i
1076; 13: S-10. 2. I’ublic Health I,aboratory Service ctorking party. 1Iicrobial contamination of mcdicincs administered to hospital patients. I'~7lrcr~77r~c,lrti~~7/ J IO7 I ; July I B: ‘K-00. 3. Schaffner \\‘, Reisig (;. Vcrrall RX. Outbreak of Psrrrdo77rontrs c~ptrcitr infection duv to contaminated anaesthetics. I,trrrc.et1073; I: lOSO-1051. 4. Redding I’J. LIc\Talter I’\\‘. /‘.ssp~~do~~~o~~~~sfE~owsct~~/s cross-infection clue to c.ontamin;~tc.d hunlidifer \vatcr. fir !TIrtr’.y 1080; 280: 2.75. 5. (;oodison RR. I’.sr,r/tior//orltr.s cl-oss-infection clue to contalninatcd humidilicr \\II~CI-. ljr Alzrtl J 19x0; 281: 12xX. 0. Revcrdy RlI<, T;rencx J, I;lrurrttc J, C‘oulct 11, SuI-got \I, AIwrmct I), I’loton C‘. Nosocomial coloniz;ktic,n and infection t,! .-I[./7ro7rrohtrc.t(,~ \~~/oso.~itlrrr/s. J C’lirr .I/ic~r~d~io/ 10x-c; 19: 140-143.