| Abstract|| |
Background: Due to the lack of sanitation measures and clean water, typhoid fever is prevalent in developing countries such as India. Also, increasing cases of antibiotic resistance as well as multiple drug resistance (MDR) have been reported in Indian subcontinents. However, there is inadequate data available on the antibiotic sensitivity pattern of Salmonella enterica serovar Typhi (S. typhi) among children in Indian subcontinents. Materials and Methods: A total of 43 isolates of S. typhi were collected from the blood samples of children in the age group of 3-12 years and further were tested for antimicrobial susceptibility according to the CLSI guidelines. Results: Of the total isolates studied, 44% were found to be multidrug resistant (MDR) (defined as resistance against more than one group of antibiotic). The isolates showed the highest resistance against aminoglycoside antibiotics and least against carbapenem antibiotics. Conclusion: The presence of MDR S. typhi imposes a serious concern about the drug of choice for treatment of typhoid fever in children. A careful consideration should be given before deciding the antibiotic for treatment in order to prevent the emergence of antibiotic resistance.
Keywords: Children, multiple drug resistant, S. typhi, typhoid
|How to cite this article:|
Chandane P, Gandhi A, Bowalekar S. Study of antibiotic susceptibility pattern of Salmonella typhi in children suffering from enteric fever. Ann Trop Med Public Health 2017;10:440-3
|How to cite this URL:|
Chandane P, Gandhi A, Bowalekar S. Study of antibiotic susceptibility pattern of Salmonella typhi in children suffering from enteric fever. Ann Trop Med Public Health [serial online] 2017 [cited 2019 Sep 18];10:440-3. Available from: http://www.atmph.org/text.asp?2017/10/2/440/208704
| Introduction|| |
Typhoid (enteric fever) caused by the organism Salmonella More Details enterica serovar Typhi (S. typhi) is a serious and an occasionally fatal disease, prevalent mainly in the developing nations owing to the lack of clean water and sanitation measures. Roughly 21.6 million people are affected by typhoid annually, resulting in 216,500 deaths with more than 90% of this morbidity and mortality occurring in Asia., According to a study conducted by Ochiai et al., 2008, among the five Asian countries, India has the highest prevalence of the disease followed by Pakistan. However, the antibiotic resistance among the isolates were found to be far higher in Pakistan than in India. Multidrug resistance (MDR) is the resistance against at least two classes of antibiotic and the resistance has increased only in recent years., In 1972, the first outbreak of chloramphenicol‐resistant S. typhi was reported in India, and thereafter, the incidence of resistant strains, including MDR ones, increased in many parts of the country. Since the global emergence of MDR S. typhi, fluoroquinolones such as ciprofloxacin has become the first‐line antibiotics for the treatment of the disease. However, the number of resistant organisms against ciprofloxacin is also gradually increasing. The antibiotic resistance among clinical isolates is associated with high mortality rates and economic burden. Especially in countries such as India and Pakistan where children below the age of 15 years are more susceptible, the antibiotic resistance increases the severity of the disease.
In spite of the increasing prevalence of the disease, there is very little information on the antibiotic resistance pattern of typhoid bacilli in children from Southeast Asia. Thus, the aim of the present study was to evaluate the antibiotic resistance pattern of the clinical isolates from the children infected with typhoid bacilli. Adequate knowledge of antibiotic resistance in the population might further help to bring out better treatment interventions against these organisms.
| Materials and Methods|| |
Blood samples were collected from children (n = 43) presented with symptoms of enteric fever in a tertiary care hospital for children, Mumbai, India. The age group of study population was between 3 and 12 years.
Isolation and identification of S. typhi
Blood samples were collected aseptically in BD BACTEC blood cultures bottles (BD Diagnostics, Sparks, MD) and processed on BD BACTEC FX 40 automated blood culture system (BD Diagnostics, Sparks, MD). Non‐lactose fermenting colonies were selected by growing the cultures further on MacConkey agar and identified by biochemical tests and categorized by group‐ and type‐specific antisera to select S. typhi.
Antibiotic sensitivity test
The antibiotic susceptibility test was performed by the Kirby‐Bauer disc diffusion method in accordance with the guidelines of Clinical and Laboratory Standards Institute, formerly National Committee for Clinical Laboratory Standards. Mueller Hinton Agar M173 (Himedia, India) plates were incubated at 37°C, and then the antibiotic disc incorporation and zone of inhibition were measured in millimeters after 24 hours of incubation. A total of 13 different antibiotic discs (Himedia, India) [Table 1] were used to check the susceptibility and resistance of the clinical isolates obtained. Based on the zone of inhibition obtained [Table 2], the isolates were classified into sensitive, intermediate, and resistant pattern.
| Results|| |
The antibiotic sensitivity patterns against S. typhi were studied using various antibiotics. Among the 13 antibiotics tested, S. typhi showed resistance against almost all antibiotics except the carbapenem antibiotics (meropenem and imipenem). Carbapenems are the antibiotic of choice for organisms showing MDR. Least resistance was observed against colistin, with only 2.44% of the isolates showing resistance against the antibiotic whereas the other peptide antibiotic polymyxin B showed 6.89% resistance. Aminoglycoside antibiotics gentamicin and amikacin showed the highest resistance with percentage resistance values of 55% and 52.5%, respectively. Co‐trimoxazole showed 40% resistance among the obtained isolates. At present, with the emergence of MDR S. typhi, a fluoroquinolone, such as ciprofloxacin, or an extended spectrum cephalosporin, such as ceftriaxone, is the recommended antibiotic for S. typhi infections.
However, the present study showed 9.3% resistance for ceftriaxone and 27.5% resistance for ciprofloxacin, contemplating the need to rethink the present use of antibiotics such as fluoroquinolones for treating salmonella infections [Figure 1].
| Discussion|| |
Enteric fever is a major public health problem in developing countries including India. Appropriate antimicrobial therapy can reduce morbidity and mortality associated with this illness. Thus, with this aim, we studied the drug resistance pattern against various S. typhi isolates and found that majority of the S. typhi isolates obtained from infected children showed resistance against 11 out of the 13 antibiotics included in the study. A similar study in Pondicherry consisting of 157 clinical isolates of S. typhi showed no antibiotic resistance against ciprofloxacin and ceftriaxone, whereas 64.9% resistance was reported against co‐trimoxazole. In contrast to this, our study demonstrated 27.5% and 9.3% resistance against ciprofloxacin and ceftriaxone, respectively. An increasing trend in ciprofloxacin resistance was observed when compared with the data obtained by Mannan et al., 2014, which showed 8% resistance compared to the 27.5% observed in the present study. Based on these observations, it is imperative to carry out various longitudinal studies to establish the existence of antibiotic resistant S. typhi in the Indian population.
A case study of 25‐year‐old traveler infected with MDR S. typhi from India has been reported by Yoon et al. in 2009. The isolate obtained from the patient was found to be resistant against fluoroquinolone antibiotics as well as nalidixic acid. However, the isolates obtained were susceptible to the third‐line drugs used for the treatment such as aztreonam and imipenem. These data are in accordance with the present study, showing a high prevalence of fluoroquinolone‐resistant isolates and high susceptibility of these organisms against meropenem and imipenem antibiotics. The use of these carbapenem antibiotics should be carefully monitored to prevent the emergence of resistant organisms. The high unresponsiveness against fluoroquinolones may be due to the overuse of these antibiotics in the treatment of typhoid and in other unrelated infections.
Another study by Rather et al., 2013, conducted in Kashmir, India, focused on antibiotic sensitivity patterns of Salmonella isolated from different water sources from Kashmir. They reported 100% sensitivity against gentamicin and 91.67% sensitivity for amikacin and ciprofloxacin. The present study demonstrates a much larger prevalence of antibiotic resistant Salmonella, but it could be because of regional as well as sample differences.
| Conclusion|| |
The present study of antibiotic sensitivity test using 13 antibiotics against S. typhi isolated from the blood samples of children hospitalized with enteric fever showed multiple drug resistance. Organisms showing resistance against two or more than two groups of antibiotics are called as multiple drug resistant (MDR). Multiple drug resistance was exhibited by 19 out of the 43 isolates (44.18%), indicating the prevalence of MDR among the Indian population. Further studies with larger population size as well as determining the minimum inhibitory concentration for antibiotics should be carried out to confirm the resistance pattern in the study group. According to this study, meropenem and imipenem antibiotics are better alternatives for the treatment of S. typhi infections and the usage of ciprofloxacin and ceftriaxone should be carefully monitored to evaluate the emergence of the resistance organisms. The study highlights the need for a strong association of physicians and the laboratory for deciding the correct antibiotics of choice to thwart the emergence of antibiotic‐resistant S. typhi.
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Conflicts of interest
There are no conflicts of interest.
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Department of Pediatrics, B J Wadia Hospital for Children, Mumbai, Maharashtra
Source of Support: None, Conflict of Interest: None
[Table 1], [Table 2]