Finally, Gram-negative bacteria are more intrinsically resistant to antibiotics - they don't absorb the toxin into their insides.
General Information about gram-negative bacteria
Gram-negative bacteria are resistant to multiple drugs and are increasingly resistant to most available antibiotics.
Due to their distinctive structure, Gram-negative bacteria are more resistant than Gram-positive bacteria, and cause significant morbidity and mortality worldwide.
Carbapenem-resistant Enterobacteriaceae (CRE) are a group of bacteria that have become resistant to “all or nearly all” available antibiotics, including carbapenems, which are typically reserved as the “treatment of last resort” against drug-resistant pathogens.
BACTERIA | Bacterial Endospores
Bacterial spores are one of the most resistant life forms known to date, being extremely tolerant against various stresses such as heat, chemicals, and harsh physical conditions.
Sometimes, bacteria causing infections are already resistant to prescribed antibiotics. Bacteria may also become resistant during treatment of an infection.
A growing number of infections – such as pneumonia, tuberculosis, gonorrhoea, and salmonellosis – are becoming harder to treat as the antibiotics used to treat them become less effective. Antibiotic resistance leads to longer hospital stays, higher medical costs and increased mortality.
Antimicrobials targeting the bacterial outer membrane and cell wall. Gram-negative bacteria tend to be more resistant to antimicrobial agents than Gram-positive bacteria, because of the presence of the additional protection afforded by the outer membrane.
Endospores are considered the most resistant structure of microbes. They are resistant to most agents that would normally kill the vegetative cells they formed from. Mycobacterial infections are notoriously difficult to treat.
E. coli strains can become resistant to beta lactam antibiotics by producing extended spectrum beta lactamase (ESBL), which is a plasmid-mediated β-lactamase that is capable of hydrolysing and inactivating β-lactams such as cephalosporins and monobactams (15).
Penicillin works best on gram-positive bacteria by inhibiting peptidoglycan production, making the cells leaky and fragile. The cells burst open and are much easier for the immune system to break down, which helps the sick person heal more quickly.
E. coli is intrinsically susceptible to almost all clinically relevant antimicrobial agents, but this bacterial species has a great capacity to accumulate resistance genes, mostly through horizontal gene transfer.
Antibiotics may be toxic. Treatment with antibiotics can lead to the emergence of resistant strains. Mass production of antibiotics is extremely difficult. Antibiotics are not effective in treating viral infections.
Antibiotics are used to treat bacterial infections. Some are highly specialised and are only effective against certain bacteria. Others, known as broad-spectrum antibiotics, attack a wide range of bacteria, including ones that are beneficial to us.
Arguably the most widely known drug-resistant infections is methicillin-resistant Staphylococcus aureus or MRSA. This resistant infection is often associated with hospitals. Others you may have heard of include C. diff (clostridium difficile), drug-resistant malaria and streptococcus pneumoniae.
Matthew Wook Chang and colleagues explain that biofilm infections are difficult to treat because the bacteria hide away under a protective barrier of sugars, DNA and proteins. That shield makes them very resistant to conventional therapies.
Other studies found that 100% of E. coli isolates were sensitive to gentamycin, amikacin, imipenem, meropenem, piperacillin-tazobactam, and tobramycin (22). Previous studies conducted in India and Kenya also showed high sensitivity to gentamycin (23, 24).
From 50 tested E. coli isolates, all of them (100%) were resistant to penicillin and erythromycin, followed by 49 (98%) to nalidixic acid, 47 (94%) to cephalexin, 43 (86%) to amoxicillin, 42 (84%) to ampicillin, 37 (74%) to ciprofloxacin, 32 (64%) to tetracycline, 27 (54%) to cefixime and 18 (36%) to gentamicin.
The cell walls of gram-negative bacteria are surrounded by a lipopolysaccharide (LPS) layer that prevents antibiotic entry into the cell. Therefore, penicillin is most effective against gram-positive bacteria where DD-transpeptidase activity is highest.
A bacterium's ability to hold onto a stain is dependent on the structure of their cell wall. A Gram positive organism lacks an outer (LPS) membrane but has a thick layer of peptidoglycan and no LPS outer membrane. This facilitates access of cell-wall active antibiotics (eg.
Penicillin works by inhibiting the repair of the peptidoglycan layer, therefore damage compounds and the peptidoglycan is compromised causing it to become susceptible to osmotic lysis. This also explains why penicillin and its derivative are more effective against Gram positive cells.