Global surveillance of antibiotic resistance

Analysis of the Occurrence of Antibiotic Resistant Bacteria in the Hospital’s Effluent and its Receiving Environment

The use of antibiotics on a regular and excessive basis is a major factor in the spread of antibiotic-resistant bacteria. Patients discharge un-metabolized or relatively low doses of non-metabolized antibiotics through urine and stool, which might enter into the environment through sewage disposal and promote the emergence of antibiotic resistant bacteria. This study is designed to investigate how excessive use of antibiotics in the hospital sector and their release into hospital wastes contribute to the spread of antibiotic-resistant bacteria in different environmental settings. In this study, liquid hospital waste was collected from the sewage of Chittagong Medical College Hospital (CMCH), Bangladesh as well as from its distribution position in Chittagong city, Bangladesh. A total of 5 samples were collected from different positions in Chittagong city, including CMCH liquid waste. After collection, total bacteria and total cefixime resistant bacteria were counted by the total viable count (TVC) method. The result of bacteriological enumeration showed that a high magnitude of cefixime-resistant bacteria were available in all the hospital’s associated waste samples. The highest proportion of cefixime resistant bacteria (23.35%) was found in sample 2, whereas 17.4%, 7.6%, 5%, and 1.32% were found in samples 1, 3, 4, and 5, respectively. The total number of cefixime-resistant bacteria decreased with the increase in distance between the sample collection site and the hospital drain. This means that resistant bacteria developed in the hospital effluent are transferred to the environmental distribution sites.

Label-free identification of individual bacteria using Fourier transform light scattering

Rapid identification of bacterial species is crucial in medicine and food hygiene. In order to achieve rapid and label-free identification of bacterial species at the single bacterium level, we propose and experimentally demonstrate an optical method based on Fourier transform light scattering (FTLS) measurements and statistical classification. For individual rod-shaped bacteria belonging to four bacterial species (Listeria monocytogenes, Escherichia coli, Lactobacillus casei, and Bacillus subtilis), two-dimensional angle-resolved light scattering maps are precisely measured using FTLS technique. The scattering maps are then systematically analyzed, employing statistical classification in order to extract the unique fingerprint patterns for each species, so that a new unidentified bacterium can be identified by a single light scattering measurement. The single-bacterial and label-free nature of our method suggests wide applicability for rapid point-of-care bacterial diagnosis.

An extracorporeal blood-cleansing device for sepsis therapy

Here we describe a blood-cleansing device for sepsis therapy inspired by the spleen, which can continuously remove pathogens and toxins from blood without first identifying the infectious agent. Blood flowing from an infected individual is mixed with magnetic nanobeads coated with an engineered human opsonin--mannose-binding lectin (MBL)--that captures a broad range of pathogens and toxins without activating complement factors or coagulation. Magnets pull the opsonin-bound pathogens and toxins from the blood; the cleansed blood is then returned back to the individual. The biospleen efficiently removes multiple Gram-negative and Gram-positive bacteria, fungi and endotoxins from whole human blood flowing through a single biospleen unit at up to 1.25 liters per h in vitro. In rats infected with Staphylococcus aureus or Escherichia coli, the biospleen cleared >90% of bacteria from blood, reduced pathogen and immune cell infiltration in multiple organs and decreased inflammatory cytokine levels. In a model of endotoxemic shock, the biospleen increased survival rates after a 5-h treatment.

Self medicated antibiotics in Bangladesh: a cross-sectional health survey conducted in the Rajshahi City

BACKGROUND

Antibiotic self medication is highly prevalent in the developing countries due to easy availability and poor regulatory controls for selling these drugs. The purpose of this study was to evaluate the prevalence of self-medication with antibiotics for the treatment of various diseases by the peoples of Rajshahi city in Bangladesh.

METHODS

A cross-sectional survey was conducted to the patient's (n = 1300) at eight locations of Rajshahi city in Bangladesh from March to April, 2014. The locations were selected by convenience and the study population within each study area was randomly selected. The survey was self-administered and included questions pertaining to self medicated drugs and antibiotic usage patterns as well. Data were analyzed using descriptive statistics.

RESULTS

It was found that 347 (26.69%) out of 1300 participants experienced self medication with antibiotics. Over fifty percent of the patients studied were between the ages of 21-30 years with 83.57% of them being males and 16.43% females. The highest percentage of self medicated antibiotics was metronidazole (50.43%) followed by azithromycin (20.75%), ciprofloxacin (11.53%), amoxicillin (10.37%) and tetracycline (7.49%) respectively. The key reasons for the self medication of antibiotics was the pre-experience (45.82%), suggestions from others (28.24%) and knowledgeable of the antibiotics (16.14%). The perceived symptoms to purchase the antibiotics independently was dysentery, diarrhea and food poisoning (36.02%), cold, cough and fever (28.24%), infection (12.97%), dental carries and toothache (9.22%), irritable bowel syndrome (3.46%), acne (4.32%), ear and throat pain (2.31%). The duration of maximum antibiotics usage was ranges between 0-10 years. Only 4.32% patient's used self medicated antibiotics longer than 10 years. The patient's compliance for self medication of antibiotics varies from excellent to no comments whereas only 6.92% patients reported side effects for the self medication of antibiotics.

CONCLUSIONS

The results of this study confirm that antibiotic self-medication is a relatively frequent problem in Bangladesh. Drug Administration of Bangladesh should implement the regulatory controls immediately on the distribution and selling of antibiotics in order to reduce the frequency of antibiotic misuse.

Utilization of antimicrobial agents with and without prescription by out-patients in selected pharmacies in South-eastern Nigeria

OBJECTIVE

We conducted a study in out-patient pharmacies in South-eastern Nigeria in order to determine the extent of self-medication of antimicrobial agents in this area, assess the dosing error associated with this practice and to ascertain the extent of involvement of community pharmacies.

METHOD

A survey was carried out daily in selected community pharmacies for a period of 90 days. Data were collected on the number of patients visiting these shops for antimicrobial agents, the number getting their medication with a prescription, the number getting their order without prescription and on the type and dose of antimicrobial agents received. MAIN OUT-COME MEASURE: The percentage of patients with prescription and without prescription was compared. The percentage under-dosages or over-dosages associated with how each antimicrobial agent was obtained were compared. The total DDDs of antimicrobial agents dispensed within this period with and without prescription were compared.

RESULTS

A total of 4,128 outpatients visited the shops for antimicrobial agents within the period and were involved in the study. Of this number, 1,742 (42.2%) came with a prescription from qualified medical personnel and 2,386 (57.8%) came without a prescription. A total of 13,693.13 DDDs of antimicrobial agents was dispensed, of which 56.38% was dispensed with prescription and 43.62% was dispensed without prescription. The degrees of under-dosing were significantly (P < 0.05) higher in regimen filled without prescription when compared to those filled with prescription.

CONCLUSION

Majority of the patients in this region still obtains their antimicrobial agents without a proper prescription, which is associated with sub-therapeutic dosing of these agents. There is a need for better regulation of antimicrobial agents dispensing and utilization in the region.

Multidrug-resistant commensal Escherichia coli in children, Peru and Bolivia

Healthy children in urban areas have a high prevalence of fecal carriage of drug-resistant E. coli.

Using a rapid screening method, we investigated the prevalence of fecal carriage of antimicrobial drug–resistant Escherichia coli in 3,174 healthy children from 4 urban settings in Peru and Bolivia. High resistance rates were observed for ampicillin (95%), trimethoprim-sulfamethoxazole (94%), tetracycline (93%), streptomycin (82%), and chloramphenicol (70%). Lower resistance rates were observed for nalidixic acid (35%), kanamycin (28%), gentamicin (21%), and ciprofloxacin (18%); resistance to ceftriaxone and amikacin was uncommon (<0.5%). In a random sample of 1,080 resistant E. coli isolates, 90% exhibited a multidrug-resistance (MDR) phenotype. The 2 most common MDR phenotypes (ampicillin/tetracycline/trimethoprim-sulfamethoxazole and ampicillin/tetracycline/trimethoprim-sulfamethoxazole/chloramphenicol) could be transferred en bloc in conjugation experiments. The most common acquired resistance genes were bla_TEM, tet(A), tet(B), drfA8, sul1, sul2, and catI. These findings underscore the magnitude of the problem of antimicrobial drug resistance in low-resource settings and the urgent need for surveillance and control of this phenomenon.

Changing the prescribing patterns of sexually transmitted infections in the White Nile Region of Sudan

BACKGROUND

The number of inappropriate prescriptions for sexually transmitted infections (STIs) in Sudan is suspected to be high. Simple multifaceted interventions directed at prescribers may improve prescribing patterns in the Sudan.

OBJECTIVE

To evaluate the effect of multifaceted interventions on prescribing for STIs in the White Nile State, Sudan.

METHODS

The study involved 20 health centres randomly assigned to four different multifaceted interventions to improve prescribing.

RESULTS

Prescriber targeted interventions involving audit and feedback together with academic detailing and practice guidelines reduced the number of inappropriate prescriptions by 50% (p < 0.001). Audit and feedback together with seminars and practice guidelines reduced inappropriate prescriptions by 43% (p < 0.001). Audit and feedback alone reduced inappropriate prescriptions by 16% (p = 0.127).

CONCLUSION

Prescribing for STIs in the White Nile State of Sudan needs improving. Multifaceted interventions appear effective in improving prescribing.

Optimizing antibiotic therapy-the Aberdeen experience

OBJECTIVE

To study the quality and continuity of treatment in the Acute Medicines Assessment Unit (AMAU) with regard to empirical prescription of antibiotics, mode of administration, adherence to ward antibiotic policy, as well as collection, awareness and utilization of microbiological investigations.

METHODS

A prospective study over a 3-month period at the AMAU, Aberdeen Royal Infirmary (ARI), a teaching hospital in north-eastern Scotland, was performed. The study included all patients started on empirical antibiotics on admission to the AMAU and followed up until their discharge.

RESULTS

Of 1303 patients admitted, 221 (17%) were started on empirical antibiotics. This was in accordance with hospital antibiotic policy in 52% of cases. Appropriate specimens were taken from 77% of patients. Culture results showed that 29% (n = 65) of the patients had clinically significant growth of organisms. Of the 65 patients with clinically significant culture results, 49% (n = 32) were on an inappropriate empirical regimen. In 55%, the medication was not changed to a more appropriate antibiotic. In 72% of the patients with a negative culture, the culture report had no obvious effect on the duration or type of antibiotic being administered. Intravenous antibiotics were used in 60% of patients.

CONCLUSION

This study demonstrates a significant overuse of antibiotics, especially intravenous forms, despite a paucity of positive sepsis parameters and chest X-ray findings in these patients The duration of treatment could be shortened and an early switch policy introduced if culture results and sepsis profiles were taken into consideration, as there was a large number of unproven infections. Suggestions are made about how these improvements in prescribing could be made within the current administrative set-up of AMAUs.

A new method for normalized interpretation of antimicrobial resistance from disk test results for comparative purposes

OBJECTIVE

To evaluate a calibration method for disk diffusion antibiotic susceptibility tests, using zone diameter values generated in the individual laboratory as the internal calibrator for combinations of antibiotic and bacterial species.

METHODS

The high-zone side of zone histogram distributions was first analyzed by moving averages to determine the peak position of the susceptible population. The accumulated percentages of isolates for the high zone diameter values were calculated and converted into probit values. The normal distribution of the ideal population of susceptible strains was then determined by using the least-squares method for probit values against zone diameters, and the ideal population was thereby defined, including mean and standard deviation. Zone diameter values were obtained from laboratories at the Karolinska Hospital (KS) and Växjö Hospital (VX), and from two laboratories (LabA, LabB) in Argentina. The method relies on well standardized disk tests, but is independent of differences in MIC limits and zone breakpoints, and does not require the use of reference strains. Resistance was tentatively set at below 3 SD from the calculated, ideal mean zone diameter of the susceptible population.

RESULTS

The method, called normalized interpretation of antimicrobial resistance, was tested on results from the KS and VX clinical microbiology laboratories, using the disk diffusion method for antimicrobial susceptibility tests, and for two bacterial species, Staphylococcus aureus and Escherichia coli. In total, 114 217 test results were included for the clinical isolates, and 3582 test results for control strains. The methodology at KS and VX followed the standard of the Swedish Reference Group for Antibiotics (SRGA). Zone diameter histograms for control strains were first analyzed to validate the procedure, and a comparison of actual means with the calculated means showed a correlation coefficient of r = 0.998. Results for clinical isolates at the two laboratories showed an excellent agreement for 54 of 57 combinations of antibiotic and bacterial species between normalized interpretations and the interpretations given by the laboratories. There were difficulties with E. coli and mecillinam, and S. aureus and tetracycline and rifampicin. The method was also tested on results from two laboratories using the NCCLS standard, and preliminary results showed very good agreement with quality-controlled laboratory interpretations.

CONCLUSIONS

The normalized resistance interpretation offers a new approach to comparative surveillance studies whereby the inhibition zone diameter results from disk tests in clinical laboratories can be used for calibration of the test.

Economic issues and antibiotic resistance in the community

BACKGROUND

Inappropriate antibiotic use is generally considered to be the primary cause of antibiotic resistance in the community. Multiple economic factors, at the level of physicians, patients, healthcare organizations, and pharmaceutical companies, foster poor antibiotic use.

OBJECTIVE

To describe the influence of economic factors on the use and development of antibiotics and to evaluate the extent to which the cost of resistance is important in the economic evaluation of antibiotic products.

DATA SOURCES

Literature identified through MEDLINE (1966-May 2001), bibliographies from relevant articles, government reports, and proceedings from conferences about antibiotic resistance.

DATA SYNTHESIS

Economic factors at all levels of the healthcare system contribute to the inappropriate use of antibiotics in the community setting. Relatively little economic research has been published on antibiotic resistance, and very few cost-effectiveness analyses of antibiotic treatment alternatives have explicitly included the cost of resistance.

CONCLUSIONS

A better understanding of economic factors that influence the prescribing, marketing, and development of antibiotics could lead to more successful efforts at curtailing the growth of antibiotic resistance in the community setting.

The emergence of erythromycin-resistant Streptococcus pyogenes in Seoul, Korea

High frequencies of erythromycin-resistant streptococci were reported in Japan in the mid-1970s, and in Finland in the late 1980s, related to an increase in the consumption of macrolide antibiotics in these countries. The frequency of erythromycin-resistant Streptococcus pyogenes was reported to be only 2% in 1994, but we know that the susceptibility of the strains to antibiotics had not been tested routinely. We studied the resistance rates of Streptococcus pyogenes to various antibiotics in Seoul, Korea, where antibiotics could be purchased without prescription. From January through December, 1998, 92 isolates of group A streptococci were collected from inpatients and outpatients with pharyngotonsillitis or invasive streptococcal infections, from institutions in five different geographic areas of Seoul; one pediatric clinic, three university hospitals, and one general hospital. All isolates were serotyped by T-agglutination, and minimum inhibitory concentrations (MICs) were determined by agar dilution methods, according to the guidelines of the National Committee for Clinical Laboratory Standards (NCCLS). The most common T-serotype was T12 (44.6%), followed by T4 (19.6%). All the isolates tested were susceptible to penicillin, vancomycin, and cefotaxime. However, 38 isolates (41.3%) were resistant to erythromycin, 32 (34.8%) were resistant to clindamycin, and 48 (52.1%) were resistant to tetracycline. Twenty-seven of 41 isolates serotyped T12 and 3 of 18 isolates serotyped T28 were multiresistant to erythromycin, clindamycin, and tetracycline. Almost half of the isolates obtained from the five different areas in Seoul showed erythromycin resistance in Streptococcus pyogenes. Routine monitoring of antibiotic susceptibility tests and further extensive nationwide surveys are needed to determine the frequency and the extent of the spread of resistant strains in various geographic regions in Korea.

Antimicrobial resistance

Antimicrobial resistance is not a new concept. For over half a century, health care providers have been faced with this problem. The overuse and misuse of antimicrobial therapy by health care providers has contributed largely to the problem, but several other factors have also been associated with antimicrobial resistance. This article reviews current literature regarding antimicrobial resistance in an effort to educate health care providers to make judicious decisions in the treatment of bacterial infections and stem the rise of antibiotic resistance by carefully scrutinizing prescribing practices. Contributing factors to antimicrobial resistance and recommendations for the control of antimicrobial resistance will be reviewed. Treatment recommendations for common health ailments (i.e., acute otitis media, rhinitis, sinusitis, and pharyngitis) are provided.

Susceptibility of group A beta-hemolytic streptococci in the lower St Lawrence region, Quebec

OBJECTIVE

To determine the susceptibility of group A beta-hemolytic streptococci (GABHS) in the lower St Lawrence region, Quebec to different antibiotics, particularly macrolides, and to compare different antibiogram methods (disk diffusion, E-test and microdilution) and incubation atmospheres (ambient air and 5% carbon dioxide).

METHODS

A total of 384 strains of GABHS isolated from 377 patients (throat 335; other sites 49) from three hospitals in the lower St Lawrence region were analyzed for their susceptibility to erythromycin, clarithromycin, azithromycin, penicillin, clindamycin, cephalothin, rifampin and vancomycin by disk diffusion on Mueller-Hinton (MH) agar supplemented with 5% defibrinated sheep blood (MHB) at 35ºC in 5% carbon dioxide. Strains that were found to be intermediately resistant or resistant to one of the antibiotics by disc diffusion, strains from sites other than throat, and a sample of 97 pharyngeal strains were evaluated by E-test on MHB (35ºC, 5% carbon dioxide) for their susceptibility to the antibiotics erythromycin, clarithromycin, azithromycin, penicillin, clindamycin and ceftriaxone. In addition, minimum inhibitory concentrations (MICs) were determined for erythromycin and azithromycin by broth microdilution using MH broth supplemented with 2.5 % of lysed horse blood (35ºC, ambient air) on strains that were resistant or intermediately resistant to the macrolides (erythromycin, clarithromycin, azithromycin). An evaluation was also carried out on these strains to determine the influence of the incubating atmosphere (ambient air versus 5% carbon dioxide) on susceptibility results obtained by disk diffusion (erythromycin, clarithromycin and azithromycin) and E-test (erythromycin and azithromycin) methods.

RESULTS

Nine strains (2%) from nine patients (throat eight, pus one) were resistant to all macrolides as tested by three different techniques (disk diffusion, E-test and microdilution). All strains were susceptible to all the other antibiotics tested. For the strains intermediately resistant or resistant to macrolides, incubation in a 5% carbon dioxide atmosphere was associated with a reduction in the diameter of inhibition determined by disk diffusion (P<0.001) with frequent minor variations in interpretation, and with an increase in the MIC by E-test (P<0.001), which had no impact on interpretation.

CONCLUSIONS

Resistance of GABHS to macrolides was not common (2%) in the lower St Lawrence Region. GABHS susceptibility to erythromycin seemed to predict the susceptibility to the other macrolides. Significant variation in antibiogram results (disk diffusion and E-test) of GABHS susceptibility to macrolides was related to the incubation atmosphere and may have an impact on the interpretation of disk diffusion results.

Detection of antimicrobial activity in urine for epidemiologic studies of antibiotic use

Antibiotic resistance is the inevitable consequence of the selective pressure of antimicrobial drug use and the adaptive plasticity of the microorganisms. Excessive and irrational use of antimicrobial drugs is a problem in all countries. It is particularly troublesome in developing countries where there is a heavy burden of infectious diseases. This study was designed to determine whether detection of antimicrobial activity in the urine might be a useful tool for epidemiologic studies of the interaction between antibiotic use and resistance in developing countries. A laboratory marker is necessary because the history of antimicrobial drug use may be unreliable. Serial specimens or spontaneously voided urine were obtained from healthy volunteers given a single oral dose of commonly used antimicrobial drugs. Urine was also obtained from hospitalized patients the morning after the last dose of an antimicrobial drug and from untreated controls. Assays were performed with standard American Type Culture Collection (Rockville, MD) stains of Bacillus stearothermophilus, Escherichia coli, and Streptococcus pyogenes. Antimicrobial activity could not be detected in pretreatment urine. After a single oral dose, the beta lactam antibiotics and erythromycin could be detected for about 12 to 24 hours, whereas clindamycin, tetracycline, trimethoprim/sulfamethoxazole, and ciprofloxacin could be detected for 48 or more hours. In hospitalized patients, receiving multiple drugs, the following were the sensitivity and specificity for detection of antimicrobial activity: for B. stearothermophilus, 100.0% and 85.9%, respectively; for S. pyogenes, 94.9% and 94.9%, respectively; and for E. coli, 71.8% and 98.7%, respectively. The combination of E. coli and Streptococcus pyogenes exhibited a sensitivity of 97.4% and specificity of 94.9%. Detection of antimicrobial activity in urine is a promising method to determine antimicrobial drug use in epidemiologic studies, particularly in populations in which drug use history is unreliable.

Are we facing a 'post-antibiotic era'?--a review of the literature regarding antimicrobial drug resistance

Since the introduction of antibiotics in the 1940s, antibiotic resistance has become an increasing problem. Today, multiple-antibiotic resistance is commonly associated with a number of clinically important pathogens and is therefore an important issue in clinical nursing practice. Epidemiological studies identify a number of important factors associated with increases in antimicrobial resistance. These include patterns of antimicrobial use, changes in medical and veterinary care and social practices affecting the transmission of microbes. Bacterial mechanisms of antibiotic resistance and the genetics of resistance-gene transfer are explored, with the intention of developing nurses' knowledge and understanding of control measures.

Patterns of antimicrobial use and antimicrobial resistance among healthy children in Bolivia

OBJECTIVE

To determine the incidence of antimicrobial-resistant, nonpathogenic Escherichia coli among healthy children aged 6-72 months in Camiri town and a rural village, Javillo, in south-eastern Bolivia.

METHOD

A community-based survey: stool samples were obtained from 296 healthy children selected by modified cluster sampling in Camiri and all 25 eligible children in Javillo. E. coli isolates were tested for antimicrobial susceptibility according to the standard disc diffusion method. By a questionnaire survey of 12 pharmacies and by using simulated patients, we investigated the antimicrobial availability and the usage patterns in Camiri town.

RESULTS

In Camiri, over 90%, and in Javillo over 70% of children carried E. coli resistant to ampicillin, trimethoprim-sulphamethoxazole (TMP/SMX) or tetracycline. Overall, 63% of children carried E. coli with multiple resistance to ampicillin, TMP/SMX, tetracycline and chloramphenicol. In the simulated patients study, antimicrobials were dispensed inappropriately for 92% of adults and 40% of children with watery diarrhoea, and were under-prescribed for males with urethral discharge (67%) or females with fever and dysuria (58%). The dose and/or duration of antimicrobials dispensed was almost always too low.

CONCLUSION

Our study showed a disturbingly high prevalence of carriage of nonpathogenic E. coli resistant to antimicrobials. The prevalence of resistance to ampicillin and TMP/SMX was higher than that previously reported in developing countries. The existence of a large reservoir of resistance genes in healthy individuals in developing countries represents a threat to the success of antimicrobial therapy throughout the world. Programmes to improve rational and effective drug use in developing countries are urgently needed.

Argentinian collaborative study on prevalence of erythromycin and penicillin susceptibility in Streptococcus pyogenes. The Argentinian Streptococcus Study Group

Two monthly studies on the prevalence of penicillin and erythromycin susceptibility of Streptococcus pyogenes were performed in May and October of 1994 in Argentina. A total of 58 centers from 27 cities participated in these studies. A total of 1072 isolates were tested by a diffusion method, although 595 isolates were tested both by the diffusion and an agar dilution method (n = 1767 isolates). No penicillin-resistant streptococci were found in our study (MIC100 = 0.03 microgram/ml). Only four isolates were confirmed as erythromycin resistant S. pyogenes (prevalence 0.14 and 0.28% in May and October 1994, respectively). Resistance in three isolates was due to an inducible mechanism, although in one strain a different phenotype was observed.

Pseudomonas aeruginosa: assessment of risk from drinking water

Pseudomonas aeruginosa is an ubiquitous environmental bacterium. It can be recovered, often in high numbers, in common food, especially vegetables. Moreover, it can be recovered in low numbers in drinking water. A small percentage of clones of P. aeruginosa possesses the required number of virulence factors to cause infection. However, P. aeruginosa will not proliferate on normal tissue but requires previously organs. Further narrowing the risk to human health is that only certain specific hosts are at risk, including patients with profound neutropenia, cystic fibrosis, severe burns, and those subject to foreign device installation. Other than these very well-defined groups, the general population is refractory to infection with P. aeruginosa. Because of its ubiquitous nature, it is not only not practical to eliminate P. aeruginosa from our food and drinking water, but attempts to do so would produce disinfection byproducts more hazardous than the species itself. Moreover, because there is no readily available sensitive and specific means to detect and identify P. aeruginosa available in the field, any potential regulation governing its control would not have a defined laboratory test measure of outcome. Accordingly, attempts to regulate P. aeruginosa in drinking water would not yield public health protection benefits and could, in fact, be counterproductive in this regard.

Can antimicrobial activity be sustained? An appraisal of orally administered drugs used for respiratory tract infections

Respiratory tract infections (RTIs) represent a major cause of illness worldwide. Therefore, it is of great concern that common RTI pathogens have become increasingly resistant to many of the antimicrobial agents used for therapy. For example, Haemophilus influenzae and Moraxella catarrhalis have become resistant to beta-lactam drugs by producing efficient beta-lactamases (> 35 and 90% of strains, respectively). More recently, pneumococci have become more resistant through the mechanism of altered penicillin-binding proteins (PBPs). The rate of penicillin nonsusceptible isolates has risen to > 25% in the United States (1994-1995). It is important to monitor the resistance characteristics of such pathogens and, if possible, to use regionally acquired data to guide empiric selection of therapeutic agents for RTIs. Currently, some antimicrobials remain effective against the majority of these three bacterial species, as exemplified by amoxicillin/clavulanic acid. Furthermore, amoxicillin alone seems to possess greater inhibition than other orally administered beta-lactams at clinically achievable concentrations against pneumococci with altered PBPs. It is critical that steps are taken to limit resistance problems, particularly through; 1) education of prescribers and the public; 2) initiation of the development of novel drugs with alternative modes of action or stability to existing resistance mechanisms; and 3) by continuing to generate quality susceptibility testing data to guide empiric chemotherapy against bacterial pathogens causing RTI.

Decreased activity of erythromycin against Streptococcus pyogenes in Taiwan

A total of 78 clinical isolates of Streptococcus pyogenes were collected from January 1992 through December 1993 from patients in southern Taiwan. The in vitro activities of 10 antimicrobial agents were determined by the agar dilution method. Penicillin, cephalothin, cefotaxime, vancomycin, and ofloxacin were shown to be active against S. pyogenes isolates, with MICs at which 90% of isolates are inhibited (MIC90s) being < or = 0.03, < or = 0.13, < or = 0.13, < or = 0.13, and < or = 0.25 microgram/ml, respectively. Erythromycin and azithromycin both had poor activities (MIC50s, 16 and >128 micrograms/ml, respectively; MIC90s, >128 and >128 micrograms/ml, respectively). The activities of tetracycline, clindamycin, and chloramphenicol against a significant number of these isolates were also limited. As the MICs of clindamycin and chloramphenicol for the isolates increased, the MICs of the two macrolides also increased. Clindamycin, chloramphenicol, and the two macrolides were less potent against isolates recovered form throat swab samples than against those from blood or other sources. Isolates of the T12 and T1 serotypes accounted for 53.8% of all isolates. The majority (87.5%) of the isolates recovered from throat swab samples were of the T12 serotype, whereas 19.2% of the isolates recovered from blood were of the T12 serotype. In contrast, 66.7% of the isolates of the T1 serotype were derived from blood but none were derived from throat swab samples. Of the 33 T12 serotype isolates, erythromycin MICs for 78.8% of the isolates were >128 micrograms/ml. Because of the poor activities of erythromycin and azithromycin against S. pyogenes isolates from patients in southern Taiwan, these drugs should no longer be considered the drugs of choice for the management of group A streptococcal infections among patients who live in this area.

Antibiotic resistance in group A streptococci

Although erythromycin resistance in GABHS has been a major problem in Japan and in Finland, it has not been a problem in the United States. The susceptibility of GABHS to the newer macrolide antibiotics seems to be similar to that of erythromycin. Comprehensive, community-wide programs to continuously monitor for erythromycin resistance in GABHS would be difficult to justify; however, because little is known about how erythromycin resistance in GABHS is acquired or spread, it would be reasonable to periodically monitor isolates of GABHS for erythromycin resistance. Despite more than four decades of use of penicillin in treating GABHS infections, no significant change has occurred in the in vitro susceptibility of GABHS to penicillin. The resurgence of severe, invasive GABHS infections and of acute rheumatic fever is not attributable to the emergence of strains of GABHS with increased resistance to penicillin. A substantial proportion of GABHS are currently resistant to tetracyclines, and these agents are inappropriate for treating GABHS infections. Although little recent information is available about the susceptibility of GABHS to sulfonamides, these agents have been shown to be ineffective in eradicating GABHS form the upper respiratory tract regardless of the in vitro sensitivities. GABHS have not been shown to be resistant to any of the commonly used oral cephalosporins; however, a great deal of variability exists among these agents in their activity against GABHS. Clindamycin resistance in GABHS has remained unusual. This agent is an alternative for treating GABHS infections due to macrolide-resistant strains in patients who cannot be treated with beta-lactam antibiotics.

Detection and surveillance of antimicrobial resistance

The clinical microbiology laboratory is strategically positioned to recognize changing patterns in bacterial resistance to antimicrobials. This requires the application of accurate testing methods and a methodological survey of drug-resistance patterns among clinically important bacteria. This information can be assembled into comprehensive international databases, using a common format to facilitate monitoring.

The use of antimicrobial drugs in Nagpur, India. A window on medical care in a developing country

The objective of the study was to determine the patterns of use of antimicrobial drugs in the general population of the large, industrial city of Nagpur, India. Interviews of pharmacists and clients were carried out in a stratified, random sample of 34 pharmacies to determine beliefs and practices in prescribing and self-prescribing of antibiotics by complaint, choice of drug, dose, duration, cost, age and sex of the consumers. The study showed that drugs were dispensed without prescription despite prohibition by the Indian Pharmaceutical Act. Sales of antimicrobial drugs accounted for 17.5% of 511 purchases and 23.3% of expenditures for drugs. Proprietary brands of penicillins, co-trimoxazole and tetracyclines were dispensed most often (64.8%). The most common indications were upper respiratory, gastrointestinal and nonspecific complaints. The median number of units obtained was 5.0 (95% range 1-20), at a median cost of $0.50 per purchase, usually taken for less than five days. Repeat purchases were made without consulting a physician. Almost two thirds of purchases (63.9%) were for males, mainly under the age of ten years. Clients had poor knowledge of the indications, side effects, adverse reactions and appropriate duration of therapy. The dispenser viewed himself as a businessman rather than a professional and rarely offered unsolicited advice. Co-prescribing of 'tonics' added to costs and decreased the purchasing power for antimicrobial drugs. Most purchases of antimicrobial drugs in community pharmacies in Nagpur were for minor indications and were limited by the purchasing power of the consumers. It is doubtful that the choice of drug and the short duration of therapy would be effective for serious infections.(ABSTRACT TRUNCATED AT 250 WORDS)

Risk factors for acquisition of multiply drug-resistant gram-negative bacteria

Some bacteria are naturally resistant to many antibiotics and most can become multiply resistant. Multiply resistant gram-negative bacteria have proved a particular problem over the last 30 years, but the development of new agents has lessened their significance for most clinicians. Now, however, clinical practice is threatened by the lack of new classes of antibiotics, the widespread emergence of resistance and the advent of plasmid-mediated cephalosporinases by which the spread of resistance is likely to be rapid. Increased use of prophylaxis in immunosuppressed and intensive care patients is likely to aggravate the problem, as is the use of new broad-spectrum agents in the community. More directed and restricted antibiotic use and better education of patients and prescriber are necessary to contain the problem of antibiotic resistance. Improved surveillance of sensitivity trends is essential. Many outbreaks also are associated with poor infection control techniques. The cost of outbreaks due to multiply resistant organisms and lack of compliance with infection control procedures needs to be properly studied. While many predisposing factors for the acquisition of these organisms and the development of infection are understood, the multifactorial nature of illness in many patients complicates the issue, necessitating further study of risk factors and preventative and therapeutic measures.