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PubMed1976

Failure of vancomycin treatment in Staphylococcus aureus endocarditis. In vivo and in vitro observations.

In a case of staphylococcal endocarditis, we failed to eradicate Staphylococcus aureus from the blood stream with vancomycin hydrochloride therapy. The strain involved was sensitive to vancomycin by disk diffusion studies but showed a wide disparity between minimal inhibitory and minimal bactericidal concentrations. The lack of a bactericidal effect was probably responsible for the failure of treatment. A synergistic effect was demonstrated for the combination of gentamicin sulfate and methicillin sodium, and the patient was ultimately cured with this combination plus vancomycin. Bactericidal tests are important in choosing an antimicrobial agent for treatment of endocarditis.

Adult↗

PubMed2006

A new antimicrobial susceptibility testing method of Escherichia coli against ampicillin by MSPQC.

A new antimicrobial susceptibility testing method by multi-channel series piezoelectric quartz crystal (MSPQC) was proposed. This method was used to test susceptibility of clinical Escherichia coli isolates against ampicillin. Both the minimum inhibitory concentrations (MICs) and interpretive categorization of clinical E. coli isolates were determined by proposed method. Comparing tests were run at the same time by the agar dilution method and the disk diffusion method. The experimental results showed that MSPQC method had a good agreement with the reference methods. Compared with those methods, the MSPQC method is simple, rapid, and convenient to perform. It can offer both a minimum inhibitory concentration (MIC) and an interpretive category result.

Ampicillin↗

PubMed2006

Comparisons of community-associated methicillin-resistant Staphylococcus aureus (MRSA) and hospital-associated MSRA infections in Sacramento, California.

Methicillin-resistant Staphylococcus aureus (MRSA) has long been a common pathogen in healthcare facilities, but in the past decade, it has emerged as a problematic pathogen in the community setting as well. A retrospective case series study of patients from whom MRSA was isolated from December 1, 2003, through May 31, 2004, was conducted at the University of California, Davis, Medical Center. Patient data were collected from electronic medical records and traditional chart reviews to determine whether MRSA acquisition was likely to have been in the community or in the hospital. Antimicrobial susceptibility testing and pulsed-field gel electrophoresis (PFGE) were performed for all confirmed isolates. Skin and soft tissue were the most common infection sites for all MRSA patients. Among the 283 MRSA infections, 127 (44.9%) were defined as community-associated (CA)-MRSA. Ninety-six percent of the CA-MRSA isolates were susceptible to clindamycin. Double-disk diffusion tests were performed to examine inducible clindamycin resistance by erythromycin induction on both CA and hospital-associated (HA) clindamycin-susceptible and erythromycin-resistant isolates. Ten percent (17 of 183) were positive. Most CA-MRSA isolates were identified by PFGE as a unique strain, genotype USA300, which was not genetically related to the predominant genotype, USA100, in the HA-MRSA isolates. Injecting drug users accounted for 49% of CA-MRSA infections but only 19% of the HA-MRSA infections (odds ratio, 4.2; 95% confidence interval, 2.4 to 7.4). Our study shows that a single clone of CA-MRSA accounts for the majority of infections. This strain originated in the community and is not related to MRSA strains from healthcare settings. Injecting drug users could be a major reservoir for CA-MRSA transmission.

Adolescent↗

PubMed2006

Evaluation of antimicrobial and antifungal effects of iodoform-integrating gutta-percha.

OBJECTIVE: The antibacterial and antifungal effects of medicated gutta-percha (MGP) over different time periods have not been evaluated. The aim of this study was to evaluate and compare the antimicrobial and antifungal effectiveness of MGP and regular gutta-percha cones over different time periods using the disk diffusion method. METHODS: Enterococcus faecalis, Pseudomonas aeruginosa, Staphylococcus aureus and Escherichia coli were spread onto Mueller-Hinton agar, and Candida albicans was spread onto Sabouraud agar supplemented with glucose. Same-size MGP cones, conventional gutta-percha cones and disks impregnated with povidone-iodine were placed on the inoculated plates. The dishes were incubated at 37 degrees C aerobically. Growth inhibition zones were inspected and measured at 24, 48 and 72 hours. For each strain, experiments were performed in triplicate. The Kruskal-Wallis test was used to compare k independent samples. RESULTS: The disks impregnated with povidone-iodine inhibited all bacterial strains for up to 72 hours. No inhibition zones were seen around regular gutta-percha cones. MGP inhibited the growth of all bacteria over 24 hours, but in some cases these effects did not continue over longer periods. Specifically, the antimicrobial properties of MGP cones against E. coli and P. aeruginosa disappeared by 48 and 72 hours. Regardless of time and bacterial strain, MGP was statistically more effective than regular gutta-percha (p < 0.05). Povidone-iodine and MGP were effective against C. albicans for up to 72 hours, but regular gutta-percha exhibited no antifungal activity. CONCLUSION: The antimicrobial and antifungal characteristics of MGP may offer additional advantages over conventional gutta-percha.

Anti-Infective Agents, Local↗

PubMedDate not supplied

[Antimicrobial susceptibility of Neisseria gonorrhoeae strains determined by disk diffusion].

The Gonoccocus Laboratory of "Pedro Kourí" Tropical Medicine Institute carried out a study of in vitro susceptibility of Neisseria gonorrhoeae to penicillin, tetracycline, cefuroxime ceftriaxone, cefotaxine and ciprofoxacin by means of a disk diffusion method with the culture medium agar base GC plus supplement. In the first phase, the method was standardized and the reference N. gonorrhoeae ATCC 49226 strain was used whereas in the second phase, 50 gonococcal strains isolated in 8 provinces during 1995 and 1996 were examined. The results of such standardization confirmed that the antimicrobial susceptibility values were within the allowable limits. 52 and 34% of strains were resistant to penicillin and tetracycline respectively and all of them showed susceptibility to the rest of evaluated antimicrobial drugs. We recommend the use of the disk diffusion method for surveillance of gonococci resistance to these drugs in our country.

Bacteriological Techniques↗

PubMed2003

Antimicrobial susceptibility testing of carbapenems: multicenter validity testing and accuracy levels of five antimicrobial test methods for detecting resistance in Enterobacteriaceae and Pseudomonas aeruginosa isolates.

From January 1996 to May 1999, Project ICARE (Intensive Care Antimicrobial Resistance Epidemiology) received 448 nonduplicate clinical isolates of Enterobacteriaceae and Pseudomonas aeruginosa that were reported to be imipenem intermediate or resistant. However, broth microdilution (BMD) confirmatory testing at the Project ICARE central laboratory confirmed this result in only 11 of 123 (8.9%) Enterobacteriaceae isolates and 241 of 325 (74.2%) P. aeruginosa isolates. To investigate this overdetection of imipenem resistance, we tested 204 selected isolates from the Project ICARE collection plus five imipenem-resistant challenge strains at the Centers for Disease Control and Prevention against imipenem and meropenem by agar dilution, disk diffusion, Etest (AB BIODISK North America, Inc., Piscataway, N.J.), two MicroScan WalkAway conventional panels (Neg MIC Plus 3 and Neg Urine Combo 3) (Dade MicroScan, Inc., West Sacramento, Calif.), and two Vitek cards (GNS-116 containing meropenem and GNS-F7 containing imipenem) (bioMérieux Vitek, Inc., Durham, N.C.). The results of each test method were compared to the results of BMD testing using in-house-prepared panels. Seven imipenem-resistant and five meropenem-resistant isolates of Enterobacteriaceae and 43 imipenem-resistant and 21 meropenem-resistant isolates of P. aeruginosa were identified by BMD. For Enterobacteriaceae, the imipenem and meropenem test methods produced low numbers of very major and major errors. All test systems in the study produced low numbers of very major and major errors when P. aeruginosa was tested against imipenem and meropenem, except for Vitek testing (major error rate for imipenem, 20%). Further testing conducted in 11 of the participating ICARE hospital laboratories failed to pinpoint the factors responsible for the initial overdetection of imipenem resistance. However, this study demonstrated that carbapenem testing difficulties do exist and that laboratories should consider using a second, independent antimicrobial susceptibility testing method to validate carbapenem-intermediate and -resistant results.

Carbapenems↗

PubMed2003

Antimicrobial resistance of community and hospital acquired Staphylococcus aureus isolates to oxacillin and glycopeptides.

OBJECTIVE: To determine sensitivity pattern of Staphylococcus aureus isolates from the community and hospitals to methicillin, glycopeptides and other antimicrobial agents. DESIGN: Descriptive study. PLACE AND DURATION OF STUDY: Private Pathology Laboratory in Lahore from January 2001 to April 2002. SUBJECTS AND METHODS: A total of 714 Staphylococcus aureus (S.aureus) isolates from the community and hospital were tested. Community acquired S.aureus strains (n=434) were isolated from specimens like pus from boils/pimples and nasal swabs of patients with asthma attending a local allergy clinic. The hospital acquired S.aureus (n=280) were isolated from specimens like pus from wounds/discharging sinuses, ear swabs, blood and urine. All the isolates were subjected to sensitivity test against Oxacillin, Vancomycin, Teicoplanin, Penicillin, Imipenem, Cefipime and other anti-staphylococcal agents by standard Kirby-Bauer disk diffusion method. Beta lactamase production by all the isolates was also determined by acidimetric test. RESULTS: Significantly higher number of hospital acquired S.aureus isolates (p<0.01) were beta lactamase producing (96.07%) as compared to community acquired (81.79%). Methicillin (Oxacillin) resistance was also higher among hospital strains (31.1%) as compared to community ones (14.1%). No isolate from the community showed resistance to glycopeptides. While 0.3 percent and 0.7 percent of all S.aureus isolates were interpreted as resistant to Vancomycin and Teicoplanin respectively as there was no zone of inhibition. The resistance to these drugs was a bit higher among the MRSA (1.1% and 2.3% respectively). More than 90% of nosocomial MRSA strains were sensitive to Ofloxacin and Fucidic Acid. Resistance to Erythromycin, Lincomycin and Gentamicin was 70.1, 33.3 and 39.1% in that order. In general resistance to different antimicrobial was lower among S.aureus strains of community origin as compared to those of hospital origin. CONCLUSION: Methicillin and multiple drug resistance is quite a significant problem in nosocomial as well as community acquired S.aureus strains. Moreover, it appears that resistance to glycopeptides has also emerged in our nosocomial S. aureus strains. Microbiology laboratories should make efforts not only to regularly screen S.aureus isolates for sensitivity to glycopeptides but also to determine MIC of the isolates.

Cross Infection↗

PubMed2002

Antimicrobial susceptibility pattern of Enterococcus species from urinary tract infections.

OBJECTIVE: To determine the extent of drug-resistance among Enterococcus species in, in vitro experiments. Test strains were isolated from cases with urinary tract infection. Antimicrobial sensitivity was determined with particular reference to the beta-lactams, glycopeptide and aminoglycoside groups of antibiotics. METHODS: Studies were carried out on pure cultures of enterococci isolated from urine specimens of 147 patients. Freshly voided, aseptically collected, midstream specimens of urine were cultured by using standard techniques. The identification and speciation of the strains of enterococci were performed by employing a battery of tests. In vitro drug-susceptibility tests of enterococci were performed against the following antibiotics: penicillin, ampicillin, ampi-sulbactum, co-amoxi-clavulanate, ciprofloxacin, vancomycin, teicoplanin, gentamicin and streptomycin, by employing the disk diffusion method. MIC values for penicillin, ampicillin, vancomycin and teicoplanin against enterococci were determined by the agar dilution technique. MIC determinations were further carried out by the E-test method, for the glycopeptide antibiotics. Prevalence of high level resistance to aminoglycoside antibiotics was determined by the agar dilution method. RESULTS: The most common species isolated was E. faecalis (87.07%), followed by E. faecium (10.88%) and E. durans (2.05%). The magnitude of resistance to both penicillin and ampicillin among the Enterococcus spp. was 23.13%, and that to ciprofloxacin was 55.78%. The three antibiotics: nitrofurantoin, co-amoxi-clavulanate, and ampi-sulbactum, showed resistance of 0.78%, 8.16% and 2.72%, respectively. High-level aminoglycoside resistance among strains of enterococci for streptomycin and gentamicin was found to be 33.84% and 36.92%, respectively. All the strains were susceptible to the glycopeptide antibiotics tested. CONCLUSION: The emergence of enterococci with alarming rates of resistance concomitantly to penicillins and aminoglycosides highlights the need for a more rational and restricted use of antimicrobials, in order to minimize the selection and spread of such strains. An early detection of these problem pathogens is also important for preventing any treatment failures.

Anti-Bacterial Agents↗

PubMed1988

Susceptibility of dysgonic fermenter 2 to antimicrobial agents in vitro.

Dysgonic fermenter 2 (DF-2) is a fastidious, gram-negative organism well recognized as a cause of fulminant septicemia in patients without spleens or patients with alcoholic cirrhosis. In vitro antibiotic susceptibility testing of eight strains with a Schaedler broth dilution technique revealed DF-2 to be susceptible to all of the antibiotics tested except aztreonam. Previous reports that DF-2 is aminoglycoside resistant were based on disk diffusion or agar dilution assays that may be less reliable given the slow growth of the organism and its requirement for CO2 incubation. Penicillin is commonly used as prophylaxis after dog bites and has excellent activity against DF-2.

Anti-Bacterial Agents↗

PubMed2006

Composition and antimicrobial activity of Equisetum arvense L. essential oil.

The volatile constituents of the sterile stems of Equisetum arvense L. (Equisetaceae) were investigated for the first time using GC, GC/MS and (13)C-NMR. Twenty-five compounds were identified. Hexahydrofarnesyl acetone (18.34%), cis-geranyl acetone (13.74%), thymol (12.09%) and trans-phytol (10.06%) were the major constituents. A disk diffusion method was used for the evaluation of the antimicrobial activity of this oil against a panel of microorganisms (bacteria: Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Salmonella enteritidis; fungi: Aspergillus niger and Candida albicans). The 1:10 dilution of the essential oil of Equisetum arvense L. was shown to possess a broad spectrum of a very strong antimicrobial activity against all tested strains.

Anti-Infective Agents↗

PubMed2001

Prevalence and mechanism of resistance against macrolides and lincosamides in Streptococcus suis isolates.

Eighty-seven Streptococcus suis isolates recovered in 1999-2000 from diseased pigs, all from different farms, were screened for resistance against macrolide and lincosamide antibiotics by the disk diffusion and agar dilution test and a PCR assay, amplifying the ermB gene and the mefA/E gene. Seventy-one percent of the isolates showed constitutive resistance to macrolide and lincosamide antibiotics (MLS(B)-phenotype). All these isolates were positive for the ermB gene in the PCR, but negative for the mefA/E gene. For all strains minimum inhibitory concentrations (MIC) against five other antimicrobial agents were determined. All strains were susceptible to penicillin. Ninety-nine percent of the isolates were susceptible to enrofloxacin and tiamulin. Eighty-five percent of the strains were resistant to doxycycline. A 540bp fragment of the ermB genes of eight S. suis strains was sequenced and compared with ermB genes of five S. pneumoniae and five S. pyogenes strains of human origin. A 100% homology was found between these fragments in seven S. suis, one S. pneumoniae and three of the S. pyogenes isolates. This study demonstrates that resistance against macrolides, lincosamides and streptogramin B is widespread in S. suis and mediated by ribosome methylation, encoded by the ermB gene.

Animals↗

PubMedDate not supplied

[Pneumococcal meningitis in children: clinical findings, most frequent serotypes and outcome].

OBJECTIVE: To determine mortality, morbidity, antimicrobial susceptibility and the most frequent serotypes in children admitted to hospital due to pneumococcal meningitis METHODS: Patients with meningitis caused by Streptococcus pneumoniae detected by culture in cerebrospinal fluid or blood, aged between 1 month and 15 years old, admitted to two hospitals in the city of São Paulo, were included in the study. Susceptibility to penicillin was determined by the disk diffusion test using oxacillin 1 microg disk. If the inhibition area with oxacillin disk was less than 20mm, the strains were tested for penicillin, chloramphenicol, ceftriaxone, vancomycin and sulfamethoxazole /trimethoprim using the E test. RESULTS: We identified 55 patients, 52.5% of which were younger than 6 months. The prevalence of penicillin-nonsusceptible strains was 36%. All the strains were intermediately resistant (0.1 microg/ml < or =; MIC < or = 1.0 microg/ml) and 35% of the penicillin intermediate resistant strains were resistant to sulfamethoxazole/trimethoprim. The mortality rate was 20% and impaired neurological outcome was present in 40% of the children. The audiometric test revealed alteration in 60% of the children tested. Age less than 6 months was associated with poor outcome. The most frequent serotypes were 1, 5, 6B, 14, 19A and 23F, and 70% of the serotypes were included in the new 7-valent vaccine. CONCLUSIONS: These findings suggest that pneumococcal meningitis presents high mortality and morbidity and that the 7-valent conjugate vaccine would be potentially useful in preventing serious pneumococcal infections.

English Abstract↗

PubMed2025

Molecular characterization of drug-resistance genes and dynamics of multidrug-resistant Salmonella spp. in waterfowl: a pre- and post-antibiotic ban surveillance in Guangdong, China from 2013 to 2023.

BACKGROUND: Multidrug-Resistant Organism (MDRO) refers to bacteria that are Resistant to three or more types of antibiotics in clinical use. The global health threat posed by multidrug-resistant (MDR) bacterial pathogens and their cross-species transmission necessitates rigorous Surveillance. This urgency is amplified in China where antibiotic growth promoters were widely used in animal husbandry until the 2020 implementation of Announcement No. 194 launched by Ministry of Agriculture and Rural Affairs (Announcement 194), banning non-therapeutic antibiotics in feed. This study conducted a decade long investigation on the correlation between antimicrobial resistance (AMR) phenotypes and genetic determinants in 314 Salmonella isolates collected from waterfowl across Guangdong Province, China, utilizing disk diffusion (Kirby-Bauer method) and PCR-based detection of antibiotic resistance genes (ARGs). The study period covered the antibiotic policy transition in China, specifically encompassing the pre-ban (2013-2019) and post-ban (2020-2023) phases of the nationwide prohibition on growth-promoting antimicrobials in animal feed. METHODS: Antimicrobial Susceptibility profiles against 16 agents were determined via Kirby-Bauer testing, while PCR amplification targeted 20 ARGs. Statistical analyses evaluated phenotype-genotype correlations using Pearson`s chi-square test. RESULTS: Surveillance revealed escalating resistance rates annually. Highest resistance prevalence was observed against β-lactams and amphenicols (92.25%), whereas amikacin exhibited the lowest resistance rate (9.55%). MDR prevalence reached 87.23%, with the AMP-CAZ-GEN-FFC-TET resistance profile predominating (51.6% of isolates). Genetic analysis identified 3 to 16 ARGs per isolate was harboring, with blaTEM demonstrating the highest detection frequency (90.76%). Significant phenotype-genotype correlations (p < 0.05) were observed for 13 genes: blaCTX-M, blaTEM, blaOXA, aacC2, aph(3')-I, aac(3)-IV, aadA1, qnrS, qnrA, clmA, floR, sulII, tetA. Notably, significant declines in resistance to aminoglycosides (e.g., gentamicin from 71.7 to 3.5%) and florfenicol (from 81.1 to 9.6%) were observed after China's 2019 antibiotic ban policy (p < 0.001), underscoring the impact of targeted antimicrobial stewardship in avian husbandry. CONCLUSIONS: Analysis of 314 waterfowl Salmonella strains revealed severe multidrug resistance (MDR) and diverse resistance genes (DRGs), with 13 DRGs linked to resistance. China's antibiotic ban reduced targeted resistance, but MDR persists alarmingly via acquired DRGs and adaptation. Continued enforcement may lower aminoglycoside/phenicol resistance, but β-lactam resistance will likely endure, worsened by transcontinental blaCTX-M spread. Critically, plasmid co-selection threatens to amplify MDR, demanding genomic surveillance. Mitigation requires boosting policy compliance, developing non-antibiotic therapies, mapping mutations, establishing cross-species barriers, and prioritizing One Health interventions to block resistance spread.

China↗

PubMed1981

Flavobacterium meningosepticum sepsis: disease due to bacteria with unusual antibiotic susceptibility.

The three cases we have presented implicate F meningosepticum as a significant pathogen causing disease in immunocompromised adult patients. Since this organism is of low pathogenicity but may be found in the hospital environment, its identification as a pathogen raises the suspicion of a nosocomial source of infection, and a search for the source should be made. Furthermore, with regard to the choice of antimicrobial therapy, it must be remembered that this organism is resistant to most antibiotics commonly used to treat gram-negative bacilli, and disk diffusion technics may not reliably predict actual antibiotic sensitivity.

Anti-Bacterial Agents↗

PubMed2005

Antimicrobial susceptibility variation of 50 anaerobic periopathogens in aggressive periodontitis: an interindividual variability study.

BACKGROUND/AIMS: The frequent use of antibiotics in developed countries has led to the emergence of widespread bacterial resistance. In this study, the interindividual variability of the antibiotic susceptibility of 50 putative microorganisms in aggressive periodontitis patients has been evaluated by means of VC (variation coefficient). MATERIAL AND METHODS: A total of 60 microbial samples were collected from 20 adult patients diagnosed with aggressive periodontitis (2-4 samples by patient). Bacterial strains of Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythia, Fusobacterium nucleatum, and Peptostreptococcus micros were isolated according to Slots' rapid identification method. The susceptibilities to 10 antibiotics were studied: penicillin G (PEN), ampicillin (AMP), amoxicillin (AMX), amoxicillin/clavulanate (AMC), tetracycline (TET), doxycycline (DOX), ciprofloxacin (CIP), erythromycin (ERY), spiramycin (SPI) and clindamycin (CLIN), using the Disk Diffusion Susceptibility test (DDS test: Kirby-Bauer's modified method for anaerobic bacteria). The broth microdilution Minimum Inhibitory Concentration test was carried out as a control test. RESULTS: Among the 50 identified bacteria, 15 were P. gingivalis, 12 P. intermedia, 8 T. forsythia, 9 F. nucleatum, and 6 P. micros. The results of the DDS test show that penicillins (especially AMC, AMP, and AMX), cyclines (especially DOX) and CLIN are highly effective against the 50 anaerobic studied bacteria. CIP and ERY have the lowest efficacy against those bacteria. CIP shows a very variable activity according to anaerobic bacteria species, being particularly inactive against P. gingivalis and very efficient against T. forsythia and P. micros. SPI is also highly efficient but not against P. micros. CONCLUSIONS: The interindividual susceptibility of principal periodontal pathogens to antibiotics is not homogeneous and seems to vary according to bacterial species and antimicrobial molecules. This variability seems to be greater with older molecules (PEN, TET, ERY) than with more recent ones, which indicates more stable results (AMC, AMX, AMP, and DOX). P. intermedia appeared to be the bacteria most resistant to penicillins and showed the highest coefficient variation. Together with scaling and root planing, the combination of two antibiotics would therefore seem to be recommended in the treatment of aggressive periodontitis, particularly in the presence of P. intermedia.

Acute Disease↗

PubMed2005

In vitro susceptibility of antibiotics against Vibrio spp. and Aeromonas spp. isolated from Penaeus monodon hatcheries and ponds.

Susceptibility patterns to 16 different antibiotics were investigated against pathogenic Vibrio spp. and Aeromonas spp. isolated from shrimp culture hatcheries and ponds in India. Thirteen species of Vibrio (N = 90) and two species of Aeromonas (N = 7) isolates were tested by agar disk diffusion. The results show that 100% of the isolates were resistant to ampicillin, and that 43.2% and 47.4% were sensitive to chlortetracycline and erythromycin, respectively. Susceptibility patterns of another 160 isolates belonging to the genera Vibrio and Aeromonas obtained from the water samples of shrimp hatcheries and ponds were tested against six commonly used antibiotics. Results indicate that isolates from the hatcheries were more resistant to antimicrobials than isolates from the ponds. The minimum inhibitory concentrations of five antibiotics against the different Vibrio spp. and Aeromonas spp. were determined. Ciprofloxacin was found to be the most effective in controlling the isolates from hatcheries and ponds compared with the other antibiotics used in the study. Our results reveal that antibiotic-resistant bacteria are widespread in the shrimp culture hatcheries and ponds in India. Potential risk to human health was not addressed in this study and remains to be elucidated.

Aeromonas↗

PubMed1992

[Mycobacterium fortuitum: the determination of its susceptibility by the disk diffusion technic].

A study was carried out on 40 Mycobacterium fortuitum strains isolated from 39 symptomatic respiratory patients and 1 from a chronic skin ulcer, the susceptibility of whom to different antimicrobial agents was determined by the disk diffusion method. The strain showed sensitivity to aminoglucosides such as amikacin, gentamicin and kanamycin, and in all cases resistance to the penicillins ans cephalosporins used.

Anti-Bacterial Agents↗

PubMed2003

In vitro susceptibility of gram-positive cocci isolated from skin and respiratory tract to azithromycin and twelve other antimicrobial agents.

This study was conducted to evaluate the activity of azithromycin in comparison to 12 other antibacterial agents against recent isolates obtained consecutively from patients with respiratory tract or skin infections, from January to July, 2000. A total of 717 Gram-positive cocci were analyzed in this study and the following species were studied: Staphylococcus aureus (n=576), beta-hemolytic streptococci (n=115), and Streptococcus pneumoniae (n=26). Susceptibility testing was carried out by the disk diffusion method and interpreted according to NCCLS breakpoints. The activity of azithromycin was compared to erythromycin, clindamycin, chloramphenicol, ciprofloxacin, ofloxacin, oxacillin, penicillin, ceftriaxone, tetracycline, trimethoprim/sulfamethoxazole, teicoplanin, and vancomycin. Of the 26 S. pneumoniae isolates recovered from the respiratory tract, 5 (19.2%) were intermediate resistant to penicillin. All of these strains were susceptible to chloramphenicol, ofloxacin, and vancomycin, and 24 (92%) were also susceptible to azithromycin, clindamycin, and erythromycin. Among the 67 beta-hemolytic streptococci strains isolated from the respiratory tract, 66 (99%) were susceptible to azithromycin, erythromycin, clindamycin, and ofloxacin. All 48 beta-hemolytic streptococci strains isolated from skin were susceptible to azithromycin and clindamycin, 47 (98%) were susceptible to erythromycin, and 46 (96%) were susceptible to ofloxacin. Of the 576 strains of S. aureus, 253 (43.9%) were isolated from the respiratory tract and 323 (56.1%) from skin. Among S. aureus isolates from the respiratory tract and skin, 46 (18%) and 78 (24%), respectively were resistant to oxacillin. Isolates from the respiratory tract and skin showed the same percentage of resistance (36%) to azithromycin. These in vitro results suggest that azithromycin can be a therapeutic option for treatment of infections caused by these bacteria since the newer macrolides have several distinct advantages over erytromycin including improved oral bioavailability, longer half-life allowing once or twice daily administration, higher tissue concentrations and less gastrointestinal adverse effects.

Anti-Bacterial Agents↗