Comparative in vitro activity of tigecycline and other antimicrobial agents against Shigella species from Kuwait and the United Arab of Emirates.

Shigella species isolated from stool samples of symptomatic patients of all age groups at the Mubarak Al Kabir Hospital and Infectious Diseases Hospital, Kuwait and Tawam Hospital, UAE during a 2-year period were investigated for their susceptibility to tigecycline and several other antibiotics by determining the minimum inhibitory concentrations (MICs) using the E test method. A total of 100 and 42 strains were collected from UAE and Kuwait, respectively. The extent of drug resistance in the Shigella spp. isolates from these two countries was analyzed by criteria recommended by the Clinical and Laboratory Standards Institute (CLSI). Amikacin, cefotaxime, cefuroxime, ciprofloxacin, imipenem, meropenem, piperacillin-tazobactam and tigecycline had excellent activities against all isolates from UAE and Kuwait with MIC(90s) of 12, 0.094, 4, 0.012, 0.25, 0.032, 3 and 0.25 microg/ml and 4, 1, 4, 0.125, 0.38, 0.19, 3 and 0.25 microg/ml, respectively. Half of all isolates from both countries were resistant to ampicillin. None of the isolates in Kuwait was resistant to amoxicillin-clavulanic acid compared with 22% in UAE. Resistance to chloramphenicol was recorded in 50 and 36% of the isolates in Kuwait and UAE, respectively. The percentages of non-susceptibility to trimethoprim-sulfamethoxazole and tetracycline were very high in Kuwait and UAE (76% vs. 92% and 76% vs. 98%, respectively). Notably, one isolate, S. flexneri, from UAE had reduced susceptibility to ciprofloxacin (MIC, 0.25 microg/ml). Four (2.8%) of the isolates were ESBL producers by the E test ESBL method but could not be confirmed by PCR using primers for bla(CTX-M), bla(SHV) and bla(TEM). In conclusion, Shigella spp. isolated from symptomatic patients in Kuwait and the UAE demonstrated high rates of resistance to the first-line antibiotics but very susceptible to the carbapenems, cephalosporins, fluoroquinolones and tigecycline. Tigecycline holds promise as a potential drug of choice for the therapy of severe shigellosis.

Role of tigecycline in the control of a carbapenem-resistant Acinetobacter baumannii outbreak in an intensive care unit.

The incidence of Acinetobacter baumannii infection has greatly increased over recent decades with infections occurring more in critically ill hospitalised patients. Hospital outbreaks of multiple antibiotic-resistant strains are posing an increasing threat to public health. Three different outbreaks of multidrug-resistant A. baumannii (MRAB) infections involving 24 patients, aged 16-75 years occurred in the intensive care unit in the course of one year. The isolates were cultured from clinical samples and identified using automated Vitek II ID system and the API 20NE system. Susceptibility testing was done by the E-test method. Molecular typing of the isolates was determined by pulsed-field electrophoresis. Screening of both patients and the environment was carried out. The acquisition time, i.e. the time of admission to time of acquiring infection, ranged from 3 to 31 days. All isolates were multiply resistant (MRAB), including resistance to carbapenems (MRAB-C) in the majority of cases but susceptible to tigecycline, with a minimum inhibitory concentration (MIC(90)) of 2 microg/mL. The overall mortality rate was 16.7%. Time-to-clearance of the MRAB-C was 8.3 days in the first outbreak, when tigecycline was not used, and 2.8 and 3.1 days during the second and third outbreaks, respectively, when tigecycline was used, and all but one patient survived. Environmental screening revealed gross contamination of many surfaces and equipment within the unit. The outbreak strains belonged to two distinct clones (D and E) whereas the 14 environmental strains belonged to three distinct groups (A-C). The outbreak of infections treated with tigecycline was successfully eliminated in conjunction with an aggressive infection control strategy.

Significance of antibiotics resistance amongst clinical bacterial isolates in Lagos.

In vitro susceptibility of several strains of six different species of clinical facultative pathogens involved in nosocomial infections in our hospital was investigated by a series of disc diffusion, broth dilution and Chequerboard titration testing. With disc diffusion method all the test strains, except Streptococcus pyogenes, were resistant to penicillin. 46% of the Klebsiella aerogenes and 73% of the Pseudomonas strains were generally resistant to cefotaxime. The minimum inhibitory concentration (MIC) of the antibiotics correlated well with the results of the disc diffusion tests. Synergistic effects were demonstrated by various combinations of gentamicin, ampicillin, clindamycin, colistin, cefoxitin, and ceftriazone against resistant strains of S. aureus, Pseudomonas aeruginosa, Escherichia coli and Klebsiella aerogenes. Against S. aureus the effect of gentamicin/clindamycin demonstrated indifference. The need for stringent caution is strongly advocated in the selection of combination therapy for serious infections caused by some hospital bacterial strains particularly in acute care units. The clinical microbiologist should be consulted at all times during the process of selection of an appropriate combined therapy for expert guidance.

Activities of Nigerian chewing stick extracts against Bacteroides gingivalis and Bacteroides melaninogenicus.

The in vitro activities of extracts of Nigerian chewing sticks against Bacteroides gingivalis and B. melaninogenicus are presented. The greatest inhibitory action was produced by Serindeia werneckei, whereas Fagara zanthoxyloides produced no appreciable inhibitory effect. A generally good correlation was found between the killing curves and MICs. Only extracts of Anogeissus leiocarpus showed acute toxicity in mice.

The effect of crude extracts of nine African chewing sticks on oral anaerobes.

Chewing sticks are widely used in Nigeria for dental and oral hygiene. In-vitro susceptibility tests were done with crude extracts from nine popular sticks on four species of Bacteroides. Serindeia warneckei chewing stick had the greatest and most consistent inhibitory effect on the four species; extracts from bark and pulp were bactericidal at concentrations of less than or equal to 1%. Extracts of other sticks, when inhibitory, were only so at higher concentrations--in the range 2-30%. All the black-pigmented oral anaerobes were very susceptible to eight of the nine chewing-stick extracts but non-pigmented anaerobes showed variable susceptibilities.