What is Cardiovascular disease (Heart disease)

Cardiovascular disease, which is also called heart disease is a class of diseases that involve the heart, the blood vessels (arteries, capillaries, and veins) or both. Bacterial infections are important health problem for patients with heart problem, especially undergoing cardiovascular surgery. The treatment includes heart valve surgery, catheterization, medications, pacemaker etc. Antimicrobial chemotherapy is one of the most important medical intervention for the control and treatment of infectious diseases. However with the development of such medications, there is increasing trend in the drug resistance pattern which challenge the modern discovery (Davies et al  2010).

 During these treatment procedures and the hospital stay, the emergence and spread of life threatening nosocomial infection occurs (Vincent et al 2000 and Vincent et al 2006). Heart patients are more likely to be cross infected particulary in ICU because of their low immune power.  Prevalence of particular type of infections caused by particular type of microorganisms varies among ICUs of different hospitals and even within the ICUs of a hospital (Tennant et al 2005). Pseudomonas spp, Acinetobacter spp, Klebsiella spp. and other Gram-negative aerobic bacilli of Enterobacteriaceae family are major nosocomially transmitted organisms.

Carbapenems are the drugs of choice for the treatment of serious infections caused by multidrug-resistant isolates, especially strains producing extended-spectrum β-lactamases (Bush et al 1997; Nordmann  et al 1998;  Elizabeth et al 2013). This is mainly because they are not inactivated by these enzymes in vitro and have been demonstrated to have adequate effectiveness for the treatment of serious Gram-negative bacterial infections at various body sites (Ensom et al 2010). Carbapenems, such as imipenem and meropenem, are antibacterial agents with activity against many Gram-negative, Gram-positive, and anaerobic microorganisms. These drugs are used for bacterial meningitis, hospital-associated sinusitis, sepsis of unknown origin, hospital-associated pneumonia etc.

The total amount of antibiotics used along with environment acts as the major factor for the emergence of antibiotic resistance (ASM 2009). Overuse of antibiotics in a hospital can cause a selective pressure on microorganisms, which in turn, can enhance the antimicrobial resistance in bacteria. Inappropriate use of antibiotics has been reported to be involved in increasing the antibiotic resistance (Namdar et al 2010). In healthcare settings, antibiotic resistance most commonly occur among patients who are receiving treatment for other conditions. Patients whose care requires devices like ventilators (breathing machines), urinary (bladder) catheters, or intravenous (vein) catheters, and patients who are taking long courses of certain antibiotics are most at risk for carbapenem resistance infections (CDC 2013).

In recent days, emergence of carbapenem resistance is in increasing trend in Gram negative bacteria. This pattern is more in patients with longer stay in the hospital or in intensive care units who are taking long course of antibiotics. Carbapenem resistance in Gram negative bacilli has become a major concern to medical community because of limited therapeutic option and challenges to infection control.

There are increasing reports of Extended Spectrum β-Lactamase (ESBL) and Metallo β-Lactamase (MBL) producing isolates expressing multidrug resistance (MDR) (Boyd et al 2004; Morosini et al 2006). Extended-spectrum β-lactamases (ESBLs) are plasmid-mediated bacterial enzymes that confer resistance to the penicillins, first, second, and third-generation cephalosporins and aztreonam (but not the cephamycins or carbapenems) by hydrolysis of these antibiotics, and are inhibited by β-lactamase inhibitors such as clavulanic acid.

Emergence of carbapenem resistance in Gram negative is due to the the ability of these organisms to produce carbapenem- hydrolysing β- lactamases (Elizabeth  et al 2013). Among β- lactamases, MBLs are most feared because it is transferable and hydrolyse almost all drugs including carbapenems. Resistance due to MBL and ESBL production has a potential for rapid dissemination as genes encoding the enzymes are plasmid mediated so that it may be transferred to other bacteria as well. The clinical utility of carbapenems is under threat with the emergence of acquired carbapenemases, particularly Ambler class B metallo β-lactamases (MBLs). Such enzymes have emerged in many geographical locations and often confer high-level resistance to all beta lactams except aztreonam..

Rates of antimicrobial resistance are greater in bacteria isolated from ICUs compared with other hospital wards and outpatient clinics (Archibald et al 1997).  The death rate for patients with serious infections caused by common bacteria treated in hospitals can be about twice that of patients with infections caused by the same non-resistant bacteria  (WHO  2004).

For the therapeutic management of clinical cases, serious challenge has been created due to acquisition of drug resistance. Mortality rates has been increased to five times with infection due to antibiotic resistance compared with infections that are caused by susceptible bacteria (Schwaber et al 2006).

The study the antibiotic resistance pattern is very important because it hampers during the medication of seriously ill patients. Heart problems are arising, particularly infective endocarditis which is a fourth leading cause of life threatening disease. Increased mortality due to ESBLs and MBL are needed to be detect for undergoing prompt action. The judicious use of antimicrobial agents and improved infection control methods must become health care priorities.

Therefore, this research was conducted with the aim of determining the prevalence and antimicrobial resistance pattern of Gram negative bacteria on heart patients, and to access the prevalence of ESBL and MBL producing strains among them.