Private experience and observational learning in pharmaceutical demand Tanja Saxell∗† February 13, 2014 I quantify the roles of the physician's own experience and the past choices of other doctorsin pharmaceutical demand. I develop a model of medical decision-making under uncer-tainty about the quality of the match between the patient and drug treatment. Unlikeprevious demand models, I take into account both private and social learning, and allowheterogeneity in product quality across individuals. I test whether information on thepast choices of other doctors improves drug choices. Using rich data from the market forcholesterol drugs, I show that treatment patterns relying heavily on the past choices ofother doctors can lead to over-prescribing in terms of eciency. My results suggest thatcontinuity of care, where a patient is repeatedly consulting the same doctor, is an ecientpolicy to limit such behavior.
UntitledOccurrence of methicillin resistant staphylococcus aureus
(MRSA) in patients requiring reconstructive surgery
Muhammad Bilal, Abdul Janan, Irfanullah, Mushtaq Ahmad Abstract
Objectives:Staphylococcus aureus is a signifi cant nosocomial pathogen and the development
of resistance to methicillin poses a major threat to its control. Th
isstudy was conducted to de- termine the incidence of methicillin resistant staphylococcus aureus in outdoor patients and
its susceptibility to diff erent anti-staphylococcal antibiotics.
Study design: Descriptive prospective study.
Sett ing and duration: Outpatient department, Plastic Surgery& BurnUnit, Khyber Teaching
Hospital Peshawar from August 2011 to July 2014.
Methods: A total of 210 patients, of either gender, who presented with septic wounds were
included in the study.Swabs were collected from infected wounds and transported in Stuart's
e Specimens were inoculated on Blood agar, MacConkey's agar and nutrient agar and incubated at 37oC for 24 hours. Th e clinical specimens submitt ed at the microbiology laboratory were processed and all methicillin resistant staphylococcus aureus (MRSA)isolates
were identifi ed morphologically and biochemically by standard laboratory procedures. All the
isolates were studied for their susceptibility and resistance patt ern.
Results:Out of 210 patients, 123 (58.57%) were male and 87(41.42%) female with mean
ageof 28.5 years. Th
e frequency of culture positive cases was 127 (60.47%), of which the fre- quency of MRSA was 81 (63.77%). Th e frequency of culture negative cases was 83 (39.52%). e MRSA were 100% sensitive to linezolid, vancomycin and teicoplanin. Out of them 49.38% were sensitive to fuscidic acid, 19.75% to cotrimoxazole and 30.86% to tetracycline group of antibiotic. Th e organism was found to be 100% resistant to most of commonly prescribed e emergence of MRSA is on the rise. Th e organism spreads easily in hospital sett ings and causes higher mortality, morbidity and increased costs. Specifi c precautions and Khyber Teaching
infection control measures must be adopted to prevent and interrupt the spread of MRSA.
Keywords: MRSA, Nosocomial infection, Antibiotic resistance
nature of staph aureus limits the treatment op- Lady Reading Hospital,
Staphylococcus aureusis a gram positive bac- tions2.To almost every new drug which is intro- terium that causes various infections in human duced, resistance follows soon.S. aureusstrains e microorganism is capable of pro- have developed resistance to virtually all anti- ducing infectious conditions like cutaneous in- biotic classes that are currently in practice.Th Junior Registrar, fections, pneumonia, toxic shocksyndrome and include ß-lactams and glycopeptides, aminogly- Plastic Surgery Unit, life threatening blood stream infections1. Th e cosides, tetracyclines, fusidic acid, quinolones, Khyber Teaching Hospital,Peshawar.
control of this organism is diffi cult because of trimethoprim sulfamethoxazoleetc.2-4.Penicillin Phone: 0333-9194317 its ability to develop resistance against multiple was the fi rst beta lactam antibiotic introduced in antimicrobial agents. Th is multidrug-resistant 1940. Soon resistance to it emerged in 1942. ß- Pak J Surg 2014; 30(4):301-305 M Bilal, A Janan, Irfanullah, M Ahmad lactamase (Penicillinase) was extracted in 1944. spectrum antimicrobial agents. Th Penicillinaseresistant ß-lactams such as cepha- worker harboring the pathogen can transmit the losporins and semi synthetic penicillins such as infection to the patients with whom they have methicillin and nafcillin became available in the contact and directly contribute to the continu-late 1950s 5.Methicillin was introduced in 1959 ance of the problem18.
but soon the S. aureusdeveloped resistant to it6.
MRSA withlimited treatment options is particu- Methicillin resistance staph aureus (MRSA) larly diffi cult to treat. Th e control of this organ- was fi rst reported in 19616. Th e resistance of ism is therefore very important so that it does staph aureus to methicillin confers cross resis- not spread to other patients. Th e present study tance to other broad spectrum beta-lactum anti- was conducted to assess the incidence of MRSA biotics like cephalosporins. Th e emergence of in the outdoor patients presenting to plastic sur- MRSA is admitt ed as a very serious health prob- gery department at tertiary care hospital in Pe- lem because of the diffi culty in controlling these shawar.
strains10. Infections with antibiotic resistant or-
ganisms generally result in higher morbidity and Methodology:
mortality rates than the susceptible micoorgan-
is study was conducted over a period of three years from August 2011 to July 2014 at the de-partment of plastic surgery, Khyber Teaching Variations in the patt ern of antimicrobial sus- Hospital, Peshawar. Th e study was conducted ceptibility of S. aureus have been reported aft er approval by the Hospital ethical commit-worldwide. In developing countries the anti- tee. A total of 210 patients were included in this microbial agents are becoming less eff ective in study. Informed consent was taken from each treating bacterial infections.Th e magnitude of patient. All these patients presented with septic MRSA incidence in Asia occupies a lower level wounds involving various regions of the body.
in contrast to Europe and the United States12. Irrespective ofage, sex, cause of sepsis, region Th e diff erence in prevalence may be due to dif- involved,and any previous surgical intervention, ferent practices and policies prevailing in dif- all the presenting patients, for various plastic ferent hospitals, even, in given areas13. Many and reconstructive procedures, were included.
studies have shown an increase in the number of Th e patient's comorbid conditions, previous MRSA cases and thus posing a challenge to the treatment including antibiotics and the length current healthcare system. For the past 20 years of treatment were not taken into account how-there has been a major increase in the number of ever the referral sourceand duration of previous infections caused by MRSA in some countries, hospitalization were recorded. 164 patients re-especially the United Kingdom14.
mainedadmitt edin various hospitals and their duration of stay ranged from 7to 21 days. Th e resistant strain of staph aureus is typically in- patients were either discharged or referred troduced into an institution by an inhabitant(i.e. from various allied specialties like orthopedics, harboring the pathogen but without discernable general surgery, maxillofacial surgery, pediatric signs of disease) or infected patient or a health surgery and gynecology. Wound swabs were care worker15. It is recognized that colonization taken from all patients registered in the study. with MRSA precedes infection16. Several modes Swabs were collected from infected wound fol-of transmission include the transient coloniza- lowing cleansing of any scrapof previously ap- tion of hospital staff and contact with heavily plied topical remedy. Swabs were immersed in contaminated fomites and environmental sur- Stuart's transport medium. Aft er collection, all faces around infected patients17.Certain caus- swabs were inoculated on Blood agar, MacCo- ative factors that subsidizethe transmission and nkey's agar and nutrient agar and incubated at dissemination of this organism include pro- 37oC for 24 hours. Morphological Examination longed hospital stay and the use of several broad of pus smear and culture smear, colonial mor- Pak J Surg 2014; 30(4): 301-305 Occurrence of methicillin resistant staphylococcus aureus (MRSA) in patients requiring reconstructive surgery phology, production of β hemolysis on blood Statistical soft ware SPSS- 17 was used to analyse agar and production of pigmentation on Nutri- ent agar and biochemical tests like catalase, co- agulase Mannitol fermentation and Novobiocin Atotal of two hundred and ten outdoor pa- sensitivity were performed for the isolation of tients presenting to the Plastic surgery unit were methicillin resistant strains of staph aureus. An- screened for the incidence of MRSA. Out of timicrobial susceptibility test was performed by total patients 123 were males and 87 females. disc diff usion method as per National Commit- e age of the patients ranged from one and half tee of Clinical Laboratory standards (NCCLs). year to seventy one years(1.5-71years) and the mean age was 28.5 years. Th e frequency of mi- Table 1: Sensitivity patt ern of MRSA crobial culture positive cases was 127(60.47%). Sensitive Resistant Total
Of the total culture positive cases the frequency of MRSA was 81 (63.77%). Out of 81 MRSA cases 52 (64.19%) were male and 29 (35.80%) e frequency of other bacteria was 46 (36.22%). All the MRSA showed 100% sensitivity to linezolid and vancomycin.Sixteen (19.75%) of the strains showed sensitivity to cotrimoxazole, 40 (49.38%) to fucidic acid and 25(30.86%) to tetracycline. Th was 100% resistant to major groups of antibiot- ics such penicillins, cephalosporins, macrolides, fl ouroquinolones, imipenem, meropenem, gen- tamicin and pipracillin/tazobactum (Table 1).
Of the total 81 MRSApatients more than 50% Table 2: Referring source of MRSA positive cases were referred from orthopedics and general No. of Patients
surgical units and the rest from other allied spe- cialties like pediatric surgery,Gynecology,maxil lofacial surgery, ENT and neurosurgery (Table Pediatric surgery e causes of septic wound in MRSA positive cases are given in table 3. Maxillofacial surgery Forty (49.38%) MRSA were present as the only microbes in the infected wounds while 41(50.61%) were associated with other bacteria as a primary pathogens. E.coli, pseudomonas aeroginosa and candida albicans were the as-sociated microorganism revealed by the culture Table 3: Etiology of Wound Sepsis No. of patients
Of the total 81 MRSA patients 77 (95.06%) patients gave the history of previous hospital- ization and 65 (84.41%) out of them remained Necrotizing fasciitis hospitalized for more than a week time.
Post tumor ablation surgery In the recent years the bacteria have evolved nu- Pak J Surg 2014; 30(4): 301-305 M Bilal, A Janan, Irfanullah, M Ahmad merous defenses against antimicrobial agents.
the prevalence rate of MRSA 18.6% over the e incidence of multidrug resistance in patho- previous study of 9.8% 25. In year 2010 Sanjana genic and opportunistic bacteria is on the rise. RK and her colleagues reported the prevalence For long time penicillin group of antibiotics was of MRSA to be 39.6% in a teaching hospital at the mainstay of treatment of various infections Nepal26.While comparing the results of present caused by staphylococcus aureus. Th e genus has study with the aforementioned fi gures it is quite gradually acquired resistanceto antibiotics and a evident that there is an increase in the occur-proportion of organisms have become resistant rence of MRSA.
to methicillin and cloxacillin. Th such resistance raises question about the future Th e current study shows the patt ern of sus- of these drugs in chemotherapy, as the transmis- ceptibility as all MRSAwere susceptible to sion of such resistance plasmid to other bacteria linezolid,vancomycin and teicoplanin. Th will help in the fast dissemination of resistance sensitivity declined for the cotrimoxazole, fu-genes19.
cidic acid and doxycycline respectively. All the MRSA isolates were resistant to certain antibi- e methicillin resistant staphylococcus au- otics like penicillin, cephalosporins,chloramphi reus has caused problems in most hospitals all niciol, macrolides, fl ouorquinolones, imipenem over the world. Since its discovery in 1961 the and getamicin. Although the same observa-pathogen has been recognized as a very seri- tions were made by Khan T. in his study where ous health problem because of diffi culties in the culture grown strains were sensitive to combatt ing these strains. Th e resurging MRSA Linezolid,vancomycin and teicoplanin however problem seems to be based on the lack of potent with slight variations in the resistant patt ern was therapeutic agents having a cell killing eff ect and also identical1. In our study we found that most capable of eliminating the MRSA from the pa- of the patients MRSA were males and majority tient's body. Hospitals and the community face of them had either undergone surgical interven-challenge to control and eradicate this microor- tions or remained hospitalized for more than a ganism because these infections are associated week time.
with an increase in mortality, longer hospital stay and higher inpatient costs compared to pa- While studying the incidence of MRSA, Khan tients with methicillin susceptible staphylococ- TA come up with the conclusion that majority of the patients with infected wounds were re-ferred from orthopedic unit and general surgical e present study reveals a signifi cant number of wards1. Our study predicted the same observa- MRSA positive cases among the patients stud- tions where more than 50% of the patients were- ied over a period of three years. About 64% of those who remained admitt ed either in ortho-the subjects were the carriers of MRSA. A study pedics or general surgery units. It demonstrates conducted by Khan T in 2013 reported the fre- that MRSA is more prevalent in patients having quency of MRSA positive cases to be 60.71%1. orthopedic problem or if they have undergone In 2002 Hafi z S. et al revealed the prevalence any surgical procedure. We observed that almost of MRSA strains to be 42 % among the various 21% of patients referred from pediatric surgery cities of our country21. Th is elucidates that the were harboring MRSA. Certain patients with emergence of MRSA is on the rise.An incidence infected wounds being referred from maxillofa-of 43.16% was reported by Hassan N. in a sur- cial surgery and ENT units were also positive for vey at a tertiary care hospital in Lahore22. Th study of Rehman S. shows an increase of 54.2% in the occurance of MRSA over a period of two Th e long duration of hospitalization could also years23. Naqvi ZA has reported an incidence of be a factor for gett ing an MRSA infection. Th 24.11% among burn patients in Karachi24.Th e study of Sanjana RK depicts that the preva- study of Orret AF showed a steady increase in lence of MRSA was higher in admitt ed patients Pak J Surg 2014; 30(4): 301-305 Occurrence of methicillin resistant staphylococcus aureus (MRSA) in patients requiring reconstructive surgery (41.1%) as compare to the outdoor patients Teaching Hospital, Abuja, Nigeria. Afr. J. Cln. Exper. Micro-biol January 2013; 14(1): 10-13 (37.4%)26. She concluded this diff erence to be 11. Chambers, H. F. Th e changing epidemiology of Staphylococ-due to prolonged hospital stay and invasive pro- cus aureus. Emerg. Infect. Dis. 2001; 7: 178-182.
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04 de mayo de 2012 Alteraciones en la biodistribución de los radiofármacoscausadas por interacciones medicamentosas Ana Agudo Martínez1, Jesús Luis Gómez Perales 2, Juan Luis Tirado 3. 1 - Servicio de Medicina Nuclear, Hos pital Univers itario Virgen Macarena (Sevilla, Es paña). 2 - Servicio de Medicina Nuclear, Hos pital Puerta del Mar (Cádiz, Es paña).