Minimum Inhibitory Concentration Values Of Ciprofloxacin Research Articles

Comparative <i>in vitro</i> activity of various antibiotic against planktonic and biofilm and the gene expression profile in <i>Pseudomonas aeruginosa</i>

P. aeruginosa is an opportunistic pathogen that is commonly found in nosocomial infections. The purpose of this study was to investigate the effects of seven antibiotics on P. aeruginosa planktonic growth, biofilm formation, and the expression of virulence factors. These antibiotics included Ciprofloxacin (CP), Amikacin (AMK), Vancomycin (VAN), Tetracycline (TET), Gentamicin (GEN), Erythromycin (Ery), and Clindamycin (CLI). Antibiotic susceptibility testing, Minimum Bactericidal Concentration (MBC), Minimum Inhibitory Concentration (MIC), growth curve, time-kill curve, biofilm inhibition and reduction assay, and RT-qPCR were used to assess the effects of these antibiotics on P. aeruginosa planktonic and biofilm. The clear zones of inhibition against P. aeruginosa for the CP, AMK, VAN, TET, GEN, Ery, and CLI were 26 mm, 20 mm, 21 mm, 22 mm, 20 mm, 25 mm and 23 mm, respectively. The MIC values for CP, AMK, VAN, TET, GEN, Ery and CLI against P. aeruginosa ranged from 0.25 to 1 µg/mL while the MBC values ranged from 1 and 0.5 to 2 µg/mL respectively. The growth, total viable counts (TVCs), bacterial adhesion and biofilm formation of P. aeruginosa were reduced after exposure to all the tested antibiotics in a dose-dependent manner. The RT-qPCR analysis showed that all the tested antibiotics share a similar overall pattern of gene expression, with a trend toward reduced expression of the virulence genes of interest (lasR, lasI, fleN, fleQ and fleR, oprB and oprC) in P. aeruginosa. The results indicate that all of the tested antibiotics possess antimicrobial and anti-biofilm activities, and that they may be multiple inhibitors and moderators of P. aeruginosa virulence via a variety of molecular targets. This deduction requires to be investigated in vivo.

Revisiting the Revised CLSI Breakpoint for Detecting Fluoroquinolones Resistance in Salmonella

Resistance towards fluoroquinolones and treatment failure is a matter of concern in enteric fever. The present study was undertaken to analyze the susceptibility pattern of Salmonella towards fluoroquinolones using 2006 and 2013 Clinical Laboratory Standards Institute (CLSI) breakpoint for interpretation and revisit the efficacy of Nalidixic acid resistance (NAR) as a phenotypic marker. A retrospective analysis of the zone of inhibition (ZOI) diameter data and minimum inhibitory concentration (MIC) data of 105 Salmonella was conducted. The ZOI diameter analysis showed that all isolates were susceptible to Ofloxacin and Ciprofloxacin using the previous 2006 ZOI breakpoint. However, with the revised 2013 breakpoint of Ciprofloxacin, the susceptibility percent dropped significantly and for Ofloxacin the breakpoint was not revised, so the percentage remained unchanged. The MIC analysis showed that all isolates were susceptible towards Ofloxacin and 97.14 % of isolates were susceptible to Ciprofloxacin using the previous 2006 MIC breakpoint, while the susceptibility decreased for both antibiotics with the revised 2013 MIC breakpoint. Statistically, the ZOI diameter of Nalidixic acid and MIC values of Ciprofloxacin and Ofloxacin was negatively correlated. To conclude, the revision of breakpoints addresses the problem of screening fluoroquinolones resistance but the emerging fluoroquinolones resistance situation is still a matter of concern in healthcare facilities of Nepal. Thus a reliable screening method is need of the hour as NAR cannot be considered a reliable marker to screen fluoroquinolones resistance

Using minimum inhibitory concentration values of common topical antibiotics to investigate emerging antibiotic resistance: A retrospective study of 134 dogs and 20 horses with ulcerative keratitis.

To identify the minimum inhibitory concentration (MIC) distribution for commonly used topical antibiotics from isolates of dogs and horses with ulcerative bacterial keratitis, and to investigate changes in MIC values over time and following treatment with topical fluoroquinolones. One hundred thirty-four client-owned dogs and 20 client-owned horses with bacterial ulcerative keratitis. Minimum inhibitory concentration values for 14 topical antibiotics were reported for canine and equine cases of bacterial ulcerative keratitis between 2013 and 2018. Changes in MIC values over time and after treatment with topical fluoroquinolones were reported. The three most common bacterial genera isolated were Staphylococcus, Streptococcus, and Pseudomonas. Together, these represented 79.4% of canine cases and 77.4% of equine cases. Overall, isolates from horses tended to have lower MIC values, as did Pseudomonas isolates from both dogs and horses, compared to other bacterial genera, especially Staphylococcus spp. The MIC values of erythromycin and trimethoprim sulfa for Staphylococcus spp., and the MIC value of moxifloxacin for Pseudomonas significantly increased over time. Previous topical fluoroquinolone use was associated with a significant increase in the MIC value of ofloxacin in canine and equine Staphylococcus isolates and current topical fluoroquinolone use was associated with significant increases in the MIC values of ciprofloxacin, moxifloxacin, and ofloxacin in canine Staphylococcus isolates. Patients previously or currently treated with topical fluoroquinolones, particularly in Staphylococcus infections, may require alternative antibiotics or additional antibiotic classes other than fluoroquinolones. Bacterial culture with MIC susceptibility testing should be highly recommended when a Staphylococcal infection is suspected.

Distribution and characterization of Stenotrophomonas maltophilia isolates from environmental and clinical samples in Thailand

Stenotrophomonas maltophilia has emerged as an important opportunistic pathogen, especially in patients who are immunocompromised, suffering from malignancy or have been hospitalized for a prolonged period. Information of this bacterium in Thailand has not been elucidated. To investigate the phenotype and genotype of environmental and clinical isolates of S.maltophilia in Songklanagarind Hospital, southern Thailand. Isolates of S.maltophilia were collected from various environmental sources on three hospital wards and clinical samples from seven wards. Antibiotic susceptibility and minimum inhibitory concentration (MIC) testing were performed using disk diffusion and E-test, respectively. Isolates were genotyped by pulsed-field gel electrophoresis. The majority of S.maltophilia environmental isolates were from sink drains (67.5%), followed by drinking water (18.7%) and tap water (7.5%). Clinical isolates of the bacterium mainly originated from sputum samples (56.2% of all isolates). Antibiotic resistance was more common in clinical isolates than in environmental isolates; resistance to co-trimoxazole was associated with the presence of the sul1 gene. The MIC values for ciprofloxacin and co-trimoxazole correlated closely with the results obtained from disk diffusion assay. DNA profile analysis revealed seven clusters with high diversity among the isolates. No genotypic relationship was detected between isolates from environmental and clinical samples. As such, acquisition of this bacterium may occur outside the hospital.

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Increasing number of patients suffering from enteric fever are being diagnosed in and around Bastar District of Chhattisgarh in last 5 years. Over 500 samples from febrile patients were cultured during May 2012 to January 2013 in a tertiary care hospital in Jagdalpur, Chhattisgarh. The aim of this study was to evaluate the ciprofloxacin and other antibiotics susceptibility patterns of Salmonella spp from blood samples of suspected enteric fever patients. Antimicrobial susceptibility tests were performed against commonly used antimicrobials by disc diffusion method and Minimum Inhibitory Concentration (MIC) of ciprofloxacin was determined by agar dilution method. Altogether 62 Salmonella Typhi and 21 Salmonella Paratyphi A were isolated from blood samples. All isolates were sensitive to ceftriaxone and ofloxacin whereas 9 isolates were resistant to ciprofloxacin. Nalidixic acid resistant isolates were significantly associated with raised MIC values for ciprofloxacin, suggesting that resistance to nalidixic acid is a reliable indicator of decreased ciprofloxacin susceptibility where disc diffusion test showed susceptible.

Prevalence of Ciprofloxacin Resistance among Gram-Negative Bacilli Isolated From Urinary Tract Infection Specimens at a Specialist Hospital in Riyadh, Saudi Arabia

Background: Susceptibility to fluoroquinolones is very important information before prescribing to the urinary tract infection (UTI) patients. Objective: The purpose of the present study was to see the sensitivity pattern of the Gram-Negative bacilli isolated from urinary tract infection to various antibiotics as well as to know the prevalence rate of Ciprofloxacin resistance. Methodology: This cross sectional study was conducted in a specialized hospital in Riyadh, Saudi Arabia from January’2006 to June’2006 for over a period of six months. The Gram-negative bacilli (GNB) were isolated from clinical specimens of UTIs and antibiotic susceptibility testing was performed. Isolates with resistance or with a decreased susceptibility to Ciprofloxacin (20 mm) were than screened for their minimum inhibitory concentration (MIC) by using the E-test. Results: Out of 510 GNB, 97(19%) isolates were resistant to Ciprofloxacin. The MIC of these isolates ranged from 4 to 32µg/ml. Most of the Ciprofloxacin resistant isolates were from urinary tract infections (UTI) of hospital patients both (indoor & outdoor). The Ciprofloxacin resistance was also closely associated with multi-drug resistance, thus limiting the treatment options. Conclusion: The considerably high MIC values for Ciprofloxacin in this study reflected the extent of the treatment problems for these resistant isolates.DOI: http://dx.doi.org/10.3329/jsf.v11i1.19395

Prevalence of Ciprofloxacin Resistance Among Gram-Negative Bacilli at a Specialist Hospital in Saudi Arabia

Background: Resistance to antimicrobials of different structural classes including fluoroquinolones has arisen in a multitude of bacterial species both in the community and the hospitals. This may complicate the therapeutic management of infections. Decreased susceptibility to fluoroquinolones arises mainly by singlestep mutations in the gyrA and parC genes, which encode the fluoroquinolones targets, the topoisomerase enzymes, conferring cross resistance to all fluoroquinolones. Accumulation of multiple mutations in several genes confers increasing level of resistance associated with clinical failure. However, even low level resistance can generate therapeutic failure. In 1998, some mobile elements with a potential for the horizontal transfer of the quinolone resistance genes were described. The loci which are responsible for this plasmid-mediated quinolone resistance, which have been designated as qnrA, qnrB and qnrS, have been identified in the Enterobacteriaceae species. Aim: To evaluate the susceptibility pattern of the isolates to various antibiotics and to know the prevalence rate of ciprofloxacin resistance in our hospital. Materials & Methods: A total of 916 gram-negative bacilli (GNB) were isolated from different clinical specimens over a period of nine months, were subjected to antibiotic susceptibility testing. Isolates with resistance or with a decreased susceptibility to ciprofloxacin (£20 mm) were then screened for their minimum inhibitory concentration(MIC) by using the E-test. Results: Out of 916 GNB, 321 (35%) isolates were resistant to ciprofloxacin. The MIC of these isolates ranged from 4 to >32?g/ml.Conclusion: The resistance rate to ciprofloxacin was 35% in our study. Most of the ciprofloxacin resistant isolates were from urinary tract infections (UTI). The ciprofloxacin resistance was also closely associated with multi-drug resistance, thus limiting the treatment options. Ciprofloxacin resistance can be used as a general surrogate marker of multidrug resistance, thus limiting the already restricted treatment options. The considerably high MIC values for ciprofloxacin in this study reflected the extent of the treatment problems for these resistant isolates and a need for the continuous evaluation of the commonly used antibiotics. DOI: http://dx.doi.org/10.3329/bjms.v11i4.12604 Bangladesh Journal of Medical Science Vol. 11 No. 04 Oct’12

Sensitivity pattern of Salmonella serotypes in Northern India.

Enteric fever continues to be a major public health problem, especially in the developing countries of the tropics. We determined the incidence of Salmonella bloodstream infections and their antimicrobial resistance patterns from May to August in the years 1997-2001 in Haryana, a large state of India. The minimum inhibitory concentration (MIC) was also determined for 60 isolates of S. typhi to various commonly used antimicrobial agents. Blood cultures of 6,956 patients (PUO/septicemia) were processed by standard procedures and the Salmonella spp. isolates were identified with specific antisera and with standard biochemical tests. Antimicrobial susceptibilities were determined by Stokes disc diffusion method. The MIC of 60 randomly isolated strains of S. typhi was determined by agar dilution method using Mueller Hinton Agar medium. Isolation rates of Salmonella spp. increased in 2000 and 2001. Multidrug resistance (MDR) in S. typhi had increased while in S. paratyphi it had decreased markedly. Ninety per cent chloramphenicol sensitivity was seen in S. typhi by MIC method. There was a decrease in the susceptibility to ciprofloxacin of S. typhi with MIC showing an upward trend. All S. typhi tested were sensitive to third generation cephalosporins and aminoglycosides with MIC well below the breakpoint. Our study indicates that MDR in S. typhi is on the rise in our area. There is also re-emergence of chloramphenicol sensitivity. Rising MIC values of ciprofloxacin may lead to prolonged treatment, delayed recovery or pose treatment failure. Thus, sensitivity pattern of causative organism must be sought before instituting appropriate therapy to prevent further emergence of drug resistance.