warned to watch for and report any signs or symptoms suggestive of the serotonin syndrome which include hyperthermia, agitation, tremors, myoclonus, altered mental
status, andor diaphoresis Rybak, 2006.
Drug-drug interactions limit the co-administration of rifampin with several antiretroviral agents including protease inhibitors and non-nucleoside reverse transcriptase inhibitors.
Rifampin is a powerful inducer of the cytochrome P450 enzyme system, leading to a decrease in antiretroviral plasma levels below the inhibitory concentration of 50 IC
50
of the latter and potentially leading to viral rebound. Rifampin should be avoided in patients
receiving protease inhibitors and an alternate antibiotic, such as clindamycin, linezolid or tetracycline should be selected.
2. Extende Spectrum β-Lactamase ESBL
There is no consensus of the precise definition of ESBLs. β-lactamases are bacterial enzymes that ineffective β-lactam antibiotics by hydrolysis, which results in ineffective
compounds. One group of β-lactamases, extended-spectrum β-lactamases ESBLs have the ability to hydrolyse and cause resistance to various types of the newer β-lactam
antibiotics, including the expanded-spectrum or third generation cephalosporins eg, cefotaxime, ceftriaxone, ceftazidime and monobactams eg, aztreonam, but not the
cephamycins eg, cefoxitin and cefotetan and carbapenem eg, imipenem, meropenem and ertapenem. ESBL has generally been defined as transmissible β- lactamases that
can be inhibited by clavulanic acid, tazobactam or sulbactam, and or which are encoded by genes that can be exchanged between bacteria. Most ESBLs can be devided into three
groups: TEM, SVH and CTX-M types. The currently most common genetic variant of ESBL is CTX-M. Paterson DL et al. 2005
2.1. Mechanisms of Transmission
A review of the literature on mechanism of transmission of MDR-GNB was problematic for three main reasons; the low number of studies; the low availability of high quality studies
and the high heterogeneity of definitions, settings and pathogens. Patient-to patient transmission was frequently thought to be the most important route of transmission
whenever several patients shared clonally related isolates. This is based on the hypothesis that colonized or infected patients are the only reservoir for the microorganism.
However, intermediate vectors for spread between patients, including contaminated hands of healthcare workers HCWs, environment, and visitors should also be taken into
consideration for the prevention and control of healthcare-associated MDR-GNB transmission.
2.2. Extended Spectrum β- lactamase Escherichia coli ESBL E-coli
ESBL producing E coli are antibiotic resistant strains. In most respect they are no different from other strains of E coli in that can harbored as part of the normal flora and can cause
urinary tract infections, bacteraemia and meningitis in susceptible individuals. A key
feature of these strains is that they carry specific genes that enable them to produce enzymes that destroy a large number of common antibiotics, making the infection they
cause very difficult to treat. In many instances, only two oral and a very limited group of intravenous antibiotics remain effective. ESBL-producing strains E coli were first noted in
2003 when East and West Midlands region of England reported.
E. coli as the constant influx of community isolates colonizing patients at hospital admission is highly significant in the epidemiology of these organisms within hospitals,
understanding the complex epidemiological behavior of E. coli in the community is a key to adequate interpretation of studies addressing the epidemiology of E. coli in hospitalized
patients. The extra-intestinal pathogenic strain are the predominant strains in 20 of individual and harbor the typical virulence factors causing extra-intestinal infections when
reaching the appropriate site from the bowel, which serve as their primary reservoir. Transmission of extra-intestinal pathogenic E. coli in the community is thought to occur by
person to person transmission, either through direct contact or by means of faecal-oral route through or by contaminated food andor water. Johnson JR et al. 2010
2.3. Klebsiella species
There have been several rescent studies of the epidemiology of K. pneumonia as a nosocomial pathogen. Cross-transmission via H
CWs‟hands seems to be important in the nosocomial spread of K pneumonia strains. However in a recent study, an outbreak
caused by contaminated food was described, indicating that transmission may also occur via the food chain.
2.4. Detection
The clinical laboratory acts as an early warning system, alerting the medical community to new resistance mechanism present in clinically important bacteria. The methods for
detection of ESBLs can be broadly devided into two groups: phenotypic methods that use non-molecular techniques, which detect the ability of the ESBL enzymes to hydrolyse
different cephalosporins and genotypic method, which use molecular techniques to detect the gene responsible for the production of the ESBL. Clinical diagnostic laboratories use
mostly phenotypic methods because these tests are easy to do, are cost effective and have been incorporated in most automated susceptibility systems, making them widely
accessible.
2.5. Treatment
This multiple drug resistance has major implications for the selection of adequate empirical therapy regimens. Empirical therapy is prescribed at the time when an infection is clinically
diagnosed, while the results of cultures and antimicrobial susceptibility profiles are awaited. Multiple studies in a wide range settings, clinical syndromes, and organisms have
shown that failure or delay in adequate therapy results in an adverse mortality outcome, which is also true of infections cause by ESBL-producing bacteria. A major challenge
