Incidence Of Antibiotic Resistance Research Articles

Microbial resistance: lessons from the EPIC study. European Prevalence of Infection.

In 1992, a one day point prevalence study (EPIC) was conducted in European intensive care units (ICUs) to determine the prevalence of nosocomial infection among ICU patients. Of the 10,038 patients included, 45% were infected and 21% had a nosocomial ICU-acquired infection. Many of the organisms responsible for these infections were resistant to commonly used antibiotics. For example, 60% of the Staphylococcus aureus isolated were resistant to methicillin and 46% of Pseudomonas aeruginosa were resistant to gentamicin. The incidence of nosocomial infection varied between countries as did the incidence of antibiotic resistance. Mortality rates were higher in countries with higher rates of nosocomial infection and higher again in those countries with higher rates of resistant organisms. Antibiotic resistance is rising and clearly efforts to contain its development and spread are vital. Basic infection control procedures such as hand-washing must be developed and implemented, and antibiotic prescribing needs to be rationalized. The international variations in resistance rates, even within Europe, highlight the importance of being familiar with local resistance patterns when prescribing. The assistance of an infectious diseases specialist can be invaluable in providing a global overview of the local microbial milieu and of antibiotic resistance patterns. Epidemiological studies of this sort can provide useful information which can be used to stimulate debate on the reasons behind regional differences in infection and help in the development of strategies to combat the rising tide of microbial antibiotic resistance.

A proteomic analysis of erythromycin resistance in Streptococcus pneumoniae.

Streptococcus pneumoniae is a significant human pathogen which is an important cause of pneumonia and bacteraemia. Over the past few years the incidence of antibiotic resistance among clinical isolates of S. pneumoniae has increased. Penicillin resistance is now widespread and the frequency of isolates that are resistant to erythromycin has risen. Erythromycin resistance in S. pneumoniae follows two basic patterns. The MLS erythromycin-resistant phenotype is due to the enzymatic methylation of ribosomal RNA that blocks erythromycin binding to the ribosome. Alternatively, in isolates of the M phenotype, a more recently documented mechanism, resistance is associated with an active efflux process that reduces intracellular levels of erythromycin. We used two-dimensional electrophoresis to examine the proteins synthesised by erythromycin-susceptible and -resistant S. pneumoniae. Erythromycin-resistant S. pneumoniae with the M phenotype showed a significantly increased synthesis of a 38,500 Dalton (pI 6.27) protein compared to susceptible isolates. Peptide mass mapping was used to identify the 38,500 Dalton protein as glyceraldehyde-3-phosphate dehydrogenase (GAPDH). It was demonstrated that S. pneumoniae synthesised at least three forms of GAPDH that differed in their isoelectric points. The form of GAPDH possessing the most basic pI showed the increased synthesis in the erythromycin-resistant S. pneumoniae isolates. Alterations in the synthesis of GAPDH were only found for those erythromycin-resistant isolates possessing the M phenotype. S. pneumoniae isolates with the MLS phenotype were indistinguishable from the susceptible strains using the analytical conditions employed for the current study. The possible role of GAPDH in erythromycin resistance of S. pneumoniae is considered.

Formula to help select rational antimicrobial therapy (FRAT): its application to community- and hospital-acquired urinary tract infections

The selection of antimicrobial agents is guided by the use of formularies which often constrain prescribing options. There are several factors which influence the inclusion of specific agents. Two of the most important factors are microbial etiology of a disease and the incidence of antibiotic resistance. Various surveillance programs have highlighted the regional differences in antimicrobial susceptibility/resistance among various pathogens. This simple formula enables individual physicians, pharmacy and therapeutic committees and managed care formulary managers to harness local etiology and susceptibility information. In this paper the formula is applied to community- and hospital-acquired urinary tract infections.

Effects of sunlight and Synechocystis sp. (picocyanobacterium) on the incidence of antibiotic resistance in wastewater enteric bacteria

Experimental study of the effects of sunlight and Synechocystis sp. (picocyanobacterium) on the incidence of antibiotic resistance in Salmonella sp. and faecal coliforms (FC), was carried out in wastewaters of Marrakesh stabilization ponds (Morocco). The effect of sunlight was found to be important on the incidence of antibiotic resistance of these enteric bacterial populations. In microcosms seeded with the mixed inoculum (40 different strains) of Salmonella or FC and exposed to sunlight, the overall resistance of these bacteria (72.5 and 57.5% respectively) was significantly higher than that noted in the dark (45 and 32.5% respectively). In microcosms seeded with a monobacterial inoculum, some FC isolates became resistant to the antibiotics cephalothin, amoxicillin or sulphamethoxazole, after their incubation in sunlight. Synechocystis appeared to have no significant effect on the incidence of bacterial antibiotic resistance. The ecological significance of sunlight and Synechocystis sp. in reducing densities and increasing antibiotic resistance of pathogenic bacteria through wastewater stabilization ponds is discussed.

Incidence of antibiotic resistance in blood and urine isolates from hospitalized patients. Report from a European collaborative study. European Study Group on Antibiotic Resistance (ESGAR).

During 1992-93, 2544 isolates from blood cultures, comprising 52% gram-negative bacilli, 24% Staphylococcus aureus, 15% other staphylococci, 7% Enterococcus faecalis and 2% E. faecium, were consecutively collected and identified in 30 laboratories in 21 European countries. In addition 2512 urine isolates, comprising 82% gram-negative bacilli, 3% S. aureus, 4% other staphylococci and 11% enterococci were collected. The bacteria were sent to 3 laboratories for susceptibility testing by the microdilution method in Mueller-Hinton broth. The MICs of penicillins and aztreonam for all susceptible gram-negative bacilli were 0.25-8 mg/l, penems 0.032-2 mg/l, cefotaxime, ceftazidime and cefpirome or cefepime 0.032-0.25 mg/l, gentamicin, tobramycin and netilmicin 0.125-2 mg/l, amikacin 0.5-4 mg/l, ciprofloxacin 0.016-1 mg/l, trimethoprim 0.25-1 mg/l and tetracycline 1-2 mg/l. For susceptible staphylococci the MICs of erythromycin were 0.25-0.5 mg/l, clindamycin 0.125-0.25 mg/l, methicillin 2-8 mg/l, vancomycin and trimethoprim 1-4 mg/l, ciprofloxacin 0.25-1 mg/l, gentamicin and tobramycin 0.25-1 mg/l. For the enterococci the MICs of ampicillin and vancomycin were 2-4 mg/l and of imipenem, teicoplanin and trimethoprim 0.5-1 mg/l. The antibiotic resistance rates varied between laboratories, being lower in northern Europe, except for the penems, cefpirome and cefepime, which showed uniformly lower resistance rates. Compared to the earlier European studies the resistance rates to beta-lactam antibiotics among the gram-negatives have not changed except with an increase to cefotaxime and ceftazidime in central Europe. Resistance to aminoglycosides had also increased in central Europe from 7-8% to 20-21%, but decreased in southern Europe from 22-24% to 13-14% among the blood isolates and from 12-28% to 6-7% among the urine isolates. There was an increase in resistance to ciprofloxacin and gentamicin in staphylococci from southern Europe. The prevalence of MRSA was significant in central and southern Europe. It is of importance that collaborative national and international studies on the incidence of antibiotic resistance are being performed on a repetitive basis.

Incidence of antibiotic resistance in fecal Escherichia coli isolated from commercial swine farms.

Sows and pigs from 10 commercial swine farms were sampled to determine patterns of resistance of fecal Escherichia coli to five commonly used antibiotics. Before testing, farms were categorized as high or low antibiotic use based on interviews with the respective producers. On each farm, fecal swabs were obtained from five sows at 7 d postpartum and from five pigs from each sow at 7, 35, and 63 d of age. A total of 6,296 E. coli isolates from 750 pig fecal samples and a total of 462 E. coli isolates from 50 sow fecal samples were tested against apramycin, carbadox, gentamicin, neomycin, and oxytetracycline using a standardized disk diffusion test. Percentage of resistant organisms was compared between pigs at the various stages of growth, between sows and their respective pigs, and between farms of high and low antibiotic use. Incidence of resistance was greater (P < .05) in pigs at 35 or 63 d of age compared with 7 d of age for most antibiotics, and patterns differed between high-use and low-use farms. Resistance differed (P < .05) among E. coli from pigs compared to their respective sows for apramycin and carbadox on low-use farms, whereas incidence of resistance on high-use farms differed (P < .05) between sows and pigs for apramycin and oxytetracycline. These data indicate that patterns of antibiotic resistance are dependent on age of pig and level of antibiotic use.

Increasing incidence and widespread dissemination of methicillin-resistant Staphylococcus aureus (MRSA) in hospitals in central Europe, with special reference to German hospitals

OBJECTIVE: to present data on prevalence and interregional spread of methicillin-resistant Staphylococcus aureus (MRSA) in Germany. METHODS: A nationwide collection of MRSA isolates from nosocomial infections in 143 hospitals was established from isolates (n=4368) sent to a microbiological reference center during 1993--95. As chosen by distinguishable resistance phenotypes at each time of occurrence during the study period, 1830 isolates were subjected to molecular typing by means of Smal macrorestriction patterns, PCR for RNA gene spacer patterns, and PCR for patterns of DNA stretches flanked by the ERIC-2 sequence and flanked by Tn916 and ribosomal binding site. In addition, data from a multicenter study on the incidence of antibiotic resistance have been analyzed (32 centers, 637 S. aureus isolates). RESULTS: In 1995 the prevalence of MRSA among S. aureus isolates was 8.7% overall in central Europe (including Germany), in comparison to 1.7% in 1990. From 1993 until now, a continuous interregional dissemination of six epidemic strains, which were identified by molecular typing, was recorded. Besides these epidemic strains, 15 MRSA strains were identified which could not be allocated to the epidemic MRSA or to the known clonal groups of the species S. aureus. MRSA from three cases of sporadic nosocomial infections exhibited characteristics of the clonal group of S. aureus with the capacity for toxic shock syndrome formation. The pattern of one MRSA corresponded to those of the S. aureus group exhibiting phage pattern 94,96. CONCLUSIONS: The prevalence of MRSA has increased in central Europe (and Germany) during the last 5 years, to 8.7%. The main source of infection with MRSA is obviously interregional dissemination of epidemic strains. At the same time, the mecA gene has been acquired by strains previously sensitive to methicillin.

The Clinical Relevance of Antibiotic Resistance in the Management of Pneumococcal Pneumonia

The incidence of antibiotic resistance is increasing in pneumococcal isolates worldwide. Current evidence suggests that the most active 13-lactam agents remain clinically useful in the treatment of penicillin-resistant pneumococcal pneumonia. These agents include intravenous penicillin, amoxicillin, cefuroxime, the third-generation cephalosporins cefotaxime and ceftriaxone, and the carbapenems. The authors recommend that penicillin or amoxicillin remain the drugs of choice for this condition. Macrolide resistance has been associated with clinical failure. The clinical relevance of resistance to trimethoprim/sulfamethoxazole has yet to be established. Most of the currently available quinolones are of borderline activity against the pneumococcus and would not be recommended for empiric therapy. Antibiotic-resistant pneumococci are increasingly found among HIV-infected patients. The therapeutic outcome appears, however, to be similar to that of patients without HIV infection.

Incidence of antibiotic resistance and sex pheromone response among enterococci isolated from clinical human samples and from municipal waste water

Incidence of antibiotic resistance and sex pheromone response among enterococci isolated from clinical human samples and from municipal waste water

Efficacy of pneumococcal vaccination in adults. A meta-analysis of randomized controlled trials.

Because of the prevalence of pneumococcal pneumonia, the substantial morbidity and mortality associated with many pneumococcal infections, and an increase in the incidence of antibiotic resistance among pneumococcal isolates, considerable efforts for disease prevention have been made using a polyvalent polysaccharide pneumococcal vaccine. Despite numerous clinical trials of the vaccine, its efficacy in the prevention of pneumococcal infections and other clinically relevant medical outcomes in adults remains uncertain. To assess quantitatively the efficacy of pneumococcal vaccination, a MEDLINE literature search, manual reviews of article bibliographies, and communications with pneumococcal vaccine investigators were used to identify randomized controlled trials of the pneumococcal vaccine. Independent review of 594 articles revealed nine randomized trials with 12 vaccine and control study groups that evaluated clinically relevant outcomes in adults. To estimate a summary effect size for all outcomes, Mantel-Haenszel odds ratios (ORs) and Dersimonian and Laird rate differences (RDs) and their associated 95% confidence intervals (CIs) were computed. Summary ORs demonstrated a statistically significant protective effect of the vaccine for four pneumococcal infection-related outcomes: definitive pneumococcal pneumonia (OR = 0.34; 95% CI = 0.24 to 0.48), definitive pneumococcal pneumonia for vaccine-containing pneumococcal antigen types only (vaccine types only) (OR = 0.17; 95% CI = 0.09 to 0.33), presumptive pneumococcal pneumonia (OR = 0.47; 95% CI = 0.35 to 0.63), and presumptive pneumococcal pneumonia (vaccine types only) (OR = 0.39; 95% CI = 0.26 to 0.59). The summary RDs, which account for heterogeneity among studies, confirmed a statistically significant protective effect for two of these same outcomes: definitive pneumococcal pneumonia (RD = 4/1000; 95% CI = 0/1000 to 7/1000) and definitive pneumococcal pneumonia (vaccine types only) (RD = 8/1000; 95% CI = 1/1000 to 16/1000). Summary ORs and RDs failed to demonstrate a protective effect for pneumonia (all causes), bronchitis, and mortality (all causes) or mortality due to pneumonia or pneumococcal infection. Subgroup analyses showed that for all four pneumococcal infection-related outcomes, vaccine efficacy differed for high- and low-risk subjects, demonstrating efficacy for low-risk subjects and lack of efficacy for high-risk subjects. Pneumococcal vaccination appears efficacious in reducing bacteremic pneumococcal pneumonia in low-risk adults. However, evidence from randomized controlled trials fails to demonstrate vaccine efficacy for pneumococcal infection-related or other medical outcomes in the heterogeneous group of subjects currently labeled as high risk.

Antibiotic Resistance of Agricultural and Foodborne Salmonella Isolates in Canada: 1986–1989

A total of 689 Salmonella cultures isolated during 1986–1989 from Canadian agricultural products and from imported fish, shellfish, and reptiles were examined for resistance to a test panel of 11 antibiotics. The incidence of antibiotic resistance in strains from all sources seemingly increased during the study period, whereas the occurrence of resistance within individual sample categories fluctuated annually. Although poultry figured as a major reservoir of resistant salmonellae (53.4%), red meats and fish/shellfish also yielded substantial numbers of resistant strains. The range of streptomycin (27.1 to 48.7%) and tetracycline (24.3 to 37.8%) resistance among poultry and red meat isolates, and identification of meat isolates carrying chloramphenicol (0.4 to 9.1%) and ampicillin (3.4 to 11.4%) resistance codons was disquieting. Most of the multiply-resistant (≥ 2 antibiotics) strains belonged to somatic serogroups B and C, with poultry occurring as the principal reservoir of multiresistant phenotypes. Of the 27 resistance patterns encountered in this study, all but two contained a resistance determinant for streptomycin and/or tetracycline. These findings underscore a disturbing level of antibiotic resistant Salmonella in the food chain, and the need to reassess the alleged benefits of subtherapeutically medicated feeds in current animal husbandry practices.

The incidence of antibiotic resistance in aerobic faecal flora in Sooth India

During a field study in South India in 1989, faecal specimens were collected from residents in villages and the town of Vellore in South India. Examination of the faecal specimens revealed that virtually the whole population carried commensal bacteria resistant to trimethoprim, ampicillin and chloramphenicol. Most specimens contained more than one type of bacterium resistant to each antibiotic. There was less resistance to nalidixic acid, with a higher proportion in the town (33%) than in the villages (13%). Although there was little cross-resistance of the ampicillin-resistant strains to later generation cephalosporins, 50% were resistant to the combination of amoxycillin and clavulanic acid. There was no significant cross-resistance of the nalidixic acid-resistant strains to fluorinated 4-quinolones, despite the free availability of ciprofloxacin and norfloxacin in the area. The probable reason for the high incidence of resistance to first generation antimicrobials is the extensive use of these agents, coupled with continuous exposure to large numbers of faecal micro-organisms.

Antibiotic resistance in Gram-negative bacteria from cultured catfish and aquaculture ponds

The incidence of antibiotic resistance was compared in Gram-negative bacteria isolated from the intestinal tracts of catfish and from water and sediment in aquaculture ponds and rivers of the southeastern United States. Resistance to tetracycline, oxytetracycline, chloramphenicol, kanamycin, ampicillin, and nitrofurantoin was determined. The predominating microflora were Plesiomonas shigelloides and Aeromonas hydrophila. Individual and multiple antibiotic resistances were associated with antimicrobial use. Resistance apparently was higher in ponds undergoing antimicrobial therapy or with a history of recent treatment than in ponds without recent antimicrobial treatment. The lowest incidence of resistance was found in riverine bacteria.

K1 Antigen, Serotype and Antibiotic Susceptibility of Escherichia coli Isolated from Cerebrospinal Fluid, Blood and Other Specimens from Japanese Infants

K1 antigens, serotypes and antibiotic susceptibilities of Escherichia coli isolates from neonates and infants were investigated. The presence of K1 antigen was tested by the K1-specific phage method. The number of K1 positive strains was 27 (84%) of 32 isolates from cerebrospinal fluid, 11 (25%) of 44 from blood and 4 (22%) of 18 from other specimens. Fourteen (33%) of the K1 positive strains were serotyped as O16:H6, and 8, 7 and 5 were serotyped as O18ac:H7, O1:H7 and O7:H-, respectively. One of 5 of the K1 negative strains were distributed into 30 different combinations of O and H antigens. The ampicillin resistance rates were 19% in K1 positive strains and 45% in K1 negative ones. The incidence of chloramphenicol resistance was the same in K1 positive and negative strains (21%). Ampicillin resistance was not noted in O16:H6 strains, but the incidence of antibiotic resistance was high (65% to ampicillin and 53% to chloramphenicol) in the rough-type strains.

Plasmid Incidence in Bacteria from Deep Subsurface Sediments

Bacteria were isolated from deep terrestrial subsurface sediments underlying the coastal plain of South Carolina. A total of 163 isolates from deep sediments, surface soil, and return drill muds were examined for plasmid DNA content and resistance to the antibiotics penicillin, ampicillin, carbenicillin, streptomycin, kanamycin, and tetracycline. MICs of Cu, Cr, and Hg for each isolate were also determined. The overall frequency of plasmid occurrence in the subsurface bacteria was 33%. Resistance was most frequent to penicillin (70% of all isolates), ampicillin (49%), and carbenicillin (32%) and was concluded to be related to the concentrations of the individual antibiotics in the disks used for assaying resistance and to the production of low levels of beta-lactamase. The frequencies of resistance to penicillin and ampicillin were significantly greater for isolates bearing plasmids than for plasmidless isolates; however, resistance was not transferable to penicillin-sensitive Escherichia coli. Hybridization of subsurface bacterial plasmids and chromosomal DNA with a whole-TOL-plasmid (pWWO) probe revealed some homology of subsurface bacterial plasmid and chromosomal DNAs, indicating a potential for those bacteria to harbor catabolic genes on plasmids or chromosomes. The incidences of antibiotic resistance and MICs of metals for subsurface bacteria were significantly different from those for drill mud bacteria, ruling out the possibility that bacteria from sediments were derived from drill muds.

Incidence of antibiotic resistance and characterization of plasmids in Campylobacter jejuni strains isolated from clinical sources in Alberta, Canada.

Antibiotic susceptibilities of 382 strains of Campylobacter jejuni isolated in Alberta, Canada, in 1980 and 1981 were determined. Although none were resistant to erythromycin or gentamicin, 5.4 and 22% of strains were resistant to ampicillin in 1980 and 1981, respectively. Tetracycline resistance was noted in 6.8% of strains in 1980 and in 8.6% in 1981. Moreover, resistance to high-level tetracycline (32-128 micrograms/mL) was always mediated by a plasmid of 45-50 kilobases. Three transmissible plasmids from the Alberta strains were compared with the prototype plasmid pMAK175 by restriction enzyme analysis and some minor differences in restriction sites were noted between pMAK175 and pUA183. The two other plasmids pUA142 and pUA143 were 4 kilobases larger than pMAK175 and contained additional restriction sites. However, in all plasmids examined, the HincII and AccI fragments where the tetracycline-resistance determinant was located were shown to be conserved.

Survey of plasmids inClostridium butyricum andClostridium beijerinckii strains from different origins and different phenotypes

A total of 50Clostridium butyricum strains from clinical and nonclinical sources and 14C. beijerinckii strains originating from dairy products were analyzed for their plasmid content, antibiotic resistance, and bacteriocinogenic activity. The incidence of antibiotic resistance and presence of plasmidic DNA was more widespred among theC. butyricum strains from clinical source than among theC. beijerinckii strains, all of the originating from dairy products. In many of theC. butyricum strains, a small plasmid of 4.5 megadaltons was encountered. No relation was found between the plasmid pattern, the antibiotic resistance, the geographic localization of the isolates, or the clinical condition of the patients.

Antibiotic resistance of faecal coliforms in hospital and city sewage in Galway

The incidence of antibiotic resistance and of R-factors in the faecal coliform populations of raw hospital and city sewage was investigated in Galway city. During a 14-month sampling period, the incidence of faecal coliform resistance to ampicillin, tetracycline, chloramphenicol and streptomycin in city sewage was on a par with, and in some cases, greater than the incidence in hospital sewage. Over 90% of resistantE. coli isolates from hospital and city sewage were simultaneously resistant to two or more antibiotics. In the majority of isolates, resistance was R-factor carried, with 90% of the city sewage isolates and 69% of the hospital sewage strains capable of conjugal transfer to a sensitiveE. coli recipient. The data indicates the presence of an undesirably high level of transferable antibiotic resistance in the gut flora of the healthy non-hospitalized population in Galway.

Spread of R-plasmids among Escherichia coli causing urinary tract infections.

The incidence of multiple-antibiotic resistance among Escherichia coli isolated from urinary tract infections at Charing Cross Hospital, London, increased over the last 10 years, and its distribution was related to O-type. Among strains of the eight O-types most frequently causing such infections at this hospital, O4, O9, and O18 had a high incidence of multiple resistance (35, 22, and 19%, respectively); O2 and O6 had a intermediate incidence (14 and 11%, respectively); and O7, O1, and O75 had a low incidence (8, 6, and less than 3%, respectively). This nonrandom distribution appears to be a consequence of unequal plasmid recipient ability. After overnight mating with antibiotic-resistant donors, R-plasmid infection frequencies among antibiotic-sensitive urinary tract isolates differed by up to 10(5)-fold, and such differences were correlated with the variation in the incidence of antibiotic resistance among the O-types. The inherent differences in the ability to achieve significant R-plasmid spread, which appear to be determined by the host, not the plasmid, may be compounded in some cases by the inhibition of potential mating partners by colicin production.

R-plasmids in hospitals — Implications for antibiotic use

R-plasmids in hospitals — Implications for antibiotic use