Analysis of our results showed that out of 13,345 COVID-19 RT-qrtPCR and 4,194 BACTEC blood culture requests from 2020.02.25 to 2022.12.24 in our hospital, bacteremia/fungemia were confirmed in 10.34% of the patients who requested both of the test simultaneously (435/4,194). The COVID-19 infection was confirmed in 25.3% of the patients with bacteremia/fungemia (110/435). Except for 2 patients with no record, the infection with Gram-negative bacteria, Gram-positive bacteria, and fungi was detected in 59.3% (257/433), 32.3% (140/433), and 8.31% (36/433) of the cases, respectively. Out of 433 blood culture samples, Pseudomonas spp. (21.3%), Klebsiella spp. (20.2%), CNS (15.8%), Acinetobacter spp. (9.6%), S. aureus (8%), Enterococcus spp. (5%), Enterobacter (3.9%) and E. coli (2.1%) were among the common isolates associated with BSI in children.
Among the patients with positive BACTEC culture for Gram-positive (BSI-GPB) or fungi (BSI-FB), no significant association was found between the microorganisms and underlying diseases, including cancer and chemotherapy, gender and age groups (Table 1). However, a significant difference was measured among different wards of the hospital (p-value= 0.01). Accordingly, the Pediatric Intensive Care Unit, Emergency Room and Bone Marrow Transplantation wards showed the highest frequency of bloodstream infection with GPB, respectively (30.2%, 21.2% and 14%, respectively) (Table 2) (Figure 1). S. epidermidis and S. aureus were common causes of BSI-GPB in all the hospital wards (Figure 2). Enterococcus was the main cause of infection in the Oncology ward (Two-fold higher than S. aureus) and the third cause of BSI-GPB in most hospital wards. Candida spp. were detected in 6.7% of the target population, which was lower than the frequency of the infection with non-Candida yeast and fungi infections (13.4%). Candida spp. were mainly isolated from the patients in the Infectious Diseases and Surgery wards. BSI-FB, regardless to their types, were mainly isolated from the blood of the patients in the PICU and Gastroenterology wards (Table 2) (Figure 1).
Table 1. The frequency of Gram-positive bacteria and fungi isolates from bloodstream infection of children according to age, gender, and underlying diseases in a pediatric hospital in Tehran, Iran, 2020-2022.
Microorganisms
Blood culturea
|
Number
|
Frequency
|
Gender
|
COVID-19
|
Age
|
Cancer
|
Chemotherapy
|
Boy
|
Girl
|
Positive
|
Pathogen %
|
Total %
|
>3 y
|
≤3 y
|
n/N
|
%
|
n/N
|
%
|
Not recorded
|
3
|
1.69%
|
1
|
2
|
2
|
67%
|
4.35%
|
2
|
1
|
|
|
|
|
Candida spp.
|
12
|
6.74%
|
8
|
4
|
5
|
42%
|
10.87%
|
7
|
5
|
1/12
|
8.33%
|
0/12
|
0
|
Other yeasts and fungi
|
24
|
13.48%
|
20
|
4
|
5
|
21%
|
10.87%
|
10
|
14
|
2/24
|
8.33%
|
1/24
|
4.17%
|
Corynebacterium
spp.
|
4
|
2.25%
|
2
|
2
|
1
|
25%
|
2.17%
|
0
|
4
|
1/4
|
25.00%
|
0/4
|
0.00%
|
Micrococcus spp.
|
3
|
1.69%
|
2
|
1
|
1
|
33%
|
2.17%
|
1
|
2
|
0/3
|
0.00%
|
0/3
|
0.00%
|
S. aureus
|
36
|
20.22%
|
24
|
12
|
5
|
14%
|
10.87%
|
17
|
19
|
5/36
|
13.89%
|
1/36
|
2.78%
|
Coagulase negative Staphylococci
|
72
|
40.45%
|
45
|
27
|
24
|
33%
|
52.17%
|
39
|
33
|
4/72
|
5.56%
|
2/72
|
2.78%
|
Streptococcus spp.
|
2
|
1.12%
|
2
|
0
|
0
|
0%
|
0.00%
|
2
|
0
|
0/2
|
0.00%
|
0/2
|
0.00%
|
Enterococcus spp.
|
22
|
12.36%
|
14
|
8
|
3
|
14%
|
6.52%
|
11
|
11
|
3/22
|
13.64%
|
0/22
|
0.00%
|
Total
|
178
|
100%
|
118
|
60
|
46
|
|
100%
|
89
|
89
|
16/175
|
9.14%
|
4/175
|
2.23%
|
a. Aerobic BACTEC system was used for detection of microbial agents responsible for bloodstream infection.
Table 2. The frequency and diversity of Gram-positive and yeasts in bloodstream infection of children according to ward of hospitalization in a pediatric hospital in Tehran, Iran, 2020-2022.
Microorganisms
|
Wardsb
|
Total
|
Not reported
|
BMTa
|
ED
|
GI
|
Infectious diseases
|
Pulmonary
|
Nephrology
|
Neurology
|
Oncology
|
PICU
|
Rheumatology
|
Surgery
|
Not reportedc
|
|
0
|
1
|
0
|
1
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
3
|
% within not reported
|
0.0%
|
33.3%
|
0.0%
|
33.3%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
100.0%
|
|
% within Ward
|
0.0%
|
2.6%
|
0.0%
|
10.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
1.7%
|
Candidia
|
|
1
|
1
|
1
|
2
|
0
|
0
|
0
|
0
|
5
|
0
|
2
|
12
|
% within Candida spp.
|
8.3%
|
8.3%
|
8.3%
|
16.7%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
41.7%
|
0.0%
|
16.7%
|
100.0%
|
% within Ward
|
4.0%
|
2.6%
|
7.7%
|
20.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
9.3%
|
0.0%
|
18.2%
|
6.7%
|
Corynebacterium spp.
|
|
0
|
0
|
2
|
1
|
1
|
0
|
0
|
0
|
0
|
0
|
0
|
4
|
% within Bacteria
|
0.0%
|
0.0%
|
50.0%
|
33.3%
|
33.3%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
100.0%
|
% within Ward
|
0.0%
|
0.0%
|
7.7%
|
10.0%
|
16.7%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
1.7%
|
Enterococcus spp.
|
|
5
|
9
|
2
|
0
|
1
|
0
|
1
|
2
|
1
|
1
|
0
|
22
|
% within Bacteria
|
22.7%
|
40.9%
|
9.1%
|
0.0%
|
4.5%
|
0.0%
|
4.5%
|
9.1%
|
4.5%
|
4.5%
|
0.0%
|
100.0%
|
% within Ward
|
20.0%
|
23.7%
|
15.4%
|
0.0%
|
16.7%
|
0.0%
|
14.3%
|
66.7%
|
1.9%
|
20.0%
|
0.0%
|
12.3%
|
Micrococcus spp.
|
|
0
|
1
|
0
|
0
|
0
|
0
|
0
|
0
|
1
|
0
|
1
|
3
|
% within Bacteria
|
0.0%
|
33.3%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
33.3%
|
0.0%
|
33.3%
|
100.0%
|
% within Ward
|
0.0%
|
2.6%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
1.9%
|
0.0%
|
9.1%
|
1.7%
|
S. aureus
|
|
5
|
9
|
1
|
3
|
0
|
1
|
3
|
1
|
7
|
1
|
5
|
36
|
% within Bacteria
|
13.9%
|
25.0%
|
2.8%
|
8.3%
|
0.0%
|
2.8%
|
8.3%
|
2.8%
|
19.4%
|
2.8%
|
13.9%
|
100.0%
|
% within Ward
|
20.0%
|
23.7%
|
7.7%
|
30.0%
|
0.0%
|
16.7%
|
42.9%
|
33.3%
|
13.0%
|
20.0%
|
45.5%
|
20.1%
|
CNS
|
|
11
|
14
|
1
|
3
|
2
|
4
|
3
|
0
|
31
|
1
|
2
|
72
|
% within Bacteria
|
15.5%
|
19.4%
|
1.4%
|
4.2%
|
2.8%
|
5.6%
|
4.2%
|
0.0%
|
43.0%
|
1.4%
|
2.8%
|
100.0%
|
% within Ward
|
44.0%
|
36.8%
|
7.7%
|
30.0%
|
33.3%
|
66.7%
|
42.9%
|
0.0%
|
55.6%
|
20.0%
|
18.2%
|
39.7%
|
Streptococcus spp.
|
|
1
|
0
|
1
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
2
|
% within Bacteria
|
50.0%
|
0.0%
|
50.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
100.0%
|
% within Ward
|
4.0%
|
0.0%
|
7.7%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
1.1%
|
Other fungi
|
|
2
|
3
|
5
|
0
|
1
|
1
|
0
|
0
|
9
|
2
|
1
|
24
|
% within other fungi
|
8.3%
|
12.5%
|
20.8%
|
0.0%
|
4.2%
|
4.2%
|
0.0%
|
0.0%
|
37.5%
|
8.3%
|
4.2%
|
100.0%
|
% within Ward
|
8.0%
|
7.9%
|
38.5%
|
0.0%
|
16.7%
|
16.7%
|
0.0%
|
0.0%
|
16.7%
|
40.0%
|
9.1%
|
13.4%
|
Total
|
|
25
|
38
|
13
|
10
|
5
|
6
|
7
|
3
|
54
|
5
|
11
|
178
|
% within microorganisms
|
14.0%
|
21.2%
|
7.3%
|
5.6%
|
2.8%
|
3.4%
|
3.9%
|
1.7%
|
30.2%
|
2.8%
|
6.1%
|
100.0%
|
% within Ward
|
|
|
|
|
|
|
100.0%
|
100.0%
|
100.0%
|
100.0%
|
100.0%
|
100.0%
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
a. Abbreviations: BMT, Bone marrow transplantation; ED, Emergency room; GI, Gastroenterology; PICU, Pediatric Intensive Care Unit; CNS, Coagulase-negative Staphylococcus spp.
b, Percentages of BSI-GPB higher than 10% are shown in bold.
c. “Not reported” indicates BSI-GPB samples that have Gram positive staining records, but names of Gram-positive bacteria were not indicated.
Results of antibiotic susceptibility testing showed highest frequency of resistance to azithromycin, oxacillin, penicillin among CNS, azithromycin, tetracycline, trimethoprim/sulfamethoxazole, oxacillin and clindamycin among S. aureus, and trimethoprim/sulfamethoxazole, tetracycline, gentamicin, ciprofloxacin, and penicillin among Enterococcus spp. blood isolates (Figure 3). The highest susceptibility was detected to minocycline, linezolid, chloramphenicol, and norfloxacin in CNS, minocycline, doxycycline, rifampicin, and norfloxacin in S. aureus, and linezolid and chloramphenicol in Enterococcus spp. MR phenotype in S. aureus (MRSA) and coagulase-negative Staphylococcus spp. (MR-CNS) isolates that showed resistance to cefoxitin was detected in 40% and 61.5% of the strains, while 33.3% of the Enterococcus isolates presented VRE phenotype. VRE, MRSA, and MR-CNS isolates mainly belonged to Emergency Room (3/6, 50%), Infectious Diseases (2/4, 50%), and PICU (11/16, 68.7%) wards, respectively. Details about the resistance frequency for each antibiotic are shown in Table 3. Multidrug resistance (MDR) phenotype was detected in 90.7%, 100%, and 77.7% of the CNS, S. aureus and Enterococcus spp. isolates, respectively. All the CNS strains with resistant phenotype to cefoxitin, oxacillin and penicillin and all vancomycin-resistant strains of Enterococcus spp. showed MDR phenotype (Table 4 and Supplementary Table 1). Statistical analysis did not show a correlation between MDR patterns and COVID-19 infection status for most of the bacterial genera, except for CNS, where an inverse correlation was shown between COVID-19 status and methicillin resistance phenotype (p-value= 0.029). Accordingly, out of 25 CNS with cefoxitin test, MR-CNS strains mainly belonged to the COVID-19 negative cases in comparison to COVID-19 positive children with CNS-bacteremia (76.4%, 13/17 vs 37.5%, 3/8).
Table 3. Antimicrobial susceptibility of Gram-positive bacterial isolates from BSI in pediatrics in a referral Children’s hospital in Tehran, Iran during 2020-2022.
Bacteriaa
|
|
Antibioticsb.
|
|
AZ
|
CIP
|
FOX
|
SXT
|
CHL
|
CLN
|
DOX
|
GEN
|
LNZ
|
MIN
|
NOR
|
OXA
|
PEN
|
RIF
|
TET
|
VAN
|
AMP
|
LEV
|
AMX
|
CEF
|
CFX
|
CNS
|
S
|
5
|
21
|
10
|
13
|
53
|
18
|
40
|
27
|
54
|
23
|
36
|
7
|
3
|
38
|
16
|
54
|
|
|
|
|
|
|
I
|
0
|
3
|
0
|
0
|
0
|
0
|
1
|
1
|
1
|
1
|
0
|
0
|
0
|
0
|
0
|
0
|
|
|
|
|
|
|
R
|
50
|
32
|
16
|
42
|
6
|
42
|
17
|
31
|
5
|
0
|
6
|
49
|
17
|
19
|
8
|
4
|
|
|
|
|
|
|
S %
|
9%
|
37.5%
|
38.5%
|
23.6%
|
89.8%
|
30%
|
68.9%
|
45.7%
|
91.5%
|
95.8%
|
85.7%
|
12.5%
|
15%
|
66.6%
|
66.6%
|
93.1%
|
|
|
|
|
|
S. aureus
|
S
|
1
|
11
|
6
|
5
|
14
|
5
|
12
|
11
|
|
8
|
14
|
3
|
4
|
13
|
1
|
18
|
|
|
|
|
|
|
I
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
|
|
|
|
|
R
|
16
|
10
|
4
|
15
|
6
|
14
|
5
|
6
|
|
2
|
3
|
12
|
3
|
5
|
10
|
1
|
|
|
|
|
|
|
S %
|
5.8%
|
52.4%
|
60%
|
25%
|
70%
|
26.3%
|
70.6%
|
64.7%
|
|
80%
|
82.3%
|
20%
|
57.1%
|
72.2%
|
9%
|
94.7%
|
|
|
|
|
|
Enterococcus spp.
|
S
|
|
5
|
4
|
1
|
10
|
|
|
2
|
17
|
|
|
|
5
|
|
3
|
12
|
5
|
3
|
|
|
|
|
I
|
|
0
|
0
|
0
|
0
|
|
|
0
|
0
|
|
|
|
0
|
|
0
|
0
|
0
|
0
|
|
|
|
|
R
|
|
13
|
6
|
9
|
0
|
|
|
8
|
0
|
|
|
|
12
|
|
13
|
6
|
6
|
7
|
|
|
|
|
S %
|
|
27.8%
|
40%
|
10%
|
100%
|
|
|
20%
|
100%
|
|
|
|
29.4%
|
|
18.8%
|
66.6%
|
45.5%
|
30%
|
|
|
|
Micrococcus spp.
|
S
|
|
|
1
|
1
|
1
|
|
1
|
1
|
|
1
|
1
|
1
|
1
|
1
|
1
|
1
|
|
|
|
|
|
|
I
|
|
|
0
|
0
|
0
|
|
0
|
0
|
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
|
|
|
|
|
R
|
|
|
0
|
0
|
0
|
|
0
|
0
|
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
|
|
|
|
|
S %
|
|
|
100%
|
100%
|
100%
|
|
100%
|
100%
|
|
100%
|
100%
|
100%
|
100%
|
100%
|
100%
|
100%
|
|
|
|
|
|
Non-Group A
Streptococcus spp.
|
S
|
|
|
|
0
|
1
|
1
|
|
|
1
|
|
|
|
1
|
1
|
1
|
1
|
|
1
|
1
|
1
|
1
|
|
I
|
|
|
|
0
|
0
|
0
|
|
|
0
|
|
|
|
0
|
0
|
0
|
0
|
|
0
|
0
|
0
|
0
|
|
R
|
|
|
|
1
|
0
|
0
|
|
|
0
|
|
|
|
0
|
0
|
0
|
0
|
|
0
|
0
|
0
|
0
|
|
S %
|
|
|
|
0
|
100%
|
100%
|
|
|
100%
|
|
|
|
100%
|
100%
|
100%
|
100%
|
|
100%
|
100%
|
100%
|
100%
|
a. Difference in the number of isolates tested for susceptibility testing of each antibiotic is related to documented data in the hospital microbiology laboratory unit.
b. AMP, ampicillin; AMC, Amoxicillin + Clavulanic acid; AMX, Amoxicillin; AZ, Azithromycin; CHL, Chloramphenicol; CIP, Ciprofloxacin; CN, Clindamycin; FOX, Cefoxitin; SXT, Trimethoprim / sulfamethoxazole; DOX, Doxycycline; GEN, Gentamicin; LNZ, Linezolid; MIN, Minocycline; NOR, Norfloxacin; OXA, Oxacillin; PEN, Penicillin; RIF, Rifampicin; TET, Tetracycline; VAN, Vancomycin; AMP-SUL, Ampicillin-Sulbactam; CTR, Ceftriaxone; MER, Meropenem; EV, Levofloxacin; CEF, Cefepime; CFX, Cefuroxime. CNS, Coagulase-negative Staphylococcus spp.
Table 4. The frequency and diversity of Multidrug Resistance phenotypes among Gram-positive bacterial isolates from BACTEC vials in a pediatric hospital in Tehran, Iran 2020-2022.
Bacteria
|
|
MDRa
|
Total MDR
|
No MDR
|
Not tested
|
|
|
3DR
|
4DR
|
5DR
|
6DR
|
7DR
|
8DR
|
9DR
|
10DR
|
|
|
|
CNS
|
73
|
6
|
7
|
11
|
11
|
8
|
7
|
3
|
2
|
55
|
6
|
12
|
|
|
10.9%
|
12.7%
|
20%
|
20%
|
14.5%
|
12.7%
|
5.4%
|
3.6%
|
90.1%
|
8.2%
|
16.4%
|
S. aureus
|
35
|
2
|
6
|
4
|
4
|
3
|
1
|
0
|
0
|
20
|
0
|
15
|
|
|
10%
|
30%
|
20%
|
20%
|
15%
|
5%
|
0
|
0
|
100%
|
0
|
42.8%
|
Enterococcus spp.
|
20
|
5
|
3
|
0
|
2
|
2
|
2
|
0
|
0
|
14
|
4
|
2
|
|
|
35.7%
|
21.4%
|
0
|
14.3%
|
14.3%
|
14.3%
|
0
|
0
|
77.7%
|
20%
|
10%
|
a. Multiple Drug Resistance phenotype (MDR): refers to bacteria that are resistant to at least one antimicrobial agent in three or more antimicrobial classes. The numbers before DR indicate No. of classes of antibiotics that the blood isolates showed resistance phenotypes.