Dual cross-linked honey coupled 3D antimicrobial alginate hydrogels for cutaneous wound healing.

We report potentiation of healing efficacy of alginate by value addition at its structural level. Dual crosslinked (ionically and covalently) sodium alginate hydrogel coupled with honey (HSAG) brings about an intermediate stiffness in the fabric, confers consistent swelling property and limits erratic degradation of the polymer which ultimately provides conducive milieu to cellular growth and proliferation. In this work honey concentrations in HSAGs are varied from 2% to 10%. FTIR, XRD and nanoindentation studies on the HSAGs exhibited physicochemical integrity. In vitro degradation study provided the crucial finding on 4% HSAG having controlled degradation rate up to 12 days with a weight loss of 87.36 ± 1.14%. This particular substrate also has an ordered crystalline surface morphology with decent cellular viability (HaCaT and 3T3) and antimicrobial potential against Methicillin Resistant Staphylococcus aureus (MRSA) and Escherichia coli. The in vivo wound contraction kinetics on murine models (4% HSAG treated wound contraction: 94.56 ± 0.1%) has been monitored by both invasive (histopathology) and noninvasive (Swept Source Optical Coherence Tomography) imaging and upon corroborating them it evidenced that 4% HSAG treated wound closure achieved epithelial thickness resembling to that of unwounded skin. Thus, the work highlights structurally modified alginate hydrogel embedded with honey as a potential antimicrobial healing agent.

Performance of SNAPPE-II score in neonatal sepsis: an experience from a tertiary care center.

BACKGROUND AND OBJECTIVES: The Score for Neonatal Acute Physiology II with Perinatal Extension (SNAPPE-II) is a vital tool for prognostication in newborns. The study was conducted with the hypothesis that the performance of the SNAPPE-II score might be affected by the presence of sepsis in newborns admitted with possible early onset septicemia and whether score performance varies between culture positive and culture negative sepsis. METHODS: The prospective observational study was conducted over a period of 1 year (January 2014 to January 2015) in neonates presenting with clinical suspicion of sepsis to the Sick Newborn Care Unit (SNCU) of a tertiary care hospital in Eastern India. RESULTS: SNAPPE-II score cut-off of ≥20 offered the highest sensitivity of 74.5% with specificity 48.3%, PPV 27.6% and NPV 87.7%. Comparison of mortality proportions between the two subgroups defined by this cut-off returned p= 0.005 with OR 3.47 (95% 1.40 to 8.64). No significant association was found between SNAPPE-II score and blood culture results; mean scores for culture positive (25.16 ± 15.6) and negative groups (24.49 ± 15.6) were comparable (p= 0.920). CONCLUSIONS: At a cut-off value of ≥20 in presence of sepsis, SNAPPE-II score offers acceptable indices to predict mortality outcome. Prediction of outcome by SNAPPE-II score is not affected by positive or negative blood culture sepsis.

Indigenous Probiotic Lactobacillus Isolates Presenting Antibiotic like Activity against Human Pathogenic Bacteria.

BACKGROUND: Indigenous lactic acid bacteria are well known probiotics having antibacterial activity against potentially pathogenic bacteria. This study aims to characterize the curd lactobacilli for their probiotic potentiality and antagonistic activity against clinical bacteria. METHODS: Four curd samples were processed microbiologically for the isolation of lactic acid bacteria (LAB). The LAB strains obtained were identified by conventional methods: cultural aspect, gram-staining, biochemical and sugar fermentation tests. The probiotic properties were justified with tolerance to low-pH, bile salt and sodium chloride, and the antagonistic activity of the lactobacilli against human pathogenic bacteria (Escherichia coli, Proteus vulgaris, Acinetobacter baumannii and Salmonella enterica serovar Typhi) was assessed. Hemolytic activity and antibiotic susceptibility were determined for the lactobacilli isolates, and the cumulative probiotic potential (CPP) values were recorded. RESULT: Four lactobacilli isolates, L. animalis LMEM6, L. plantarum LMEM7, L. acidophilus LMEM8 and L. rhamnosus LMEM9, procured from the curd samples, survived in low-pH and high bile salt conditions, and showed growth inhibitory activity against the indicator bacteria by agar-well (zone diameter of inhibition; ZDIs: 13.67 ± 0.58-29.50 ± 2.10 mm) and agar overlay (ZDIs: 11.33 ± 0.58-35.67 ± 2.52 mm) methods; the average growth inhibitory activity of lactobacilli ranged 233.34 ± 45.54-280.56 ± 83.67 AU/mL, against the test bacterial pathogens. All the lactobacilli were non-hemolytic and sensitive to most of the test antibiotics. The CPP values of the isolated LAB were recorded as 80-100%. CONCLUSION: The curd lactobacilli procured might be used as the valid candidates of probiotics, and bio-therapeutics against bacterial infection to humans.

Molecular characterization and evaluation of the emerging antibiotic-resistant Streptococcus pyogenes from eastern India.

BACKGROUND: Group A Streptococcus strains causing wide variety of diseases, recently became noticeable in eastern India, are not amenable to standard treatment protocol thus enhancing the possibility of disease morbidity by becoming antibiotic resistance. METHODS: The association of Lancefield group A Streptococcal variation with degree of vir architectural diversity was evaluated using emm typing and restriction fragment length polymorphism analyses. The antibiotic sensitivity patterns were examined by modified Kirby-Bauer method of disk diffusion. Percentage calculations, 95% confidence interval and one-way ANOVA were used to assess differences in proportions. RESULTS: Our observations revealed 20 different emm types and 13 different HaeIII vir typing patterns. A 1.2 kb fragment was found in all HaeIII typing pattern. Fragments of 1.2 kb and 550 bp were conserved in majority of the isolates. HinfI digestion was found proficient in differentiating the strains of same vir typing patterns. Strong predominance of speC (85%) and speF (80%) genes have been observed encoding exotoxins production. 4 isolates were found to be erythromycin resistant and were of genotype emm49. High degree of tetracycline resistance was shown by 53.57% isolates which belonged to 12 different emm genotypes. CONCLUSIONS: These findings suggested that in addition to emm typing, sequential application of HaeIII and HinfI restriction enzymes in vir typing analysis is an effective tool for group A streptococcal molecular characterization associated with antibiotic resistance.

Correlates of treatment outcomes and drug resistance among pulmonary tuberculosis patients attending tertiary care hospitals of Kolkata, India.

BACKGROUND: Worldwide highest number of new pulmonary tuberculosis (PTB) cases, was reported from India in 2012. Adverse treatment outcomes and emergence of drug resistance further complicated the prevailing scenario owing to increased duration, cost and toxicity associated with the treatment of drug-resistant cases. Hence to reinforce India's fight against TB, identification of the correlates of adverse treatment outcomes and drug resistance, seemed critical. METHODS: To estimate the associations between diagnostic findings, patient types (based on treatment outcomes), drug resistance and socio-demographic characteristics of PTB patients, a cross-sectional study was conducted in two tertiary-care hospitals in Kolkata between April 2010 and March 2013. Altogether, 350 consenting Mycobacterium tuberculosis sputum-culture positive PTB patients were interviewed about their socio-demographic background, evaluated regarding their X-ray findings (minimal/moderately advanced/far advanced/cavities), sputum-smear positivity, and treatment history/outcomes (new/defaulter/relapse/treatment-failure cases). Multiple-allele-specific polymerase chain reaction (MAS-PCR) was conducted to diagnose drug resistance. RESULTS: Among all participants, 31.43% were newly diagnosed, while 44%, 15.43% and 9.14% patients fell into the categories of relapsed, defaulters and treatment-failures, respectively. 12.29% were multi-drug-resistant (MDR: resistant to at least isoniazid and rifampicin), 57.71% had non-MDR two-drug resistance and 12% had single-drug resistance. Subjects with higher BMI had lower odds of being a relapse/defaulter/treatment failure case while females were more likely to be defaulters and older age-groups had more relapse. Elderly, females, unmarried, those with low BMI and higher grade of sputum-smear positivity were more likely to have advanced X-ray features. Higher grade of sputum-smear positivity and advanced chest X-ray findings were associated with relapse/treatment-failures. Elderly, unmarried, relapse/defaulter/treatment-failure cases had higher odds and those with higher BMI and moderately/far advanced X-ray findings had lower odds of having MDR/non-MDR two-drug resistant PTB. CONCLUSION: Targeted intervention and appropriate counseling are needed urgently to prevent adverse treatment outcomes and development of drug resistance among PTB patients in Kolkata.

Alteration of serum inflammatory cytokines in active pulmonary tuberculosis following anti-tuberculosis drug therapy.

Active pulmonary tuberculosis (APTB) is associated with a failure of the host immune system to control the invading Mycobacterium tuberculosis (Mtb). The objective of this study was to quantify and assess the role of serum inflammatory cytokines in active pulmonary tuberculosis patients following anti-tuberculosis drug (ATD) therapy. Blood samples were collected from APTB patients and normal healthy subjects (NHS) (total n=204) at baseline and 2, 4 and 6 months post-therapy and the abundance of serum inflammatory cytokines were measured by cytokine specific ELISA. Compared to NHS, APTB patients at baseline had higher levels of serum pro-inflammatory cytokines IL-12p40 (P<0.001), IFN-γ (P<0.001), TNF-α (P<0.01), IL-1ß (P<0.001) and IL-6 (P<0.001) and anti-inflammatory cytokines IL-10 (P<0.001) and TGF-ß1 (P<0.001) while there was no change in the level of IL-4. In APTB patients, the serum levels of IFN-γ, TNF-α, IL-6 and TGF-ß1 directly relate to the bacterial load while the TNF-α, IL-1ß, IL-6 and TGF-ß1 relate to radiological severity. At baseline, the IL-6 level in NHS and APTB patients differed most and following ATD therapy, this level rapidly decreased and stabilized by 4-month in APTB patients. It is concluded that a subtle reduction in the serum level of IL-6 of the APTB patients following ATD therapy might play a vital role in immune-protection of the host against Mtb infection and hence the serum IL-6 level can be a useful marker to diagnose the effectiveness of therapy in the patients.

Antibacterial potential of hydroalcoholic extracts of triphala components against multidrug-resistant uropathogenic bacteria--a preliminary report.

"Triphala", the Ayurvedic wonder is used traditionally for the treatment of different types of diseases since antiquity. The hydroalcoholic extracts of the three components of Triphala powder demonstrated varying degrees of strain specific antibacterial activity against multidrug-resistant uropathogenic bacteria. Terminalia chebula fruit extract was active against all the test isolates followed by Terminalia belerica and Emblica officinalis. There was a close association between antibacterial activity and total phenolic content of Triphala components.The test plant extracts were also found to be non-toxic on human erythrocyte membrane at recommended and even higher doses. The preliminary results of the present study may help in developing effective and safe antimicrobial agents from Triphala components for the treatment of urinary tract infections caused by multidrug-resistant bacteria.

Antibiotic resistance of Salmonella enterica serovar Typhi in Kolkata, India, and in vitro experiments on effect of combined chemotherapy.

This communication states the changing patterns of Salmonella enterica serovar Typhi (S. Typhi) isolates causing enteric fever in and around Kolkata, India. Among the isolates resistance to ampicillin (A), chloramphenicol (C), cotrimoxazole (Co) and tetracycline (T) were plasmid mediated; the plasmid was unstable in S. Typhi, and the other enteric bacteria like Escherichia coli, Klebsiella pneumoniae and Proteus vulgaris were found to be the potential source of dissemination of such plasmids into S. Typhi. The infection with such S. Typhi strains were successfully treated with ciprofloxacin (Cp: MICs 0.0075-0.075 µg mL⁻¹) and/or ofloxacin (Ofx: MICs 0.0125-0.075 µg mL⁻¹), but in the later course, the S. Typhi strains, showing resistance to nalidixic acid, developed low level of resistance to Cp and Ofx, causing the treatment failure. Thus, the treatment regimen was shifted to the third generation cephalosporins like ceftriaxone (Ct) and cefotaxime (Cf). Keeping in mind the anticipation of development of resistance to Ct/Cf, we prepared the treatment regimen for MDR enteric fever, based on the double-drug synergy tests in vitro; Cp-gentamycin (FICI 0.121-0.216) and Cp-trimethoprim (FICI 0.14-0.483) combinations were found effective against S. Typhi isolates having decreased sensitivity to cp (MICs: 0.5-1.25 µg mL⁻¹).

In vitro antibacterial potential of Eugenia jambolana seed extracts against multidrug-resistant human bacterial pathogens.

The present study was carried out to evaluate the possible in vitro antibacterial potential of extracts of Eugenia jambolana seeds against multidrug-resistant human bacterial pathogens. Agar well diffusion and microbroth dilution assay methods were used for antibacterial susceptibility testing. Kill-kinetics study was done to know the rate and extent of bacterial killing. Phytochemical analysis and TLC-bioautography were performed by colour tests to characterize the putative compounds responsible for this antibacterial activity. Cytotoxic potential was evaluated on human erythrocytes by haemolytic assay method and acute oral toxicity study was done in mice. The plant extracts demonstrated varying degrees of strain specific antibacterial activity against all the test isolates. Further, ethyl acetate fraction obtained from fractionation of most active ethanol extract showed maximum antibacterial effect against all the test isolates. Phytochemical analysis and TLC-bioautography of ethyl acetate fraction revealed that phenolics were the major active phytoconstituents. Ethyl acetate fraction also demonstrated no haemolytic activity on human erythrocytes and no gross behavioural changes as well as toxic symptoms were observed in mice at recommended dosage level. The results provide justification for the use of E. jambolana in folk medicine to treat various infectious diseases and may contribute to the development of novel antimicrobial agents for the treatment of infections caused by these drug-resistant bacterial pathogens.

A molecular approach to identification and profiling of first-line-drug-resistant mycobacteria from sputum of pulmonary tuberculosis patients.

Conventional and molecular techniques were applied to detect and characterize drug resistance of mycobacteria in the sputum samples of clinically confirmed tuberculosis. The sensitivities of mycobacterium detection by ZN staining, culture, multiplex PCR, and restriction fragment length polymorphism (RFLP) were 27.7%, 19.9%, 92.9%, and 95.7%, respectively, but all were 100% specific. The conventional and multiple-allele-specific PCR (MAS-PCR) methods enabled establishment of the drug resistance in 19.3% and 86.9% cases, respectively. We demonstrated that molecular techniques have potential in the accurate diagnosis of tuberculosis.

Enhancing chloramphenicol and trimethoprim in vitro activity by Ocimum sanctum Linn. (Lamiaceae) leaf extract against Salmonella enterica serovar Typhi.

OBJECTIVE: To evaluate the antibacterial activity of Ocimum sanctum (O. sanctum) leaf extract, alone, and in combination with chloramphenicol (C) and trimethoprim (Tm) against Salmonella enterica serovar Typhi (S. typhi). METHODS: The antibacterial activity of ethanolic extract of tulsi, O. sanctum, leaf (TLE; 500 µg) for 23 S. typhi isolates was determined following agar diffusion. The C (30 µg) and Tm (5 µg) activity alone and in combination with TLE (250 µg) was determined by disk diffusion. The zone diameter of inhibition (ZDI) for the agents was recorded, and growth inhibitory indices (GIIs) were calculated. RESULTS: The S. typhi isolates (n=23), which were resistant to both C (ZDI 6 mm) and Tm (ZDI 6 mm), had TLE (500 µg) ZDIs 16-24 mm. The ZDIs of C and Tm were increased up to 15-21 mm and 17-23 mm, respectively, when TLE (250 µg) was added to the C and Tm discs. The GIIs ranged 0.789-1.235 and 0.894-1.352, due to combined activity against S. typhi isolates, of C and TLE and Tm and TLE, respectively. CONCLUSIONS: The data suggest that TLE, in combination with C and Tm, had synergistic activity for S. typhi isolates, and hence O. sanctum is potential in combating S. typhi drug resistance, as well promising in the development of non-antibiotic drug for S. typhi infection.

Inhibition of the emergence of multi drug resistant Staphylococcus aureus by Withania somnifera root extracts.

OBJECTIVE: To search systematically for an alternative therapy with compounds particularly from plant origin. METHODS: Efficacy test of different root extracts of Withania somnifera (W. somnifera) (L) Dunal against multi drug resistant (MDR) Staphylococcus aureus (S. aureus) variants was performed following the agar well diffusion method. Evaluation of susceptibility pattern of the isolates was carried out by employing disk diffusion method using standard antibiotic disks. RESULTS: In vitro study with W. somnifera root extracts was found to be effective against all the MDR S. aureus strains isolated from local and patient sources. Different root extracts of WS showed different degree of effectiveness against the isolates. CONCLUSIONS: The major active principles responsible for the antibacterial efficacy were mainly present in methanol (MeOH)extract and ethanol (EtOH) extracts as well as in butanol (BuOH) extract fraction. Amongst all the extracts the BuOH fraction was found to be most active against all the isolates but aqueous extract was the least active one. Finally it may be concluded that the antimicrobials from W. somnifera may raise an alternative therapy for MDR staphylococcal infections in near future.

Serologic evidence of human leptospirosis in and around Kolkata, India: a clinico-epidemiological study.

OBJECTIVE: To investigate the prevalence of leptospirosis among patients from within and outside Kolkata, India, attending the Calcutta School of Tropical Medicine, for treatment during August 2002 to August 2008. METHODS: The leptospirosis cases were determined on the basis of clinical, epidemiological, and biochemical factors, and were tested for leptospiral antibodies using IgM ELISA. Serum samples with absorbance ratio ≥ 1.21 were interpreted as reactive. RESULTS: The commonest presentation involved fever, headache and jaundice. The male-female ratio was 61:46. A total of 65(64.20%) cases had abnormal liver and renal functions respectively, and 57.1% had both the abnormalities. The highest incidence (75, 35.04%) was recorded in September-October followed by July-August (53, 24.77%). The reactive cases had absorbance ratios between 1.21 and 8.21, and 53 showed equivocal result, while IgM non reactivity were seen in 90 patients (absorbance ratios 0.10-0.90). The patients responded to treatment with parenteral antibiotics, penicillin, ceftriaxone and cefotaxime; follow up did not reveal case fatality. CONCLUSIONS: The cardinal signs of leptospirosis help in making clinical diagnosis, but in any hyper-endemic situation any patient reporting with acute fever and signs of pulmonary, hepatic or renal involvement should be suspected to have leptospirosis and investigated accordingly. Increased awareness, and early diagnosis and treatment, can reduce mortality due to leptospirosis.

In Vitro Antibacterial Activity of three Indian Spices Against Methicillin-Resistant Staphylococcus aureus.

OBJECTIVE: To explore the in vitro antibacterial activity of ethanolic extracts of cinnamon (Cinnamomum zeylanicum; CIN), clove (Syzygium aromaticum, CLV) and cumin (Cuminum cyminum, CMN) against clinical isolates of methicillin resistant Staphylococcus aureus (MRSA), from Kolkata, India. METHODS: The CIN, CLV and CMN were tested for their antibacterial activity against MRSA by in vitro methods. Minimum inhibitory concentration (MIC) values of the three extracts were determined, and time-kill studies were performed in order to investigate the bactericidal activity of the extracts (at the MIC level) for the isolates. The killing efficacy of the extracts was determined at various concentrations. RESULTS: The zone diameter of inhibition (ZDI) obtained due to CIN, CLV and CMN ranged between 22-27 mm, 19-23 mm and 9-15 mm, respectively; while the MICs, for the isolates, were in the range of 64-256, 64-512 and 128-512 µg/ml, respectively. When tested for their MIC levels; the CIN and CLV were found to be bactericidal after 6 hrs of incubation, while CMN showed bactericidal activity after 24 hrs. However, when tested at various concentrations; CIN, CLV and CMN displayed bactericidal activity against S. aureus, after 24 hrs of incubation, at 200, 200 and 300 µg/ml, respectively. CONCLUSION: The C. zeylanicum and S. aromaticum showed the strongest in vitro antibacterial activity followed by C. cyminum against MRSA, and such findings could be considered a valuable support in the treatment of infection and may contribute to the development of potential antimicrobial agents for inclusion in anti- S. aureus regimens.

Cholera: a great global concern.

Cholera, caused by the infection of toxigenic Vibrio cholerae (V. cholerae) to humans, is a life threatening diarrheal disease with epidemic and pandemic potential. The V. cholerae, both O1 and O139 serogroups, produce a potent enterotoxin (cholera toxin) responsible for the lethal symptoms of the disease. The O1 serogroup has two biotypes (phenotypes), classical and El Tor; each of which has two major serotypes (based on antigenic responses), Ogawa and Inaba and the extremely rare Hikojima. V. cholerae O1 strains interconvert and switch between the Ogawa and Inaba serotypes. Fluid and electrolyte replacement is the mainstay of treatment of cholera patients; the severe cases require antibiotic treatment to reduce the duration of illness and replacement of fluid intake. The antibiotic therapy currently has faced difficulties due to the rapid emergence and spread of multidrug resistant V. cholerae causing several outbreaks in the globe. Currently, cholera has been becoming endemic in an increasing number of geographical areas, reflecting a failure in implementation of control measures. However, the current safe oral vaccines lower the number of resistant infections and could thus represent an effective intervention measure to control antibiotic resistance in cholera. Overall, the priorities for cholera control remain public health interventions through improved drinking water, sanitation, surveillance and access to health care facilities, and further development of safe, effective and appropriate vaccines. Thus, this review describes the facts and phenomena related to the disease cholera, which is still a great threat mainly to the developing countries, and hence a grave global concern too.

Bacteriological study of aerobic isolates from plantar ulcers of paucibacillary leprosy patients.

BACKGROUND: Plantar ulcers commonly occur in leprosy patients, which usually recur and cause morbidity in such cases. AIMS: The aim of the study is to find out the bacteriological profile of these ulcers and to find out the antibiotic susceptibility of the isolates so that appropriate drugs may be chosen for treatment and for prevention of recurrence. MATERIALS AND METHODS: Fifty-six samples from recurrent plantar ulcers of paucibacillary leprosy patients (attending the outpatient department of Calcutta School of Tropical Medicine) were studied for the purpose. Proper sample collection, gram staining, inoculation on culture media, and final identification by biochemical methods were undertaken. Antibiotic susceptibility testing was done for appropriate choice of drugs. RESULTS: Mixed growth of bacteria was seen in 20 (36%) cases while single organism was isolated from the rest. Staphylococcus aureus is the predominant single isolate followed by E. coil, Proteus sp. and Pseudomonas sp. Chloramphenicol and gentamycin are the two drugs that have shown efficacy to the extent of 75 to 100% and 25 to 100% respectively in vitro studies. CONCLUSION: Bacteriological study of plantar ulcers of leprosy patients has revealed Staphylococcus aureus as the main pathogen. Treatment with chloramphenicol and gentamycin holds good prospect as per our study.

Plasmid-mediated dimethoate degradation by Bacillus licheniformis isolated from a fresh water fish Labeo rohita.

The Bacillus licheniformis strain isolated from the intestine of Labeo rohita by an enrichment technique showed capability of utilizing dimethoate as the sole source of carbon. The bacterium rapidly utilized dimethoate beyond 0.6 mg/mL and showed prolific growth in a mineral salts medium containing 0.45 mg/mL dimethoate. The isolated B licheniformis exhibited high level of tolerance of dimethoate (3.5 mg/mL) in nutrient broth, while its cured mutant did not tolerate dimethoate beyond 0.45 mg/mL and it was unable to utilize dimethoate. The wild B licheniformis strain transferred dimethoate degradation property to E coli C600 (Nar, F-) strain. The transconjugant harbored a plasmid of the same molecular size (approximately 54 kb) as that of the donor plasmid; the cured strain was plasmid less. Thus a single plasmid of approximately 54 kb was involved in dimethoate degradation. Genes encoding resistance to antibiotic and heavy metal were also located on the plasmid.

Scattergram analysis to explore the emerging problem related to in vitro susceptibility test for Salmonella enterica serovar Typhi to ciprofloxacin.

Ciprofloxacin susceptibility using a disk diffusion method and minimum inhibitory concentration (MIC) value determination for 421 S. Typhi isolates showed comparable results for 296 (70%) isolates with an MIC /=0.1 mg/L, signifying resistance, 123 (98.4%) showed discrepant results with the disk diffusion test (66 sensitive, 57 intermediately sensitive). This raises questions about National Committee for Clinical Laboratory Standards guidelines regarding the interpretative zone size for ciprofloxacin.

Synergism of ciprofloxacin and trimethoprim against Salmonella enterica serovar typhi isolates showing reduced susceptibility to ciprofloxacin.

The activity of the combination of ciprofloxacin and trimethoprim against 16 Salmonella enterica serovar typhi isolates from blood cultures were tested by agar dilution checkerboard technique. When used in combination, minimum inhibitory concentrations (MICs) of ciprofloxacin and trimethoprim ranged from 0.5 to 1.25 and from 10 to 125 microg/ml, respectively, and fractional inhibitory concentrations (FICs) from 0.025 to 0.125 and from 2.5 to 10 microg/ml, respectively. The FIC index was 0.140-0.483, indicating a marked synergy between ciprofloxacin and trimethoprim against trimethoprim-resistant S. enterica serovar typhi isolates (100%) with high MICs for ciprofloxacin.

Ofloxacin minimum inhibitory concentration versus disk diffusion zone diameter for Salmonella enterica serovar Typhi isolates: problems in the detection of ofloxacin resistance.

Using the guidelines of the National Committee for Clinical Laboratory Standards (NCCLS), a total of 421 blood culture isolates of Salmonella enterica serovar Typhi obtained during 1991-2001 were tested for susceptibility to ofloxacin (OFX) by the disc diffusion method, and for the determination of minimum inhibitory concentration (MIC) values of OFX by the agar dilution method. Among 421 isolates, 248 were fully OFX-sensitive showing MICs of 0.0125-0.075 microg/ml and inhibitory zone diameters of > or =24 mm. The remaining 173 isolates (MICs of 0.5-1.5 microg/ml) that were treated with OFX did not respond to the therapy. However, 169 (97.69%) of the 173 isolates were determined to be susceptible (zone diameter > or =16 mm) by the disc diffusion method, whereas only 3 were intermediately susceptible (zone diameter 13-15 mm) and the final isolate showed OFX-resistance (zone diameter 12 mm). Thus, following the NCCLS guidelines, OFX-resistance in S. enterica serovar Typhi was not detected by the disc diffusion test. The present data suggest a revision of the NCCLS breakpoints in selecting OFX as the preferred treatment regimen for S. enterica serovar Typhi