Before using this antibiogram you should know:
- The antibiogram is used to direct initial empiric therapy only. Antibiotics need to be reassessed based on susceptibility testing and patient clinical status.
- Data presented in the antibiogram should be considered in combination with an individual patient’s risk factors for resistant organisms, clinical syndrome and hospital epidemiology.
- The antibiogram provides the percentage of isolates which are susceptible to an antibiotic. For life-threatening infections, it is reasonable to choose an antibiotic regimen with the lowest resistance rate.
- Fewer than 30 isolates may not be reliable for guiding empiric treatment and cannot be used to statistically compare results to other years.
- A shaded box indicates that the particular antibiotic/microorganism combinations are not recommended.
- Calculation of results was based on the first isolate per patient for the year 2020. Duplicate isolates and surveillance isolates were removed.
For further information, contact the Microbiology Laboratory, Hamilton Regional Laboratory Medicine Program
All Specimens Excluding Surveillance for July 2022 – June 2023
% Susceptible
| Gram Negative Organisms | Number of Isolates | Ampicillin | Ceftriaxone | Ceftazidime | Piperacillin-Tazobactam | Ertapenem | Meropenem | Gentamicin | Tobramycin | TMP/SMX | Ciprofloxacin |
| E. coli | 1138 | 51 | 84 | – | 94 | 99 | 100 | 92 | 92 | 72 | 66 |
| Klebsiella Pneumoniae | 469 | 0 | 85 | – | 90 | 98 | 99 | 96 | 94 | 87 | 84 |
| Enterobacter spp. | 94 | – | – | – | – | 83 | 98 | 96 | 95 | 86 | 90 |
| Proteus Mirabilis | 107 | 79 | 95 | – | 100 | 99 | 99 | 96 | 96 | 83 | 80 |
| Pseudomonas Aeruginosa | 269 | – | – | 86 | 86 | – | 92 | 95 | 98 | – | 82 |
* Cefazolin is not included in this table as automated susceptibility results are not reliable. Refer to the table on blood cultures where alternative methods (Kirby-Bauer) are used for testing.
| Gram Positive Organisms | Number of Isolates | Ampicillin | Cloxacillin | Cefazolin | Clindamycin | Erythromycin | TMP/SMX | Ciprofloxacin* | Tetracycline | Rifampin (not to be used as monotherapy) | Vancomycin |
| Staphylococcus aureus (includes MSSA and MRSA) | 559 | – | 75 | 75 | See MSSA & MRSA | See MSSA & MRSA | See MSSA & MRSA | See MSSA & MRSA | See MSSA & MRSA | See MSSA & MRSA | See MSSA & MRSA |
| Methicillin Sensitive S. aureus (MSSA) | 424 | – | 100 | 100 | 78 | 69 | 97 | 87 | 97 | 100 | 100 |
| Methicillin Resistant S. aureus (MRSA) | 142 | – | 0 | 0 | 55 | 23 | 95 | 24 | 90 | 100 | 100 |
| Enterococcus spp | 259 | 80 | – | – | – | – | – | – | – | – | 96 |
* Ciprofloxacin monotherapy is NOT recommended for serious infections caused by Staphylococcus spp.
Blood Culture Specimens:
% Susceptible
| Organism | Number of Isolates | Ampicillin | Cloxacillin | Cefazolin | High-Level Gentamicin * | Vancomycin |
| Staphylococcus aureus | 132 | – | 82 | 82 | – | 100 |
| Coagulase negative Staphylococcus | 30 | – | 50 | 50 | – | 100 |
| Enterococcus faecalis | 59 | 100 | – | – | 84 | 100 |
| Enterococcus faecium | #17 | 0 | – | – | 64 | 100 |
# Fewer than 30 isolates may not be reliable for guiding empiric treatment decisions and cannot be used to statistically compare results to other years
* For use in combination with Ampicillin or Vancomycin for synergy
| Organism | Number of Isolates | Ampicillin | Cefazolin | Ceftriaxone | Ceftazidime | Piperacillin-Tazobactam | Ertapenem | Meropenem | Gentamicin | Tobramycin | TMP/SMX | Ciprofloxacin |
| E. coli | 140 | 45 | 55 | 77 | – | 95 | 100 | 100 | 89 | 87 | 65 | 58 |
| Klebsiella pneumoniae | 57 | 0 | 57 | 85 | – | 87 | 96 | 96 | 96 | 96 | 85 | 84 |
| Enterobacter spp | #13 | – | – | – | – | – | 76 | 100 | 92 | 84 | 76 | 69 |
| Pseudomonas aeruginosa | #21 | – | – | – | 71 | 76 | – | 85 | 100 | 100 | – | 80 |
# Fewer than 30 isolates may not be reliable for guiding empiric treatment decisions and cannot be used to statistically compare results to other years.
Urine Culture Specimens:
% Susceptible
| Organism | Number of Isolates | Ampicillin | Cefazolin (Urinary) * | Ceftriaxone | Ceftazidime | Piperacillin-Tazobactam | Ertapenem | Meropenem | Gentamicin | Tobramycin | Nitrofurantoin (for urine only) | TMP/SMX | Ciprofloxacin |
| E. coli | 1029 | 51 | 82 | 85 | – | 94 | 99 | 100 | 92 | 92 | 95 | 73 | 66 |
| Klebsiella pneumoniae | 398 | 0 | 75 | 84 | – | 90 | 97 | 99 | 95 | 94 | 40 | 85 | 83 |
| Enterobacter spp | 67 | – | – | – | – | – | 83 | 100 | 97 | 97 | 56 | 83 | 89 |
| Proteus mirabilis | 85 | 77 | 91 | 95 | – | 100 | 98 | 98 | 95 | 95 | 0 | 81 | 80 |
| Pseudomonas aeruginosa | 154 | – | – | – | 86 | 87 | – | 90 | 96 | 98 | – | – | 81 |
* Cefazolin (urinary) predicts for cephalexin and cefprozil when used for treatment of uncomplicated UTIs due to E. coli, K. pneumoniae, and P. mirabilis but not for therapy of infections other than uncomplicated UTIs.
| Organism | Number of Isolates | Ampicillin | Cefazolin/Cloxacillin | TMX/SMP | Ciprofloxacin | Nitrofurantoin (for urine only) | Tetracycline | Rifampin (not to be used as monotherapy) | Vancomycin |
| Staphylococcus aureus (includes MSSA and MRSA) | 55 | – | 78 | 96 | 70 | 100 | 92 | 100 | 100 |
| Enterococcus spp | 356 | 84 | – | – | 64 | 85 | 29 | – | 96 |
Intrinsic Resistance for Selected Organisms
| Organism | Antibiotics that are INEFFECTIVE ***DO NOT USE*** |
| Enterococcus | Cephalosporins, Cloxacillin, Clindamycin, TMP/SMX Ciprofloxacin and Tetracycline should be used only for urinary source |
| SPICE organisms High risk for inducible resistance: Citrobacter freundii complex, Enterobacter cloacae, Klebsiella aerogenes Low risk for inducible resistance: Serratia, Providencia, Morganella | Penicillins, cephalosporins, broad spectrum penicillins and β-lactam/ β-lactamase inhibitor combinations (eg. piperacillin-tazobactam) are not recommended as SPICE organisms contain an induciblechromosomal AmpC β-lactamase. For lower risk SPICE organisms: 3rd generation cephalosporins that test in vitro susceptible, can be used for uncomplicated urinary tract infection |
| Salmonella spp | Aminoglycosides, 1st and 2nd generation cephalosporins |
| Methicillin resistant S. aureus (MRSA) | Penicillins, cephalosporins, broad spectrum penicillins and β-lactam/ β-lactamase inhibitor combinations, carbapenems (e.g. meropenem) |
Helpful Web Sites
Centers for Disease Control and Prevention
http://www.cdc.gov/drugresistance
http://www.cdc.gov/getsmart
Infectious Diseases Society of America
http://www.idsociety.org
Choosing Wisely Canada
http://www.choosingwiselycanada.org
Association of Medical Microbiologists and Infectious Diseases Canada (AMMI)
http://www.ammi.ca
Johns Hopkins Infectious Diseases
http://www.hopkinsguides.com
AidsInfo (US Dept of Health and Human Services)
http://www.aidsinfo.nih.gov/