Table 1. Comparison of key variables in neonatal hospital-acquired bloodstream infection at Tygerberg Hospital from 2009–2018, and comparison between the Period 1 (2009–2013) and Period 2 (2014–2018).
| Variable | Overall estimate (2009–2018) Number (%) [95% CI] | Period 1 (2009–2013) Number (%)* [95% CI] | Period 2 (2014–2018) Number (%)* [95% CI] | p-value (two-sided) |
|---|---|---|---|---|
| Number of admissions | 52204 | 23920 | 28284 | - |
| Number of inpatient-days | 400614 | 183846 | 216768 | - |
| Blood culture collection rate per total admission count | 13461/52204 (25.8) [25.4–26.2] | 6521/23920 (27.3) [26.7–27.8] | 6940/28284 (24.5) [24.0–25.0] | <0.001 |
| HA-BSI rate/1000 inpatient-daysa | 3.6 (3.4–3.8) | 3.9 (3.6–4.2) | 3.3 (3.1–3.6) | 0.002 |
| HA-BSI rate/1000 admissionsa | 27.5 (26.1–28.9) | 30.0 (27.9–32.2) | 25.4 (23.6–27.3) | 0.002 |
| Absolute blood culture positivity rate, including duplicate blood culturesb | 2544/13461 (18.9) [18.2–19.6] | 1145/6521 (17.6) [16.7–18.5] | 1399/6940 (20.2) [19.2–21.1] | <0.001 |
| Pathogen yield (deduplicated) b | 1435/13461 (10.7) [10.2–11.2] | 717/6521 (11.0) [10.3–11.8] | 718/6940 (10.4) [9.6–11.1] | 0.233 |
| Blood culture contamination rate (deduplicated) b | 701/13461 (5.2) [4.8–5.6] | 333/6521 (5.1) [4.6–5.7] | 368/6940 (5.3) [4.8–5.9] | 0.636 |
| Number of BSI episodes | 1435 | 717 | 718 | - |
| Monomicrobial BSI episodes | 1225/1435 (85.4) [83.4–87.1] | 650/717 (90.7) | 575/718 (80.1) | <0.001 |
| Proportion pathogen countsc | ||||
| Gram-negatives | 1047/1641 (63.8) [61.4–66.1] | 519/796 (65.2) [61.7–68.5] | 528/845 (62.5) [59.1–65.7] | 0.275 |
| Gram-positives | 522/1641 (31.8) [29.6–34.1] | 244/796 (30.7) [27.5–34.0] | 278/845 (32.9) [29.8–36.2] | 0.356 |
| Yeasts | 67/1641 (4.1) [3.2–5.2] | 33/796 (4.2) [2.9–5.8] | 34/845 (4.0) [2.8–5.6] | >0.999 |
| Pathogen proportion for the 10 most frequently isolated pathogens overall, by organism grouping (rank) | ||||
| Klebsiella species (1) | 432/1047 (41.3) [38.3–44.3] | 235/519 (45.3) [40.9–49.7] | 197/528 (37.3) [33.2–41.6] | 0.011 |
| Staphylococcus aureus (2) | 246/522 (47.1) [42.8–51.5] | 112/244 (45.9) [40.0–52.4] | 134/278 (48.2) [42.2–54.2] | 0.662 |
| Serratia marcescens (3) | 200/1047 (19.1) [16.8–21.6] | 84/519 (16.2) [13.2–19.7] | 116/528 (22.0) [18.6–25.8] | 0.021 |
| Enterococcus species (4) | 198/522 (37.9) [33.8–42.3] | 88/244 (36.1) [30.1–42.5] | 110/278 (39.6) [33.8–45.6] | 0.464 |
| Acinetobacter baumannii (5) | 137/1047 (13.1) [11.1–15.3] | 69/519 (13.3) [10.6–16.6] | 68/528 (12.9) [10.2–16.1] | 0.914 |
| Escherichia coli (6) | 119/1047 (11.4) [9.5–13.5] | 58/519 (11.2) [8.7–14.3] | 61/528 (11.6) [9.0–14.7] | 0.924 |
| Group B streptococcus (8) | 57/522 (10.9) [8.4–14.0] | 36/244 (14.8) [10.7–19.9] | 21/278 (7.6) [4.9–11.5] | 0.013 |
| Enterobacter species (7) | 46/1047 (4.4) [3.3–5.9] | 15/519 (2.9) [1.7–4.8] | 31/528 (5.9) [4.1–8.3] | 0.028 |
| Candida albicans (9) | 33/67 (49.3) [37.0–61.6] | 18/33 (54.6) [36.6–71.5] | 15/34 (44.1) [27.6–61.9] | 0.542 |
| Pseudomonas aeruginosa (10) | 32/1047 (3.1) [2.1–4.3] | 12/519 (2.3) [1.3–4.1] | 20/528 (3.8) [2.4–5.9] | 0.227 |
| Crude mortalityd | 318/1435 (22.2) [20.1–24.4] | 139/717 (19.4) [16.6–22.5] | 179/718 (24.9) [21.8–28.3] | 0.014 |
| BSI-attributable mortalitye | 215/318 (67.6) [62.1–72.7] | 97/139 (69.8] [61.3–77.1] | 118/179 (65.9%) [58.4–72.7] | 0.542 |
| Crude mortality by pathogen groupf | ||||
| Gram-negative | 153/806 (19.0) [16.4–21.9] | 78/433 (18.0) [14.6–22.0] | 75/373 (20.1) [16.2–24.6] | 0.506 |
| Gram-positive | 27/358 (7.5) [5.1–10.9] | 15/186 (8.1) [4.7–13.2] | 12/172 (7.0) [3.8–12.2] | 0.850 |
| Yeast | 6/60 (10.0) [4.1–21.2] | 3/31 (9.7) [2.5–26.9] | 3/29 (10.3) [2.7–28.5] | 0.731 |
CI: confidence interval; HA-BSI: hospital-acquired bloodstream infection; MRSA: methicillin-resistant S. aureus; MDR: multidrug-resistant; BSI: bloodstream infection.
aNumber (%) [95% CI] applies to all variables listed with the exception of HA-BSI rate, expressed per 1000 inpatient-days, or per 1000 admissions.
bAbsolute blood culture positivity rate comprises all neonatal blood cultures flagging positive on or after day 3 of admission, including duplicate blood cultures, over all neonatal blood cultures submitted, while pathogen yield and contamination rate refer to deduplicated blood cultures as a proportion of all neonatal blood cultures submitted.
cAn additional 5 pathogens were unclassified in Period 2 (2014–2018), including Rhodotorula species, Wickerhamomyces anomalus.
dCrude mortality defined as deaths in neonates with pathogen-containing BSI, as a proportion of all neonates with BSI episodes.
eBSI-attributable mortality defined as deaths occurring within 72 hours of blood culture collection, as a proportion of all deaths in neonates with BSI episodes.
fMonomicrobial cultures only.