Incidence, and Outcomes of Fusobacterium Species Bacteremia
During the 11-year study, there were 72 incident cases of Fusobacterium bacteremia. Basic demographic (age, gender, residency) and microbiologic data were available for all cases. Of the ten cases not requiring admission, 3 were F. necrophorum, 5 were F. nucleatum and 2 were unspeciated. Age, gender, and further clinical data was available on 62 patients admitted to one of four acute care hospitals in the region. Among the 72 incident Fusobacterium bacteremias, 35 (49%) were community-acquired, 23 (32%) were healthcare-associated community onset, and 14 (19%) were hospital-acquired. F. nucleatum was identified in 44 cases (61%) and, F. necrophorum in 18 cases (25%). Of the remaining 10 cases (14%), 3 were F. mortiferum, 2 were F. peridonticum, and 5 could only reliably be identified as Fusobacterium spp.
The overall annual incidence of Fusobacterium bacteremia was 0.55 per 100,000 population (Figure 1). Annual variability was seen in keeping with a relatively rare infection, without any clear pattern evident. Incidence of F. nucleatum was 0.34/100,000 and F. necrophorum was 0.14/100,000. Overall median age was 42.1 years. However, a differing pattern of incidence was evident between F. nucleatum and F. necrophorum bacteremia (Figure 2). F. nucleatum cases had a median age of 53.5 years (IQR 36.7–72.0), while F. necrophorum cases had a median age of 21 years (IQR 18.1–23.4). There were no cases of F. necrophorum bacteremia in individuals over the age of 40. Of the 72 incident cases, 45 occurred in men (incidence rate ratio 1.676; 95% confidence interval 1.02–2.81; P = 0.016). Much of the increased risk in men was seen in the elderly (Figure 3).
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Figure 1.
Annual incidence of Fusobacterium bacteremia by Acquisition Type. CA = community-acquired; HCA = healthcare-associated community onset; HA = hospital-acquired.
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Figure 2.
Incidence of Fusobacterium bacteremia by species and age group.
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Figure 3.
Incidence Rates of Fusobacterium bacteremia by age and gender.
Among the 62 incident cases with detailed clinical data, 39 were F. nucleatum, 15 were F. necrophorum, and the remaining 8 were other Fusobacterium spp. bacteremia. One or more co-morbidity was present in 39 cases of Fusobacterium bacteremia (63%). The presence of an underlying co-morbidity was more frequently seen in cases of F. nucleatum bacteremia (29/39, 74%) than in cases of F. necrophorum bacteremia (4/15, 27%). Malignancy and dialysis were the greatest risk factors for acquiring Fusobacterium bacteremia (Table 1).
The primary diagnoses at the time of F. nucleatum and F. necrophorum bacteremia are shown in Table 2. Primary bacteremia, intra-abdominal sepsis, and active hematological disorder were the most common diagnoses in the setting of F. nucleatum bacteremia. F. necrophorum bacteremia was seen most commonly in the setting of primary bacteremia and obstetrical-related infections. Two cases were associated with intravascular thrombus, but it is unclear if this represents Lemierre's disease as that is not coded within the database.
Susceptibility testing results were available for 70 (97%) isolates. All isolates were susceptible to metronidazole and clindamycin. Penicillin resistance was present in 9% of F. nucleatum isolates and 6% of F. necrophorum isolates.
Overall mortality was 7/62 (11%). There were no deaths in patients with F. necrophorum infection. Four deaths occurred in patients with F. nucleatum bacteremia. The remaining deaths were in patients with other Fusobacterium spp.
Results
During the 11-year study, there were 72 incident cases of Fusobacterium bacteremia. Basic demographic (age, gender, residency) and microbiologic data were available for all cases. Of the ten cases not requiring admission, 3 were F. necrophorum, 5 were F. nucleatum and 2 were unspeciated. Age, gender, and further clinical data was available on 62 patients admitted to one of four acute care hospitals in the region. Among the 72 incident Fusobacterium bacteremias, 35 (49%) were community-acquired, 23 (32%) were healthcare-associated community onset, and 14 (19%) were hospital-acquired. F. nucleatum was identified in 44 cases (61%) and, F. necrophorum in 18 cases (25%). Of the remaining 10 cases (14%), 3 were F. mortiferum, 2 were F. peridonticum, and 5 could only reliably be identified as Fusobacterium spp.
The overall annual incidence of Fusobacterium bacteremia was 0.55 per 100,000 population (Figure 1). Annual variability was seen in keeping with a relatively rare infection, without any clear pattern evident. Incidence of F. nucleatum was 0.34/100,000 and F. necrophorum was 0.14/100,000. Overall median age was 42.1 years. However, a differing pattern of incidence was evident between F. nucleatum and F. necrophorum bacteremia (Figure 2). F. nucleatum cases had a median age of 53.5 years (IQR 36.7–72.0), while F. necrophorum cases had a median age of 21 years (IQR 18.1–23.4). There were no cases of F. necrophorum bacteremia in individuals over the age of 40. Of the 72 incident cases, 45 occurred in men (incidence rate ratio 1.676; 95% confidence interval 1.02–2.81; P = 0.016). Much of the increased risk in men was seen in the elderly (Figure 3).
(Enlarge Image)
Figure 1.
Annual incidence of Fusobacterium bacteremia by Acquisition Type. CA = community-acquired; HCA = healthcare-associated community onset; HA = hospital-acquired.
(Enlarge Image)
Figure 2.
Incidence of Fusobacterium bacteremia by species and age group.
(Enlarge Image)
Figure 3.
Incidence Rates of Fusobacterium bacteremia by age and gender.
Among the 62 incident cases with detailed clinical data, 39 were F. nucleatum, 15 were F. necrophorum, and the remaining 8 were other Fusobacterium spp. bacteremia. One or more co-morbidity was present in 39 cases of Fusobacterium bacteremia (63%). The presence of an underlying co-morbidity was more frequently seen in cases of F. nucleatum bacteremia (29/39, 74%) than in cases of F. necrophorum bacteremia (4/15, 27%). Malignancy and dialysis were the greatest risk factors for acquiring Fusobacterium bacteremia (Table 1).
The primary diagnoses at the time of F. nucleatum and F. necrophorum bacteremia are shown in Table 2. Primary bacteremia, intra-abdominal sepsis, and active hematological disorder were the most common diagnoses in the setting of F. nucleatum bacteremia. F. necrophorum bacteremia was seen most commonly in the setting of primary bacteremia and obstetrical-related infections. Two cases were associated with intravascular thrombus, but it is unclear if this represents Lemierre's disease as that is not coded within the database.
Susceptibility testing results were available for 70 (97%) isolates. All isolates were susceptible to metronidazole and clindamycin. Penicillin resistance was present in 9% of F. nucleatum isolates and 6% of F. necrophorum isolates.
Overall mortality was 7/62 (11%). There were no deaths in patients with F. necrophorum infection. Four deaths occurred in patients with F. nucleatum bacteremia. The remaining deaths were in patients with other Fusobacterium spp.
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