National Salmonella Reference Laboratory of Ireland
Annual Report for 2008
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NATIONAL SALMONELLA REFERENCE LABORATORY
1
Introduction
The National Salmonella Reference Laboratory was established in 2000 with
support from the Department of Health and Children to provide reference
services related to human health.
time scientific staff.
It is a public service laboratory with 3 full
It operates from the Department of Bacteriology at the
Clinical Science Institute, NUIGalway.
http://www.nuigalway.ie/salmonella_lab/.
The NSRL website is at
The reference laboratory uses a
number of phenotypic methods (serotyping, antibiotic-resistance testing and
phage typing) and molecular methods ( pulse-field gel electrophoresis (PFGE)
and multi-locus variable number tandem repeat analysis (MLVA) ) to precisely
characterise Salmonella isolates.
This process can be considered as genetic
fingerprinting of Salmonella. The goal of this genetic fingerprinting is to assist
relevant agencies in protecting public health by identifying and interrupting
chains of transmission of Salmonella infection. In addition the NSRL provides
typing services for Shigella species and Listeria monocytogenes.
The Laboratory is committed to providing a high quality and timely service and
has conditional accreditation from Clinical Pathology Accreditation (UK). The
continued success of the laboratory is entirely dependent on the support of the
staff in the laboratories that submit isolates for typing. My colleagues and I
appreciate that the preparation, packing and dispatch of isolates is a significant
burden and would like to thank you for your support over the years.
I would also like to acknowledge the support of all those agencies with whom we
work closely to ensure that the service we provide works as information for
action. In particular I would like to thank the Food Safety Authority of Ireland,
the Health Protection Surveillance Centre and colleagues in Public Health
Departments and Environmental Health Departments throughout the country
and to acknowledge the work of colleagues in the National Reference Laboratory
Salmonella (Food, Feed and Animal Health)1.
2
If you have any comments or questions arising from the report please feel free to
contact me at the email address given below.
Martin Cormican
Director National Salmonella Reference Laboratory
martin.cormican@hse.ie
1. The Annual Report of National Reference Laboratory Salmonella (Food, Feed
and Animal Health is available at
http://www.agriculture.gov.ie/media/migration/animalhealthwelfare/labservice/n
rl/NRL%20Salmonella%20Annual%20Report%202008.pdf
3
Ireland
In 2008, 1402 isolates were submitted to the National Salmonella Reference
Laboratory. When non-Salmonella, QC contaminants and duplicate isolates were
removed a total of 1262 Salmonella isolates were typed. This represents a 14 %
increase in the number of isolates received in 2007.
There were 447 human clinical isolates, including 14 blood (incl. 3 S.Typhi, 4
S.Paratyphi A and 3 S.Virchow), 7 other invasive isolates (incl. 2 S.Enteritidis) and 1
from unknown site. Among the faecal isolates (n = 425) S.Typhimurium (n = 135)
and S.Enteritidis (n = 120) predominated (Table 2). There was marked seasonal
variation with the highest number of isolates occurring in months June to October.
This coincides with the warmer months of the year and with the peak season for
foreign travel (Fig.1) and may be related in part to one or both of these factors.
In some cases more than one isolate was received from a patient.
For example we
may have received an invasive isolate (e.g. from a blood culture) and an isolate from
faeces of the same patient. Where an invasive and faecal isolates from the same
patient, only the invasive isolate is recorded to avoid duplication. The average
turnaround time for testing was 5 days (range 1-41 days). There was a 2.5% decrease
in the number of Salmonella isolates from humans received in the NSRL compared
with 2007 (Table 1).
Table 1:
Number of Salmonella isolates received in NSRL
Year Human
Non-human
2008
447
815
2007
457
653
2006
430
308
2005
357
494
2004
420
650
2003
486
634
2002
394
540
4
2001
508
574
2000
636
214
Table 2:
Top sixteen serotypes of Human Isolates (inc typhoidal)
Serotype
Frequency
%*
Typhimurium
139
31
Enteritidis
122
27
Agona
13
3
Virchow
10
2
Worthington
7
1.5
Panama
7
1.5
Java
7
1.5
Newport
6
1.3
Kentucky
6
1.3
Bredeney
6
1.3
Hadar
6
1.3
Paratyphi A
6
1.3
Typhi
5
1
Infantis
5
1
Javiana
5
1
Saintpaul
5
1
Others
92
21
Total
447
100
* Approximate figures
5
Figure 1
80
70
60
50
40
30
20
10
0
Seasonal Variation in Salmonella isolates
Enteritidis
Typhimurium
All Salmonella
Foreign travel
Jan Feb Mar Apr
May
JunJuly Aug Sep Oct
Nov Dec
It is important to note that there is always an interval gap between the time of onset of
symptoms and date of isolate receipt in the NSRL. This includes time taken for
patient to access doctor, taking and transporting the sample to the primary laboratory,
isolation of Salmonella, and referral to NSRL.
Salmonellosis non-typhoidal
S.Typhimurium
S.Typhimurium accounted for 31% of all cases of Salmonella. Phage types DT104
and DT104b each accounted for 20% and DT193 accounted for 13% of the total
number of S.Typhimurium isolates.
The predominance of phage type DT104 and
related phage types is similar to recent years.
S.Enteritidis
S.Enteritidis accounted for 27% of all cases of Salmonella. The predominant phage
types were PT1 (19%), PT4 (18 %), PT21 (18%), PT8 (11%), PT14b (9%), and PT6
(7%). The pattern of predominant phage types is similar to previous years.
6
Salmonellosis Typhi and Paratyphi
Five isolates of S.Typhi, 6 isolates of S.Paratyphi A and 1 isolate of S.Paratyphi B
were received. A history of recent travel was recorded for 4 of the S.Typhi isolates; 3
to the Indian subcontinent and 1 to Nigeria. Four of the S.Paratyphi A isolates were
associated with reported travel to the Indian subcontinent, 1 with travel to Tasmania
and 1 to Indonesia. A history of travel to South America (country not stated) was
recorded for the S.Paratyphi B isolate.
Antimicrobial resistance
Fifty-six percent of isolates were susceptible to all antimicrobial agents tested.
Twenty-five percent of isolates were multi-drug resistant (four or more antibiotics).
Of the 25% of multi-drug resistant isolates, 47% had the profile of resistance to
ampicillin, chloramphenicol, streptomycin, sulphonamide and tetracycline (ACSSuT)
and were mainly S.Typhimurium DT104 or closely related phage types. This group
of S. Typhimurium DT104 has accounted for a high proportion of multidrug-resistant
Salmonella isolates for some years now.
Five extended spectrum beta-lactamase (ESBL) producing isolates were detected.
These included 3 S.Worthington isolates associated with an outbreak in a nursing
home; a S.Enteritidis PT1 isolate associated with recent travel to Portugal and an
S.Concord isolate with a CTX-M-group 1 ESBL from a child adopted from Ethiopia.
The association of ESBL producing S. Concord with children adopted from Ethiopia
has been noted in a number of countries and a report of an international collaborative
study on this phenomenon in which NSRL participated with be published shortly.
Two isolates of Salmonella resistant to ciprofloxacin were detected. There was no
report of foreign travel with either isolate. In addition 68 isolates resistant to nalidixic
acid and with reduced susceptibility to ciprofloxacin were detected; an increase from
47 in 2007.
Travel related infection
A history of recent foreign travel was recorded in 35% (155) of human cases of
infection (Table 3).
Spain was the most commonly recorded travel destination
7
(recorded in 24 cases) with S. Enteritidis (n = 12) and S. Typhimurium (n = 8)
accounting for the majority of these cases. More than half (53%) of S.Enteritidis
isolates were associated with foreign travel compared to 24% for S.Typhimurium.
Although NSRL does not have access to data on the number of Irish people who
travel to each country it is likely that the number of cases associated with each
country is at least in part accounted for by the popularity of the country as a holiday
destination.
Table 3:
Foreign travel history
Continent
Country
Number
Europe (n = 75)
Spain
24
Portugal
11
Greece
8
Turkey
8
Italy
7
France
6
Poland
3
England
2
Lithuania
2
Azores
1
Bulgaria
1
Czech Republic
1
Russia
1
Africa (n = 31)
Egypt
11
Morocco
4
Tunisia
4
8
Gambia
2
Nigeria
2
Tanzania/Zanzibar
2
S.Africa
1
Kenya
1
Ethiopia
1
Zambia
1
Africa *
2
Australasia (n = 35)
Thailand
12
India
10
Malaysia
3
Australia
2
Pakistan
2
Philippines
2
Cambodia
1
Indonesia
1
Maldives
1
Asia*
1
Americas (n = 12)
USA
4
Barbados
3
Cuba
2
Brazil
1
Costa Rica
1
Dominican Republic 1
S.America*
1
1 Unknown
* Country not stated
9
Clusters
Twenty-nine clusters of cases involving 90 isolates were identified in 2008.
S.Typhimurium was involved in 17 clusters while S.Enteritidis was implicated in 3
clusters.
Seven of the clusters were family outbreaks while 5 outbreaks were associated with
foreign travel. There was an outbreak of antibiotic resistant S.Worthington in a
nursing home which became apparent when NSRL identified two isolates of this rare
serovar from residents in the facility. The outbreak was investigated and resolved by
relevant agencies with microbiological support from NSRL.
In July of 2008 the NSRL alerted revelant national agencies to a cluster of human
cases of S. Agona.
The alert lead to a multi-country outbreak investigation.
The
outbreak strain S.Agona PT39 (PFGE pattern SAGOXB.0066) was detected in 11
patients from different parts of Ireland. In total more than 160 cases were identified
throughout the United Kingdom and Ireland with cases also detected in 5 other
European countries.
S. Agona indistinguishable from the strain associated with the
human cases was detected in food products and in the environment of a food
processing plant.
The outbreak was terminated following withdrawal of implicated
products.
The NSRL liaises with the European Centre for Disease Control (ECDC) in the
investigation of outbreaks that may have an international dimension. The UK declared
an outbreak of S.Typhimurium DT191a, resistant to tetracycline and with MLVA
profile 01-04-02-14-03 involving more than 100 isolates since August 2008. A case
control study showed a strong association with reptile contact, especially snakes. The
NSRL has documented 4 of these strains since July 2008 but none had a reported
history of reptile contact, though one had travel history to Spain.
The NSRL also typed a S.Napoli (S08-1180) isolate which had an indistinguishable
PFGE profile to that of a S.Napoli outbreak linked to ruccola salad from Italy. The
patient had a history of travel to Spain.
10
Evidence of Links between S. Typhimurium in Humans, Food and Food
Animals.
Multi locus variable number tandem repeat analysis (MLVA) is a new technology that
allows for very fine discrimination between isolates that appear very closely related
by other methods including PFGE. This precise discrimination has proved a useful
technique in showing persuasive evidence of links between human S.Typhimurium
clusters and individual cases and recent food and animals sources.
Table 4 illustrates
evidence of links between human infection and food /food animal types.
In some
cases the link is complete from animal, to animal related food product and to human
cases.
The importance of using standardised and readily comparable methods for
“fingerprinting” human, food and animal isolates of Salmonella not just within Ireland
but across Europe and the world is illustrated by this body of work over the past year.
Table 4
MLVA profiles of human and food/animal isolates
Isolate no.
Source
Phage type
Resistance
MLVA profile
S08-1082
Bovine
DT104
ACSSuT
02-06-10-05-03
S08-1147
Bovine
DT104
ACSSuT
02-06-10-05-03
S08-1154
Bovine
DT104
ACSSuT
02-06-10-05-03
S08-1155
Bovine
DT104
ACSSuT
02-06-10-05-03
S08-0155
Human
DT104
ACSSuT
02-06-10-05-03
S08-0158
Human
DT104
ACSSuT
02-06-10-05-03
S08-0159
Human
DT104
ACSSuT
02-06-10-05-03
S08-0544
Human
DT104
ACSSuT
02-06-10-05-03
S08-0839
Swine
DT104b
SSu
02-07-00-03-03
S08-1067
Human
DT104b
ACSSuTTm 02-07-00-03-03
S08-1091
Human
DT104b
ACSSuTTm 02-07-00-03-03
S08-0436
Bovine
Rough:i:2*
ACSSuT
02-07-03-21-03
11
S08-0370
Human
DT104b
ACSSuT
02-07-03-21-03
S08-0341
Bovine
DT104
ACSSuT
02-07-09-05-03
S08-0342
Bovine
DT104
ACSSuT
02-07-09-05-03
S08-0343
Bovine
DT104
ACSSuT
02-07-09-05-03
S08-0337
Human
DT104
ACSSuT
02-07-09-05-03
S08-0369
Human
DT104
ACSSuT
02-07-09-05-03
S08-0746
Poultry
DT104
ACSSuT
02-07-10-04-03
S08-0163
Human
DT104
ACSSuT
02-07-10-04-03
S08-0188
Pork sausages
DT104
ACSSuT
02-07-11-04-03
S08-0189
Pork sausages
DT104
ACSSuT
02-07-11-04-03
S08-0359
Swine faeces
DT104
ACSSuT
02-07-11-04-03
S08-0603
Human
DT104
ACSSuT
02-07-11-04-03
S08-0821
Human
DT104
ACSSuT
02-07-11-04-03
S08-0943
Human
DT12
ACSSuT
02-07-11-04-03
S08-0663
Bovine
DT104
ACSSuT
02-07-11-05-03
S08-0488
Human
DT104
ACSSuT
02-07-11-05-03
S08-0358
Swine faeces
DT104
ACSSuT
02-07-13-04-03
S08-0186
Human
DT104
ACSSuT
02-07-13-04-03
S08-0310
Raw sausage
DT104b
ACSSuT
02-07-19-05-03
S08-1308
Swine carcase
DT104b
ACSSuTTm 02-07-19-05-03
S08-0269
Human
DT104b
ACSSuT
02-07-19-05-03
S08-0224
Swine
DT12*
ACSSuT
02-08-03-03-03
S08-0227
Swine
DT12
ACSSuT
02-08-03-03-03
S08-0229
Swine
DT12
ACSSuT
02-08-03-03-03
S08-0801
Swine
DT104b
ACSSuTTm 02-08-03-03-03
S08-0339
Human
DT104b
ACSSuT
S08-0826
Human
DT104b
ACSSuTTm 02-08-03-03-03
02-08-03-03-03
12
S08-0860
Human
DT104b
ACSSuTTm 02-08-03-03-03
S08-0905
Human
DT104b
ACSSuTTm 02-08-03-03-03
S08-0911
Human
DT104b
ACSSuTTm 02-08-03-03-03
S08-0918
Human
DT104b
ACSSuTTm 02-08-03-03-03
S08-1142
Human
DT104b
ACSSuT
02-08-03-03-03
S08-1184
Human
DT104b
ACSSuT
02-08-03-03-03
S08-1327
Human
DT104b
ACSSuT
02-08-03-03-03
S08-0448
Raw sausage
DT104b
ACSSuT
02-08-03-04-03
S08-0823
Human
DT104b
ACSSuTTm 02-08-03-04-03
S08-0207
Pig liver
DT104
ACSSuT
02-08-03-05-03
S08-1295
Human
U302*
ACSSuT
02-08-03-05-03
S08-0416
Raw sausage
DT193
ACSSuTTm 04-11-06-00-02
S08-0417
Raw sausage
DT193
ACSSuTTm 04-11-06-00-02
S08-0414
Human
DT193
ACSSuTTm 04-11-06-00-02
S08-0438
Human
DT193
ACSSuTTm 04-11-06-00-02
S08-0062
Pork sausage
DT193
ACSSuTTm 04-15-05-13-02
S08-0379
Human
DT193
ACSSuTTm 04-15-05-13-02
*
DT104, DT104b, DT12 and U302 are closely related phage types.
*
Rough:i:2
Isolate has mutation resulting in poorly expressed O antigen
genes. Not possible to phage type but H antigens indicative of S.Typhimurium.
13
Animal Contact
A history of animal contact was recorded for 44 patients with salmonellosis including
contact with turtles, lizards, fish, dogs and farm animals (Table 5). Strong links
included isolates of Salmonella subspecies IV 44:z44,z23 in 2 patients that had
contact with lizards; a subsp. IIIb 48:i:z from a patient with pet reptiles; and a
S.Pomona from an infant who had contact with turtles.
Table 5:
Animal contact history
NSRL no.
Sub1. Strain
Animal Contact
S08-0020
I
Typhimurium DT104
Birds, Turtles, Dog
S08-0113
I
Infantis
Turtles
S08-0155
I
Typhimurium DT104
Dog
S08-0158
I
Typhimurium DT104
Dog
S08-0159
I
Typhimurium DT104
Dog
S08-0163
I
Typhimurium DT104
Horses, cattle
S08-0164
I
Typhimurium DT104
Cattle, sheep
S08-0166
I
Thompson
Turtles
S08-0186
I
Typhimurium DT104
Farm visit; Sheep, cattle, dogs
S08-0261
I
Typhimurium U302
Pigs, cattle, ponies, dog
S08-0262
I
Java
Tropical fish, lovebird, dog
S08-0277
I
Bredeney
Dog
S08-0309
I
Typhimurium DT104b
Cattle
S08-0336
I
4,5,12:i:- DT193
Dog, goldfish, visited petshop
S08-0337
I
Typhimurium DT104
Farm- Cattle, sheep, dogs
S08-0344
I
Pomona
Turtles
S08-0369
I
Typhimurium DT104
Farm- Cattle, sheep, dogs
S08-0370
I
Typhimurium DT104b
Cow on farm had Salmonella
S08-0453
I
Infantis
Terrapins, reptiles
14
S08-0470
IIIb
48:i:z
Reptiles, Exotic rodents
S08-0479
I
Enteritidis PT21
Cat, dog
S08-0488
I
Typhimurium DT104
Hens, rabbits
S08-0545
I
Enteritidis PT14b
Dog
S08-0566
I
Anatum
Cat
S08-0571
I
Virchow
Dog
S08-0572
I
Typhimurium DT193
Turtles
S08-0587
I
Worthington
Dog
S08-0613
I
Enteritidis PT1
Cattle
S08-0634
I
Litchfield
Terrapins, cold water fish, dogs
S08-0635
I
Typhimurium DT191A
Raw chicken
S08-0651
I
Typhimurium DT104
Cold water fish, cats, dogs
S08-0683
I
Typhimurium DT104b
Cats, dogs
S08-0775
I
Enteritidis PT4
Dog
S08-0858
I
Hadar
Lives on farm
S08-0882
I
Typhimurium
Dog
S08-0953
I
Kumasi
Reptile
S08-1035
I
4,5,12:i:- DT195
Fish
S08-1047
I
Enteritidis PT6
Dog
S08-1145
IV
44:z4,z23:-
Lizard
S08-1226
I
Typhimurium DT104
Farm animal Salmonella positive
S08-1327
I
Typhimurium DT104b
Greyhounds, turtles
S08-1328
IV
44:z4,z23:-
Lizard
1. Sub = Subspecies. There are over 2500 Salmonella serotypes of which approximately 60% belong
to subspecies I. These account for about 99% of human infections. Subspecies I is present in both warm
and cold blooded animals while the other Salmonella subspecies are generally associated with coldblooded animals.
15
Non-Human isolates
In 2008, 815 isolates of Salmonella of non-human origin were submitted to the
NSRL. This represents an increase of 25% in the number of non-human isolates
received. The majority of isolates were from poultry (n = 405) and swine (n = 254)
while there were 44 isolates from bovine sources. S.Typhimurium (n = 234) and
S.Kentucky (n = 290) were the most prevalent serovars.
Table 6
Top fifteen serotypes among non-human isolates
Serotype
Frequency
%*
Kentucky
290
36
Typhimurium
234
29
Mbandaka
68
8
Agona
31
4
Indiana
29
3.5
Tennessee
19
2.5
Derby
18
2.5
Virchow
18
2.5
Dublin
11
1.5
London
10
1.5
Minnesota
9
1
Enteritidis
9
1
Give
8
1
Kottbus
8
1
Senftenberg
6
1
48
6
Others
Total
815
100
* Approximate figures
16
Salmonella serotypes and correlation with Human Infection
S.Typhimurium
S.Typhimurium accounted for 29% of all non-human isolates and were isolated from
a variety of sources predominantly swine (n = 199) but also including bovine (n = 23)
and poultry (n = 7) sources. Phage types DT104b (n = 47), DT193 (n = 39), DT104
(n = 22), U302/U302var (n = 25), DT12 (n = 15), U310 (n = 10) and Untypable (n =
10) were the most common phage types from swine. Phage types DT104 (n = 10),
Untypable (n = 5) and DT104b (n = 4) were the most common phage types among
bovine isolates. As illustrated in table 4 (above) there is evidence from molecular
typing of a significant link between isolates from pigs and pig products and human
infection. As previously indicated a history of travel outside of Ireland is reported in
only 24% of cases of S. Typhimurium.
Salmonella Enteritidis.
S.Enteritidis PT4 isolates were received from poultry house swabs (n = 4) and egg
shell (n = 1). It is of interest that S. Enteritidis is rarely detected from poultry or
poultry products in Ireland but that S. Enteritidis is the second most common serovar
isolated from human infections. In this context it is worth noting that a history of
travel outside of Ireland is reported in relation to 53% of cases S. Enteritidis compared
with only 24% of S. Typhimurium.
Sources of Isolates
Swine
A total of 13 serovars accounted for the 254 isolates received from swine with
S.Typhimurium (n = 199) accounting for the majority of isolates.
Poultry
A total of 406 isolates comprising 16 serovars were received from poultry sources. S.
Kentucky was the most common serovar (n = 281) and most isolates were susceptible
to all antimicrobial agents tested. Four of 6 human isolates of S.Kentucky referred to
the NSRL were fully susceptible while a multi-resistant isolate was associated with
17
foreign travel to Africa. Some of the S.Kentucky isolates from humans had pulsed
field profiles (PFPs) that were indistinguishable from those of some poultry isolates.
Other common serovars from poultry sources include S.Indiana (n = 29; no human
cases), S.Tennessee (n = 18; 1 human case) and S.Virchow (n = 16; 10 human cases).
Bovine
A total of 44 isolates were received from bovine sources. S.Typhimurium accounted
for the majority of isolates (n = 23) while there were also S.Dublin (n = 8; 3 human
cases) and S.Agona (n = 5) isolates.
Antimicrobial Resistance
Fifty-seven percent of isolates were susceptible to all antimicrobial agents tested.
Twenty-four percent were multi-drug resistant (four or more antibiotics). Ten percent
of isolates had the profile of resistance to ampicillin, chloramphenicol, streptomycin,
sulphonamide and tetracycline (ACSSuT) and most of these typed as S.Typhimurium
DT104 or closely related phage types.
Resistant to third generation cephalosporins was identified in two S. Kentucky isolates
from poultry received in the latter part of 2008. These included a CMY-2 plasmidmediated AmpC producer (S08-1060) and an SHV-12 ESBL-producer (S08-1259).
This is the first report of third generation cephalosporin resistance in Salmonella from
food animals in Ireland and is a cause of concern.
None of the isolates were resistant to ciprofloxacin; however 28 isolates exhibited
resistance to nalidixic acid and reduced susceptibility to ciprofloxacin.
Laboratory Contamination
False-positive Salmonella results due to laboratory cross-contamination are a serious
problem for laboratories and can be difficult to detect. Corss contamination in a
laboratory can result in inappropriate diagnosis of patient infection or in unfounded
concerns regarding the safety of a food product. Detailed subtyping of isolates by the
NSRL helps in detection and confirmation of laboratory contamination incidents
(Role of Subtyping in Detecting Salmonella Cross Contamination in the Laboratory;
BMC Microbiology: In press). The NSRL recognised 9 such incidents (14 isolates)
18
with Salmonella in 2008 with 4 of the incidents involving the laboratory positive
control strain, S.Nottingham, and 5 incidents involving test isolates. Most of the
incidents involved food laboratories with just 1 incident recorded for a human clinical
sample.
Other Testing:
Listeria monocytogenes
Fig. 2 Dendrogram of L.monocytogenes 4b isolates digested with ApaI
Dice (Opt:0.50%) (Tol 1.5%-1.5%) (H>0.0% S>0.0%) [0.0%-100.0%]
PFGE-ApaI
100
90
92
94
PFGE-ApaI
96
98
88
86
L08-005
.Placenta
.
.
4b
L08-007
.Blood
.
culture
.
4b
L08-003
.Blood
.
culture
.
4b
L08-004
.Blood
.
culture
.
4b
L08-011/#1
.CSF
.
.
4b
L08-014
.Blood
.
culture
.
4b
L08-002
.Blood
.
culture
.
4b
L08-025
.Blood
.
culture
.
4b
L08-006
.Blood
.
culture
.
4b
The NSRL received 27 Listeria monocytogenes isolates in 2008. These included 14
human clinical isolates; 12 from blood cultures, 1 from CSF and 1 from placenta.
Nine of the isolates typed as serotype 4b while 5 typed as serotype 1/2. Pulsed field
gel electrophoresis (PFGE) with ApaI showed 3 separate clusters; (a) two isolates
L08-005 (placenta) and L08-007 (blood) from the same hospital; (b) two isolates L08002 (blood) and L08-025 (blood) isolated 10 months apart from different parts of the
country; (c) and two isolates L08-004 (blood) and L08-011 (CSF) 4 months apart
from different parts of the country. These isolates which appeared related on digestion
with ApaI also appeared related on digestion with a second enzyme, AscI.
Comparison of the 2008 ApaI patterns with those from other years showed that there
were some instances of matches with isolates from previous years.
19
There is no indication from the molecular typing of any connection between the
human serotype 1/2 cases and it is likely that they represent isolated sporadic cases.
The majority of the food isolates serotyped as 1/2 (n =12), while 1 isolate was
untypable.
Shigella species
Fig. 3
Dendrogram of PFGE of S.sonnei digested with XbaI
Dice (Opt:0.50%) (Tol 1.5%-1.5%) (H>0.0% S>0.0%) [0.0%-98.3%]
PFGE-XbaI
80
PFGE-XbaI
82
84
86
88
90
92
94
96
98
100
SH08-034
SH08-039
SH08-017
SH08-049
SH08-018
SH08-019
SH08-035
SH08-020
SH08-015
SH08-033
SH08-014
SH08-032
SH08-007
SH08-008
SH08-002
SH08-003
SH08-004
SH08-006
SH08-009
SH08-010
SH08-045
A total of 50 isolates were referred to the NSRL in 2008 for Shigella typing. When
non-Shigella, QC and duplicate isolates were removed a total of 43 Shigella isolates
were typed. These included 22 S.sonnei, 16 S.flexneri and 5 S.boydii. The S.flexneri
isolates were further divided into 2 S.flexneri 1b, 7 S.flexneri 2a, 1 S.flexneri 2b, 3
S.flexneri 3a, 1 S.flexneri 3b and 2 S.flexneri 4.
Nineteen of these patients had a recorded history of recent foreign travel, primarily to
Asia (n = 9) and Africa (n = 6). PFGE analysis confirmed a S.sonnei outbreak (n = 9)
20
in the Midwest at the beginning of the year; a S.sonnei outbreak in the Midlands in
June (n = 3); and a family outbreak of S.flexneri 2a (n = 2) in the East in October.
All the S.boydii patterns were unique.
21
NSRL Publications and Presentations 2008
Oral Presentations
Molecular Subtyping of Salmonella enterica
UCD Centre for Foodborne Zoonomics
Dec 12th , 2008
Poster Presentations
Prevalence of plasmid mediated AmpC -lactamases in non-Typhi Salmonella from
Ireland.
In: Proceedings of the European Congress of Clinical Microbiology and Infectious
Diseases (ECCMID), Barcelona, Spain, April 19th – 22nd , 2008.
Defining Salmonella enterica serotype Paratyphi C, Choleraesuis and Typhisuis
Abstract for 7th International Symposium on Invasive Salmonellose
The Wellcome Trust Sanger Institute, Hinxton Cambridge 2008.
Papers
Human listeriosis: surveillance, epidemiology, transmission and prevention.
EPI-Insight
2008;9 (July)
A multi-country outbreak of Salmonella Agona
Euro-surveillance, Vol. 13 Issue 33, 14th August 2008.
22