Culture and antimicrobial susceptibility testing was performed for 313 clinical specimens (211 blood and 102 CSF) from 238 neonates suspected to have sepsis. Of these, 75 neonates had both blood and CSF cultures done. Overall, 63.5% (134/211) of the blood cultures and 3.9% (4/102) of the CSF cultures were found to be positive for microbial growth. From these clinical specimens (blood and CSF), a total of 135 bacterial and 8 fungal etiologies were isolated. Sepsis episodes caused by Gram-positive bacteria, Gram-negative bacteria, and Candida species were 50.3% (70/139), 43.9% (61/139), and 5.8% (8/139), respectively. Among the 131 bacterial pathogens isolated from blood culture, the predominant isolates were CoNS 27.5% (36/131), S. aureus 20.6% (27/131), Klebsiella spp. 14.5% (19/131), and Acinetobacter species 10.7% (14/131) (Figure 1). Of these, double bacterial isolates were detected in cultures from five neonates.
From CSF samples, two Acinetobacter spp. and two K. pneumoniae were isolated. In one neonate, three types of bacterial pathogens were isolated simultaneously; S. aureus and Acinetobacter species from blood culture and K. pneumoniae from CSF.
CoNS – coagulase-negative Staphylococcus, GBS – group b Streptococcus, spp – species
Figure 1: Etiologies identified from blood culture in neonates admitted with sepsis to neonatal intensive care unit of Jimma Medical Center, Ethiopia
Antibiotic susceptibility pattern of isolates
The most common Gram-negative bacterial pathogens isolated in this study (from both blood and CSF) were Klebsiella spp., Acinetobacter spp., and Citrobacter spp. accounting for 32.3% (21/65), 24.6% (16/65), and 15.4% (10/65) of the isolates, respectively. All of the isolated Klebsiella spp. were resistant to ampicillin, amoxicillin/clavulanic-acid, cefoxitin, ceftriaxone, cefepime, chloramphenicol, sulfamethoxazole-trimethoprim, and tetracycline. Similarly, all isolates of Acinetobacter spp. were found to be resistant to ampicillin, amoxicillin/clavulanic acid, cefoxitin, ceftazidime, ceftriaxone, chloramphenicol, tetracycline and sulfamethoxazole-trimethoprim. However, all isolates of Klebsiella spp. were susceptible to meropenem, whereas 25% of Acinetobacter spp. were meropenem resistant. The other commonly isolated Gram-negative bacteria causing neonatal sepsis, Citrobacter spp., also showed MDR patterns, being resistant to ampicillin, amoxicillin/clavulanic acid, cefoxitin, ceftazidime, ceftriaxone, cefepime, and tetracycline. Three (30%) of the isolated Citrobacter spp. were resistant to meropenem (Table 1).
Table 1: Antibiotic resistance patterns of Gram-negative bacterial pathogens in neonates admitted with sepsis to neonatal intensive care unit of Jimma Medical Center, Ethiopia
Antibiotics
|
Klebsiella spp. (n=21)
|
Acinetobacter spp. (n=16)
|
Citrobacter spp. (n=10)
|
E. coli (n=5)
|
P. aeruginosa (n=5)
|
*Other GNB (n=8)
|
Total (n=65)
|
Ampicillin
|
100%
|
100%
|
100%
|
100%
|
100%
|
100%
|
100%
|
Amoxicillin/clavulanate
|
100%
|
100%
|
100%
|
100%
|
100%
|
100%
|
100%
|
Cefoxitin
|
100%
|
100%
|
100%
|
60%
|
100%
|
100%
|
100%
|
Ceftazidime
|
95%
|
100%
|
100%
|
60%
|
100%
|
100%
|
95%
|
Ceftriaxone
|
100%
|
100%
|
100%
|
40%
|
100%
|
100%
|
95%
|
Cefepime
|
100%
|
81%
|
100%
|
40%
|
100%
|
100%
|
91%
|
Tetracycline
|
100%
|
100%
|
100%
|
80%
|
100%
|
100%
|
98%
|
Chloramphenicol
|
100%
|
100%
|
90%
|
20%
|
0%
|
88%
|
74%
|
Trimethoprim-sulphamethoxazole
|
100%
|
100%
|
90%
|
60%
|
80%
|
88%
|
92%
|
Ciprofloxacin
|
76%
|
31%
|
30%
|
20%
|
20%
|
63%
|
48%
|
Gentamycin
|
76%
|
50%
|
80%
|
40%
|
20%
|
63%
|
62%
|
Meropenem
|
0%
|
25%
|
30%
|
0%
|
60%
|
12.5%
|
17%
|
* Includes: Enterobacter spp. (3), Providencia spp. (3), Serratia spp. (1), and Proteus mirabilis (1)
GNB – Gram-negative bacteria
Coagulase negative Staphylococci (51.4%; 36/70) and S. aureus (38.6%; 27/70) were the most common Gram-positive bacteria isolated from the study participants. The CoNS group showed high level of resistance to penicillin (89.0%) and oxacillin (83.3%). Similarly, S. aureus, showed a high rate of resistance against sulfamethoxazole-trimethoprim (88.9%), penicillin (85.2%), tetracycline (74.1%) and erythromycin (70.4%). Moreover, 63.0% of S. aureus were methicillin resistant (MRSA). On the other hand, the Micrococcus spp. identified in three neonates were found to be susceptible to almost all antibiotics tested (Table 2).
Table 2: Antibiotic resistance pattern of isolated Gram-positive bacterial pathogens in neonates admitted with sepsis to neonatal intensive care unit of Jimma Medical Center, Ethiopia
Antibiotics
|
CoNS (n=36)
|
S. aureus (n=27)
|
*Other GPB (n=7)
|
Total (n=70)
|
Penicillin
|
89%
|
85%
|
71.4%
|
86%
|
Oxacillin
|
83%
|
63%
|
71.4%
|
74%
|
Cefoxitin
|
83%
|
63%
|
71.4%
|
74%
|
Erythromycin
|
56%
|
70%
|
57.1%
|
61%
|
Clindamycin
|
33%
|
33%
|
57.1%
|
36%
|
Ceftriaxone
|
78%
|
67%
|
57.1%
|
73%
|
Tetracycline
|
81%
|
74%
|
71.4%
|
76%
|
Trimethoprim-sulphamethoxazole
|
89%
|
89%
|
57.1%
|
86%
|
Vancomycin
|
6%
|
11%
|
0%
|
7%
|
* Includes: Group B Streptococcus (n=3), Micrococcus spp. (n=3), and L. monocytogenes (n=1)
GPB – Gram-positive bacteria
Resistance to more than one agent in three or more antimicrobial categories was seen in 84.4% (114/135) of the bacterial isolates. MDR patterns were observed predominantly in Gram-negative bacterial pathogens. All of the isolated Klebsiella spp., Acinetobacter spp., P. aeruginosa, Providencia spp., Serratia spp., P. mirabilis, and 90% of Citrobacter spp. were MDR (Figure 2). Amongst the isolated Gram-negative MDR strains, one strain of each of Providencia spp., Klebsiella spp. and Citrobacter spp., and two strains of Acinetobacter spp. were resistant to all of the tested antibiotics, including carbapenem antibiotics.
MDR – multidrug resistant, NMDR – non-multidrug resistant, GNB – Gram-negative bacteria, GPB – Gram-positive bacteria.
Figure 2: Distribution of MDR and non-MDR patterns of bacterial isolates in neonates admitted with sepsis to neonatal intensive care unit of Jimma Medical Center, Ethiopia
Twenty-four, 10.1% (24/238) of the neonates died in the hospital. Of these, 66.7% (16/24) had positive blood and/or CSF culture and a total of 17 pathogens were identified from them. The predominant isolates in these groups were Klebsiella spp. (n=5), Acinetobacter spp. (n=2), P. aeruginosa (n=2) and Citrobacter species (n=2), all of which were MDR. E. coli and Enterobacter spp. isolated in this group were also found to be MDR. Though the sample size of this group is too small to determine any statistical association, it is highly possible that MDR organisms might have contributed to neonatal mortality at the hospital. It is also important to note here that 81% (13/16) of the deaths in culture-confirmed cases occurred in patients identified with Gram-negative bacterial sepsis.