Question

Select a bacterium, which shows antibiotic resistance in your hospital or your preceptor site. Interpret the specific pattern of resistance for that specific bacterium. For example, to what antibiotics are the bacterium resistant, and what is the evolutionary mechanism or pattern of resistance? What percentage of cases of infection in your hospital need to be caused by resistant organisms before action is taken?PLEASE MENTION YOUR REFRENCES!

Answer 1

What is antibiotic resistance?

Antibiotic resistance is the ability of bacteria or other microbes to resist the effects of an antibiotic. Antibiotic resistance occurs when bacteria change in some way that reduces or eliminates the effectiveness of drugs, chemicals, or other agents designed to cure or prevent infections. The bacteria survive and continue to multiply causing more harm.

MRSA Resistance to Vancomycin:

S. aureus is a leading cause of nosocomial infections, including bacteremia, surgical wound infections, as well as pneumonia. we have case with Nosocomal Pneumonia with MRSA with vancomycin resitance has showed after starting copule days of drug,the hospital setting due to the now intensive use of the many antibiotics, particularly cephalosporins, to which the organism is resistant.Vancomycin has been regarded as the first-line drug for treatment of MRSA. Unfortunately there has been an increase in the use of this antibiotic for other infections, such as pseudomembranous colitis due to Clostridium difficile and coagulase-negative staphylococcal infections in hospitalized patients. When this drug was introduced in 1858, it was perceived that there would be no resistance to this antibiotic as resistance was very difficult to induce. However, in 1997 the first stain of S. aureus with reduced susceptibility to vancomycin was reported from Japan.Since then, there has been an increase in the number of cases with both VISA and VRSA (vancomycin-intermediate and vancomycin-resistant S. aureus). This has triggered off alarms in the medical community as S. aureus causes life-threatening infections in hospitalized and nonhospitalized patients.

Speific patterns of resistance:

compared restriction endonuclease patterns of chromosomal or plasmidDNA. The second-generation of genotyping methods included s southern blot hybridization using gene-specific probes, ribotyping, polymerase chain reaction (PCR)–based approaches, and pulsed-field gel electrophoresis (PFGE). These methods require subjective interpretation and comparison of patterns and fingerprint images. However, they still remain difficult to standardize between laboratories, and the image-based information is difficult to organize for rapid search and retrieval by computer. In addition, image-based methods do not provide biological criteria to evaluate the relatedness between different strains. DNA sequence analysis is an objective genotyping method; the genetic code (A-T-C-G) is highly portable and easily stored and analyzed in a relational database. Recent advances in DNA-sequencing technology, including rapid, affordable, high-throughput systems, have made it possible for sequencing to be considered as a viable typing method. Two different strategies have been used to provide genotyping data: multilocus sequence typing (MLST), which compares sequence variation in numerous housekeeping gene targets; and single-locus sequence typing, which compares sequence variation of a single target among strains to be typed.

The emergence of new epidemic strains of MRSA in the community, among patients without established MRSA risk factors, may present new challenges to MRSA control in healthcare settings. Community stains of MRSA.Such as Example we have find case Noscomal Pneumonia with resitance to vancomycin with resistance to Vanco now day every where in the world Abx are dumping in the body with finding a valid organism in the body

Mechanism of vancomycin resistance:

Vancomycin binds with the D-alanyl-D-alamine C terminus of the bacterial cell precursors, thereby preventing cross-linking by transpeptidation resulting in inhibition of cell wall production by attacking sites responsible for cell wall production.] VISA and hetero-VISA strains have been found to have thickened cell wall with reduced glycoprotein. This could be due to changes in peptidoglycan synthesis resulting in increased residues of D alanyl-D-alanine, which bind vancomycin molecules and prevent them from reaching the target sites.

MRSA Cases percentage:

We determine MRSA infection status and the use of vancomycin in its treatment at a teaching hospital in China. Methods: We retrospectively reviewed 140 cases of MRSA infection that were treated from January 2013 to October 2018. We analyzed the etiology of MRSA infection and the use of vancomycin in these cases. Results: MRSA infection mainly occurred in elderly patients concomitant with a variety of diseases, which incidence was more in men than women. More cases of MRSA infection were encountered in the ICU than in other departments. The positive culture results for MRSA were obtained in the sputum (38.57%), pharyngeal swab (19.29%), blood (5.71%), and wound secretion (11.43%) samples. The MRSA patients were sensitive to vancomycin, with the minimum inhibitory concentration (MIC) being 1 μg/mL in 53.80% of the cases and 2 μg/mL in 44.10% of the cases, respectively. Among the 35 (25%) cases treated with vancomycin, 23 were cured, while 3 died and 7 (20%) were considered as an unreasonable application. Conclusions: MRSA infection mainly appeared in patients admitted to the ICU. The MIC of vancomycin had a tendency to increase gradually

Reference:

Deurenberg RH, Vink C, Kalenic S, Friedrich AW, Bruggeman CA, Stobberingh EE. The molecular evolution of methicillin-resistant Staphylococcus aureus. Clin Microbiol Infect. 2007;13:222–35.[PubMed]