G_IPC_25 Multi Resistant Gram Negative Bacteria


The increasing prevalence of antibiotic resistant micro-organisms, especially those with multiple resistances, is causing international concern. Their control is vital.

As antibiotic resistance makes infections difficult to treat, increases the length of severity of illness, the period of infection, adverse reactions, length of hospital admission and overall costs.

What are multi-resistant gram negative bacteria?

Gram negative bacteria (GNB) are commonly found in the gastro-intestinal tract, in water and in soil. In hospitalised patients, colonisation of the gastro-intestinal tract and oropharynx is common. GNB can be part of the transient flora on the hands of healthcare workers.

Some species of bacteria commonly found in the bowel (e.g. Escherichia coli, E.Coli, Klebsiella, Proteus, Pseudomonas Enterobacter and Acinetobacter) can develop multi- resistance to antibiotics where they become collectively referred to as Multi-resistant gram negative bacteria or MRGNB. MRGNB are seen most frequently in patients who have received broad spectrum antibiotics and where patients have diminished immunity. MRGNB may cause urinary tract infections, pneumonia and surgical site infections.

Some MRGNB contain beta-lactamases which can destroy/inactivate even broad spectrum antibiotics such as cefuroxime and cefotaxime. These are referred to as extended spectrum beta lactamases or ESβLs.

ESβL-producing coliforms are resistant to intravenous cephalosporins and they are frequently-resistant to many other antibiotics including ciprofloxacin and aminoglycosides. Multi-resistant Acinetobacter are defined as isolates which are resistant to any aminoglycoside and to any third generation cephalosporin. Some multi-resistant Acinetobacter strains are also resistant to carbapenem antibiotics (these strains are designated MRAB-C). Multi-resistant Pseudomonas are resistant to at least two of the following: ceftazidime or piperacillin/tazobactam or gentamicin (or other aminoglycoside) or ciprofloxacin. Multi-resistant Pseudomonas strains are occasionally resistant to carbapenem antibiotics.

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