Prevalence of bacterial respiratory infections
Out of the 175 outpatients, 125 (71.4 %) presenting with lower respiratory infections had their sputum samples screened and 50 (28.6 %) presenting with upper respiratory infections had their throat swabs screened. A total of 58 (46.4 %) 0f sputum samples showed significant growth of bacterial isolates while 23 (46.0 %) of throat swabs showed significant growth of bacterial isolates (Table 1). 81 patients (46.3%) were found to have bacterial respiratory infections while 94 (53.7 %) were not infected.
Table 1 Prevalence of bacterial respiratory tract infections
Respiratory infections
|
Number
|
Positive cases
|
Prevalence (%)
|
Lower respiratory tract infections
|
125
|
58
|
46.6
|
Upper respiratory tract infections
|
50
|
23
|
46.0
|
Total
|
175
|
81
|
46.3
|
Prevalence of bacterial isolates
In this study, the bacteria isolates obtained were; Pseudomonas sp. 25 (30.9 %), Staphylococcus aureus 18 (22.2 %), Klebsiella sp. 16 (19.8 %), Streptococcus pyogenes 12 (14.8 %) and Streptococcus pneumoniae 10 (12.4 %). Staphylococcus aureus (45 %) was the most prevalent Gram positive bacteria followed by Streptococcus pyogenes (30 %) then Streptococcus pneumoniae (25 %). Among the Gram negative bacteria, Pseudomonas species (61 %) was the most prevalent followed by Klebsiella species (39 %) (Figure 1).
Bacterial isolates obtained from the samples
Out of the 81 isolates, 58 bacterial isolates were obtained from sputum samples while 23 bacterial isolates from throat swabs. Pseudomonas species (43.1 %) were the predominant organism obtained from sputum samples followed by Klebsiella species (27.6 %), Staphylococcus aureus (17.2 %) and Streptococcus pneumoniae (12.1 %).
Streptococcus pyogenes (52.2 %) was the most common organism obtained from throat swab samples followed by Staphylococcus aureus (34.8 %) then Streptococcus pneumoniae (13.0 %) (Table 2).
Table 2 Bacterial isolates obtained from sputum and throat swab samples
Sputum samples
n=58
Bacterial isolate
|
Number
|
Throat swab samples n=23
Bacterial isolate
|
Number
|
Pseudomonas species
|
25 (43.1)
|
Streptococcus pyogenes
|
12 (52.2)
|
Klebsiella species
|
16 (27.6)
|
Staphylococcus aureus
|
08 (34.8)
|
Staphylococcus aureus
|
10 (17.2)
|
Streptococcus pneumoniae
|
03 (13.0)
|
Streptococcus pneumoniae
|
07(12.1)
|
|
|
Key: *Values in parenthesis represent percentage of bacterial isolates.
Prevalence of respiratory bacterial pathogens in different age groups and gender
The prevalence of isolated respiratory bacterial pathogens in patients in relation to their age group and gender were determined (Table 3). Out of the 81 positive bacterial growth recorded, the percentage prevalence of isolates in different age groups ranged from 2.5 to 30.9 %. In relation to gender, bacterial isolates were more predominant in males (79 %) than in females (21 %).
Table 3 Prevalence of respiratory bacterial pathogens in different age groups and gender
Risk factors
|
Proportion of bacterial isolates n (%)
|
|
Age groups
|
Pseudomonas sp.
|
Klebsiella sp.
|
S. pne
|
S. aur
|
S.pyog
|
Total n (%) P value
|
5-14
|
5 (6.2)
|
2 (2.5)
|
2 (2.5)
|
2 (2.5)
|
3 (3.7)
|
14 (17.3)
|
15-24
|
3 (3.7)
|
2 (2.5)
|
0 (0)
|
3 (3.7)
|
1 (1.2)
|
9 (11.1)
|
25-34
|
7 (8.6)
|
4 (4.9)
|
3 (3.7)
|
6 (7.4)
|
5 (6.2)
|
25 (30.9)
|
35-44
|
5 (6.2)
|
6 (7.4)
|
5 (6.2)
|
4 (4.9)
|
1 (1.2)
|
21 (25.9)
|
45-54
|
2 (2.5)
|
1 (1.2)
|
0 (0)
|
1 (1.2)
|
2 (2.5)
|
6 (7.4)
|
55-64
|
2 (2.5)
|
1 (1.2)
|
0 (0)
|
1 (1.2)
|
0 (0)
|
4 (4.9)
|
Above 65
|
1 (1.2)
|
0 (0)
|
0 (0)
|
1 (1.2)
|
0 (0)
|
2 (2.5)
|
Total n (%)
|
25 (30.9)
|
16
(19.8 %)
|
10 (12.3%)
|
18 (22.2)
|
12
(14.8)
|
81
(100) 0.9815
|
Gender
|
P value
|
Male
|
21 (25.9)
|
15
(18.5)
|
3
(3.7)
|
15 (18.5)
|
10
(12.3)
|
|
Female
|
4
(4.9)
|
1
(1.2)
|
7
(8.6)
|
3
(3.7)
|
2
(2.5)
|
|
Total
|
25 (30.9)
|
16
(19.8)
|
10 (12.3)
|
18 (22.2)
|
12
(14.8)
|
0.0017
|
Key: (S. pyog- Streptococcus pyogenes, S. aur- Staphylococcus aureus, S. pne- Streptococcus pneumoniae). P- Values were obtained using χ2 test.
Antimicrobial sensitivity profile of the bacterial isolates
Antimicrobial susceptibility profile of bacteria isolates to frequently prescribed antibiotics (Table 4). The isolates were highly susceptible to cefuroxime, amikacin and gentamicin but displayed resistance to amoxicillin and ampicillin.
Table 4 Antimicrobial susceptibility of respiratory bacterial isolates
Antibiotics
|
Percentage of bacterial isolates sensitive to antibiotics
|
|
S. aureus
n=18
|
S.pyogenes n=12
|
S.pneumoniae n=10
|
Pseudomonas sp. n=25
|
Klebsiella sp. n=16
|
|
|
|
|
|
|
Gentamicin
|
100
|
100
|
100
|
92
|
100
|
Cephalexin
|
-
|
83.3
|
80
|
-
|
-
|
Amoxicillin
|
0.0
|
16.7
|
0.0
|
0.0
|
0.0
|
Amikacin
|
100
|
100
|
100
|
96
|
87.5
|
Ampicillin
|
0.0
|
0.0
|
0.0
|
0.0
|
0.0
|
Cefuroxime
|
100
|
100
|
100
|
92
|
100
|
Ceftazidiime
|
-
|
91.7
|
70
|
80
|
68.8
|
Piperacillin/tazobactam
|
-
|
-
|
-
|
16
|
-
|
Ciprofloxacin
|
-
|
-
|
-
|
12
|
87.5
|
Resistance of the bacterial isolates to the antimicrobial agents used.
The total of 81 bacterial isolates were screened for antimicrobial resistance. Among the screened bacterial isolates, resistance to more than 2 antibiotics was recorded in 54 (66.7%) of the isolates (Table 5).
Table 5 Resistance of the bacteria isolates to the antimicrobial agents used
Bacterial isolate
|
Total (%)
|
R0
|
R1
|
R>2
|
S. aureus
|
18
|
2(11.1%)
|
3(16.7%)
|
13(72.2%)
|
S.pyogenes
|
12
|
8(66.7%)
|
0(0.0%)
|
4(33.3%)
|
S.pneumoniae
|
10
|
1(10.0%)
|
1(10.0%)
|
8(80.0%)
|
Pseudomonas sp.
|
25
|
7(28.0%)
|
2(8.0%)
|
16(64.0%)
|
Klebsiella sp.
Total
|
16
81
|
0(0.0%)
18(22.2%)
|
3(18.8%)
9(11.1%)
|
13(81.2%)
54(66.7%)
|
Key: R0-Resistance to no antibiotic, R1-Resistance to one antibiotic, R>2-Resistance to more than two antibiotics.