Infection Surveillance Report For
Trust B
Published March 2005
It is proposed that this document will be published in
Trust B’s website
Trust B Infection Surveillance Report
National Surveillance Components
Bacteraemia Surveillance
Clostridium difficile
Surgical Site Infections (Orthopaedics)
Surgical Site Infections (Caesarean sections)
Surgical Site Infections (Vascular)
Hospital Outbreak
Point Prevalence Survey 2005
ITU Level 1
Status
Start Date
01/04/2001
01/01/2005
01/08/2003
Infection reduction target 2005:
Clostridium difficile in the geriatric wards, by review of antibiotic policy and cleaning
policies.
Local surveillance components:
 Only national schemes undertaken.
Surveillance Summary for Trust B
Bacteraemia surveillance
 The overall rate of bacteraemia in the trust is 5.8 per 1000 bed days. The full
report is available here and lists our current top ten organisms.
 The rates of MSSA and MRSA bacteraemias in Trust X are 0.47 and 0.25 per
1000 bed days respectively. These rates are not significantly different from the all
Wales rates.
 The rates of MRSA and MSSA bacteraemias are both showing downward trends
in Trust B.
C. difficile surveillance
Surveillance of C. difficile in Trust B is under development. It is anticipated that the
surveillance scheme will be up and running by April 2005, with data able to be
backdated to 01/01/2005.
Orthopaedic SSI surveillance
Trust B does not currently undertake surveillance of infections following orthopaedic
surgery. It is hoped to implement this surveillance in 2006.
Caesarean Section SSI surveillance
The rate of SSI following Caesarean section is 10.1%. This rate is not significantly
different from the all Wales rate.
Vascular SSI surveillance
Surveillance of infections following vascular surgery in Trust B is currently under
development. Surveillance will commence July 2005.
Hospital Outbreak Surveillance
 6 outbreaks have been reported from Trust B during the surveillance period,
affecting 53 patients and 12 staff.
 All the outbreaks were of Diarrhoea and Vomiting, which lasted an average of 3
days and resulted in the closure of 2 wards.
 The mean duration of D & V outbreaks in Trust B is significantly shorter than the
all Wales rate.
Prevalence Survey
A point prevalence survey for Trust B is planned for November 2005.
ITU SurveillanceHighest rates of infection in ITU were for UTIs, with the majority
being caused by E. coli infections.
 Rates of UTI and pneumonia in the ITU in Trust B were not significantly
different from all-Wales rates.
 Overall rates of bloodstream infections in the ITU in Trust B and rates of
MRSA bloodstream infections were significantly higher than all-Wales rates.
The reasons for this should be investigated.
Notes for Interpretation
Please see the notes at end of report for explanations of data sources etc.
Bacteraemia Report for Trust B
For Trust B during the past year, the significant bacteraemia are listed in the top ten
organisms list below. There has been little change since reporting from the last
quarter in the ranks. Coagulase negative staphylococci remain the most commonly
isolated organism. While some of these will undoubtedly be false positives (such
organisms are common skin organisms), the large number, approximately 45% of all
isolates, is probably a reflection of modern healthcare where we rely heavily on IV
access. These organisms commonly colonise the line and are picked up during
sampling.
These organisms from such sites can cause clinical illness, particularly in ITU or high
dependency patients. Our infection reduction target is currently aimed at improving
IV line management and it will be this marker that we will be watching over the
coming months to see if we can achieve an overall reduction in bacteraemias and
specifically of this common organism.
Our second highest organism is likely to be a reflection of urinary tract infection.
MRSA is currently at number 5, up from number 6 in the previous quarter. This
movement is probably not significant but you may view the specific information in
relation to Staphylococcus aureus or MRSA from the nationally collated information.
1 April 03 – 31 March 04
Organism
Staphylococcus coagulase negative
Escherichia coli
Staphylococcus aureus (MSSA)
Enterococcus sp
Staphylococcus aureus (MRSA)
Streptococcus pneumoniae
Corynebacterium sp
Gram negative bacillus
Klebsiella pneumoniae
Serratia marcescens
Others
Total
Count
Rank
233 1(1) 70 2(2) 52 3(3) 38 4(4) 17 7(6) 
21 5(5) 20 6(6) 17 7(9) 
10 9(8) 
9 10(-) 
122
609
per 1000 bed days
2.10
0.63
0.47
0.34
0.25
0.19
0.18
0.15
0.09
0.08
1.10
5.80
Our trend data in relation to Staphylococci appears on the next page
Staphylococcus aureus bacteraemia Trend data for Trust B
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Moving annual rate of MSSA bacteraemias per
1000 bed days in Trust B
Bacteraemias/1000 bed days
0.25
A
Bacteraemias/1000 bed days
Moving annual rate of MRSA bacteraemias per
1000 bed days in Trust B
Staphylococcus aureus bacteraemia data by Specialty in Trust B
Specialty
ITU
General Surgery
GP Other
Paediatrics
General Medicine
Gynaecology
Trauma & Orthopaedics
Old Age Psychiatry
SA/1000 beds MRSA/1000 beds MSSA/1000 beds
4.38
3.13
1.25
0.44
0.31
0.13
0.39
0.00
0.39
0.28
0.07
0.21
0.25
0.11
0.14
0.10
0.00
0.10
0.02
0.02
0.00
0.02
0.02
0.00
Key Messages
 Surveillance shows that for every 100,000 patients occupying a bed for a night
in a Welsh NHS Trust, 12 patients have an MRSA bacteraemia and 15 have an
MSSA bacteraemia.
 For every 100,000 patients spending a night in a bed in Trust B, 25 patients
have an MRSA bacteraemia and 47 have an MSSA bacteraemia.
 Rates of MRSA and MSSA for Trust X and for its major acute hospital are not
significantly different from the overall rates for Wales.
 Trend data show downward trends for both MRSA and MSSA bacteraemias in
Trust B, but they are not significant.
 Data by specialty show highest rates in ITU. The S. aureus bacteraemia rates
for all specialties in Trust B are not significantly different from any other
Trust in Wales.
Caesarean Section Surgical Site Infection Surveillance
Surveillance period: 01/01/2001-30/06/2004
Total forms received: 700; Total forms analysed: 688; Number of SSI: 70
Operation Type
Elective
Emergency
Scheduled
Urgent
All procedures
% SSI in Trust B
13.0
11.4
22.7
9.7
10.1
SSI by Age Group of Patient
Age Group
% SSI in Trust B
16-25
12.1
26-35
10.7
36-45
20.0
SSI by Duration of Procedure
Duration (mins)
% SSI in Trust B
< 30
11.6
31-45
12.2
46-60
14.3
61+
11.8
Type of SSI following Caesarean section in Trust B
Unknown
4%
Deep
15%
Superficial
81%
Mean number of days from procedure to infection = 14
Proportion of SSI detected post-discharge = 88%
Key Messages
 The crude SSI rate following Caesarean Section at Trust B is 10.1%. This is
not significantly different from the all Wales rate.
 Highest rates of SSI occurred following Scheduled procedures, but the rate for
Scheduled procedures was not significantly different from other procedure
types.
 There were no significant differences in the rates for patients in different age
groups nor for differences in procedure durations.
 The majority of surgical site infections following Caesarean Section are
superficial incisional.
Questionnaire Return for Trust B
Caesarean Section Procedures
Surgery Type
% Form return compared to PEDW data
(All Wales)
(a) Emergency
80.5
(66.8%)
(b) Elective
90.5
(85.9%)
Total
88.3
(78.3%)
Surveillance of Hospital Outbreaks
Surveillance period: 01/10/2003- 30/09/2004
Type of
outbreak
No of
outbreaks
D&V
No of
patients
involved
6
No of staff
involved
53
Mean
No of
length of wards
outbreaks closed
12
3
2
Outbreaks by Specialty
Specialty
General medicine
General surgery
No of OBs
No of patients No of staff
involved
involved
3
33
10
3
20
2
Key Messages
 6 outbreaks were reported from Trust B during the surveillance period,


affecting 53 patients and 12 staff.
All outbreaks were viral D & V (confirmed and suspected) and the mean
duration of D & V outbreak was 3 days. The duration of the D & V outbreaks
was significantly shorter than for the all Wales data.
Two wards were closed as a result of outbreaks during the surveillance period.
Surveillance of Infections in ITU
Surveillance type: Level 1 Unit based surveillance
Surveillance period: 01/04/2004-31/12/2004
ITU type: Mixed
No of Patient days in ITU in surveillance period: 700
Total Infections in surveillance period: 27
Infection rate: 4 per 100 bed days
Types of infection
Infection Type
Urinary Tract Infection (UTI)
Upper Respiratory Tract Infection (URTI)
Pneumonia
Blood stream infection
Proportion of infections
52
22
15
11
Key messages
 Highest rates of infection were for UTIs, with the majority being caused by E.
coli infections.
 Rates of infection in the ITU in Trust B were not significantly different from
all-Wales rates.
 Overall rates of bloodstream infections in the ITU in Trust B and rates of
MRSA bloodstream infections were significantly higher than all-Wales rates.
The reasons for this should be investigated.
Notes for Interpretation
1.
The bed day denominator data was obtained from the Health Solutions Wales database, Quest 1
(available to all NHS web users).
2. Bed days were calculated from the average daily occupied beds, provided from Quest 1 and
multiplied by the average number of days in the surveillance period. One patient in one bed for one
night is one occupied bed day.
3. Rates given for the S. aureus and gram negative bacteraemias and C. difficile surveillance are the
number of cases of diagnosed per 1000 bed days. The bed day rate relates the diagnosed cases to
the total number of days during which patients have been in hospital in the surveillance period.
4. 95% Poisson exact confidence limits have been calculated around each Trust’s rate. These assist in
determining whether particular Trusts are outliers in terms of their rates or whether normal
variation could account for their result in this period.
5. The data have also been represented in the form of statistical process control charts. The rates for
individual Trusts or individual specialties are plotted on the chart. The lines on the chart represent
the mean, upper and lower limits of the Welsh rate (defined by 3 standard deviations of the Welsh
rate). This assumes that rates in specialties/Trusts will be largely similar. They allow the
distinction between natural variation (rates that fall within the limits) and special cause variation,
where something unusual is occurring in a specialty/Trust (rates that fall outside the limits). A rate
that falls outside the control limits should lead to a search for the explanation for the situation,
which has resulted in the outlier rate. This could be the result of either a true high or low rate of the
organism or due to reporting biases e.g incomplete reporting or over-reporting.
6. For those Trusts where a noticeable increase / decrease in the trend data was observed statistical
analysis (ANOVA, t-test) was carried out for the Trust to compare annual rates for the period. The
5% level was used to determine the statistical difference, e.g. for a statistical difference to occur,
the probability figure should be below 0.05 (P<0.05).
7. Data represents S. aureus /gram negative bacteraemias diagnosed in a specialty/Trust; the
organism was not necessarily acquired in that specialty nor in that Trust.
8. Trusts vary in their case mix and in their proportion of acute beds. Differences in numbers of
patients with increased vulnerability to bacteraemias may contribute to differences in bacteraemia
rates in different locations.
9. Surveillance of C. difficile only covers hospital inpatients aged over 65 with diarrhoea. The bed
day denominator data however, covers all hospital inpatients, not just those aged over 65.
Variations between Trusts in the proportions of inpatients over 65 may contribute to differences in
C. difficile associated diarrhoea rates in different locations.
10. The patient days denominator data for the ITU surveillance is the sum of the number of patients in
the ITU in the surveillance period multiplied by the length of stay of each patient.
11. Patients staying less than 3 days in the ITU are excluded from the surveillance. These patients add
a lot of patient-days and also device-days to the denominator but are not at risk of developing an
infection after 2 days in the ICU.
12. Infections appearing after discharge from the ITU are excluded from the ITU surveillance. Level 1
ITU surveillance offers limited inter-ITU comparison possibilities, but can be used to follow up
trends of infection rates in the same unit. Level 2 ITU surveillance is more suited for
benchmarking.