A Simple Scoring Algorithm That Predicts Abscesses in Adults with Community-Onset Klebsiella pneumoniae Bacteremia: Hypermucoviscosity Matters

Figures & data

Figure 1 Schematic flow chart.

Table 1 Clinical Characteristics of Adults with Community-Onset Monomicrobial K. pneumoniae Bacteremia, Categorized by the Presence or Absence of Abscesses

Characteristics	Patient Number (%)		P values
	Abscess, n=79	Non-Abscess, n=179
Old age (≥65 years)	39 (49.4)	113 (63.1)	0.04
Male gender	58 (73.4)	111 (62.0)	0.08
Nursing home residents	2 (2.5)	9 (5.0)	0.51
Events During the Previous 4 Weeks
Prior hospitalization	16 (20.3)	55 (30.7)	0.08
Surgery	4 (5.1)	6 (3.4)	0.55
Immunosuppression	2 (2.5)	1 (0.6)	0.22
Steroid therapy	3 (3.8)	5 (2.8)	0.70
Chemotherapy	0 (0)	19 (10.6)	0.003
Invasive procedure	1 (1.3)	5 (2.8)	0.67
Severity of Sepsis at Bacteremia Onset
Pitt bacteremia score ≥4 points	17 (21.5)	49 (27.4)	0.32
Admitted to intensive care units	18 (22.8)	39 (21.8)	0.86
Severe sepsis	44 (55.7)	90 (50.3)	0.42
Septic shock	19 (24.1)	50 (27.9)	0.52
Severity of Underlying Disease (McCabe Classification)			0.03
Rapidly or ultimately fatal	16 (20.3)	60 (33.5)
Non-fatal	63 (79.7)	119 (66.5)
Major Comorbidity
Diabetes mellitus	40 (50.6)	69 (38.5)	0.07
Hypertension	28 (21.5)	78 (43.6)	0.22
Malignancy	17 (21.5)	64 (35.5)	0.02
Neurological disorder	13 (13.9)	48 (26.8)	0.07
Liver cirrhosis	11 (13.9)	38 (21.2)	0.17
Coronary artery disease	7 (8.9)	19 (10.6)	0.66
Chronic kidney disease	6 (7.6)	31 (17.3)	0.04
Urological disease	6 (7.6)	13 (7.3)	0.93
Chronic obstructive pulmonary diseases	5 (6.3)	16 (8.9)	0.48
Laboratory Data at Bacteremic Onset^a
Leukocytes >9000/mm^3	51 (64.6)	108 (60.3)	0.52
Platelets <150,000/mm^3	45 (57.0)	74 (41.3)	0.02
Blood urea nitrogen >20 mg/dL	39/72 (54.2)	96/171 (56.1)	0.78
Serum creatinine >1.5 mg/dL	17 (21.5)	66 (36.9)	0.02
C-reactive protein >100 mg/L	63 (79.7)	62 (34.6)	<0.001

Note: ^aNot all patients had the indicated laboratory data.

Figure 2 Microbiological characteristics of K. pneumoniae isolates causing community-onset bacteremia with or without abscesses (A) and with a hepatic abscess or extra-hepatic abscess (B).

Abbreviation: HMV, hypermucoviscosity.

Table 2 Multivariate Analysis of Risk Factors for Abscess Formation Among Community-Onset Monomicrobial K. pneumoniae Bacteremia

Variables	Adjusted OR (95% C.I.)	P value	CoKPBAS
			Model 1	Model 2^a	Model 3^b
Gender, male	2.21 (1.02–4.78)	0.04	1	1	1
HMV phenotype	3.17 (1.56–6.43)	0.001	1	1	–
Capsular K1 serotype (magA-harboring isolates)	4.00 (1.92–8.36)	<0.001	1	-	-
Recent chemotherapy	0.22 (0.07–0.71)	0.01	−1	−1	−1
Comorbidities, n (%)
Neurological disorder	0.40 (0.17–0.94)	0.04	−1	−1	−1
Diabetes mellitus	2.43 (1.19–4.96)	0.02	1	1	1
C-reactive protein >100 mg/L at bacteremia onset	7.98 (3.76–16.94)	<0.001	1	1	1

Notes: ^aExclusion of variable with magA. ^bExclusion of variables with magA and hypermucoviscosity phenotype.

Abbreviations: CoKPBAS, community-onset K. pneumoniae bacteremia abscess score; HMV, hypermucoviscosity; OR, odds ratio.

Table 3 The Sensitivity, Specificity, Predictive Value, and Likelihood Ratio of the CoKPBAS (Model 1) for Abscess Occurrences in Various Cut-Off Points

Cut-Off Points	Case Number with Abscess (%)	Sensitivity (%)	Specificity (%)	Predictive Value (%)		Likelihood Ratio (%)
				Positive	Negative	Positive	Negative
4	29 (82.9)	36.7	96.6	82.9	77.6	10.79	0.66
3	53 (60.9)	67.1	81.0	60.9	84.8	3.53	0.41
2	74 (45.7)	93.7	50.8	45.7	94.8	1.90	0.12

Abbreviations: CoKPBAS, community-onset K. pneumoniae bacteremia abscess score.

Figure 3 Receiver operating characteristic curves of three models of K. pneumoniae abscess scoring to predict abscess formation in community-onset monomicrobial K. pneumoniae bacteremia. The area under the ROC curve is 0.83 (95% confidence interval [CI], 0.77–0.88; P<0.001) in model 1, 0.80 (95% CI, 0.74–0.86; P<0.001) in model 2, and 0.77 (95% CI, 0.71–0.83; P<0.001) in model 3.

Table 4 Infection Sources, Clinical Management, and Outcome of Adults with Community-Onset Monomicrobial K. pneumoniae Bacteremia, Categorized by the Presence or Absence of Abscesses^a

Characteristics	Patient Number (%)		P values
	Abscess, n=79	Non-Abscess, n=179
Major Sources of Bacteremia^b
Hepatobiliary tracts	52 (65.8)	29 (16.2)	<0.001
Respiratory tracts	8 (10.1)	48 (26.8)	0.003
Skin and soft-tissue	8 (10.1)	1 (0.6)	<0.001
Urinary tract	7 (8.9)	42 (23.5)	0.006
Bone and joint	3 (3.8)	3 (1.7)	0.37
Intra-abdominal	2 (2.5)	23 (12.8)	0.01
Primary bacteremia	0 (0)	30 (16.8)	<0.001
Vascular catheter-related	0 (0)	6 (3.4)	0.18
Central nervous systems	0 (0)	2 (1.1)	1.00
Antibiotic Therapy
Inappropriate administration during ED stay	3 (3.8)	16 (8.9)	0.15
Appropriate administration delay ≥3 days	0 (0)	13 (7.3)	0.01
Appropriate administration delay ≥5 days	0 (0)	8 (4.5)	0.11
Multiple portals of entry	18 (22.8)	4 (2.2)	<0.001
Image Studies
Chest X-ray	79 (100)	179 (100)	1.00
Abdominal sonography	45 (57.0)	142 (79.3)	<0.001
Abdominal CT scan	68 (86.1)	140 (78.2)	0.14
Periods Between ED Arrival and Image Study (Hours), Mean ± SD
Chest X-ray	2.0 ± 1.3	1.8 ± 1.2	0.38
Abdominal sonography	39.6 ± 91.6	45.6 ± 75.9	0.66
Abdominal CT scan	59.4 ± 98.1	71.2 ± 107.1	0.46
Lengths of Hospital Stay (Days), Mean ± SD
Total hospitalization	20.2 ± 13.7	13.7 ± 14.9	0.001
Intensive Care Units	2.7 ± 7.1	3.8 ± 12.1	0.46
Clinical Outcomes
14-day mortality	4 (5.1)	33 (18.4)	0.005
28-day mortality	8 (10.1)	43 (24.0)	0.01
Mortality at discharge	9 (11.4)	47 (26.3)	0.008

Notes: ^aData are expressed as case numbers (percentages), unless specifically indicated. ^bIndicates the type of abscesses in patients in the abscess group.

Abbreviations: ED, emergency department; CT, computed tomography; SD, standard deviation.

Table 5 Hypermucoviscosity and Risk Factors of 28-Day Crude Mortality

Variable	Patient Number (%)		Univariate Analysis		Multivariate Analysis
	Death n=51	Survival, n=207	OR (95% CI)	P value	Adjusted OR (95% CI)	P value
Nursing-home residents	5 (9.8)	6 (2.9)	3.64 (1.07–12.45)	0.04	1.22 (0.22–6.83)	0.82
HMV phenotype	19 (37.3)	91 (44.0)	0.76 (0.40–1.42)	0.39	0.82 (0.29–2.34)	0.72
Capsular K1 serotype (magA-harboring isolates)	11 (21.6)	62 (30.0)	0.64 (0.31–1.34)	0.23	0.83 (0.30–2.34)	0.71
RmpA-harboring isolates	31 (60.8)	131 (63.3)	0.90 (0.48–1.69)	0.74	1.10 (0.34–3.56)	0.87
Pitt bacteremia score ≥4 points at onset	35 (68.6)	31 (15.0)	12.42 (6.14–25.11)	<0.001	8.98 (3.80–21.24)	<0.001
Delayed administration of appropriate antimicrobials ≥3 days	7 (13.7)	6 (2.9)	5.33 (1.71–16.63)	0.002	6.85 (1.23–37.99)	0.03
Sources of Bacteremia
Pneumonia	30 (58.8)	29 (14.0)	8.77 (4.43–17.34)	<0.001	5.81 (2.46–13.73)	<0.001
Urinary tract infections	3 (5.9)	48 (23.2)	0.21 (0.06–0.69)	0.005	0.39 (0.09–1.65)	0.20
Fatal comorbidities (McCabe classification)	27 (52.9)	49 (23.7)	3.63 (1.92–6.86)	<0.001	5.05 (2.09–12.22)	<0.001
Comorbid diabetes mellitus	15 (29.4)	94 (45.4)	0.50 (0.26–0.97)	0.04	0.37 (0.15–1.02)	0.06

Abbreviations: HMV, hypermucoviscosity; CI, confidence interval; OR, odds ratio.