Antibiotic sensitivity pattern of Citrobacter isolated from various clinical specimens in a tertiary care hospital

A total of 709 isolates of Citrobacter species were recovered from different clinical specimens at Kasturba Medical College, Mangalore. The antimicrobial susceptibility testing of the isolates was performed using Kirby-Bauer's method of disk diffusion. All the isolates were susceptible to Imipenem (100%) and 100% resistance to Ampicillin was recorded. Susceptibility to third generation cephalosporins varied between 29 - 43%. The beta-lactamase inhibitor combination used along with beta-lactam antibiotics increased their sensitivity. The minimum inhibitory concentration (MIC) of cephotaxime to Citrobacter species was determined by agar dilution method (MIC value = or < 8 microg/ml are considered susceptible). Two hundred and fifty three strains were found to be completely susceptible, 71 strains showed intermediate susceptibility and 385 strains were completely resistant to Cephotaxime.     

Non tuberculous mycobacteria isolated from clinical specimens at a tertiary care hospital in South India

Purpose: This is a retrospective analysis of the isolation rates of nontuberculous mycobacteria (NTM) from various clinical specimens and their antimicrobial susceptibility patterns. Methods: All NTM isolated between 1999 and 2004 at Christian Medical College, Vellore, South India, were identified with various biochemical tests. Antimicrobial susceptibility test for all NTM was performed by standard methods. Results: A total of 32,084 specimens were received for culture, of which 4473 (13.9%) grew acid fast bacilli (AFB). Four thousand three hundred (96.1%) of the AFB were M. tuberculosis while 173 (3.9%) were NTM. Of the 173 NTM, 115 (66.5%) were identified to the species level. Pus, biopsy specimens and sputum specimens yielded most of the NTM of which M. chelonae (46%) and M. fortuitum (41%) accounted for majority of them. M. chelonae and M. fortuitum, showed highest susceptibility to amikacin (99.2%). NTM were repeatedly isolated from seven sputum specimens, 15 biopsy and pus specimens, two CSF and two blood cultures. Six were isolated from patients with AIDS and five from post transplant patients. Conclusions: The isolation of NTM from various clinical specimens is reported in this study to highlight the associated diseases and therapeutic options in these infections.     

Prevalence, identification and distribution of various species of enterococci isolated from clinical specimens with special reference to urinary tract infection in catheterized patients

Various clinical specimens were processed to find the prevalence rate of enterococci and to identify the species of clinical isolates of enterococci. Screening of various clinical specimens revealed that enterococci were prevalent in 22.19% of the total specimens, with Foley's catheters and burn wounds to be the major site of isolation. High rate of colonization was noted as opposed to infection. Conventional test scheme proposed by Facklam and Collins were successfully used to speciate enterococcal strains. Seven species of enterococci were identified in the study from a set of 202 cultures, with E.faecalis (49.50%) and E. faecium (35.64%) predominating. E. avium (9.40%), E. hirae (2.47%), E. raffinosus (1.98%) and one isolate each of E.gallinarum and E. casseliflavus were the other members of Enterococcus species identified. Urinary tract infection (UTI) by enterococci due to catherisation was found in 8.92% of the patients and is probably the result of high rate of colonization of Foley's catheters and use of broad-spectrum antibiotics.     

Species identities of enterococci isolated from clinical specimens.

Conventional tests and commercially available systems were used to determine the species identities of clinical isolates of enterococci. Strict adherence to the conventional test scheme of Facklam and Collins (R. R. Facklam and M. D. Collins, J. Clin. Microbiol. 27:731-734, 1989) resulted in the misidentification of lactose-negative Enterococcus faecalis isolates as Enterococcus solitarius, but this problem was overcome by the application of additional tests. The commercially available systems tested were unable to recognize some of the more recently described enterococcal species. E. faecalis accounted for 87.1% of 302 consecutive isolates. Enterococcus faecium (8.6%), Enterococcus avium (0.7%), Enterococcus durans (0.3%), Enterococcus gallinarum (1.0%), Enterococcus casseliflavus (1.0%), Enterococcus hirae (0.3%), and Enterococcus raffinosus (0.3%) isolates were also identified. None of the isolates produced beta-lactamase, but 15.4% of 235 isolates tested, including 1 strain of E. gallinarum, displayed high-level resistance to gentamicin.     

Prevalence and antimicrobial resistance pattern of multidrug-resistant enterococci isolated from clinical specimens

Purpose: Vancomycin-resistant enterococci (VRE) pose an emerging problem in hospitals worldwide. The present study was undertaken to determine the occurrence, species prevalence, antibacterial resistance, and phenotypic and genetic characteristics of VRE isolated in Riyadh hospitals, KSA. Materials and Methods: Two hundred and six isolates of enterococcal species were obtained from clinical samples. The antibiotic susceptibility of isolates and minimum inhibitory concentration (MIC) tests for vancomycin and teicoplanin were determined. Molecular typing of VRE isolates was carried out by using pulsed field gel electrophoresis (PFGE) and the resistance genotype was determined by polymerase chain reaction (PCR). Results: VRE accounted for 3.9% of the isolates and were detected mostly in urine, wound and blood specimens isolated from ICU, internal medicine and surgical wards. All strains were identified to species level and were found to consist of E. faecalis (69.2%), E. faecium (11.3%), E. avium (2.1%), E. hirae (0.8%), E. casseliflavus (1.3%) and E. gallinarum (1.3%) species. According to the susceptibility data obtained, 8 (3.9%) out of 206 isolates were found to be VRE (MICs > 32 µg/ml). The vanA, vanB and vanC gene fragments of E. faecalis, E. faecium and E. gallinarum were amplified from isolates and were detected. PFGE patterns of the VRE isolates revealed homogenous patterns with dominant clone suggesting that the strains intrinsic resistance is independent. Conclusions: This study shows an emergence of VRE along with increased rate of multidrug-resistant enterococci in the area of the study. Regular surveillance of antimicrobial susceptibilities should be done regularly and the risk factors should be determined.     

Carrier rate of resistant enterococci in a tertiary care hospital in Norway.

The prevalence of resistant enterococci varies geographically. In the present study we looked at the carrier rate of resistant enterococci in the hematology and gastrointestinal surgery units of a tertiary care hospital in Norway. Anal swabs were taken from all 82 hospitalized patients on 4 different dates, at least 4 weeks apart, in 1995. 51% had positive cultures for enterococci. 6% of all patients carried enterococci resistant to ampicillin. 7% carried enterococci with high-level gentamicin resistance. Two strains resistant to vancomycin were found, including the first vanA Enterococcus faecium isolated in a Norwegian hospital. There was a correlation between use of antibiotics and being a carrier of enterococci per se, but the correlation with resistant enterococci did not reach statistical significance owing to the small number of isolates. The carrier rates both for presence of enterococci and for resistant enterococci were generally lower than those found in other studies.     

Metallo-beta-lactamase-producing clinical isolates of Acinetobacter species and Pseudomonas aeruginosa from intensive care unit patients of a tertiary care hospital

Prompt detection of metallo-beta-lactamase (MBL) producing isolates is necessary to prevent their dissemination. Frequency of MBLs producing strains among multidrug resistant (MDR) Acinetobacter species and Pseudomonas aeruginosa was evaluated in critical care patients using imipenem-EDTA disk method. One hundred MDR Acinetobacter spp. and 42 Pseudomonas aeruginosa were checked for MBL production, from January to June 2001. MBL was produced by 96.6 % of imipenem-resistant Acinetobacter isolates, whereas 100% imipenem-resistant Pseudomonas aeroginosa isolates were MBL producers. Carbapenem resistance in MDR Acinetobacter spp. and Pseudomonas aeruginosa isolates in this study was due to MBLs. This calls for strict infection control measures to prevent further dissemination.     

Species distribution and antibiotic sensitivity pattern of Coagulase negative staphylococci isolated from various clinical specimens

A study of 192 strains of Coagulase negative staphylococcus (CONS) showed that Staphylococcus epidermidis was the most common species, 158 (82.29%) isolated from all clinical specimens followed by S. saprophyticus (30, 15.62%) isolated mainly from urine. Slime production was exhibited by 77 (48.7%) strains of S. epidermidis and 8 (26.6%) of S. saprophyticus and the difference in the slime producing activity was statistically significant (p< 0.005). Antibiotic susceptibility testing against 15 commonly used antibiotics showed multidrug resistance with more than 90% resistance to penicillin, more than 50% to cephalexin and ciprofloxacin and more than 20% to methicillin, thus, highlighting the importance of species identification and antibiotic susceptibility testing for clinical isolates of CONS.     

Fungemia at a tertiary care hospital: incidence,therapy, and distribution and antifungal susceptibility of causative species

The aim of this study was to review fungal bloodstream infections at a large tertiary care hospital to evaluate the incidence of fungemia and the distribution of causative species during the period 2001–2005. Another aim was to assess the extent of antifungal resistance. A review of all episodes of fungemia at the University Hospitals of Leuven (Belgium) was conducted between January 2001 and December 2005. For the first yeast isolate collected from each non-mould fungemic episode during a 1-year period (June 2004–June 2005), susceptibility to seven antifungal agents was determined using Sensititre YeastOne plates (Trek Diagnostic Systems, East Grinstead, UK), and the antifungal therapy was reviewed. The annual incidence of fungemia ranged between 1.30 and 1.68 episodes per 10,000 patient-days (on a total of 2,680,932 patient-days), with a decreasing trend observed over the 5-year study period. The most common species were Candida albicans (59%), Candida glabrata (22%), Candida parapsilosis (10%), and Candida tropicalis (4%). Overall, fluconazole resistance was rare (1.6%) and was detected only in C. glabrata and C. krusei. Voriconazole and caspofungin inhibited 100% of the isolates at a concentration of ≤1 μg/ml. Fluconazole was used to treat 75% of fungemic patients. Caspofungin was the second most commonly used antifungal agent (used to treat 11.7% of patients). The incidence of fungemia was higher than usually reported in other European countries. The low proportion of resistance supports the use of fluconazole as the treatment of first choice for candidemia in patients not previously exposed to this drug.     

Molecular characterization of vancomycin-resistant enterococci isolated from a hospital in Beijing,China

ObjectiveTo investigate the occurrence of vancomycin-resistant enterococci (VRE) isolated from patients in Peking Union Medical College Hospital, Beijing, China from 2011 to 2017, and to evaluate their resistance mechanisms and genetic relatedness.MethodsAll isolates were identified using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF). Antibiotic susceptibility testing was performed using the broth microdilution method. Molecular characterization were detected by PCR and sequencing. Genotyping of VRE isolates was performed by multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE) analysis. Virulence genes were detected by multiplex PCR.ResultsA total of 87 consecutive VRE were collected, including 84 isolates of vancomycin resistant Enterococcus faecium (VREfm) and 3 isolates of Enterococcus faecalis (VREfs). Urine (40.2%, 35/87) and blood (17.2%, 15/87) were the most commonly specimens. All VREfm isolates were resistant to ampicillin, and were susceptible to daptomycin, linezolid and tigecycline. The resistant rate of teicoplanin was 47.6%. All of the VREfm isolates carried the vanA gene, no isolates carried vanB. 11.9% (10/84) VREfm isolates carried both vanA and vanM. Among them, 76.2% (64/84) and 66.7% (56/84) carried esp and hyl, respectively. The 3 vancomycin resistant E. faecalis (VREfs) isolates were varied, and only one carried vanB. A total of 3 and 18 STs were detected among VREfs and VREfm strains, respectively. PFGE results indicated a genetic diversity among VREfm isolates.ConclusionThis study confirms that VREfm isolates associated with ST78 were the main epidemic lineage responsible for nosocomial infections in China, as were also observed in other nations worldwide.     

Multiply high-level-aminoglycoside-resistant enterococci isolated from patients in a university hospital.

Enterococci isolated from different body sites were tested for high-level gentamicin resistance. A total of 259 enterococcal isolates were screened for resistance (MIC, greater than 2,000 micrograms/ml) by a broth-tube method. Thirty-nine (15.1%) were found to exhibit resistance and were confirmed by agar screening (1,000 micrograms/ml) and agar dilution MIC determinations. The majority of isolates also showed high-level resistance to kanamycin and streptomycin. The remaining isolates showed high-level resistance to gentamicin and kanamycin but not streptomycin. Synergy testing of several isolates confirmed the correlation between lack of synergy and high-level resistance. A retrospective clinical review was performed. Most patients had a source of definite or likely infection (79%). Serious infections such as endocarditis or meningitis were not observed during the course of this study. Retrospective clinical data suggest that in cases not involving endocarditis or meningitis, neither infection refractory to therapy nor relapse of infection is a common sequela of infection with gentamicin-resistant enterococci in hospitalized patients.     

Prevalence of extended spectrum Beta-Lactamase producing Klebsiella species from patients' specimens in a tertiary teaching hospital in Ile-Ife,Southwest Nigeria

ObjectiveThis study determined the prevalence of ESBL genes amongst Klebsiella species isolated from patients'' specimens attending a Tertiary Teaching Hospital, in Ile-Ife, Southwest Nigeria.MethodsA cross sectional study of presumptive isolates of Klebsiella (n=180) were collected, after ethical approval in the microbiology laboratory. Isolates were identified to species level by conventional biochemical tests and MicrobactTM 24E Identification Kits. Antibiotic susceptibility testing was performed by the Kirby Bauer''s disk diffusion method. ESBL production was detected by the double disc synergy and ESBL genes by the multiplex PCR protocol.ResultsThe Klebsiella species identified were Klebsiella pneumoniae 95.6%, Klebsiella oxytoca 3.3%, Klebsiella ornithinolytica 0.6% and Klebsiella terrigena 0.6%. The prevalence of ESBL genes among the Klebsiella isolates was 47.2%, and the most common ESBL gene was blaSHV (38.9%), also 75% of the study isolates had MAR index greater than 0.2.ConclusionsThe study establishes the prevalence of Extended Spectrum Beta-Lactamase producing Klebsiella sp in the hospital and identified the most prevalent ESBL genes circulating as blaSHV followed by blaTEM and blaCTX-M in this environment. This underscores the need for regular and continuous surveillance of antimicrobial resistance trend as a strong component of the antibiotics stewardship and infection prevention and control programs in the hospital.     

Corynebacterium tuberculostearicum: a potentially misidentified and multiresistant Corynebacterium species isolated from clinical specimens

Corynebacterium tuberculostearicum is a lipophilic corynebacterium validly characterized in 2004. We provide clinical information on 18 patients from whom this organism was isolated. The majority of the patients were hospitalized and had a history of prolonged treatment with broad-spectrum antimicrobials. In 7 (38.9%) of the 18 cases, the isolates were found to be clinically relevant. The present report also includes detailed data on the biochemical and molecular identification of C. tuberculostearicum, as well as its identification by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Our data demonstrate that routine biochemical tests do not provide reliable identification of C. tuberculostearicum. MALDI-TOF MS represents a helpful tool for the identification of this species, since all of the strains matched C. tuberculostearicum as the first choice and 58.3% (7/12) of the strains processed with the full extraction protocol generated scores of >2.000. Nevertheless, partial 16S rRNA gene sequencing still represents the gold standard for the identification of this species. Due to the challenging identification of C. tuberculostearicum, we presume that this organism is often misidentified and its clinical relevance is underestimated. The antimicrobial susceptibility profile of C. tuberculostearicum presented here reveals that 14 (87.5%) of the 16 strains analyzed exhibited multidrug resistance.     

Anti-biofilm efficacy of silver nanoparticles against MRSA and MRSE isolated from wounds in a tertiary care hospital

Purpose: Different approaches have been used for preventing biofilm-related infections in health care settings. Many of these methods have their own de-merits, which include chemical-based complications; emergent antibiotic resistant strains, etc. The formation of biofilm is the hallmark characteristic of Staphylococcus aureus and S. epidermidis infection, which consists of multiple layers of bacteria encased within an exopolysachharide glycocalyx. Nanotechnology may provide the answer to penetrate such biofilms and reduce biofilm formation. Therefore, the aim of present study was to demonstrate the biofilm formation by methicillin resistance S. aureus (MRSA) and methicillin resistance S. epidermidis (MRSE) isolated from wounds by direct visualisation applying tissue culture plate, tube and Congo Red Agar methods. Materials and Methods: The anti-biofilm activity of AgNPs was investigated by Congo Red, scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) techniques. Results: The minimum inhibitory concentration (MIC) was found to be in the range of 11.25-45 μg/ml. The AgNPs coated surfaces effectively restricted biofilm formation of the tested bacteria. Double fluorescent staining (propidium iodide staining to detect bacterial cells and fluorescein isothiocyanate concanavalin A (Con A-FITC) staining to detect the exopolysachharides matrix) technique using CLSM provides the visual evidence that AgNPs arrested the bacterial growth and prevent the glycocalyx formation. In our study, we could demonstrate the complete anti-biofilm activity AgNPs at a concentration as low as 50 μg/ml. Conclusions: Our findings suggested that AgNPs can be exploited towards the development of potential anti-bacterial coatings for various biomedical and environmental applications. In the near future, the AgNPs may play major role in the coating of medical devices and treatment of infections caused due to highly antibiotic resistant biofilm.