The killing of bacteria on metallic copper surfaces in minutes to hours is referred to as contact killing. Why copper possesses such strong antimicrobial activity has remained enigmatic. Based on the physicochemical properties of metals, it was recently predicted that cadmium should also be active in contact killing [Hans et al., Biointerphases 11, 018902 (2010)]. Here, the authors show that cadmium is indeed antimicrobial. It kills three logs of bacteria in 9 h, compared to copper which kills eight logs of bacteria. Metallic silver kills less than one log of bacteria in 9 h. These findings support the novel concept whereby oxide formation, metal ion dissolution, and a Pearson soft character are the key factors for a metal to be antibacterial. Based on these parameters, copper and cadmium are expected to be the two most antibacterial metals.

1.
J. O.
Noyce
,
H.
Michels
, and
C. W.
Keevil
,
Appl. Environ. Microbiol.
72
,
4239
(
2006
).
2.
G.
Grass
,
C.
Rensing
, and
M.
Solioz
,
Appl. Environ. Microbiol.
77
,
1541
(
2011
).
3.
C. D.
Sifri
,
G. H.
Burke
, and
K. B.
Enfield
,
Am. J. Infect. Control
44
,
1565
(
2016
).
4.
M. G.
Schmidt
,
B.
von Dessauer
,
C.
Benavente
,
D.
Benadof
,
P.
Cifuentes
,
A.
Elgueta
,
C.
Duran
, and
M. S.
Navarrete
,
Am. J. Infect. Control
44
,
203
(
2016
).
5.
J.
Inkinen
,
R.
Makinen
,
M. M.
Keinanen-Toivola
,
K.
Nordstrom
, and
M.
Ahonen
,
Lett. Appl. Microbiol.
64
,
19
(
2017
).
6.
H. T.
Michels
,
C. W.
Keevil
,
C. D.
Salgado
, and
M. G.
Schmidt
,
Health Environ. Res. Design J.
9
,
64
(
2015
).
7.
C. D.
Salgado
,
K. A.
Sepkowitz
,
J. F.
John
,
J. R.
Cantey
,
H. H.
Attaway
,
K. D.
Freeman
,
P. A.
Sharpe
,
H. T.
Michels
, and
M. G.
Schmidt
,
Infect. Control Hosp. Epidemiol.
34
,
479
(
2013
).
8.
C.
Espirito Santo
,
N.
Taudte
,
D. H.
Nies
, and
G.
Grass
,
Appl. Environ. Microbiol.
74
,
977
(
2008
).
9.
C.
Molteni
,
H. K.
Abicht
, and
M.
Solioz
,
Appl. Environ. Microbiol.
76
,
4099
(
2010
).
10.
J.
Elguindi
,
J.
Wagner
, and
C.
Rensing
,
J. Appl. Microbiol.
106
,
1448
(
2009
).
11.
S. L.
Warnes
,
V.
Caves
, and
C. W.
Keevil
,
Environ. Microbiol.
14
,
1730
(
2012
).
12.
S.
Mathews
,
M.
Hans
,
F.
Mücklich
, and
M.
Solioz
,
Appl. Environ. Microbiol.
79
,
2605
(
2013
).
13.
J. L.
Hobman
and
L.
Crossman
,
J. Med. Microbiol.
64
,
471
(
2015
).
14.
15.
S.
Silver
and
L. T.
Phung
,
Annu. Rev. Microbiol.
50
,
753
(
1996
).
16.
L.
Zhu
,
J.
Elguindi
,
C.
Rensing
, and
S.
Ravishankar
,
Food Microbiol.
30
,
303
(
2012
).
17.
M.
Hans
,
S.
Mathews
,
F.
Mücklich
, and
M.
Solioz
,
Biointerphases
11
,
018902
(
2016
).
18.
F. F.
Xu
and
J. A.
Imlay
,
Appl. Environ. Microbiol.
78
,
3614
(
2012
).
19.
G.
Nucifora
,
L.
Chu
,
T. K.
Misra
, and
S.
Silver
,
Proc. Natl. Acad. Sci. U. S. A.
86
,
3544
(
1989
).
20.
J.
Luevano
and
C.
Damodaran
,
J. Environ. Pathol. Toxicol. Oncol.
33
,
183
(
2014
).
21.
X.
Wu
,
S. J.
Cobbina
,
G.
Mao
,
H.
Xu
,
Z.
Zhang
, and
L.
Yang
,
Environ. Sci. Pollut. Res. Int.
23
,
8244
(
2016
).
22.
O.
Faroon
,
A.
Ashizawa
,
S.
Wright
,
P.
Tucker
,
K.
Jenkins
,
L.
Ingeman
, and
C.
Rudisill
,
Toxicological Properties of Cadmium
(
Agency for Toxic Substances and Disease Registry
,
Atlanta, GA
,
2012
).
23.
B.
Yousuf
,
J. J.
Ahire
, and
L. M.
Dicks
,
Appl. Microbiol. Biotechnol.
100
,
5569
(
2016
).
24.
C.
Espirito Santo
,
E. W.
Lam
,
C. G.
Elowsky
,
D.
Quaranta
,
D. W.
Domaille
,
C. J.
Chang
, and
G.
Grass
,
Appl. Environ. Microbiol.
77
,
794
(
2011
).
25.
J. O.
Noyce
,
H.
Michels
, and
C. W.
Keevil
,
J. Hosp. Infect.
63
,
289
(
2006
).
26.
H. K.
Abicht
,
Y.
Gonskikh
,
S. D.
Gerber
, and
M.
Solioz
,
Microbiology
159
,
1190
(
2013
).
27.
D. B.
McPhail
and
B. A.
Goodman
,
Biochem. J.
221
,
559
(
1984
).
28.
P.
Bleichert
,
S. C.
Espirito
,
M.
Hanczaruk
,
H.
Meyer
, and
G.
Grass
,
Biometals
27
,
1179
(
2014
).
29.
S.
Mehtar
,
I.
Wiid
, and
S. D.
Todorov
,
J. Hosp. Infect.
68
,
45
(
2008
).
30.
H. I.
Cervantes
,
J. A.
Alvarez
,
J. M.
Munoz
,
V.
Arreguin
,
J. L.
Mosqueda
, and
A. E.
Macias
,
Am. J. Infect. Control
41
,
e115
(
2013
).
31.
M.
Sokolowska
and
W.
Bal
,
J. Inorg. Biochem.
99
,
1653
(
2005
).
32.
M.
Hans
,
A.
Erbe
,
S.
Mathews
,
Y.
Chen
,
M.
Solioz
, and
F.
Mücklich
,
Langmuir
29
,
16160
(
2013
).
33.
L.
Macomber
and
J. A.
Imlay
,
Proc. Natl. Acad. Sci. U. S. A.
106
,
8344
(
2009
).
34.
T. P.
Dirkse
,
IUPAC
23
,
286
(
1986
).
35.
J.
Gibbard
,
Am. J. Public Health Nat. Health
27
,
112
(
1937
).
36.
R.
Rebelo
,
N. K.
Manninen
,
L.
Fialho
,
M.
Henriques
, and
S.
Carvalho
,
Appl. Surf. Sci.
371
,
1
(
2016
).
37.
G.
Franci
,
A.
Falanga
,
S.
Galdiero
,
L.
Palomba
,
M.
Rai
,
G.
Morelli
, and
M.
Galdiero
,
Molecules
20
,
8856
(
2015
).
38.
H.
Kawakami
,
K.
Yoshida
,
Y.
Nishida
,
Y.
Kikuchi
, and
Y.
Sato
,
ISIJ Int.
48
,
1299
(
2008
).
39.
Y.
Kampmann
,
E.
De Clerck
,
S.
Kohn
,
D. K.
Patchala
,
R.
Langerock
, and
J.
Kreyenschmidt
,
J. Appl. Microbiol.
104
,
1808
(
2008
).
40.
M. B.
McNeil
and
B. J.
Little
,
J. Am. Inst. Conserv.
31
,
355
(
1992
).
41.
W. J.
Tomlinson
,
S.
Campbell
, and
S.
Carr
,
J. Mater. Sci. Lett.
4
,
715
(
1985
).
42.
M.
Pourbaix
,
Atlas of Electrochemical Equilibria in Aqueous Solutions
(
NACE: National Association of Corrosion Engineers
,
Houston
,
1974
).
43.
R. G.
Pearson
,
J. Chem. Educ.
45
,
581
(
1968
).
44.
W.
Feitknecht
and
P.
Schindler
,
Pure Appl. Chem.
6
,
125
(
1963
).
You do not currently have access to this content.