Espos, Coleen C.Ocenar, Joyce Ann C.

Medicine II

March 23, 2009

INTRODUCTIONBackground

Antibiograms are tables that document antimicrobial resistance of isolates processed in hospital laboratories. This can be aggregated to give a picture of antibiotic resistance in a particular place. It appears as a grid showing organisms on one axis and antibiotics on the other. Individual grid cells report the number of isolates tested and the percentage of isolates susceptible to a given antimicrobial. The basic components includes antibiotics tested, organisms tested, number of isolates for each organism, percentage susceptibility data for each drug/pathogen combination, specimen sites notations and specific area or unit being tested.

Antimicrobial sensitivity tests are used to select effective antimicrobial drugs for the treatment and control of infectious diseases, especially when caused by pathogens that are often drug resistant. And also, it is an important resource for healthcare professionals involved in deciding and prescribing empiric antibiotic therapy. Appropriate empiric therapy is essential in attempting to treat infections correctly and quickly in an effort to decrease mortality. The uses of antibiograms are also helpful in identifying and tracking antimicrobial resistance trends over time within a hospital.

The research sought to construct an antibiogram wall chart for quick reference intended for the hospital use and to address the growing problem of antibiotic resistance with many microorganisms. This includes drug-resistant Streptococcus pneumoniae, methicillin-resistant Staphylococcus aureus, Vancomycin-resistant Enterococcus and emerging resistance patterns. Research was done only in RTR hospital. Data was collected in the year 2006-2007 antibiogram report. No comparison with other hospital was done.

Statement of the ProblemDetermine the susceptibility pattern of

the most common bacteria that has been isolated from biologic specimens submitted at Remedios Trinidad Romualdez Hospital for culture and sensitivity in January 2006 to December 2007.

General ObjectivesTo determine the susceptibility pattern

of the most common bacteria that has been isolated from biologic specimen submitted at Remedios Trinidad Romualdez Hospital for culture and sensitivity in January 2006 to December 2007.

Review of Related LiteraturesAntimicrobial susceptibility testing is

routinely performed by most hospital laboratories. The hospital antibiogram is a periodic summary of antimicrobial susceptibilities of local bacterial isolates submitted to the hospital's clinical microbiology laboratory. Antibiograms are often used by clinicians to assess local susceptibility rates, as an aid in selecting empiric antibiotic therapy, and in monitoring resistance trends over time within an institution. Antibiograms are also used to compare susceptibility rates across institutions and track resistance trends (Pakyz, 2007).

Lacy et al, 2004 used the Analysis and Presentation of Cumulative Antimicrobial Susceptibility Test Data: Approved Guideline” (NCCLS M39-A) published reviewed common antimicrobial susceptibility testing methods and relevant issues, discussed the antibiogram preparation process and challenges in data interpretation, and provided an overview of how antibiogram data may be applied to clinical practice.

According to an article by Zapantis et al, 2005, a lack of standardization in the preparation and data assimilation of antibiograms (ABGMs) has not been addressed until recently, though susceptibility testing has been standardized for years. The objective of the study was to analyze current antibiograms using the recently published NCCLS M39-A guidelines for preparation of antibiograms to identify areas for improvement in the reporting of antibiogram susceptibility data.

The selection of antibiotic therapy is based largely on antimicrobial susceptibility rates compiled in a hospital's antibiogram. Binkley et al in 2006 collected antimicrobial susceptibility results for all inpatient clinical bacterial isolates recovered over a 3-year period. They evaluated a total of 9,970 bacterial isolates. The percentages of bacterial isolates resistant to antibiotics were significantly higher in the medical intensive care unit (ICU) and surgical ICU than the hospital-wide antibiogram would have predicted. In contrast, the percentages of isolates susceptible to antibiotics were significantly higher in the non-ICU units compared with the hospital overall. The authors conclude that unit-specific antibiograms are important for making informed decisions about antibiotic therapy.

Boehme and Somsel (2004) measured effectiveness of efforts to promote AST practice guidelines and determined if guidelines are being implemented in Michigan hospital laboratories by analyzing antibiograms submitted to Michigan Department of Community Health (MDCH) Bureau of Laboratories. Antibiograms were analyzed for unlikely resistance patterns, appropriateness of reported drugs and compliance with selected recommendations from M39-A. Errors found were categorized as major reporting misleading or inappropriate organism/drug combinations, reporting impossible/ unlikely resistance patterns) or minor (misspelled organism names/antimicrobials, obvious math errors). The results were that compliance with NCCLS M-39 A is increasing in some areas, and most errors are decreasing.

Specific ObjectiveTo determine the demographic profile of the

patient as to:agesex

To determine the most common microorganism(s) in biologic specimen submitted at RTRH.

To provide an antibiogram wall chart showing the susceptibility pattern of the most common microorganism isolated.

Significance of the StudyThe result of the study will contribute to

the existing knowledge about the antimicrobial susceptibility pattern of the most common organisms present in biologic specimens. The research will also help the following:

Department of Health: to monitor the susceptibility pattern of the most common microorganism(s) present in biologic specimens and to be able to highlight some findings that may be for further research and improvements;

Clinicians: to support clinical decision making, infection-control interventions, antimicrobial-resistance containment strategies, and to guide appropriate antibiotic selection because of an antimicrobial misuse;

Laboratory: to make available a quick reference guide of antibiogram, to know emerging trends or patterns in antimicrobial resistance and;

Patients: to ensure that they are given the most effective yet inexpensive antibiotic course of therapy for their illness.

Scope and LimitationThe study includes only the samples that

showed positive results in bacterial cultures and not the total samples analyzed during the year 2006 to 2007. It covers only the biological specimens referred to the Laboratory Department of Remedios Trinidad Romualdez Hospital (RTRH) for the year 2006 - 2007. The study is limited to the determination of the most common organisms found in biologic specimens, its antibiotic susceptibility patterns and the demographic profiles, which includes age and sex of the patients whose samples showed growth in the cultures. Data collected are those only with adequate information (Patient’s name, age, sex and isolated organism).

METHODOLOGYResearch Design

A retrospective descriptive type of research design was utilized in the study in order to obtain relevant information from a particular phenomenon that has occurred in the past that might be useful in the present situation.

Data Collection ProcedureRecords of biologic specimens submitted to the Laboratory department of Remedios Trinidad Romualdez Hospital (RTRH) for the year 2006 to 2007 were used in the study. Common microorganisms isolated from these biologic specimens that were submitted for culture and sensitivity tests were listed down together with their antibiotic susceptibility patterns. The frequency of the microorganisms isolated from these biologic specimens and their antibiotic susceptibility patterns were determined. Only the biologic specimens with complete data such as age and sex were tallied. The results were then tabulated and analyzed.

Theoretical Framework

RESULTS AND DISCUSSIONDemographic Data

Identified Organisms in the Different Cultures

Sensitivity and Resistance to Antibiotics

Antibiogram Table

Figure 3. Percent Sensitivity of Escherichia coli on Selected Antibiotics for the Year 2006-2007, Blood Cultures, RTRH.

Figure 4. Percent Sensitivity of Acinetobacter baumanii on Selected Antibiotics for the Year 2006-2007, ETA Cultures, RTRH.

Figure 5. Percent Sensitivity of Pseudomonas aeruginosa on Selected Antibiotics for the Year 2006-2007, Sputum Cultures, RTRH.

Figure 6. Percent Sensitivity of ATB Staphylococcus on Selected Antibiotics for the Year 2006-2007, Throat Cultures, RTRH.

Figure 7. Percent Sensitivity of Klebsiella pneumoniae on Selected Antibiotics for the Year 2006-2007, Transudate/Exudate Cultures, RTRH.

Figure 8. Percent Sensitivity of Escherichia coli on Selected Antibiotics for the Year 2006-2007, Urine Cultures, RTRH.

Figure 9. Percent Sensitivity of Staphylococcus organism on Selected Antibiotics for the Year 2006-2007, Wound Discharge Cultures, RTRH.

Table 11. Antibiogram showing Resistance Pattern of Selected Organisms Isolated, RTRH 2006-2007.

Legend:No – total number of isolatesNR – number of isolate resistant to antibiotic% R – percent resistance to antibiotic

SUMMARY AND CONCLUSIONA total of 129 positive cultures were done

at Laboratory Department of Remedios T. Romualdez Hospital during the year 2006-2007. This is consisted of 37 from wound discharge cultures; 26 from urine cultures; 26 from endotracheal aspirate cultures; 11 from throat swab cultures; 10 from transudate/exudates cultures; positives from 10 blood cultures; and 9 from sputum cultures.

Positive cultures according to age group of more than 60 years old had greatest number with 53 positives. Distribution of patients according to sex has a total of 78 male patients and 51 female patients.

The antimicrobial sensitivity pattern shows that Escherichia coli is the common microorganism that were isolated from urine and blood culture. E. coli has widely been implicated in various clinical infections as hospital acquired and community infections. Pathogenic isolates of E. coli have relatively high potentials for developing resistance. Prevalence of high resistances of E. coli to antimicrobial agents which produce extended spectrum beta-lactamases make the Penicillins and Cephalosporins inefficient use for therapy. Resistance to Quinolones like ciprofloxacin is because of the wholesale switch to alternative agents accelerated the widespread emergence of resistance to this antimicrobial class.

The other common microorganism isolated from throat culture and wound discharge is Staphylococcus organism. S. aureus is the most virulent of the many staphylococcal species, has demonstrated its versatility by remaining a major cause of morbidity and mortality despite availability of numerous effective anti-staphylococcal antibiotics. Antimicrobial agents for this organism have become increasingly problematic because of the prevalence of multidrug-resistant strains. As a result of the widespread dissemination of plasmids containing the enzyme penicillinase, few strains of staphylococci remain susceptible to penicillin. Resistance to Methicillin indicates resistance to all semisynthetic penicillinase-resistant penicillins (SPRPs) such as Oxacillin. Many MRSA isolates are also resistant to another antimicrobial family including macrolides which in this case Erythromycin.

The most common microorganism isolated from sputum culture is Pseudomonas aeruginosa. This is mainly associated with infections in hospitalized patients. Cytotoxic chemotheraphy, mechanical ventilation, and broad spectrum antibiotic therapy probably paved the way for increasing colonization and infection by P. aeruginosa. The results of antibiotic therapy for this organism have been unsatisfactory. Aminoglycoside resistance mechanism, which has been identified predominantly in clinical isolates of P. aeruginosa, is the decreased antibiotic uptake, presumably due to alterations in bacterial outer membrane. Resistance to Penicillins and extended spectrum Cephalosphorins can be explained through a decrease in outer membrane permeability with rapid efflux of the antibiotic from periplasm to the cell exterior. Also, resistance to Cotrimoxazole is due to the acquisition of plasmid-encoded genes that produce a new drug-insensitive target.

Klebsiella pneumonia is the most important Klebsiella species from a medical standpoint, it occurs primarily in host with underlying conditions. Resistant to third-generation Cephalosphorin is increasing, mediated primarily by plasmid-encoded ESBLs. In addition, these plasmids usually encode resistance to Aminoglycosides and Cotrimoxazole. Also, prevalence of Quinolone resistant strains is increasing.

The most common microorganism isolated from endotracheal aspirate is Acinetobacter baumanni. It is responsible for most Acinetobacter infections and highly prevalent in the environment, being found in most water and soil samples. Colonization of the skin and respiratory and gastrointestinal tracts are common in hospitals. Many strains of this organism are extensively resistant to antimicrobial agents. The first- and second-generation Cephalosporins exhibit little or no activity. However, Quinolones, third-generation Cephalosporins, Gentamicin, Cotrimoxazole, Aminoglycosides, and some beta-lactamase resistant Penicillins showed a wide range of sensitivity and Amikacin is often the active antimicrobial agent.

RECOMMENDATIONThis paper can serve as reference guide to

the antibiotic susceptibility testing done in RTRH during 2006-2007. The researchers recommend the following for the improvement of the antimicrobial susceptibility testing:

Antibiotic susceptibility testing must be designed to provide clinicians with information on current trends in resistance.

Powerful antibiotics should be tightly regulated so as to lessen rapid resistance of microorganisms to these antibiotics.

Antimicrobial susceptibility testing should be continued especially on patients with life threatening infections.

Antibiotic susceptibility testing should be used on epidemiologic surveillance of clinically important resistant organisms such as MRSA and multiple-resistant nosocomial organisms.

Antimicrobial susceptibility testing must be performed under controlled and standardized conditions to provide accurate results.

The antimicrobial susceptibility test performed on etiologic organism must provide valuable information for patient care and must result in predicting the clinical outcome and or response to therapy.

Antimicrobial susceptibility testing should be correlated with the pharmacological properties of the antimicrobial drug and the clinical results when the drug is used.

The researchers recommend storing results from all isolates tested by the laboratory in a database, as this will help the clinicians for future use.

Annual antibiogram should be conducted in all hospitals in order to compile cumulative percentage susceptibility rates.