Background
Pneumonia caused by Streptococcus pneumoniae is the leading cause of death among children in Ethiopia. S. pneumoniae nasopharyngeal carriage can result in endogenous infections and bacterial spread in the community. S. pneumoniae drug resistance is rapidly increasing worldwide. The aim of the study was to assess the nasopharyngeal carriage and antimicrobial susceptibility pattern of S. pneumoniae among pediatric outpatients.
Methods
A cross-sectional study was conducted on children aged ≤10 years from February to May of 2012. Data on potential risk factors were gathered using an interview-based questionnaire. Nasopharyngeal specimens were collected with a sterile plastic cotton tip swab. Bacteria were characterized by colony appearance, Gram staining, and optochin susceptibility and bile solubility tests. An antimicrobial susceptibility test was performed using the disk diffusion method. A logistic regression analysis was used to examine the possible risk factors. All tests with p value less than 0.05 were considered statistically significant.
Results
Of the 234 children screened, 41.03% carried S. pneumoniae. Age-related downward trend for S. pneumoniae carriages (50.9% in <3-year-olds, 40.7% in 3- to 5-year-olds, 40.0% in 5- to <8-year-olds, and 33.3% in 8- to 10-year-olds) were observed. Children living with siblings < 5 years old (p = 0.003) and in a house having one room (p = 0.004) were associated with higher S. pneumoniae carriage. S. pneumoniae showed 33.2% resistance to erythromycin and tetracycline, 29.2% to cotrimoxazole, 14.6% to chloramphenicol and ciprofloxacin, and 10.4% to penicillin.
Conclusion
The S. pneumoniae carriage rate was higher among younger children. High antimicrobial resistance of S. pneumoniae against erythromycin, tetracycline, and cotrimoxazole was observed. Being in the young age group and living with younger children are risk factors for pneumococcal carriage.
Key Words
1. Introduction
Streptococcus pneumoniae is a component of normal nasopharyngeal flora in children. Nasopharyngeal colonization begins shortly after birth. Although nasopharyngeal pneumococcal carriage is usually asymptomatic, it may subsequently serve as the focus for infections in children, the elderly, the immune-compromised, and individuals with chronic disease. S. pneumoniae is the etiology of many diseases including pneumonia, bacteremia, meningitis, otitis media, and sinusitis.
1
One million children die annually from pneumococcal diseases.
1
Pneumonia constitutes a major proportion of the global burden of childhood disease, being responsible for about 20% of childhood deaths, the majority of which occur in developing countries.2
Childhood community-acquired pneumonia accounts for 30% to 40% of hospital admissions with associated case fatality rates of between 15% and 28%.3
Pneumonia kills more children than any other illness and is responsible for 4300 childhood deaths every day, or one in every 20 seconds globally.4
In Ethiopia, pneumonia is the leading cause of death among children, and each year more than 100,000 children die before their 5th birthday due to pneumonia, which accounts for 28% of under-5 mortality.World Health Organization. GAVI Alliance partners to tackle childhood killer in Ethiopia. GAVI press release 2011. Available at: http://www.who.int/immunization/newsroom/press/introduction_pneumococcal_vaccine_in Ethiopia/en/index.html Accessed December 12, 2011.
5
S. pneumoniae is the leading cause of bacterial pneumonia, being identified in 30–50% of cases,6
and it is therefore considered the biggest infectious killer of children under 5 years old in Ethiopia.4
World Health Organization. GAVI Alliance partners to tackle childhood killer in Ethiopia. GAVI press release 2011. Available at: http://www.who.int/immunization/newsroom/press/introduction_pneumococcal_vaccine_in Ethiopia/en/index.html Accessed December 12, 2011.
In Africa, pneumococcal meningitis case fatality rates reach 45%. Even with appropriate treatment, pneumococcal meningitis kills approximately one-third of affected African children.
7
In sub-Saharan Africa, S. pneumoniae was found to account for about 25% to >30% of meningitis cases in children under 5 years, with a case fatality rate of >50%.8
For many years, penicillin and chloramphenicol have been the mainstay of treatment for pneumococcal disease in developing countries, as they are both inexpensive and effective. Unfortunately, the rapid increase in resistance to penicillin and other antimicrobial agents worldwide has made the choice of antimicrobial drugs for S. pneumoniae infections more difficult and costly.
9
, 10
Moreover, nasopharyngeal colonization by antibiotic-resistant S. pneumoniae has been increasing steadily.10
, 11
, 12
, 13
, 14
, 15
, 16
Several clinical and demographic characteristics have been positively associated with an increase in S. pneumoniae colonization, such as young age, crowding, day-care attendance, family size, number of siblings, poverty, smoking, and recent antibiotic use.
17
, 18
Although nasopharyngeal isolates are not useful in predicting the causative agent of invasive disease in individuals, they reflect the epidemiological aspects of S. pneumoniae disease in the community.19
The bacteria carried in the nasopharynx of healthy children reflect the infection-causing strains currently circulating in the community.20
Studies conducted over the past decades have gradually revealed the connection between S. pneumoniae carriage, and mucosal and invasive infections caused by the organism.17
, 21
It was also identified that asymptomatic carriage was a prerequisite for developing invasive and noninvasive S. pneumoniae diseases,
17
and carriers serve as sources of S. pneumoniae transmission to others in the community and in the hospital.22
Furthermore, S. pneumoniae carriage strains have been used as indicators for antimicrobial resistance strains and are helpful in designing appropriate empirical antimicrobial therapies.23
, 24
Therefore, studies of the prevalence of S. pneumoniae, their resistance patterns, and possible risk factors can provide useful indications for more rational therapeutic and preventive strategies. In African countries, children are suffering from extremely high burdens of S. pneumoniae diseases, and therapy for pneumococcal disease remains empiric because of the lack of rapid, sensitive, and specific diagnostic tests. In many African countries and particularly in Ethiopia, there are no epidemiologic data on S. pneumoniae. Therefore, the aim of this study was to determine nasopharyngeal carriage rate, antimicrobial susceptibility pattern, and possible risk factors of S. pneumoniae among pediatric outpatients attending Gondar University Hospital, Ethiopia.2. Methods and Materials
2.1 Study design and participants
This study was conducted on children who were attending Gondar University Hospital pediatrics outpatient department from February 15 to May 15, 2012. Based on figures from the Central Statistical Agency in 2008, Gondar has an estimated total population of 231,977. Gondar University Hospital is a referral hospital with more than 400 beds for North West Ethiopia serving a population of about 5 million. All children aged 10 years and below and who were seen for either well-child care visits or sick care visits were eligible for the study. There were no exclusion criteria. Study participants were selected using a systematic random sampling method. Based on the available data, the total number of children aged 10 years and below who visited the pediatrics outpatient department for any reason in the 3-month period reached 600 (280 respiratory cases and 320 nonrespiratory cases). Every third child seen in this 3-month period was recruited for the study, giving a total study population of 234 (110 respiratory and 320 nonrespiratory cases).
2.2 Collection of demographic and clinical characteristics
The study was reviewed and approved by the institutional review board of the University of Gondar. Written informed consent was obtained from each participant's parent(s) or legal guardian. Individual records were coded and accessed only by research staff. After written informed consent was obtained, three trained interns from the pediatrics department conducted questionnaire-based interviews with the parents or guardians of the children to collect the necessary sociodemographic information. Sociodemographic information included in this study comprised age, sex, family size, siblings < 5 years, siblings ≥ 5 years, number of rooms in the house, and habits of sleeping with parents. In addition, the clinical presentation of illness (upper and lower respiratory tract infection) was collected after clinical diagnosis by the same questionnaire. Each child suspected of having tuberculosis (TB) was sent to the radiology department for chest X-ray and with the same radiologist performing the procedure.
2.3 Nasopharyngeal specimen collection and processing
Nasopharyngeal specimens were obtained by the same trained interns according to the Centers for Disease Control manual.
25
One nasopharyngeal specimen per child was obtained with a sterile synthetic cotton swab on flexible aluminum wire (Fisher Scientific, Pittsburgh, PA, USA). After sampling, swabs were placed immediately into Amies medium (Oxoid, Basingstoke, Hamsphire, England) and transported to the microbiology laboratory. Within 4 hours of collection, the specimens were inoculated onto blood agar (HiMedia, Mumbai, India) supplemented with 5 μg/mL gentamycin plates (Nathan Pirumal, Bombay, India) by rolling the swab over a small area of the plate and streaking the sample using a sterile loop. The inoculated media were then incubated under 5% CO2-enriched atmosphere at 37°C for 24–48 hours.2.4 Identification of bacterial isolates
All isolates were identified based on the method outlined by the Centers for Disease Control.
25
Gram-positive cocci α-hemolytic colonies on blood agar supplemented with 5 μg/mL gentamycin plates were picked up with a wire loop and subcultured onto blood agar plates. An optochin disk with a diameter of 6 mm (5 μg ethylhydrocupreine) was placed aseptically on the streak of inoculum. The plate was incubated in a 5% CO2 atmosphere at 37°C for 18–24 hours. Isolates with a zone of inhibition ≥ 14 mm in diameter were considered susceptible to optochin. Strains with zones of inhibition ranging from 9 mm to 13 mm were tested for bile solubility for confirmation using 2% sodium deoxycholate (bile salt) (Oxoid, Basingstoke, Hamsphire, England).2.5 Antimicrobial susceptibility testing
Antimicrobial susceptibility test to erythromycin (15 μg), chloramphenicol (30 μg), ceftriaxone (10 μg), cotrimoxazole (25 μg), tetracycline (30 μg), vancomycin (30 μg), ciprofloxacin (5 μg), and oxacillin (1 μg) (Oxoid, Basingstoke, Hamsphire, England) were carried out using a disk diffusion method (modified Kirby–Bauer) on Muller Hinton agar (Oxoid, Basingstoke, Hamsphire, England) supplemented with 5% sheep's blood. Based on nonmeningeal isolates of S. pneumoniae interpretation, penicillin susceptibility testing was performed using oxacillin (1 μg) disks.
26
, 27
To standardize the inoculum density for susceptibility tests, a 0.5 McFarland standard (Thermo Oxoid Remel) was used. Within 15 minutes after adjusting the turbidity of the inoculum suspension, a sterile cotton swab was dipped into the adjusted suspension. The dried surface plates were inoculated by streaking the swab over the entire sterile agar surface. The antimicrobial disks were placed on the lawn of bacterial isolates using sterile forceps. Inoculated media were incubated in a 5% CO2 atmosphere for 18–24 hours at 37°C. The results were interpreted by comparing the results to the standard zone sizes of the Clinical and Laboratory Standard Institute. S. pneumoniae ATCC 49619 was used as the quality control strain for each run as recommended by the Clinical and Laboratory Standard Institute.27
2.6 Statistical analysis
The data were analyzed by SPSS package software version SPSS 16.0.2 (SPSS Inc., Chicago. IL, USA). A descriptive analysis was used to determine the demographic characteristics and the prevalence of each isolate. The association between the characteristics of the children and the carriage of S. pneumoniae was first analyzed by a series of bivariate analyses. Then, to control simultaneously for the possible confounding effects of the different variables, the risk of being an S. pneumoniae carrier was estimated by multivariate analysis with stepwise variable selection. In both analyses, the association was expressed in odds ratios (ORs) and 95% confidence intervals (CI). All tests of multivariate analysis with p value <0.05 were considered statistically significant.
3. Results
3.1 Demographic and clinical characteristics
A total of 234 children were enrolled in the study, of whom 121 (51.7%) were female. The mean age of the children was 5.2 years with a standard deviation of 3.0 years. One hundred and thirty-three (56.8%) lived in urban environments. The majority of the children 148 (63.2%) were living within a single room (house with only one room), and only 17 (7.3%) of the children had their own bed. Eighty-seven (37.2%) children had received antibiotics within the past 2 weeks of enrolment. During enrolment, 98 (41.9%) of the children were clinically diagnosed as having a respiratory infection (Table 1).
Table 1Sociodemographic and clinical characteristics of 234 study participants recruited from pediatric outpatients at University of Gondar Hospital, February 15 to May 15, 2012.
| Characteristics of children (n = 234) | n | % | |
|---|---|---|---|
| Sex | Male | 113 | 48.3 |
| Female | 121 | 51.7 | |
| Residence | Urban | 133 | 56.8 |
| Rural | 101 | 43.2 | |
| Age (y) | <3 | 57 | 24.4 |
| 3 to <5 | 54 | 23.4 | |
| 5 to <8 | 60 | 25.6 | |
| 8 to 10 | 63 | 26.9 | |
| Family size | <5 | 90 | 38.5 |
| 5+ | 144 | 61.5 | |
| Siblings < 5 y | Yes | 102 | 43.6 |
| No | 132 | 56.4 | |
| Siblings ≥ 5 y | Yes | 156 | 66.7 |
| No | 78 | 33.3 | |
| Sleeping with parents | Yes | 217 | 92.7 |
| No | 17 | 7.3 | |
| Number of rooms | 1 | 148 | 63.2 |
| 2+ | 86 | 36.8 | |
| Recent use of antibiotics | Yes | 87 | 37.2 |
| No | 147 | 62.8 | |
| URTI | No | 195 | 83.3 |
| TP | 16 | 6.8 | |
| Sinusitis | 23 | 9.8 | |
| LRTI | No | 175 | 74.8 |
| Pn | 27 | 11.5 | |
| TB | 32 | 13.7 | |
| Otitis media | Yes | 12 | 5.1 |
| No | 222 | 94.9 | |
LRTI = lower respiratory tract infection; Pn = pneumonia; TB = tuberculosis; TP = tonsilopharyngitis; URTI = upper respiratory tract infection.
3.2 Nasopharyngeal carriage of S. pneumoniae
Of the 234 children screened, 96 (41.03%) were carriers of S. pneumoniae. The highest S. pneumoniae carriage rate was observed in children aged < 3 years (29 children, 50.9%). The proportion of S. pneumoniae carriage was 49 (43.4%) in males versus 47 (38.8%) in females. In children living with <5-year-old siblings, the overall S. pneumoniae carriage rate was 50 (49.0%). Of the 156 children living with ≥5-year-old siblings, 64 (41.0%) had S. pneumoniae (Table 2).
Table 2Bivariate and multivariate analyses of risk factors for Streptococcus pneumoniae carriage in 234 study participants recruited from pediatric outpatients at the University of Gondar Hospital.
| Variable | n (%) | S. pneumoniae (n = 96) | OR with 95% CI | ||||
|---|---|---|---|---|---|---|---|
| No | Yes | Crude OR (95% CI) | Adjusted OR (95% CI) | p | |||
| n (%) | n (%) | ||||||
| Sex | Female | 121 (51.7) | 74 (61.2) | 47 (38.8) | 0.830 (0.49–1.4) | 0.92 (0.51–1.7) | 0.783 |
| Male | 113 (48.3) | 64 (56.6) | 49 (43.4) | 1 | 1 | ||
| Age (y) | <3 | 57 (24.4) | 28 (49.1) | 29 (50.9) | 2.07 (0.99–4.3) | 3.5 (1.4–8.7) | 0.007 |
| 3 to <5 | 54 (23.4) | 32 (59.3) | 22 (40.7) | 1.38 (0.65–2.9) | 1.6 (0.68–3.9) | 0.275 | |
| 5 to <8 | 60 (25.6) | 36 (60.0) | 24 (40.0) | 1.33 (0.64–2.8) | 1.8 (0.75–4.4) | 0.183 | |
| 8-10 | 63 (26.9) | 48 (76.2) | 21 (33.3) | 1 | 1 | ||
| Residence | Rural | 133 (56.8) | 78 (58.6) | 55 (41.4) | 1.03 (0.61–1.7) | 0.69 (0.33–1.4) | 0.324 |
| Urban | 101 (43.2) | 60 (59.4) | 41 (40.6) | 1 | 1 | ||
| Family size | <5 | 90 (38.5) | 54 (60.0) | 36 (40.0) | 1.07 (0.63–1.8) | 1.38 (0.69–2.74) | 0.358 |
| 5+ | 144 (61.5) | 84 (58.3) | 60 (41.7) | 1 | 1 | ||
| Siblings < 5 y | Yes | 102 (43.6) | 52 (51.0) | 50 (49.0) | 1.79 (1.06–3.05) | 2.84 (1.40–5.76) | 0.004 |
| No | 132 (56.4) | 86 (65.2) | 46 (34.8) | 1 | 1 | ||
| Siblings ≥ 5 y | Yes | 156 (66.7) | 92 (59.0) | 64 (41.0) | 1.00 (0.58–1.7) | 0.70 (0.33–1.51) | 0.362 |
| No | 78 (33.3) | 46 (59.0) | 32 (41.0) | 1 | 1 | ||
| Sleeping with parents | Yes | 156 (66.7) | 92 (59.0) | 64 (41.0) | 1.73 (0.59–5.09) | 0.72 (0.22–2.42) | 0.600 |
| No | 78 (33.3) | 46 (59.0) | 32 (41.0) | 1 | 1 | ||
| Number of rooms in house | 1 | 148 (63.2) | 126 (58.1)) | 91 (41.9) | 2.25 (1.28–3.96) | 2.96 (1.46–5.99) | 0.003 |
| 2+ | 86 (36.8) | 12 (70.6) | 5 (29.4)) | 1 | 1 | ||
| Recent antibiotic use | Yes | 87 (37.2) | 77 (52.0) | 71 (48.0) | 0.879 (0.51–1.51) | 0.89 (0.48–1.64) | 0.701 |
| No | 147 (62.8) | 61 (70.9) | 25 (29.1) | 1 | 1 | ||
| Otitis media | Yes | 12 (5.1) | 5 (41.7) | 7 (58.3) | 2.1 (0.65–6.80) | 2.20 (0.58–8.31) | 0.246 |
| No | 222 (94.9) | 133 (59.9) | 89 (40.1) | 1 | 1 | ||
| URTI | TP | 16 (6.8) | 10 (62.5) | 6 (37.5) | 1.61 (0.58–4.49) | 2.84 (0.82–9.86) | 0.101 |
| Sinusitis | 22 (9.4) | 12 (54.5) | 10 (45.5) | 1.48 (0.62–3.54) | 1.92 (0.71–5.15) | 0.198 | |
| No | 196 (83.8) | 108 (58.7) | 76 (41.3) | 1 | 1 | ||
| LRTI | Pn | 27 (11.5) | 15 (55.6) | 12 (44.4) | 1.85 (0.81–4.24) | 3.55 (1.37–9.20) | 0.009 |
| TB | 32 (13.8) | 23 (71.9) | 9 (28.1) | 1.24 (0.58–2.65) | 1.60 (0.64–4.03) | 0.316 | |
| No | 175 (74.8) | 100 (57.1) | 75 (42.9) | 1 | 1 | ||
CI = confidence interval; LRTI = lower respiratory tract infection; OR = odds ratio; Pn = pneumonia; TB = tuberculosis; TP = tonsilopharyngitis; URTI = upper respiratory tract infection.
3.3 Risk factor analysis for S. pneumoniae nasopharyngeal carriage
The highest S. pneumoniae carriage rate (50.9%) was observed in children aged less than 3 years old. Being within the younger age groups (<3 years) was significantly associated with S. pneumoniae carriage (adjusted OR = 3.4; 95% CI, 1.4–8.73; p = 0.007). In addition, S. pneumoniae carriage was significantly higher in children living with siblings < 5 years old (adjusted OR = 2.84; 95% CI, 1.40–5.76; p = 0.004). Moreover, there was a significant association between carriage by S. pneumoniae and number of rooms in the house (OR = 2.96; 95% CI, 1.46–5.99; p = 0.003) and being pneumonia patients (adjusted OR = 3.55; 95% CI, 1.37–9.20; p = 0.009). However, there was no significant association between, sex, residence, and family size, children living with siblings ≥ 5 years old, sleeping with parents or use of antibiotics within the previous 2 weeks, and carriage rate by S. pneumoniae (Table 2).
3.4 Antimicrobial susceptibility patterns of bacterial isolates
The antibiotic susceptibility pattern of all isolates of S. pneumoniae is shown in Table 3. Only two S. pneumoniae were susceptible to all of the antibiotics tested, 75 (78.1%) were resistant to one antimicrobial agent, eight (8.3%) were resistant to two, and 11 (11.5%) to more than two. Ten (10.4%) penicillin-resistant S. pneumoniae were isolated. Thirty-two (33.3%) S. pneumoniae isolates were resistant to erythromycin and tetracycline, and 22 (22.9%) were resistant and six (6.3%) were intermediately resistant to cotrimoxazole. However, all isolates of S. pneumoniae were susceptible to ceftriaxone and vancomycin. Nineteen (19.8%) of the S. pneumoniae isolates were resistant to two or more antimicrobial agents. Six penicillin-resistant S. pneumoniae were also resistant to two or more antibiotics tested.
Table 3Antimicrobial susceptibility patterns of Streptococcus pneumoniae, isolated from 234 study participants recruited from the pediatric outpatients at the University of Gondar Hospital.
| Antimicrobials | S. pneumoniae (n = 96) | ||
|---|---|---|---|
| Resistant | Intermediate | Susceptible | |
| n (%) | n (%) | n (%) | |
| Cotrimoxazole | 22 (22.9) | 6 (6.3) | 66 (68.8) |
| Chloramphenicol | 14 (14.6) | 0 (0) | 82 (85.4) |
| Erythromycin | 32 (33.2) | 0 (00) | 64 (66.7) |
| Tetracycline | 32 (33.2) | 0 (00) | 64 (66.7) |
| Ceftriaxone | 0 (0) | 0 (0) | 96 (100) |
| Ciprofloxacin | 2 (2.1) | 12 (12.5) | 82 (85.4) |
| Vancomycin | 0 (0) | 0 (0) | 96 (100) |
| Penicillin | 10 (10.4) | 0 (0) | 86 (89.6) |
4. Discussion
In this study, a high carriage rate (41.03%) of S. pneumoniae was observed. Although the nasopharyngeal carriage rate of S. pneumoniae among children varies widely throughout the world, the current result was in harmony with various studies.
23
, 28
, - Zemlicková H.
- Urbásková P.
- Adámková V.
- Motlová J.
- Lebedová V.
- Procházka B.
Characteristics of Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis and Staphylococcus aureus isolated from the nasopharynx of healthy children attending day-care centres in the Czech Republic.
Epidemiol Infect. 2006; 134: 1179-1187
29
, 30
This may, therefore, suggest that large numbers of pneumococcal carriers are at high risk of developing invasive and noninvasive pneumococcal diseases and that family members are at risk of acquiring the pathogens. The higher isolation rates of S. pneumoniae among children place at risk not only their families but also their peers with whom they interact in the community. The high prevalence of S. pneumoniae could be because many children may be immunocompromised as a result of the diseases that prompted them to visit the hospital. Comparatively lower S. pneumoniae carriage was reported in Taiwan (14%),31
Turkey (13.9%),14
and Finland (5.4%).32
However, higher carriage of S. pneumoniae (87%) was reported in Mozambique among younger children (1 month to <5 years)33
and in Belgium 69%.23
Seasonal variation and methodological differences may explain the differences in reported pneumococci carriage.In our results, S. pneumoniae showed an age-related downward trend. Children belonging to the age group of <3 years were the most colonized (29: 50.9%), followed by those 3–5 years of age (22: 40.7%). Children between 8 years and 10 years were the least vulnerable to pneumococcal nasopharyngeal carriage (21: 33.3%). These findings are concordant with reports from the Czech Republic, Israel, and Kenya.
28
, - Zemlicková H.
- Urbásková P.
- Adámková V.
- Motlová J.
- Lebedová V.
- Procházka B.
Characteristics of Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis and Staphylococcus aureus isolated from the nasopharynx of healthy children attending day-care centres in the Czech Republic.
Epidemiol Infect. 2006; 134: 1179-1187
29
, 34
The decline in S. pneumoniae carriage rate associated with increasing age may reflect the gradual acquisition of mucosal immunity and reduction of exposure. The findings may highlight that younger age groups have a higher risk of acquiring S. pneumoniae compared with older age groups.Various demographic characteristics have been described to be associated with an increase in S. pneumoniae carriage including family size, recent antibiotic use, and habit of sleeping with parents.
17
In our study, none of these factors were found to be associated with nasopharyngeal S. pneumoniae carriage. Unidentified environmental or host factors (underlying diseases, immunosuppression) may be the prime determinants of the carriage distribution in the study participants. However, in logistic regression analysis, S. pneumoniae carriage rates were significantly associated with younger age (<3 years old). The environmental factor, children living with <5-year-old siblings, showed significantly higher S. pneumoniae carriage compared with children who do not have any younger siblings. These findings were similar to reports from Israel, Mozambique, and Gambia.15
, 29
, 33
This is of great relevance because exposure to other children during childhood, especially to younger siblings, has been clearly associated with an increased risk for invasive and noninvasive pneumococcal disease. Moreover, we observed significantly higher S. pneumoniae nasopharyngeal carriages rates among children who lived with their family in a house with only one room and other children. This result is consistent with the report from Mozambique.33
These findings may highlight high S. pneumoniae transmission in overcrowded areas.The results of the antimicrobial susceptibility study revealed higher S. pneumoniae resistance: 32 (33.3%) to erythromycin and tetracycline; 28 (29.1%) to cotrimoxazole; and 14 (14.6%) to ciprofloxacin. Nineteen (19.8%) isolated S. pneumoniae were multidrug resistant. This observation of S. pneumoniae resistance to erythromycin, tetracycline, and cotrimoxazole is consistent with previous reports in Venezuela and Gambia.
10
, 15
By contrast, 10 (10.4%) S. pneumoniae were penicillin-resistant. Comparable penicillin-resistant S. pneumoniae results were reported in various studies: 14.3% in Gambia15
and 7% in Brazil and Turkey.11
, 12
However, higher proportions of penicillin-resistant pneumococci were found in Japan (60.6%),30
Mexico (34%),35
and Mozambique (58.9%).33
Pneumococci resistance rates to penicillin vary according to geographic region and different population subgroups. Geographical variations in the antimicrobial susceptibility of S. pneumoniae can be explained by the general consumption of antimicrobial agents. The most effective antimicrobial agents for the S. pneumoniae isolates were ceftriaxone and vancomycin, to which these isolates were 100% susceptible. This pneumococcal sensitivity to vancomycin was consistent with the report in Venezuela.10
Ceftriaxone and vancomycin, however, are relatively more costly. Together with biological factors, these factors could be responsible for the low rate of resistance recorded for ceftriaxone and vancomycin drugs. Although cotrimoxazole, erythromycin, and tetracycline are cheap and readily available to the local population, they showed higher resistance. Therefore, the uncontrolled availability of some antimicrobial agents, leading to frequent use and misuse, exerts greater selection pressure for the resistant strains and thereby makes these agents almost ineffective.5. Conclusions
S. pneumoniae nasopharyngeal carriage was higher among children under 3 years of age. These high numbers of carrier children could serve as reservoirs for the transmission of S. pneumoniae to younger children in the community, which could lead to serious pneumococcal diseases and associated health consequences. Therefore, there is an urgent need to expand the pneumococcal conjugate vaccination in the community. Being in the young age group, living with younger children, and living in a house having a single room are risk factors for S. pneumoniae carriage. Higher S. pneumoniae drug resistance was observed for erythromycin, tetracycline, and cotrimoxazole. Further determination of the association of nasopharyngeal carriage of resistant strains with development of invasive resistant strain infection is important for establishing rational treatment for presumptive S. pneumoniae infections.
Acknowledgments
We gratefully acknowledge the staff of the Pediatrics Outpatient Department and the Microbiology Laboratory of Gondar University Hospital for participating in and facilitating this study. We are also deeply grateful to the University of Gondar for providing the grant that made this research possible.
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Article info
Publication history
Published online: May 16, 2013
Accepted:
April 2,
2013
Received in revised form:
February 4,
2013
Received:
December 23,
2012
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© 2013 Published by Elsevier Inc.
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