Antibiotic susceptibility profiles and detection of genes mediating extended-spectrum ß-lactamase (Esbl) production in escherichia coli isolates from National Hospital, Abuja.

Background: Extended-spectrum beta-lactamases (ESBL) are the most widespread of the new beta-lactamases and are a significant threat to patient care in the hospital and the community. Aim: The study assessed the prevalence, antibiotic susceptibility profile, and major ESBL encoding genes among Escherichia coli isolated from clinical specimens of patients in the National Hospital, Abuja (NHA). Materials and Methods: E. coli isolated from diverse clinical specimens obtained from clinically proven cases of infection managed at the NHA were included in the study. The antimicrobial susceptibility was performed by the Kirby-Bauer method and E-test was used to confirm the ESBL phenotype. Multiplex polymerase chain reaction (PCR) was used to detect the genes mediating ESBL production. Results: Meropenem, fosfomycin, and tigecycline demonstrated excellent activities against all isolates: of the 400 isolates, 392 (98%), 386 (96.5%), and 362 (90.5%) were susceptible, respectively. Similarly, 358 (89.5%) were susceptible to amikacin, 323 (80.3%) nitrofurantoin, 281 (70.3%) ceftazidime, and 279 (69.8%) cefotaxime. A total of 271 (67.8%), 219 (54.8%), and 208 (52.0%) were resistant to amoxicillin-clavulanate, ciprofloxacillin, and gentamicin, respectively. However, all the isolates were resistant to ampicillin. There was a significantly higher proportion of multidrug resistance among ESBL-producing isolates compared to non-ESBL-producing isolates (P = 0.0001). Of the 121 phenotypically detected ESBL isolates, 119 (98.3%) harbored genes mediating the production of Cefotaximase- Munich (CTX-M), Temoniera (TEM) or Sulfhydryl Variable (SHV) enzymes. Conclusion: The prevalence of ESBLs among E. coli was relatively high, at 30.2%. About 81% of all blood isolates were ESBL-producers. blaCTX-M is the predominant type of ESBL gene among E. coli. A high proportion of the ESBL-producing isolates expressed a combination of two or three genes together.

Comparative evaluation of two matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) systems for the identification of clinically significant yeasts.

OBJECTIVES: To prospectively evaluate the performance of two matrix-assisted laser desorption/ionization time-of-flight mass spectrometry systems (MALDI-TOF MS) for the identification of clinically significant yeast isolates compared to the VITEK 2 system. METHODS: One hundred and eighty-eight consecutive yeast isolates were analyzed by Bruker Biotyper and VITEK MS. The results were compared with the conventional VITEK 2 yeast identification system. Discrepant results were resolved by direct sequencing of rDNA. RESULTS: Accurate identification by VITEK 2, VITEK MS, and Bruker Biotyper MS was 94.1% (177/188), 93.0% (175/188), and 92.6% (174/188), respectively. Three isolates were not identified by VITEK MS, while nine Candida orthopsilosis were misidentified as Candida parapsilosis, as this species is not present in its database. Eleven isolates were not identified or were wrongly identified by Bruker Biotyper and although another 14 were correctly identified, the score was unreliable at <1.7. CONCLUSION: The overall accuracy of rapid MALDI-TOF MS systems was essentially comparable to that of the conventional VITEK 2 yeast identification system. However, future expansion of the databases may further improve the outcome and accuracy of identification of yeast species.

Correlation of multidrug resistance, toxinotypes and PCR ribotypes in Clostridium difficile isolates from Kuwait.

Clostridium difficile is a common cause of nosocomial diarrhea. its role in community-acquired diarrhea is also becoming an important public health concern. Hardly any studies have correlated strain ribotypes, toxinotypes and multidrug resistant (MDR) profiles. To investigate these characteristics, 65 C. difficile isolates obtained from stool samples of patients whose cultures were negative on admission but became positive after 48 h of admission to the ICUs of our hospitals were studied to determine the prevalent ribotypes, toxinotypes and their relationship with the MDR profiles using ELISA/cytotoxicity assays, PCR and Etest methods. The toxin-producing strains were toxinotyped by the PCR-RFLP technique. Of the 65 isolates, 42 (64.6%) were toxigenic (T). The isolates were of diverse ribotypes but types 097, 078, 056 and 039 (NT) were predominant. thirty (71.4%) of 42 T and 13 (56.5%) of 23 NT strains were multiresistant to 3 or more antibiotics. Only 3 toxinotypes (0, "V-like" and XII) were encountered. Of the 42 t strains, 30 (71.4%) were of toxinotype 0, and 12 belonged to variant toxinotypes: 4 (9.4%) to toxinotype XII and 8 (19%) to "V-like" toxinotype in which amplified B1 PCR fragments was amplified as expected for toxinotype V but the A3 PCR fragment could not be amplified. The 43 mDR strains were assigned to 3 arbitrary resistance groups; groups 1, 11 and III. the most prevalent isolates (37; 86.1%) were in group II. Of the predominant T ribotypes (097, 078 and 056), c. 62% clustered in group II. Although the number of strains toxinotyped was small, ribotyping and toxinotyping correlated well with the published literature, except for 078 with a novel "V-like" toxinotype. Antibiogram was not as clear-cut.

Comparative in vitro activity of tigecycline and nine other antibiotics against gram-negative bacterial isolates, including ESBL-producing strains.

The enterobacteriaceae, especially Escherichia coli and Klebsiella spp., as well as Acinetobacter spp., are important agents of nosocomial infections in hospitalized patients. A total of 460 Gram-negative bacteria (GNb), were investigated for their susceptibility to tigecycline and 9 other antibiotics by the etest. ESBL production was inferred from ESBL etest phenotypes. All the GNb, including the ESBL-producers, were susceptible to tigecycline with MIC(90 )ranges of 0.25 to 2 microg/ml. Imipenem and meropenem were very active against ESBL and non-ESBL producers; mean MIC(90)s of 0.19 and 0.09 microg/ml and 0.05 microg/ml and 0.02 microg/ml, respectively. The MIC(90)s of imipenem and meropenem for the Acinetobacter spp. were 16 and >32 microg/ml, respectively with resistance rates of 64.3 and 66.1%. ESBL production was detected in 62% and 82.1% of the E. coli and K. pneumoniae isolates, respectively. Resistance to ciprofloxacin was higher among the ESBL-producing strains of E. coli and K. pneumoniae than the non-ESBL producers. Comparatively, tigecycline had excellent in vitro activities against ESBL-producing enterobacteriaceae and demonstrated superior activity against Acinetobacter spp. Increasing ESBL production and resistance to ciprofloxacin and gentamicin in enterobacteriaceae require careful selection of empirical therapy. Tigecycline holds promise as an alternative choice of therapy for infections caused by ESBL-producing isolates and multi-drug resistant Acinetobacter spp.

Listeria monocytogenes meningitis in an immunocompetent adult patient.

OBJECTIVE: To report an interesting case of meningitis caused by Listeria monocytogenes in an immunocompetent adult. PATIENT AND METHODS: A previously healthy 25-year-old man presented with typical clinical features of meningitis. Cerebrospinal fluid (CSF) was obtained on the day of admission for biochemical and microbiological investigations. In addition, blood was also taken for culture and hematological studies. Antibiotic susceptibility test was performed using the Etest method. Microscopic examination of the CSF showed pleocytosis, which was predominantly lymphocytic, while the biochemical investigation revealed raised concentrations of protein and lactic acid as well as decreased glucose concentration. A 24-hour culture yielded pure growth of gram-positive bacilli identified by standard methods as L. monocytogenes. It was susceptible to ampicillin and trimethoprim-sulfamethoxazole. The patient was treated with intravenous ampicillin combined with gentamicin and made a complete recovery. CONCLUSION: This presentation describes an unusual case of meningitis caused by L. monocytogenes in a previously healthy young adult with no risk factor. Only a few similar cases have been reported in the literature.

Comparative in vitro activity of PH-027 versus linezolid and other anti-anaerobic antimicrobials against clinical isolates of Clostridium difficile and other anaerobic bacteria.

PH-027 is a new 5-triazole oxazolidinone synthesized in our laboratories, which shows strong activity against gram-positive aerobic bacteria including clinical isolates. The objective of this study was to investigate the in vitro activity of this compound in comparison with linezolid and other antibiotics against gram-positive and gram-negative anaerobes. The in vitro activity of PH-027 in comparison with those of linezolid and other antimicrobial agents was evaluated against 201 clinical isolates of gram-positive and gram-negative anaerobic bacteria by agar dilution and Etest methods. PH-027 showed excellent activity, with minimum inhibitory concentrations (MIC) in the range of 0.12-4.0 microg/ml against all isolates; MIC90s being 4.0, 1.0, 2.0, 2.0 and 2.0 microg/ml against Clostridium difficile, Peptostreptococcus spp., Bacteroides fragilis, Prevotella bivia and Fusobacterium spp. respectively. In comparison, linezolid had MIC in the range of 0.5-4.0 microg/ml against all isolates, with MIC90s of 2.0, 4.0, 4.0, 4.0 and 2.0 microg/ml against the same set of bacteria respectively. PH-027 demonstrated excellent in vitro activity that is superior to linezolid against Peptostreptococcus spp., B. fragilis and P. bivia. However, against C. difficile and Fusobacterium spp, PH-027 and linezolid showed comparable in vitro activity. Against all anaerobes, metronidazole, PH-027 and, to a lesser extent, linezolid had the most potent activity. From the results of in vitro susceptibility testing, both linezolid and PH-027 show promise in the treatment of anaerobic infections.

Hospital-acquired Clostridium difficile infection amongst ICU and burn patients in Kuwait.

OBJECTIVES: To prospectively study the prevalence of nosocomially acquired Clostridium difficile, a major cause of diarrhoea in hospitalized patients, in the intensive care units (ICUs) and burn unit (BUs) of three teaching hospitals in Kuwait. METHODS: During a 1-year prospective study, stool/rectal swabs were obtained from 344 patients admitted into the ICUs of Mubarak Hospital (ICU-1), the Kuwait Cancer Control Centre (ICU-2), and the BU of Ibn Sina Hospital. The presence of C. difficile and/or its toxin was detected by serially culturing the specimens on differential, selective and enriched media and the use of TOX-A/B test, on admission and at subsequent 1-weekly interval until discharge. RESULTS: Out of the 344 patients admitted into these units, over a study period of 1 year, only 263 (77%) were evaluable. All of them had negative stool culture/toxin on admission. Overall, 25 (9.5%) of these 263 patients acquired C. difficile during their hospitalization. Thirteen (7%) of 187 patients acquired C. difficile in ICU-1, 9 (36%) of 25 on ICU-2 and 3 (5.9%) of 51 patients in BU. Eight (32%) developed diarrhoea attributable only to C. difficile and/or toxin, and the remaining 17 (68%) were asymptomatic: none had pseudomembranous colitis. The diarrhoea in these patients was associated with antibiotic use, the main trigger-antibiotics being the third-generation cephalosporins. Acquisition occurred within 4-53 days of admission, with the majority occurring in the first 15 days. CONCLUSION: Overall, the prevalence of hospital-acquired C. difficile infection/colonization was less than 10%. The use of third-generation cephalosporins was high and was related to the development of diarrhoea. Once acquired, diarrhoea developed in about one third of C. difficile-positive cases, an indication that C. difficile infection/colonization endemic in the hospital ICUs studied is usually transmitted among the hospitalized patients.

An analysis of hospital-acquired bacteraemia in intensive care unit patients in a university hospital in Kuwait.

An analysis of hospital-acquired bacteraemia among ICU patients was carried out over a two-year period in order to determine the incidence, associated mortality rate and susceptibility pattern of causative pathogens. There was a high incidence of bacteraemia, occurring in 127 (18.4%) of 692 patients. Mortality attributable to nosocomial bacteraemia was 52% of the total 79 deaths from all causes. The highest mortality rate (58.5%) occurred in patients with fungal infections, whilst death from Gram-negative bacteraemia was only 17%. Over 98% of patients had underlying disease. Nearly half (46.8%) of 267 organisms isolated were Gram-positive. In comparison, Gram-negative bacteria accounted for 36.6% and the rest (17.6%) were fungi (mainly Candida albicans). The majority of the bactereamic episodes were monomicrobial (90.2%). Coagulase-negative staphylococci (CNS) were the commonest pathogens isolated, representing 32.6% of all organisms. Inducible beta-lactamase producing organism (Enterobacter spp. 9.7%, Serratia marcescens 6.7%, Klebsiella pneumoniae 6% and Pseudomonas aeruginosa 6%) formed the bulk of Gram-negative bacteria. In contrast, Escherichia coli (7.5%) and K. pneumoniae (4%) were the commonest Gram-negative bacteria from hospital-acquired bacteraemia in the general hospital population. The majority (80%) of CNS were resistant to methicillin (MRSE) but susceptible to vancomycin; they were relatively resistant to erythromycin, clindamycin and beta-lactams antibiotics. Whilst Gram-negative organisms were relatively susceptible to imipenem (85%), ciprofloxacin (88%) and amikacin (87%), they had unacceptably low levels of susceptibility to cefuroxime (59.3%), cefotaxime (71%), ceftazidime (60.9%), and piperacillin (51.1%). This study shows that hospital-acquired bacteraemia in ICU patients carries a poor prognosis. Information regarding the infective agents and their susceptibility in the ICU setting is valuable for the selection of empirical therapy before culture and susceptibility results are known.

Causative bacteria of respiratory tract infections in Kuwait by quantitative culture of sputum.

To determine the bacterial etiology of lower respiratory tract infections in Kuwait, we performed quantitative culture of sputum and measured the susceptibilities of the isolated bacteria against different antibiotics. A total of 140 sputum samples were collected for a period of 14 months for the study. Single and multiple pathogens as a cause of infection were isolated from 55 and 15 samples, respectively. A total of 53.8% of Streptococcus pneumoniae were penicillin-resistant and 52% and 57% of Hemophilus influenzae and Moraxella catarrhalis were beta-lactamase positive, respectively. We concluded that the major pathogens of respiratory tract infections in Kuwait were H. influenzae, M. catarrhalis, S. pneumoniae, and Pseudomonas aeruginosa, and there was an increased resistance among the isolated bacteria against commonly used antibiotics.

Susceptibility of 497 clinical isolates of gram-negative anaerobes to trovafloxacin and eight other antibiotics.

Trovafloxacin is a novel investigational trifluoronaphthyridone antibiotic with broad-spectrum activity against Gram-positive and Gram-negative organisms. Its in-vitro activity and those of eight other antimicrobial agents were evaluated against 497 clinical isolates of Gram-negative anaerobic bacteria by the agar dilution method. Trovafloxacin had excellent activity, with a minimum inhibitory concentration (MIC) range of <0.03-4 microg/ml, against all species. Out of the 497 isolates tested, 496 (99.5%) were inhibited by a concentration of < or = 2.0 microg/ml of trovafloxacin; the remaining two strains were inhibited by a concentration of 4.0 microg/ml. The MIC50s and MIC90s were 0.12 microg/ml and 1.0 microg/ml, respectively. Meropenem, imipenem and piperacillin/tazobactam were also very active. Overall, at the MIC90s, trovafloxacin was as active as meropenem, slightly more active than metronidazole and imipenem, twice as active as amoxicillin-clavulanic acid, five times more active than piperacillintazobactam and 68 times more active than clindamycin. About 21% of the isolates were resistant to cefoxitin, 30% to clindamycin and 40% to piperacillin. Five species in the Bacteroides fragilis group of isolates were highly resistant to metronidazole (MIC >128 microg/ml). In general, the relatively more resistant species were the B. vulgatus, B. ovatus, B. thetaiotaomicron, and B. fragilis sensu stricto, in that order. All the isolates of the B. fragilis group and about 50% of the Prevotella spp. were beta-lactamase positive. Trovafloxacin certainly holds promise as an alternative drug for therapy of anaerobic infections.

Prevalence and susceptibility of Shigella species to 11 antibiotics in a Kuwait teaching hospital.

During the 5-year period 1990-1993 and 1996, 202 Shigella spp. were isolated from stool specimens of symptomatic patients of all age groups seen in our hospital. Over these periods the trend of the incidence of shigellosis showed that 18% of the total strains were isolated during the invasion year (1990) followed by an upsurge (24%) during the Gulf War period (1991) and a steady decline in the post-war period, 17% in 1992 and 14% in 1993. There was another wave of increased isolation rate (27%) during a period of relative calm in the country (1996) studied for comparison. The predominant Shigella species was S. flexneri which accounted for 46% of the 202 isolates, followed by S. sonnei (42%), S. dysenteriae (7%) and S. boydii (5%). Fifty-four percent of the 202 Shigella isolates were resistant to ampicillin, 56% to trimethoprim/sulfamethoxazole, 35% to chloramphenicol, 13% and 9% to cephalothin and amoxicillin/clavulanic acid respectively. All the isolates were fully susceptible to ciprofloxacin, the aminoglycosides and the second- and third-generation cephalosporins. Eighty-seven (43%) of the 202 isolates were resistant to two or more antibiotics. Of the 87 multiply resistant Shigella spp., 58 (67%) were S. flexneri while 19 (22%) were S. sonnei. Shigella resistance to the first-line antibiotics is a major problem that frequently limits the therapeutic options with orally available active antibiotic therapy.

Serogroups and antimicrobial susceptibility of clinical isolates of Salmonella species from a teaching hospital in Kuwait.

Salmonella strains isolated in a teaching-cum-general hospital in Kuwait during 1990-1993 and 1996 were analysed to determine the trend in the prevalence of the serogroups and their changing pattern of susceptibility. The records were reviewed for all the 661 isolates encountered during these periods. The most prevalent serogroup in both children and adults was serogroup B, followed by serogroup C and D. A sizeable proportion of the strains were resistant to first-line drugs. About 39% of the isolates were resistant to ampicillin, 17% to co-trimoxazole, 13% to chloramphenicol, and 15% to cephalothin. The majority were, however, susceptible to the other drugs with low to very low resistance rates: 7% to amoxicillin/clavulanic acid, and 0.3% to cefotaxime. All the strains were susceptible to ciprofloxacin. In all, resistant strains were more prevalent among children than adults.