Hatch­ing su­per­bugs

At a time when chicken con­sump­tion is at an all time high in In­dia, a study by Delhi non-profit Cen­tre for Sci­ence and En­vi­ron­ment shows poul­try meat could be churn­ing out ro­bust mi­crobes that can ren­der all an­tibi­otics in­ef­fec­tive

Down to Earth - - COVER STORY - RA­MAKANT SAHU & LAB STUDY POORN­IMA SAX­ENA AMIT KHU­RANA & RE­SEARCH MOUNA NA­GARAJU ANKUR PALI­WAL & RE­PORT­ING JY­OT­SNA SINGH

In 1945,af­ter re­ceiv­ing the No­bel Prize for his chance dis­cov­ery of mir­a­cle cure, peni­cillin an­tibi­otic, Alexan­der Flem­ing is­sued a warn­ing. “There is the dan­ger that the ig­no­rant man may eas­ily un­der-dose him­self and by ex­pos­ing his mi­crobes to non-lethal quan­ti­ties of the drug make them re­sis­tant,” he said. Since the dis­cov­ery of peni­cillin, sci­en­tists have made an­tibi­otics to cure mul­ti­tudes of dis­eases—tu­ber­cu­lo­sis, ty­phoid, uri­nary tract in­fec­tion,

sep­ti­caemia, and the list goes. But Flem­ing’s warn­ing con­tin­ues to haunt them. More so, be­cause an­tibi­otics are no more re­stricted to hu­mans nor limited to treat­ing dis­eases.In poul­try, for in­stance, the in­dus­try has found an­other use for an­tibi­otics: as a growth pro­moter. Chick­ens are fed an­tibi­otics so that they gain weight and grow fast.

Public health ex­perts have long sus­pected that such ram­pant use of an­tibi­otics could be a rea­son for in­creas­ing an­tibi­otic re­sis­tance in In­dia. But the gov­ern­ment has no data on the use of an­tibi­otics in the coun­try, let alone on the preva­lence of an­tibi­otic re­sis­tance.

A re­cent study now con­firms what has for long been sus­pected. Delhi non-profit Cen­tre for Sci­ence and En­vi­ron­ment (cse) has found residues of an­tibi­otics in 40 per cent of the chicken sam­ples it tested. This sug­gests that the chick­ens were ex­posed to an­tibi­otics through­out their short life cy­cle of 35-42 days.

The Pol­lu­tion Mon­i­tor­ing Lab­o­ra­tory of cse

tested 70 chicken sam­ples pro­cured from 16 mar­kets in Delhi and the Na­tional Cap­i­tal Re­gion. Three tis­sues—mus­cle, liver and kid­ney—were tested for the pres­ence of six an­tibi­otics widely used in poul­try: oxyte­tra­cy­cline, chlorte­tra­cy­cline and doxy­cy­cline (from class tetra­cy­clines); en­rofloxacin and ciprofloxacin (from flu­o­ro­quinolones) and neomycin, an amino­gly­co­side.

Residues of five of the six an­tibi­otics were found in the chicken sam­ples.The an­tibi­otic residues were de­tected in all the three tis­sues. They were in the range of 3.37-131.75 μg/kg. Of the 40 per cent sam­ples found tainted with an­tibi­otic residues,22.9 per cent con­tained residues of only one an­tibi­otic while the re­main­ing 17.1 per cent sam­ples had residues of more than one an­tibi­otics. Liver sam­ples con­tained the max­i­mum an­tibi­otic residue, fol­lowed by mus­cle and kid­ney tis­sue (see ‘Know the chicken you eat’). To un­der­stand any sea­sonal vari­a­tion in the lev­els of an­tibi­otic residues, cse re­searchers con­ducted the study in two phases: first dur­ing Septem­ber-Oc­to­ber 2013,and then between May and June 2014.

The find­ings were alarm­ing in both the phases. They sug­gest an indis­crim­i­nate use of an­tibi­otics in poul­try.

“Re­peated and pro­longed ex­po­sure to an­tibi­otics lead, by nat­u­ral se­lec­tion, to the emer­gence of re­sis­tant strains of bac­te­ria,” says Neil Sch­luger, chief sci­en­tific of­fi­cer, World Lung Foun­da­tion, New York. Th­ese mu­tated ro­bust strains by­pass toxic ef­fects of an­tibi­otics, mak­ing them in­ef­fec­tive. They can eas­ily spread among the flock raised in squalor and con­tam­i­nate the food chain. They can also al­ter the ge­netic ma­te­rial of other bac­te­ria, of­ten path­o­genic ones, mak­ing them re­sis­tant to sev­eral drugs and re­sult­ing in a global pan­demic. Hu­mans are at a dou­ble threat. The mu­tated ro­bust mi­crobe strain can in­vade the body and cause dis­eases that are dif­fi­cult to treat. Se­condly, an­tibi­otic residues present in the meat can di­rectly un­leash

an as­sault on mi­crobes in hu­mans.

“Residues of an­tibi­otics present in meat can eas­ily find their way into the hu­man body, where they can cre­ate re­sis­tant mi­crobes,” says Ran­deep Gu­le­ria, pro­fes­sor of pul­monary medicine at the All In­dia In­sti­tute of Med­i­cal Sciences, Delhi (see ‘Smart moves...’ on p29).

The scale of threat can be gauged from the fact that an­tibi­otics are fre­quently pumped into chicken dur­ing its life cy­cle: they are oc­ca­sion­ally given as a drug to treat in­fec­tions, reg­u­larly mixed with feed to pro­mote growth and rou­tinely ad­min­is­tered to all birds for sev­eral days to pre­vent in­fec­tions, even when there are no sign of it. “Find­ing an­tibi­otics in chicken is wor­ry­ing be­cause sev­eral an­tibi­otics used in poul­try are also used in hu­man be­ings,” Gu­le­ria adds.

To as­cer­tain the link­age between overuse of an­tibi­otics in poul­try farms and an­tibi­otic re­sis­tance in hu­mans, cse re­searchers re­viewed 13 stud­ies con­ducted by var­i­ous gov­ern­ment and pri­vate hos­pi­tals across the coun­try between 2002 and 2013. The re­sult was star­tling. Re­sis­tance was very high against ciprofloxacin, doxy­cy­cline and tetra­cy­cline. In cer­tain stud­ies re­viewed by cse, al­most all of Pseu­domonas,

En­ter­obac­ter, Escherichia-Coli and Kleb­siella were found to be re­sis­tant to ciprofloxacin (see ‘Bac­te­ria have be­come highly re­sis­tant...’).

A world out­smarted by mi­crobes

“Re­sis­tance to an­tibi­otics is a ma­jor cri­sis that is go­ing to hit the health­care sec­tor soon,” says Devi Shetty, car­diac sur­geon and founder of Narayana Health, a char­i­ta­ble hos­pi­tal (see in­ter­view on p30).

Th­ese drug-re­sis­tant bac­te­ria could nul­lify the gains of mod­ern medicine by com­pro­mis­ing the suc­cess of or­gan trans­plants, high-end surg­eries and can­cer chemo­ther­apy.

“Not long ago, I treated a pa­tient with drug-re­sis­tant tu­ber­cu­lo­sis,” says Sch­luger. “What could have been a sim­ple six month course of treat­ment turned into a two-year or­deal which in­volved drugs that dam­aged the pa­tient’s hear­ing and nerves. Ma­jor surgery was required to re­move dis­eased ar­eas of his lung,” he adds.

With drugs los­ing their ef­fec­tive­ness, the world would need newer an­tibi­otics. Un­for­tu­nately, no new class of an­tibi­otic has hit the mar­ket since late 1980s. In the US, more than 2 mil­lion peo­ple suf­fer from an­tibi­otic-re­sis­tance-re­lated ill­nesses ev­ery year; 23,000 of them suc­cumb to the dis­eases. An­nual health­care cost due to an­tibi­otic re­sis­tance is es­ti­mated to be as high as $20 bil­lion, with an ad­di­tional pro­duc­tiv­ity loss of up to $35 bil­lion in the US.

No such es­ti­mates are avail­able for In­dia, but cases of high an­tibi­otic re­sis­tance are emerg­ing from across the coun­try. Vipin Vashishtha, who runs Mangla Hos­pi­tal in Bi­jnor, Ut­tar Pradesh, writes on the pervasiveness of an­tibi­otic re­sis­tance in the Fe­bru­ary 2011 is­sue of In­dian Pae­di­atrics. Bac­te­ria found in 14 in­fants at his hos­pi­tal were re­sis­tant to all classes of an­tibi­otics— cephalosporins, amino­gly­co­sides, mono-bac­tams, quinolones, piperacillin-tazobac­tam com­bi­na­tion and car­bapen­ems. Th­ese chil­dren were ad­min­is­tered ex­pen­sive an­tibi­otics like polymyxin B and col­istin, but only eight could be saved. Four of th­ese eight de­vel­oped com­pli­ca­tions like menin­gi­tis and arthri­tis, he wrote (see ‘Fa­tal re­sis­tance,’ Down To Earth, Oc­to­ber 16-31,2011).

Gu­le­ria elab­o­rates. An­tibi­otic re­sis­tance leads to two prob­lems—mild in­fec­tions re­quire stronger dosage and no effective an­tibi­otics are left for treat­ing se­vere in­fec­tions. Re­sis­tance to a class of an­tibi­otics, for in­stance flu­o­ro­quinolone, has fa­tal con­se­quences. Flu­o­ro­quinolone an­tibi­otics are promi­nently used to com­bat in­fec­tions in in­ten­sive care units. Treat­ing fa­tal dis­eases like sep­sis, pneu­mo­nia and tu­ber­cu­lo­sis (TB) are be­com­ing tough be­cause mi­crobes that cause th­ese dis­eases are in­creas­ingly be­com­ing re­sis­tant to flu­oro----

Newspapers in English

Newspapers from India

© PressReader. All rights reserved.