Neonatal Intensive Care Unit in Dr Jan Biziel University. Hospital in Bydgoszcz between years 2004-2008. Material and methods. The retrospective analysis has ...
Archives of Perinatal Medicine 15(1), 26-30, 2009
ORIGINAL PAPER
Healthcare-associated bloodstream infection in neonatal intensive care unit IWONA SADOWSKA-KRAWCZENKO1,2, PIOTR KORBAL2 Abstract Healthcare-associated infection is a common problem of patients from neonatal intensive care units. The most common healthcare-associated infection among these groups of patients is a healthcare-associated bloodstream infection. The aim of the study was to assess the incidence, mortality and the etiology of healthcare-associated bloodstream infections of newborn in neonatal intensive care unit between 2004 and 2008. Material and methods: The research involved documentation of 2181 neonates hospitalized in neonatal intensive care unit in this period. The incidence, mortality and causing factors of healthcare-associated bloodstream infections were assessed. Newborns were classified into 4 birth weight categories: (1) #1000, (2) 1001-1500, (3) 15012500, (4) >2500. The infected patient rate was calculated in each group. Results: The prevalence of healthcareassociated bloodstream infection was 4.86%; the mortality rate was 2.83%. The highest prevalence was among children below 1500 g. The most frequent pathogen was coagulase-negative staphylococci. Conclusion: The rate of healthcare-associated bloodstream infections in analyzed department is low taking into consideration the specificity of the department. The microbiological characteristic is typical for neonatal intensive care unit. Key words: healthcare-associated bloodstream infection, newborn, neonatal intensive care unit
Introduction
Material and methods
Healthcare-associated bloodstream infection (HABSI) is a serious problem for neonates who are admitted to neonatal intensive care unit (NICU). As it is associated with increases in mortality, morbidity, and prolonged length of hospital stay, both the human costs and economic burden of these infections are high. The rate of HABSI increases with the degree of both prematurity and low birth weight. There are many risk factors of healthcare-associated infection in this group of patients like immaturity of the immune system and barrier functions of the skin and gastrointestinal tract and the invasive diagnostic and therapeutic procedures which newborns undergo [1-3]. The most common healthcare-associated infection among patients from NICUs is a healthcare-associated bloodstream infection (HABSI) [4-10].
The retrospective analysis has been made. The medical charts of patients with HABSI admitted to the NICU in our hospital from January 1, 2004 to December 31, 2008 were reviewed. The incidence, mortality and pathogens causing HABSIs were assessed. A case of HABSI was defined as one or more positive blood cultures obtained over 72 h after admission to the NICU, and the presence of clinical symptoms or signs suggestive of infection. The blood cultures were processed in BacT/Alert automated system. Newborns in NICU were classified into 4 birth weight categories: (1) #1000, (2) 1001-1500, (3) 15012500, (4) > 2500. The infected patient rate was calculated in each group. Mortality due to HABSI was defined as death occurring within 7 days of the onset of infection episodes.
Aim of the study
Results
The aim of the study was to assess the incidence, mortality and the pathogens of HABSI of newborn in Neonatal Intensive Care Unit in Dr Jan Biziel University Hospital in Bydgoszcz between years 2004-2008.
During the study period, from January 1, 2004 to December 31, 2008, 2181 neonates were hospitalized in our NICU, including 424 in 2004, 482 in 2005, 474 in 2006, 436 in 2007, and 365 in 2008. HABSI were diagno-
1
Departament of Pediatric Nursing, Faculty of Heath Science, Nicolaus Copernicus University in Toruń, Ludwik Rydygier Collegium Medicum in Bydgoszcz, Poland
2
Departament of Neonatology, Dr Jan Biziel University Hospital No. 2 in Bydgoszcz, Poland
Healthcare-associated bloodstream infection in neonatal intensive care unit Table 1. Healthcare-associated bloodstream infection rates in the neonatal intensive care unit, 2004-2008 Year
No. of admitted patients in NICU
No. of healthcare-associated bloodstream infections
Healthhcare-associated bloodstream infection patient rate
2004
424
23
5.45%
2005
482
35
7.26%
2006
474
28
5.90%
2007
436
8
1.83%
2008
365
12
3.29%
Total
2181
106
4.86%
Table 2. Birth weight-specific healthcare-associated bloodstream infection rates, 2004-2008 Infection episodes
No. of admissions
Healthcare-associated bloodstream infection patient rate (%)
#1000
8
54
14.81
1001-1500
5
75
6.67
1501-2500
8
185
4.32
> 2500
2
110
1.82
#1000
10
78
12.82
1001-1500
13
71
18.31
1501-2500
8
180
4.44
> 2500
4
153
2.61
#1000
9
63
14.29
1001-1500
13
73
17.81
1501-2500
4
180
2.22
> 2500
2
158
1.27
#1000
4
65
6.15
1001-1500
2
78
2.56
1501-2500
1
190
0.53
> 2500
1
103
0.97
#1000
2
55
3.64
1001-1500
7
60
11.67
1501-2500
1
134
0.75
>2500
2
116
1.72
#1000
33
315
10.48
1001-1500
40
357
11.20
1501-2500
22
869
2.53
> 2500
11
640
1.72
Birth weight (g) 2004
2005
2006
2007
2008
Total 2004-2008
27
I. Sadowska-Krawczenko,, P. Korbal
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sed in 106 cases, including 23 episodes in 2004, 35 in 2005, 28 in 2006, 8 in 2007, and 12 episodes in 2008. The HABSI patient rate over 5-year period was 4.86%. In 2004 HABSI patient rate was 5.45%, in 2005 7.26%, in 2006 – 5.9%, in 2007 – 1.83%, and in 2008 – 3.29% (table 1). The highest frequency of HABSI was among newborns with birth weight below 1500 g. The HABSI rate was a bit higher in group (2) 1001-1500 (11.2%) than in group (1) #1000 (10.48%). In patients with birth weight over 1500 g the HABSI rate was significantly lower, 2.53% in group (3) 15012500, and 1.72% in group (4) >2500. In the year 2004 and 2007 the HABSI rate was the highest in group 1 #1000, and in 2005, 2007 and 2008 the HABSI rate was the highest in group 2 – 1001-1500. Of the total 106 infection episodes 3 patients had more than one episode. 2 patients were from group (1)
#1000 and 1 was from group (2) 1001-1500. The distribution of pathogens associated with HABSIs is shown in table 3. The most common healthcare-associated bloodstream pathogens in all neonates were Gram-positive rods (55/106) and among them coagulase-negative staphylococci. Gram-negative rods caused 43 HABSI and in 16 cases Klebsiella pneumoniae was a causing factor. During the study period 3 newborns died of HABSI, 2 in 2004 and 1 in 2006. Overall mortality rate was 2.83%, 13.04% in 2004 and 3.57% in 2006. All these patients were from group (1) #1000. Two of them had HABSI caused by Klebsiella pneumoniae and one caused by Stenotrophomonas maltophilia. Owing to the fact that all cases were caused by Gram-negative pathogens the mortality rate due to this pathogens was 6.98%.
Table 3. Distribution of pathogens associated with healthcare-associated bloodstream infection, 2004-2008 Total no. of isolates (%)
No. of isolates (%)
Pathogen
Rank
2004
2005
2006
2007
2008
Staphylococcus aureus
0
0
0
1
0
1
Enterococcus
0
1
0
0
0
1
CONS
6
22
4
11
10
53
1
Gram-positive
Total Gram-positive
55
Gram-negative
Klebsiella pneumoniae
1
1
12
1
1
16
2
Enterobacter cloacae
2
6
1
1
0
10
3
Escherichia coli
1
1
0
0
0
2
7
Serratia marcescens
2
1
2
0
1
6
4
Acinetobacter baumani
5
0
0
0
0
5
5
Pseudomonas aeruginosa
1
0
1
0
0
2
7
Morganella morgani
1
0
0
0
0
1
8
Stenotrophomonas maltophilia
1
0
0
0
0
1
8
Total Gram-negative
43
Fungus
Candida albicans
1
3
0
0
0
4
6
Candida crusei
2
0
0
2
0
4
6
12
106
Total fungus Total no. of isolates
8 23
35
2
8
Healthcare-associated bloodstream infection in neonatal intensive care unit
Discussion HABSI constitute a major problem among neonates admitted to NICU and may be associated with substantial morbidity and mortality. The HABSI patient rate in the NICU of Dr Jan Biziel University Hospital was 4.86%. Previous studies have reported rates of HABSI in NICUs ranged from 5 to 32% [10, 11]. The variability in HABSI rate depends on the gestational age, distribution of the infants surveyed for the report, and on the specific environment and care practices [9]. The incidence of HABSI in analyzed NICU seems to be too low taking into consideration data from other NICUs. It can be caused by established definition of HABSI; it was diagnosed only if blood culture was positive. Some investigators recognized HABSI also due to clinical features without positive blood culture. The other reason is that patients in the NICU usually had a course of antibiotic after delivery and it could disturb microbiological culture procedure. In this study, the ranges of infection rate among four birth weight groups differ. The highest rate of HABSI was in patients with weight below 1500 g. However it is surprising that the HABSI rate was the highest in group (1) #1000 only in the years 2004 and 2007 and in the years 2005, 2006, 2008 the highest HABSI rate was in group (2) 1001-1500. The majority of investigators indicated that the risk of developing HABSI increased with lower birth weight. Stoll et al. revealed infection rates of 50% for infants weighting below 750 g, 33% for those between 751 and 1000 g, 21% for those between 1001 and 1250 g, and 10% for those between 1251 and 1500 g [12]. During the study period, the most common health care-associated bloodstream pathogen in all neonates was coagulase-negative staphylococci. The same findings had Gaynes et al. and Stoll et al. [9, 12]. They found that coagulase-negative staphylococci were the most common pathogen, presenting in 51% and 55% of cases, respectively. The similar observation had Makhoul et al., they found that Gram-positive rods account for 55.4% of HABSI, and the most common organisms were Staphylococci [13]. However, there are investigators who found Gram-negative rods as the most common etiological factors [4, 14]. The mortality rate was low in this study; overall mortality rate was 2.83%. Since all fatality cases were associated with Gram-negative pathogens mortality rate for this reason was 6.98%. Other authors show that mortality caused by Gram-negative pathogens is much higher, about 26% to 40% [8, 13, 15]. Gram-negative HABSI often presents with a more rapid clinical deterioration and is
29
commonly associated with shock and coagulation problems. According to Makhoul et al. mortality after Gram-negative sepsis (26.2%) and Candida sepsis (27.6%) is similar and significantly higher than with Gram-positive sepsis (8.7%) [13]. However, the virulence of organisms like coagulase-negative Staphylococci may be underestimated because many cultures that grow Gram-positive bacteria represent skin contaminants rather than true bloodstream infections. Conclusion The rate of healthcare-associated bloodstream infections in analyzed department is low taking into consideration the specificity of the department. The microbiological characteristics is typical for neonatal intensive care unit. References [1] Bartels D.B., Schwab F., Geffers C. et al. (2007) Noso-
comial infection in small for gestational age newborns with birth weight
