# Presentation: 798706

## Relationship of biocide use to antibiotic resistance

**Stuart B. Levy, M.D.**
**Tufts University School of Medicine**
**Alliance for the Prudent Use of Antibiotics**

## ?

**It’s A Question of Residues**

**Non-residues**

**Triclosan**
**QACs**
**Triclocarban**

**Bleach**
**Peroxides**
**Alcohols**

**Residues**

## Cross- and Co- Resistance

**(Biocides and antibiotics)**

** ****Target mutations**
** ****Multidrug efflux systems**
** ****Plasmids & transposons**

## Triclosan

- O

- C

- l

- C

- l

- H

- O

- C

- l

**Triclosan**

## Triclosan Resistance

** **

** **

** **

** **

**AG100**

** **

**AG100 (low)**

** **

**AG100 (medium)**

** **

**AG100 (high)**

** **

**MIC**

** **

**(μg/ml)**

** **

** **

**  ****0.05**

** **

**  ****0.2**

** **

**  ****1.9**

** **

**25**

** **

**Fold **

** **

**Change**

** **

** **

**    ****1.0**

** **

**    ****4.0**

** **

**  ****40**

** **

**500**

** **

**Mutated **

** **

**Gene**

** **

** **

**---**

** **

***fabI***

** ****(F203L)**

** **

***fabI***

** ****(M159T)**

** **

***fabI***

** ****(G93V)**

** **

** **

## Inhibitors of Enoyl reductase (fabI, inhA)

**Inhibitors of Enoyl reductase (*****fabI, inhA*****)**

**Triclosan**

**Diazaborine**

**Isoniazid**

## Mutations in InhA confer triclosan resistance in Mycobacterium smegmatis

**Strain****	****        Selected****	****      InhA ****	****     Relative MIC **
**	****	****             ****on*****	****    mutation****	****   (in 7H9 medium)****	**
**	****	****	****	****	****	****Triclosan   Isoniazid**
**mc****2****155 (wt)        --    ****	****     none****	****     1.0****	****	****  1.0**
**MT 1****	****             TRC****	****     M161V****	****     6.3****	****	****  8.5**
**MT 9****	****             TRC****	****     M103T****	****     6.3****	****	****  1.2**
**MT 17****	****             TRC****	****     A124V****	****     5.8****	****	****  2.0****	**
**mc****2****651             INH****	****     S94A****	****     6.3****	****	****22.0**
**mc****2****155                -- ****	****     none****	****     6.3****	****         >64**
**(p::*****inhA*****)**
**	****	****	****	****	**

***TRC = triclosan, INH = isoniazid**                  **McMurry *****et al*****, AAC 43:711, 1999.**

## Efflux as a Common Mechanism of Biocide and Antibiotic Resistance

## mar

*acrAB*

- antibiotics

- organic solvents

- pine oils

- bile salts
- triclosan
- chloroxylenol
- quaternary amines
- chlorhexidine

## Biocide resistance and antibiotic resistance: Regulators and efflux pumps

| Biocide Inducer/Substrate | Affected proteins | Drugs |
| --- | --- | --- |
| QACs, chlorhexidine, triclosan
Morita et al JAC: 51:991 (2003) | NfxB 
MexCD-OprJ
(P. aeruginosa) | Multiple antibiotics |
| Triclosan
Schweizer et al AAC 42:394 (1998)
Schweizer FEMS Microb Lett 202:1 (2001) | MexAB-OprM
MexJK 
(P. aeruginosa) | Multiple antibiotics |

## Genetic linkage of resistance to QACs and to ß-lactam antibiotics in staphylococci

**Genetic linkage of resistance to QACs and ****to ****ß****-lactam antibiotics in staphylococci**

**Sidhu *****et al *****MDR 7:363 (2001)**

**Sidhu *****et al *****AAC 46:2797 (2002)**

## DECREASED DRUG SUSCEPTIBILITY

**DRUG RESISTANCE**

**Penicillin resistant *****S. pneumoniae***
**Fluoroquinolone resistant *****E.coli***
**Vancomycin resistant *****S. aureus***

## Triclosan Susceptibility (Staphylococcus)

**0**

**10**

**20**

**30**

**40**

**50**

**60**

**0.0312**

**0.0625**

**0.1250**

**0.2500**

**0.5000**

**1.0**

**2.0**

**4.0**

**Triclosan MIC (ug/ml) **

**% of total isolates**

***S. aureus N=43***

***S. capitis N=42***

***S. epidermidis N=73***

***S. warneri N=155***

**Triclosan Susceptibility (Staphylococcus)**

- A. Aiello *et al. *Antimicrob. Agnts. Chemother. 48:2973-2979, 2004.** **

- Household hand isolates

## Triclosan Susceptibility 

***Klebsiella pneumoniae *****(N = 69)**

**0**

**5**

**10**

**15**

**20**

**25**

**30**

**35**

**0.0312**

**0.0625**

**0.1250**

**0.2500**

**0.5000**

**1.0**

**2.0**

**4.0**

**8.0**

**16.0**

**32.0**

**Triclosan MIC (ug/ml)**

**% of total isolates**

- Household hand isolates

- A. Aiello *et al. *Antimicrob. Agnts. Chemother. 48:2973-2979, 2004.** **

## Slide 15

## Antibiotic susceptibility of MRSA andbenzalkonium chloride resistant derivatives

- <date/time>

**Antibiotic susceptibility of MRSA and****benzalkonium chloride resistant derivatives**

**MIC (********g/ml)**
**Antibiotic****	****	****	****	****    MRSA**
**	****	****	****	****  ****Parent****	****BZ-R-1****	****            BZ-R-2**
**                **
**Oxacillin****	****	****     **** 16****	****	****    ****512****	****	****    ****512**
**Cloxacillin****	****	****     ****0.5****	****	****    ****256****	****	****    ****512**
**Moxalactam****	****	****      ****64****	****	****    ****256****	****	****  ****1024**
**Flomoxef****	****	****        ****8****	****	****    ****128****	****	****    ****128**
**Cefmetazole****	****	****        ****8****	****	****    ****128****	****	****      ****64**
**Cephalothin****	****	****      ****64****	****	****    ****128****	****	****    ****128**
**Ampicillin****	****	****      ****16****	****	****      32****	****	****      32**
**                       **
**Chloramphenicol****	****        4****	****	****        4****	****	****        4**
**Ofloxacin****	****	****        8****	****	****      32****	****	****      32**
**Tetracycline****	****	****    128****	****	****    128****	****	****    128**
**Benzalkonium chloride       5****	****	****      10****	****	****      10**

**Akimitsu *****et al*****, AAC 43:3042, 1999.**

## Antibiotic Susceptibility of 

- S. Langsrud *et al. *Appl. Microb. 140:321 (2003)

**Antibiotic Susceptibility of **
**Benzalkonium Chloride selected mutants**

## Antibiotic Resistance and Hand Soaps

**Figure 2.** Proportion of study participants with _>_1 bacterial species resistant to an antimicrobial agent on their hands. In the group that used antibacterial products, 82 and 105 hand samples were available at baseline and at year-end, respectively. In the group that used nonantibacterial products (i.e., plain soap), 82 and 96 hand samples were available at baseline and at year-end, respectively.

- Aiello, et al. Emerg Inf Dis 11:1565, 2005.

**Antibiotic Resistance and Hand Soaps**

## Resistance evolves 

**in time and volume **
**of drug**

## VISA

**VRSA**

- MRSA

- PenRSA

**Evolution of MDR in *****S. aureus***

- Penicillin

- Methacillin

**Vancomycin**

## TODAY

**TODAY**

**ANTIBIOTICS ****(people, animals, agriculture)**

**DRUG RESISTANT MICROBES**

**BIOCIDES**

## TOMORROW?

**ANTIBIOTICS ****(people, animals, agriculture)**

**DRUG RESISTANT MICROBES**

**BIOCIDES**

**TOMORROW?**