Superbugs Making Life Scary

The resistance observed in different bacterial and fungal species to range of antimicrobial drugs has been a cause of public health threat. Due to the new resistance mechanisms adapted by microbes and decrease in efficiency of treating common infectious diseases, it results in failure of microbial response to standard treatment, leading to prolonged illness, higher expenditures for health care, and an immense risk of death. Many microbes have employed high levels of Multidrug Resistance (MDR) with enhanced morbidity and mortality; thus, they are referred to as "superbugs."

Superbugs are strains of bacteria that are resistant to several types of antibiotics. For nearly a century, bacteria-fighting drugs known as antibiotics have helped to control and destroy many of the harmful bacteria. But in recent decades, antibiotics have been losing their punch against some types of bacteria. In fact, certain bacteria are now unbeatable with today's medicines. Sadly, the way we've been using antibiotics is helping to create new drug-resistant "superbugs."[more info]

Antimicrobial resistance occurs naturally over time, usually through genetic changes. Moreover, the misuse and overuse of antimicrobials is accelerating this process. Antimicrobial resistance is one of the major public health problems especially in developing countries where relatively easy availability and higher consumption of medicines have led to disproportionately higher incidence of inappropriate use of antibiotics and greater levels of resistance compared to developed countries. [more info]

Production of the hydrolytic enzyme β-lactamases is one of the strategies adopted by bacteria to develop resistance to β-Lactam class of antibiotics. Some major mechanisms adapted are as follows.

Extended Spectrum β –lactamases (ESBL) producers are the bacteria resistant against third generation cephalosporin class of antibiotics.

AmpC β-lactamases are also resistant to third generation cephalosporins. They differ from ESBL's in that they are cephalosporinases and are resistant to beta lactamase inhibitors. They are inactivated by Cloxacillin and ESBL's are inactivated by Clavulanic acid.

The introduction of carbapenems into clinical practice represented a great advance for the treatment of serious bacterial infections caused by β-Lactam resistant bacteria. Due to their broad spectrum of activity and stability to hydrolysis by most β-lactamases, the carbapenems have been the drug of choice for treatment of infections caused by penicillin-or cephalosporin-resistant Gram-negative bacilli especially ESBL type. MBL have potent hydrolysing activity not only against carbapenem but also against other β -Lactam antibiotics resulting in a serious threat.

Carbapenem antibiotics have an important antibiotic niche in that they retain activity against the cephalosporinases and extended-spectrum β-lactamases found in many Gram-negative pathogens. Carbapenemases are carbapenem hydrolyzing β-lactamases that confer resistance to carbapenem class of antibiotics. Carbapenemases belong to two major molecular families :

Metallo β-lactamase (MBL) belongs to a class B, β-lactamase which requires divalent cations of zinc (a metal) as co-factors for enzyme activity.

Klebsiella pneumoniae Carbapenemases (KPCs) are an important mechanism of resistance for an increasingly wide range of Gram-negative bacteria and are no longer limited to K. pneumoniae. The resistance gene was associated with a large plasmid. Infections caused by bacteria-producing KPCs are becoming an increasingly significant problem worldwide as they are resistant to carbapenems class of antibiotics.

Other superbugs like Methicillin Resistant Staphylococcus aureus (MRSA) are resistant to nearly all antibiotics, including oxacillin, methicillin, amoxicillin, and even penicillin. Although methicillin is no longer produced, the name MRSA has persisted and can be regarded as referring to resistance to virtually all β-lactam antibiotics. Susceptibility testing now typically uses oxacillin and/or cefoxitin. Methicillin resistance is mediated by PBP-2a, a penicillin-binding protein encoded by the mecA gene that permits the organism to grow and divide in the presence of methicillin and other β-lactam antibiotics.

Vancomycin Resistant Enterococci (VRE) is a bacterial strain of Enterococcus that has acquired resistance to the vancomycin through the uptake of resistant plasmid. Vancomycin is the most common drug used to treat against Enterococcus infection. VRE can be resistant to not just Vancomycin; it can be resistant to other antibiotics commonly used for Enterococcus infections such as aminoglycosides, and ampicillin. VRE is a major concern to hospitals. Healthcare workers can carry the bacteria and pass it along to patients. VRE is most associated with nosocomial infections, making up about 30% of all Enterococcus infections in hospitals.

Under such pressure of superbugs there is need for better and better antibiotics. To decide the exact remedial antibiotic and exact resistance type we need very sensitive, accurate and efficient tools for diagnosis of both. HiMedia's antibiotic resistance wing is one-stop solution for this.

HiMedia Products in Diagnosis of Antibiotic Resistance :
HiMedia Laboratories have a wide range of resistance detection system such as antibiotic disc, gradient based Ezy MIC™ Strips and selective & differential media etc.