Indian J Pediatr 1992; 59 : 221-224
Multidrug Resistant Salmonella typhi in Delhi L. Dar, B.L. Gupta, A. Rattan, R.A. Bhujwala and Shriniwas
Department of Microbiolo~,, All hldia hlstitute of Medical Sciences, New Delhi
In 1990, we isolated 158 strains of Salmonella typhi from blood cultures of patients suffering from typhoid fever, Seventy nine (50%) of these isolates were found to be simultaneously resistant to chloramphenicol, ampicillin and cotrimoxazole. These strains were also resistant to streptomycin and tetracycline, but sensitive to gentamicin, amikacin and cephalexin. The minimum inhibitory concentrations of chloramphenicol and trimethoprim for a representative number of these strains were found to be > 1024 u g / m l and > 128 ug/ml respectively. Majority of the multidrug resistant (MDR) strains tested against cefotaxime (23/23), ciprofloxacin (38/38) and amoxycillin plus clavulanic acid (23/24) were sensitive to these drugs.
Key Words : Salmonella typhi; Drug effects; Multiresistant Typhoid fever is endemic in India. The drugs used in its treatment a r e chloramphenicol, ampicillin or cotrimoxazole. In India, a high minimum inhibitory concentration of chloramphenicol for Salmonella ~hi strains was first reported in 1962.1 However, the first outbreak of plasmid mediated multidrug resistant S. tj~ohi was documented in 1972 from Calicut. 2 These strains were simultaneously resistant to chloramphenicol, streptomycin, sulphamethoxazole and tetracycline. Chloramphenicol and multidrug resistance in S. typhi has been reported from various parts of India since then. a-6 Trimethoprim resistant strains Reprint requests : Dr. R.A. Bhujwala, Additional Professor, Department of Microbiology, All India Institute of Medical Sciences, Ansari Nagar, New Delhi- 110 029.
have been isolated in France, the U.K. and other countries] During 1990, multidrug resistant S. typhi which does not respond to chloramphenicol, ampicillin or trimethoprim has appeared in both, North s and South 9 India. We report here a profile of the multidrug resistant S. typhi strains isolated in our laboratory during 1990. MATERIAL AND METHODS
Isolates of S. typhi obtained from blood culture of cases of suspected enteric fever, septicemia or prolonged pyrexia from January to December, 1990 were studied. Blood culture was carried out in glucose citrate broth and biochemically identified strains confirmed as S. typhi by slide agglutination test were put up for antibiotic susceptibility testing by Kirby-Bauer disk diffusion tech221
222
THE INDIANJOURNALOF PEDIATRICS
nique. 1~Susceptibility of all strains to chloramphenicol, ampicillin, cotrimoxazole, tetracycline, streptomycin, gentamicin, amikacin and cephfilexin was determined. A representative set of strains was also tested against cefotaxime, ciprofloxacin and amoxyc'dlin plus clavutanic acid. Minimum inhibitory concentration was determined by plate dilution methodn for some strains for chloramphenicol and trimpethoprim. RESULTS In 1990, 158 blood culture samples grew S.
typhi. Of these, 62 (39.2%) were in the pediatric age group. Seasonal analysis of the data (Table 1) indicates that strains were susceptible to all the drugs till February, 1990. Ampicillin resistance emerged first, T~Lg 1. Seasonal Emergence of Resistance (1990) Months
Resistant to
Jan-Feb March April
Nil. Ampicillin Ampicillin and Chloramphenicol Ampiciltin,Chloramphenicol and Cotrimoxazole (and multidrug resistance)
May onwards
T~L~ 2. Seasonal Variation in MDR (1990) Month No. of isolates Multidrug resistance May June July August September October November December
15 29 26 4 11 16 22 15
4 16 17 2 5 7 17 11
(26.7%) (55.2%) (65.4%) (50.0%) (45.5%) (43.8%) (77.3%) (73.3%)
Vol. 59, No. 2
followed by chloramphenicol resistance. Cotrimoxazole resistance and multidrug resistance was seen from May, 1990 onwards. Multidrug resistimt S. typhi isolation rates peaked twice in the course of the year i.e. in June-July and November-December (Table 2). Of the 158 S. (yphi isolates, 50% were multidrug resistant including resistance to the three commonly used drugschloramphenicol, ampicillin and cotrimoxazole (Table 3); where as 35 (56.5%) of the 62 S. ~phi isolates from children were resistant to these drugs as compared to 45.8% of isolates from adults. The other antibiotics to which resistance was common were tetracycline and streptomycin. Isolates were generally susceptible to cephalexin (except 6 strains), gentamicin (except 4 strains) and amikacin. Representative MDR strains were tested against cefotaxime, ciprofloxacin and amoxycillin plus clavulanlc acid (Table 4) and were found to be sensitive to these drugs. Minimum inhibitory concentrations (MIC) of chloramphenicol and trimethoprim were high (> 1024 ug/rnl and 128 ug/ml respectively) for the isolates tested. DISCUSSION In 1990, there has been a tremendous increase in multidrug resistant S. typhi and an emergence of trimethoprim resistance in India. In the usual peak season for typhoid fever i.e. the summer months from May to July, in 1990, there were 70 isolates of S. typhi of which 37 (52.9%) were multidrug resistant. In comparison during the same period in 1989, only 2 (6.9%) of 29 S. (yphi strains showed this type of resistance. This itself demonstrates a remarkable increase, without taking into account the extra peak
BHUJWALA ET AL : MULTIDRUG
R E S I S T A N T SALMONELLA TYPIH
223
TAnLr3. Resistance to Various Drugs
Drug Ampicillin Chloramphenicol Cotrimoxazole Tetracycline Streptomycin Cephalexin Gentamicin Amikacin MDR
Age < or = 12 yr (n = 62)
No. (%) strains resistant Age > 12 yr (n = 96)
41 (66.1) 38 (613) 35 (56.5) 39 (62.9) 38(61.3) 3 (4.8) Nil 1 (0.2) 35 (56.5)
60 (62.5) 53 (55.2) 44 (45.8) 48 (50.0) 52 (54.2) 3 (3.1) Nil 3 (0.3) 44 (45.8)
T,~LE 4. MDR Strains Tested Against More
Drugs Drugs
Total tested Resistant
Cefotaxime
23
Nil
Ciprofloxacin
38
Nil
AmoxyciUin + clavulanic acid
24
1
T~L~ 5. Month wise Distribution of S.typhi Isolated in 1991 Month
Sensitive
MDR
Total
Jan Feb March April May June
11 3 4 17 8 7
12 9 10 13 25 49
23 12 14 30. 33 56
Total
50
118
168
Total (n = 158) 101 (63.9) 91 (57.6) 79 (50.0) 87 (55.1) 90 (57.0) 6 (3.8) Nil 4 (0.25) 79 (50.0)
seen in the winter (November-December) of 1990, a period usually free from typhoid fever in the past. The increase in the S- typhi isolation and in multidrug resistance'and its persistence through the winter months suggests an increase in communicability and survivability of these strains. The plasmid for multidrug res~tance is also known to confer the properties of an increase in communicability on the S. typhi strains which acquire them? The emergence of trimethoprim resistance in S. typhi in India is also alarming because cotrimoxazole is an effective and inexpensive alternative for treating chloramphenicol resistant S. typhi. 12 The changing sensitivity pattern of S. typhi, which seems to be continuing in 1991 (Table 5), demands a change in the therapeutic regimen. Current observations indicate that isolates are sensitive to cephalexin, gentamicin, amikacin, cefotaxime and amoxycillin plus clavulanic acid, as well as ciprofloxacin. The higher percentages of drug resistance in S. typhi isolates from the pediatric age group is disturbing. Multidrug resis-
29.24
rll-tE INDIAN JOURNAL OF PEDIATRICS
tance, along with a possible increase in virulence conferred by the same plasmid, would naturally increase the risk as far as this particular age group is specially concerned. ACKNOWLEDGEMENT The authors would like to gratefully acknowledge the excellent technical help provided by Mr. Satdev, Mr. R a m e s h Chand Yadav and Mr. Veer Singh. REFERENCES 1. Agarwal SC. Chloramphenicol resistance of Salmonella species in India, 1959-1961. Bull ;41110 1962; 27 : 331-353. 2. Panikar CKJ, Vimala KN. Transferable chloramphenicol resistance in S. typhi. Nature 1972; 239 : 109-110. 3. Agarwal KC, Panhotra BR, Mahanta J e t al. T~qahoid fever due to chloramphenicol resistant S. typhi, b~dian J Med Res 1981; 73 : 484-488. 4. Kapil A, Agarwal KC, Ayyagiri A et al. Invitro susceptibility of thiamphenicol against Salmonella typhi, h~dian J Med Res 1988; 88 : 395-397. 5. Jain S, Chitnis DS, Sham A e t al. Outbreak of chloramphenicol resistant typhoid fever.
Vol. 59, No. 2 Indian Pediatr 1987; 24 : 193-197. 6. Sharma KB. Epidemiology of multi-drug resitant Salmonellae in India. Prov I / N a t Cong Indian Assoc Med Micro 1982; 5-9. 7. Goldstein FW, Chumpitz JC, Guevara JM et al. Plasmid-mediated resistance to multiple ant~iotics in Sabnonella typhi. J Infect D/s 1986; 153 : 261-266. 8. Gupta BL, Bhujwala RA, Shriniwas. Multiresistant Sahnonella typhi in India. Lancet 1990; ii : 252. 9. Jesudasan MV, Jacob John T. Multiresitant Salmonella r in India. Lancet 1990; ii : 252. 10. Bauer AW, Kirby WMM, Sherris JC et al. Antibiotic susceptibility testing by a standardized single disk method. A m J Clin Pathol 1966; 45 : 493-496. 11. Matsen JM. Antibiotic susceptibility tests. In : Sonnewirth AC, Jarett L, eds. Gradwohl's Clinical Laboratory Methods and Diagnosis, Vol 2. St Louis : The CV Mosby Co, 1980 : 1950-1952. 12. Butler T, Ruman SL, Arnold K. Response of typhoid fever caused by chloramphenicol susceptible and chloramphenicol resistant strains of Sahnonella ~yphi to treatment with trimethoprim-sulpharrleth-oxazole. Rev lnfect Dis 1982; 4:551-561.
Multidrug Resistant Salmonella typhi in Delhi L. Dar, B.L. Gupta, A. Rattan, R.A. Bhujwala and Shriniwas
Department of Microbiolo~,, All hldia hlstitute of Medical Sciences, New Delhi
In 1990, we isolated 158 strains of Salmonella typhi from blood cultures of patients suffering from typhoid fever, Seventy nine (50%) of these isolates were found to be simultaneously resistant to chloramphenicol, ampicillin and cotrimoxazole. These strains were also resistant to streptomycin and tetracycline, but sensitive to gentamicin, amikacin and cephalexin. The minimum inhibitory concentrations of chloramphenicol and trimethoprim for a representative number of these strains were found to be > 1024 u g / m l and > 128 ug/ml respectively. Majority of the multidrug resistant (MDR) strains tested against cefotaxime (23/23), ciprofloxacin (38/38) and amoxycillin plus clavulanic acid (23/24) were sensitive to these drugs.
Key Words : Salmonella typhi; Drug effects; Multiresistant Typhoid fever is endemic in India. The drugs used in its treatment a r e chloramphenicol, ampicillin or cotrimoxazole. In India, a high minimum inhibitory concentration of chloramphenicol for Salmonella ~hi strains was first reported in 1962.1 However, the first outbreak of plasmid mediated multidrug resistant S. tj~ohi was documented in 1972 from Calicut. 2 These strains were simultaneously resistant to chloramphenicol, streptomycin, sulphamethoxazole and tetracycline. Chloramphenicol and multidrug resistance in S. typhi has been reported from various parts of India since then. a-6 Trimethoprim resistant strains Reprint requests : Dr. R.A. Bhujwala, Additional Professor, Department of Microbiology, All India Institute of Medical Sciences, Ansari Nagar, New Delhi- 110 029.
have been isolated in France, the U.K. and other countries] During 1990, multidrug resistant S. typhi which does not respond to chloramphenicol, ampicillin or trimethoprim has appeared in both, North s and South 9 India. We report here a profile of the multidrug resistant S. typhi strains isolated in our laboratory during 1990. MATERIAL AND METHODS
Isolates of S. typhi obtained from blood culture of cases of suspected enteric fever, septicemia or prolonged pyrexia from January to December, 1990 were studied. Blood culture was carried out in glucose citrate broth and biochemically identified strains confirmed as S. typhi by slide agglutination test were put up for antibiotic susceptibility testing by Kirby-Bauer disk diffusion tech221
222
THE INDIANJOURNALOF PEDIATRICS
nique. 1~Susceptibility of all strains to chloramphenicol, ampicillin, cotrimoxazole, tetracycline, streptomycin, gentamicin, amikacin and cephfilexin was determined. A representative set of strains was also tested against cefotaxime, ciprofloxacin and amoxyc'dlin plus clavutanic acid. Minimum inhibitory concentration was determined by plate dilution methodn for some strains for chloramphenicol and trimpethoprim. RESULTS In 1990, 158 blood culture samples grew S.
typhi. Of these, 62 (39.2%) were in the pediatric age group. Seasonal analysis of the data (Table 1) indicates that strains were susceptible to all the drugs till February, 1990. Ampicillin resistance emerged first, T~Lg 1. Seasonal Emergence of Resistance (1990) Months
Resistant to
Jan-Feb March April
Nil. Ampicillin Ampicillin and Chloramphenicol Ampiciltin,Chloramphenicol and Cotrimoxazole (and multidrug resistance)
May onwards
T~L~ 2. Seasonal Variation in MDR (1990) Month No. of isolates Multidrug resistance May June July August September October November December
15 29 26 4 11 16 22 15
4 16 17 2 5 7 17 11
(26.7%) (55.2%) (65.4%) (50.0%) (45.5%) (43.8%) (77.3%) (73.3%)
Vol. 59, No. 2
followed by chloramphenicol resistance. Cotrimoxazole resistance and multidrug resistance was seen from May, 1990 onwards. Multidrug resistimt S. typhi isolation rates peaked twice in the course of the year i.e. in June-July and November-December (Table 2). Of the 158 S. (yphi isolates, 50% were multidrug resistant including resistance to the three commonly used drugschloramphenicol, ampicillin and cotrimoxazole (Table 3); where as 35 (56.5%) of the 62 S. ~phi isolates from children were resistant to these drugs as compared to 45.8% of isolates from adults. The other antibiotics to which resistance was common were tetracycline and streptomycin. Isolates were generally susceptible to cephalexin (except 6 strains), gentamicin (except 4 strains) and amikacin. Representative MDR strains were tested against cefotaxime, ciprofloxacin and amoxycillin plus clavulanlc acid (Table 4) and were found to be sensitive to these drugs. Minimum inhibitory concentrations (MIC) of chloramphenicol and trimethoprim were high (> 1024 ug/rnl and 128 ug/ml respectively) for the isolates tested. DISCUSSION In 1990, there has been a tremendous increase in multidrug resistant S. typhi and an emergence of trimethoprim resistance in India. In the usual peak season for typhoid fever i.e. the summer months from May to July, in 1990, there were 70 isolates of S. typhi of which 37 (52.9%) were multidrug resistant. In comparison during the same period in 1989, only 2 (6.9%) of 29 S. (yphi strains showed this type of resistance. This itself demonstrates a remarkable increase, without taking into account the extra peak
BHUJWALA ET AL : MULTIDRUG
R E S I S T A N T SALMONELLA TYPIH
223
TAnLr3. Resistance to Various Drugs
Drug Ampicillin Chloramphenicol Cotrimoxazole Tetracycline Streptomycin Cephalexin Gentamicin Amikacin MDR
Age < or = 12 yr (n = 62)
No. (%) strains resistant Age > 12 yr (n = 96)
41 (66.1) 38 (613) 35 (56.5) 39 (62.9) 38(61.3) 3 (4.8) Nil 1 (0.2) 35 (56.5)
60 (62.5) 53 (55.2) 44 (45.8) 48 (50.0) 52 (54.2) 3 (3.1) Nil 3 (0.3) 44 (45.8)
T,~LE 4. MDR Strains Tested Against More
Drugs Drugs
Total tested Resistant
Cefotaxime
23
Nil
Ciprofloxacin
38
Nil
AmoxyciUin + clavulanic acid
24
1
T~L~ 5. Month wise Distribution of S.typhi Isolated in 1991 Month
Sensitive
MDR
Total
Jan Feb March April May June
11 3 4 17 8 7
12 9 10 13 25 49
23 12 14 30. 33 56
Total
50
118
168
Total (n = 158) 101 (63.9) 91 (57.6) 79 (50.0) 87 (55.1) 90 (57.0) 6 (3.8) Nil 4 (0.25) 79 (50.0)
seen in the winter (November-December) of 1990, a period usually free from typhoid fever in the past. The increase in the S- typhi isolation and in multidrug resistance'and its persistence through the winter months suggests an increase in communicability and survivability of these strains. The plasmid for multidrug res~tance is also known to confer the properties of an increase in communicability on the S. typhi strains which acquire them? The emergence of trimethoprim resistance in S. typhi in India is also alarming because cotrimoxazole is an effective and inexpensive alternative for treating chloramphenicol resistant S. typhi. 12 The changing sensitivity pattern of S. typhi, which seems to be continuing in 1991 (Table 5), demands a change in the therapeutic regimen. Current observations indicate that isolates are sensitive to cephalexin, gentamicin, amikacin, cefotaxime and amoxycillin plus clavulanic acid, as well as ciprofloxacin. The higher percentages of drug resistance in S. typhi isolates from the pediatric age group is disturbing. Multidrug resis-
29.24
rll-tE INDIAN JOURNAL OF PEDIATRICS
tance, along with a possible increase in virulence conferred by the same plasmid, would naturally increase the risk as far as this particular age group is specially concerned. ACKNOWLEDGEMENT The authors would like to gratefully acknowledge the excellent technical help provided by Mr. Satdev, Mr. R a m e s h Chand Yadav and Mr. Veer Singh. REFERENCES 1. Agarwal SC. Chloramphenicol resistance of Salmonella species in India, 1959-1961. Bull ;41110 1962; 27 : 331-353. 2. Panikar CKJ, Vimala KN. Transferable chloramphenicol resistance in S. typhi. Nature 1972; 239 : 109-110. 3. Agarwal KC, Panhotra BR, Mahanta J e t al. T~qahoid fever due to chloramphenicol resistant S. typhi, b~dian J Med Res 1981; 73 : 484-488. 4. Kapil A, Agarwal KC, Ayyagiri A et al. Invitro susceptibility of thiamphenicol against Salmonella typhi, h~dian J Med Res 1988; 88 : 395-397. 5. Jain S, Chitnis DS, Sham A e t al. Outbreak of chloramphenicol resistant typhoid fever.
Vol. 59, No. 2 Indian Pediatr 1987; 24 : 193-197. 6. Sharma KB. Epidemiology of multi-drug resitant Salmonellae in India. Prov I / N a t Cong Indian Assoc Med Micro 1982; 5-9. 7. Goldstein FW, Chumpitz JC, Guevara JM et al. Plasmid-mediated resistance to multiple ant~iotics in Sabnonella typhi. J Infect D/s 1986; 153 : 261-266. 8. Gupta BL, Bhujwala RA, Shriniwas. Multiresistant Sahnonella typhi in India. Lancet 1990; ii : 252. 9. Jesudasan MV, Jacob John T. Multiresitant Salmonella r in India. Lancet 1990; ii : 252. 10. Bauer AW, Kirby WMM, Sherris JC et al. Antibiotic susceptibility testing by a standardized single disk method. A m J Clin Pathol 1966; 45 : 493-496. 11. Matsen JM. Antibiotic susceptibility tests. In : Sonnewirth AC, Jarett L, eds. Gradwohl's Clinical Laboratory Methods and Diagnosis, Vol 2. St Louis : The CV Mosby Co, 1980 : 1950-1952. 12. Butler T, Ruman SL, Arnold K. Response of typhoid fever caused by chloramphenicol susceptible and chloramphenicol resistant strains of Sahnonella ~yphi to treatment with trimethoprim-sulpharrleth-oxazole. Rev lnfect Dis 1982; 4:551-561.
