antibiotic resistance

see also:

• antibiotics
• clinically important bacteria
• Australia's National Alert System for Critical Antimicrobial Resistances: CARAlert
• the Australian Group on Antimicrobial Resistance (AGAR) website
• Australian Prescriber 2004: Antibiotic prescribing: how can emergence of antibiotic resistance be delayed?
• WHO main page on drug resistance
• WHO report 2014 (pdf)

• whenever antibiotics are used, this puts biological pressure on bacteria that promotes the development of resistance
• we are rapidly heading into the “post-antibiotic era” - when our antibiotics are near useless against our major infections and the organisms continue to evolve with ever higher degrees of antibiotic resistance
• despite billions of dollars research, science has not been able to produce new types of antibiotics over the last few decades to meet this threat
• in this scenario we can expect not only will our complication rates and mortality rates increase from infectious illnesses, but complex surgical patients, those with immunosuppression such as HIV / AIDS patients, cancer patients on chemotherapy, dialysis patients, transplant patients, and patients with autoimmune diseases such as severe rheumatoid arthritis on immunosuppressants will also have much higher morbidity and mortality
• much of this is due to indiscriminate antibiotic usage, particularly in our food chain.
• whilst most antibiotic resistant organisms are picked up during a hospital admission, increasingly, these are community acquired, particularly, MRSA, tuberculosis (TB), pneumococcus, and gonorrhoea.

• see US CDC: antibiotic resistance threats in the US 2013 (pdf)

• Clostridium difficile
  • this bacteria spreads rapidly because it is naturally resistant to many drugs used to treat other infections
  • fluoroquinolone resistant strain emerged in 2000
  • deaths related to C. difficile increased 400% between 2000 and 2007, mainly in those older than 65 yrs
• Carbapenem-resistant Enterobacteriaceae (CRE) (PDR-Enterobacteriaceae identified in 2009)
  • includes E.coli and Klebsiella sp
  • some Enterobacteriaceae are resistant to nearly all antibiotics, including carbapenems, which are often considered the antibiotics of last resort
  • a major issue in Asia, but rapidly spreading globally
  • in 2019, it was shown that seagulls in Australia have high rates of antibiotic resistant E.coli as detected by their fecal droppings and presumably could spread this to migrating birds and other animals
• Drug-resistant Neisseria gonorrhoeae (ceftriaxone resistance identified in 2009)
  • currently < 1% in US are resistant to ceftriaxone or azithromycin but up to 30% have antibiotic resistance to penicillins, tetracycline &/or fluoroquinolones
  • in 2017, azithromycin non-susceptible N. gonorrhoeae are now common in Australia
  • increasing resistance to ceftriaxone and azithromycin will have an enormous impact

• multidrug-resistant Acinetobacter (identified in 2004/2005)
  • mainly an issue for critically patients
  • most Acinetobacter are now multidrug resistant
• Drug-resistant Campylobacter
  • in the US, a quarter are now resistant to azithromycin or ciprofloxacin
• Fluconazole-resistant Candida
  • the fourth most common cause of healthcare-associated bloodstream infections in the US where 7% of Candida systemic infections are now resistant to fluconazole
• Extended spectrum β-lactamase producing enterobacteriaceae (ESBLs) and carbapenemase producing or resistant enterobacteriaceae (CPE/CRE)
• Vancomycin-resistant Enterococcus (VRE) (identified in 1988, gentamicin resistance in 1979)
  • in the US, ~30% of Enterococcus healthcare-associated infections are vancomycin resistant
• Multidrug-resistant Pseudomonas aeruginosa
  • in the US, 13% of severe healthcare-associated infections caused by Pseudomonas aeruginosa are multidrug resistant
• Drug-resistant Non-typhoidal Salmonella
• Drug-resistant Salmonella Typhi
  • in the US, ~2/3rds of cases are resistant to ciprofloxacin
• Drug-resistant Shigella (tetracycline resistance identified in 1959)
• Methicillin-resistant Staphylococcus aureus (MRSA) (identified in 1962)
• Drug-resistant Streptococcus pneumoniae (penicillin resistance identified in 1965)
• Drug-resistant tuberculosis (TB) (XDR TB identified in 2000)
  • MDR TB shows resistance to at least INH and rifampicin (RMP), the two essential first-line drugs
    • 1% of cases in US are MDR TB
  • XDR TB is defined as MDR TB plus resistance to any fluoroquinolone and to any of the three second-line injectable drugs (i.e., amikacin, kanamycin, capreomycin)

• Vancomycin-resistant Staphylococcus aureus (VRSA) (identified in 2002, ceftaroline resistance in 2011 only 1 year after ceftaroline was introduced)
  • VRSA is currently rare
• Erythromycin-resistant Group A Streptococcus (identified in 1968)
• Clindamycin-resistant Group B Streptococcus

• prevent infections and the spread of resistant organisms
  • minimise hospital admissions and length of stay
  • vaccinations - eg. pneumococcal vaccine
  • safe sex
  • reduce foodborne infections - improved sanitation, food handling, safe food and water
  • hand washing
  • minimise travel to regions with high antibiotic resistance such as Asia
  • contact tracing
• tracking resistance
• improve use of antibiotics
  • remove from food chain
  • improved prescribing indications to reduce unnecessary prescribing
  • ensure appropriate regimes to minimise development of resistant organisms (esp. tuberculosis (TB))
• develop new diagnostic tests to better target antibiotic usage and find sources of contamination
• develop new antibiotics
  • unlikely to play a major role

• The Age Dec 2013 - superbugs and the post-antibiotic era