Audit of Pseudomonas aeruginosa in a general hospital in Saudi Arabia.

All isolates of Pseudomonas aeruginosa in our laboratory from hospitalised patients were collected over a 4-month period in 1993/94. Details of the patients including length of stay, transfer from another hospital, nationality, diagnosis and antibacterial treatment were noted. Each patient was assessed as to whether the first isolate during the study period was of clinical significance and whether the infection or colonization was nosocomially acquired. The isolates of P. aeruginosa were identified and sensitivity was determined by recognized methods. Isolates were serotyped. 108 different patients were included in the study (median age 50 years, 58% males). 57/77 (74%) isolates where information was noted were nosocomial acquired. Length of patient stay for the nosocomial acquired isolates ranged from less than 1 day to more than 1 year. 19% of patients were transfers from other hospitals. Clinical significance was graded 31% isolates were judged to be highly significant and 44% to have little or no clinical significance. 41% isolates were from superficial sites including wounds, 27% from respiratory sites, 23% from urine and 6% were from blood cultures. Heavy growth of P. aeruginosa was correlated with clinical significance. Coliforms were the other organisms most frequently isolated with the P. aeruginosa but highly significant isolates were usually in pure culture. Serotypes 11, 2 and 4 were the dominant isolates. Serotype 11 was also the most common environmental isolate from the hospital. 60% patients were receiving antibacterial agents when the sample was taken but only 12% patients were receiving potentially anti-pseudomonal agents.

Methicillin resistant Staphylococcus aureus (MRSA) isolated in Saudi Arabia: epidemiology and antimicrobial resistance patterns.

Methicillin resistant Staphylococcus aureus (MRSA) comprised about 7.5% per annum of all S. aureus isolated in a general hospital in Jeddah, Saudi Arabia during the 3 year period 1990-1992. Most isolates were from wound sites (71%). Resistance to gentamicin (83%) and tetracycline (93%) was frequently observed whilst resistance to ciprofloxacin (1%) and rifampicin (6%) was uncommon. Low levels of mupirocin resistance (MIC 8 mg l-1), were detected in 3% of all MRSA isolates.

Otitis externa: clinical comparison of local ciprofloxacin versus local oxytetracycline, polymyxin B, hydrocortisone combination treatment.

Thirty patients with otitis externa were included in a prospective, randomized, parallel group comparison study. Treatment regimens used were ciprofloxacin (2 mg/ml) as ear drops twice daily or drops containing oxytetracycline (5 mg/ml) polymyxin B (10,000 units/ml) and hydrocortisone (15 mg/ml) twice daily for 7 days. Evaluation was by clinical signs and symptoms and bacteriological findings from ear swabs prior to and 3 and 8 days after start of therapy, together with long-term follow-up if necessary. Sixteen patients were included in the ciprofloxacin and 14 in the combined antibiotic group. Six of 16 and 7 of 14 initial swabs, respectively, contained Pseudomonas aeruginosa. Mixed Gram-negative and Gram-positive pathogens were found in 3 patients in the ciprofloxacin group. All Gram-negative isolates were sensitive to ciprofloxacin. Microbiological evaluation showed rapid eradication of all bacterial pathogens in the ciprofloxacin group with 1 persistence of Candida albicans but eradication of Staphylococcus aureus in the same ear with marked clinical improvement. There was 1 case of supercolonization in the ciprofloxacin group with Candida parapsilosis. In the combined antibiotic group, there were 7 persistencies of which 5 were P. aeruginosa. No adverse effects were noted in either group. Treatment was assessed as a complete success in 14/16 and 5/14 cases, partial success in 2/16 and 4/14 cases and unsuccessful or indeterminate in 0/16 and 5/14 cases, respectively. Ciprofloxacin thus appears to be a useful and effective agent in the local therapy of otitis externa.

Description and evaluation of a simple method for microbiological studies on otitis externa.

A simple cultural method for identification of the bacteria and yeasts likely to cause external otitis in divers is described. The method employs a commercial dip-slide system (Urotube) in which ear swabs are rolled onto the three agar surfaces, spread by a loop, and then incubated for a period of 18 h or more at 37 degrees C. The method was compared with traditional culture methodology on agar plates. Use of reference strains of bacteria and stored clinical isolates of bacteria and yeasts from ear infections showed stable patterns of growth for each species. Semiquantitative investigation of growth showed that there was a constant relationship between amount of growth on agar plates as compared to the dip-slide. Results were reproducible and were not affected by prolonged incubation. Directly inoculated swabs from normal ear canals and clinically infected ear canals showed identical findings by the traditional culture and Urotube methods. The Urotube method has also been evaluated in practical situations offshore with favorable experience. The Urotube method thus provides a rapid and simple way of identifying the causes of external otitis in divers in isolated areas where laboratory facilities are not readily available. This can have consequences for speed and choice of therapy in isolated environments.

Microbial aetiology of otitis externa.

Microbiological samples were collected from the ears of patients with otitis externa for a period of 1 year. Altogether, 226 evaluable samples from 104 males and 122 females were received. The age range of the patients was similar to that of the Norwegian population. A wide variety of bacteria and fungi was isolated. The commonest isolates, excluding normal flora, were Staphylococcus aureus (34.1%), Pseudomonas aeruginosa (22.1%) and Streptococcus pyogenes (8.8%); 9.3% samples contained fungi. Of all samples, 15% showed a mixture of Gram-positive and Gram-negative, potentially pathogenic, bacteria. Infection due to Gram-negative organisms alone was commoner in males, while the lack of any obvious microbial aetiology was more frequent in females. Isolation of S. aureus together with S. pyogenes was common but that of S. aureus together with S. pyogenes was common but that of S. aureus together with P. aeruginosa was unusual. In treated patients, the finding of streptococci and S. aureus was rare whereas that of P. aeruginosa or absence of growth was common. Otitis externa involving Gram-positive bacteria seems to be more prevalent in our area than in that of other reported studies.

The normal microbial flora of the outer ear canal in healthy Norwegian individuals.

The microbial flora of the outer ear canal was determined for 77 healthy individuals (M = 44, F = 33). No growth of any microbe was found in 5% of males and 15% of females. Coagulase-negative staphylococci, dominated by Staphylococcus epidermidis, were the commonest microbe group found (83% of persons sampled). Staphylococcus aureus was found in 7% males and no females. Diptheroids were cultured from 32% of the samples. The only Gram-negative rod found was Hafnia alvei in 4% of individuals. No Vibrio spp. or anaerobic Gram-negative organisms were found. A variety of yeasts and moulds were seen, significantly (p = 0.02) more often in males. In a separate experiment, Malassezia furfur was found in 4/9 males and 0/10 females sampled. Various sampling techniques (dry swab, second dry swab, moist swab) that were compared showed broadly similar results. The normal flora of the outer ear canal is predominantly Gram-positive and the use of a dry swab seems to be a satisfactory method for sample-taking from this area.

In vitro activities of A-56619 (difloxacin) and A-56620, two aryl fluoroquinolones.

The in vitro activities of A56619 (difloxacin) and A-56620, two newer quinolones, have been compared with the activities of ciprofloxacin, ofloxacin, ceftazidime and netilmicin. A total of 782 clinical, bacterial isolates were employed. Minimal inhibitory concentrations (MICs) were determined under standard conditions with all isolates and, for 100 isolates against difloxacin and A-56620, with variation of agar pH and bacterial inoculum size. On a weight-for-weight basis, ciprofloxacin and A-56620 were the most active agents against Enterobacteriaceae (MIC90 = 0.03 and 0.12 mg/l, respectively). Difloxacin was the least active quinolone, particularly against Proteus, Morganella and Providencia spp. Except for ceftazidime, all agents were highly active against staphylococci, but difloxacin and ofloxacin were somewhat less active against Staphylococcus saprophyticus. The streptococcal isolates were moderately sensitive to the quinolones, difloxacin being least active. Haemophilus influenzae and Neisseria gonorrhoeae were extremely susceptible to all the quinolones; nearly all isolates were inhibited by the lowest concentrations of the agents that were employed in the study (0.03 mg/l). The quinolones all showed moderate activity against Bacteroides fragilis. The activities of difloxacin and A-56620 were affected little by inoculum size. Difloxacin showed lower activity against most isolates at pH 8.0 as compared to the activity at pH 7.4 and 6.8. A-56620 was minimally influenced by pH variation.

The comparative in vitro activity of spiramycin and erythromycin against Norwegian bacterial isolates.

The in vitro activity of spiramycin and erythromycin has been determined by an agar diffusion method against relevant clinical isolates. Generally, erythromycin was more active than spiramycin on a weight-for-weight basis. Spiramycin showed only moderate activity against Haemophilus influenzae and Streptococcus pyogenes. Gonococci were sensitive in vitro to both agents. Many erythromycin-resistant staphylococci were sensitive to spiramycin.

Effects of carbon dioxide upon the in vitro activity of erythromycin.

The in vitro activity of erythromycin against clinical isolates of Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, Streptococcus pyogenes and Haemophilus influenzae was examined by agar dilution and agar diffusion methods. The plates were incubated in air alone or in 8% CO2 and air. The minimal inhibitory concentrations (MICs) measured in air alone were lower for most of the isolates, compared to those found in 8% CO2. The greatest differences in MIC values were found for H. influenzae; the MIC 50% was 0.5 mg/l in air and 4 mg/l in 8% CO2. Sensitivity testing by the agar diffusion method (ICS) showed considerable differences between results obtained in air and in 8% CO2; the inhibition zones were generally smaller in CO2. The most marked reduction in zone sizes after incubation in 8% CO2 was seen with the H. influenzae isolates; 15 out of 43 isolates moved from the "sensitive" to "moderately sensitive" group. Sensitivity determination of aerobic bacteria for erythromycin should be performed in air alone in the routine laboratory.

Coumermycin: in vitro activity against 251 clinical isolates of bacteria compared with the activities of eight other antibacterial agents.

The in vitro activity of coumermycin has been compared with those of ampicillin, clindamycin, cloxacillin, doxycycline, erythromycin, netilmicin, penicillin G and vancomycin. A total of 251 clinical isolates of Gram-positive cocci were examined. The minimal inhibitory concentration (MIC) was determined by an agar dilution method. Clindamycin, coumermycin and erythromycin were the most active drugs against Staphylococcus aureus and S. epidermidis on a weight-for-weight basis. All the staphylococcal isolates were inhibited by coumermycin at a concentration of 0.12 mg/l or less. Netilmicin seemed to be somewhat more active against S. epidermidis than against S. aureus. The MICs of vancomycin for the staphylococcal isolates were clustered around 1 mg/l. Streptococcus pneumoniae, S. pyogenes and S. agalactiae were highly susceptible to penicillin G and erythromycin; most isolates were inhibited by 0.03 mg/l or less of either drug. Coumermycin showed poor activity against S. pyogenes, S. agalactiae and enterococci. Most of the S. pneumoniae isolates had also high MICs, although a wide range of sensitivities was found.

In vitro efficacy of Otic Domeboro against Pseudomonas aeruginosa.

The in vitro activity of prophylactic ear drops (Otic Domeboro) which are widely used by saturation divers against external otitis has been assessed. Four strains of Pseudomonas aeruginosa, 1 reference strain and 3 clinical isolates from cases of external otitis were employed. Two of the clinical isolates were from saturation divers who were using Otic Domeboro. Otic Domeboro solution was bactericidal even when diluted 1:2 in serum or broth. There were no significant differences between strains. There was no measurable inoculum effect. Survival kinetic analysis showed 60% killing at 5 min and 99.9% killing at about 2 h. Otic Domeboro is an effective anti-P. aeruginosa agent. There was no evidence of increased resistance among strains isolated from divers. The rate of killing in relation to usual prophylactic recommendations suggests that frequent dripping may be more effective. The therapeutic use of Otic Domeboro in saturation diving should be evaluated to avoid unnecessary use of antibiotic drops.

In vitro activities of ciprofloxacin, ofloxacin, norfloxacin and rosoxacin compared with cinoxacin and trimethoprim.

The in vitro activities of ciprofloxacin, ofloxacin, norfloxacin, rosoxacin, cinoxacin and trimethoprim have been compared. An agar dilution method has been employed for the measurement of minimal inhibitory concentrations (MICs). 426 clinical, bacterial urinary isolates mainly from hospitalised patients were included; all common urinary tract pathogens were represented. The newer quinolones were highly active against Enterobacteriaceae species, Pseudomonas aeruginosa and Acinetobacter calcoaceticus. Ciprofloxacin was the most active agent against these organisms (MICs less than or equal to 2 mg/l). A few strains of Escherichia coli and Klebsiella were resistant to rosoxacin (MIC greater than or equal to 128 mg/l). Cinoxacin and trimethoprim were considerably less active against gram-negative strains. The new quinolones were also active against staphylococci of various species and enterococci (MICs less than or equal to 4 mg/l) except for rosoxacin for which 16 mg/l was needed to inhibit all gram-positive isolates. Cinoxacin was virtually inactive against this group whereas trimethoprim showed variable activity.

Ro 17-2301: in vitro comparison with aztreonam, imipenem, ceftazidime, cefotaxime and netilmicin.

The in vitro activity of the novel monobactam antibiotic, Ro 17-2301 has been compared with those of aztreonam, imipenem, ceftazidime, cefotaxime and netilmicin. A total of 438 clinical isolates of aerobic gram-negative rods were employed and an agar dilution method was used for measurement of MIC. Ro 17-2301 was highly active against a wide variety of Enterobacteriaceae species (MIC range less than or equal to 0.03-8, MIC50 less than or equal to 0.03, MIC90 0.06 mg/l). The activity of aztreonam parallelled that of Ro 17-2301 although the latter seemed to have more uniformly high activity against Klebsiella sp. The other agents showed generally high activity against Enterobacteriaceae except netilmicin against Providencia stuartii (MIC50 4, MIC90 greater than or equal to 16 mg/l). Activity against Pseudomonas aeruginosa. was more variable. Ro 17-2301 and aztreonam were moderately active (MIC50 2, MIC90 8 and 16 mg/l, respectively). Imipenem was the most active agent against Acinetobacter, whereas Ro 17-2301 was moderately active. In conclusion, Ro 17-2301 shows impressive activity against Enterobacteriaceae and moderate activity against Acinetobacter and P. aeruginosa. Ro 17-2301 may well prove to be a useful agent in the treatment of gram-negative infections.

Evaluation of Rosco diagnostic beta-glucuronidase tablets in the identification of urinary isolates of Escherichia coli.

Rosco diagnostic beta-glucuronidase tablets have been evaluated as a method for the identification of urinary isolates of Escherichia coli. Results were compared with those from traditional biochemical testing. A total of 539 isolates were employed, representing a variety of Gram-negative species. Reproducibility testing was also performed. After 4h incubation, 86% of E. coli isolates (both lactose-positive and lactose-negative) gave a positive reaction. Some Salmonella, many Shigella and one Citrobacter freundii isolate also gave positive reactions. All other organisms gave negative reactions. Results were highly reproducible and not influenced by choice of primary medium. The tablets are suitable for routine use in the diagnostic laboratory for the identification of lactose-positive E. coli. A suitable diagnostic table has been suggested.

Septicaemia in granulocytopenic patients caused by multiresistant diphtheroid rods. A study of two cases.

Two cases of septicaemia in granulocytopenic patients are reported. Both were caused by multiresistant aerobic (JK-group) diphtheroid rods. The bacterial isolates were resistant to all commonly used antibacterial agents but showed good sensitivity to vancomycin and rifampicin. These agents should be included in the routine sensitivity testing of such isolates and diphtheroids should always be reported by the routine laboratory for granulocytopenic patients.

Norfloxacin: in vitro activity compared with that of seven other antibacterial agents against urinary tract pathogens.

The minimal inhibitory concentrations (MICs) of norfloxacin, nalidixic acid, ampicillin, amoxycillin/clavulanic acid (4:1), mecillinam, cefaclor , sulphamethoxazole/trimethoprim (20:1) and netilmicin against 435 clinical isolates of bacterial urinary tract pathogens have been determined. An agar dilution method was employed. Norfloxacin was the most active agent in the study on a weight-for-weight basis. The drug was highly active against Enterobacteriaceae. Norfloxacin was more active than netilmicin against Pseudomonas aeruginosa (MICs less than or equal to 2 mg/l and less than or equal to 4 mg/l, respectively). Norfloxacin was also active against Gram-positive bacteria including enterococci and Staphylococcus saprophyticus (MICs less than or equal to 4 mg/l). Norfloxacin may well become a useful agent for the oral treatment of urinary tract infection, particularly as a drug for the treatment of infections caused by multiresistant organisms.

Ceftazidime: in vitro comparison with cephalothin, cefuroxime, and netilmicin. A Norwegian study.

The in vitro activity of ceftazidime has been compared with those of cephalothin, cefuroxime, and netilmicin against a variety of gram-positive and gram-negative bacteria in order to register sensitivity patterns in the western part of Norway. An agar dilution method was used for minimal inhibitory concentration (MIC) determination. Ceftazidime was the most active agent against Enterobacteriaceae; all isolates being inhibited by 2 mg/l or less, whereas netilmicin was slightly less active, especially against Providencia. Cephalothin and cefuroxime were markedly less active than the other two agents against Enterobacteriaceae. Ceftazidime and netilmicin were active against our Pseudomonas aeruginosa isolates (MICs less than or equal to 4 and less than or equal to 8 mg/l, respectively). Only netilmicin had useful activity against Acinetobacter calcoaceticus. Ceftazidime was the least active agent against Staphylococcus aureus; nearly all the isolates had MICs of 4-8 mg/l. Cefuroxime was the most active agent against Bacteroides fragilis, whereas ceftazidime was inactive. Ceftazidime may, in the future, be a useful alternative to the aminoglycosides in the treatment of serious gram-negative infections, particularly when P. aeruginosa might be involved.

Comparison of four methods for differentiation of Staphylococcus aureus from other Micrococcaceae in the routine laboratory.

Four methods for the identification of Staphylococcus aureus (tube coagulase test, thermostable nuclease test, indirect agglutination of fibrinogen coated erythrocytes and a commercial latex kit: SeroSTAT Staphylococcus Test) have been compared. Clinical isolates (698) and 40 reference strains of Micrococcaceae were included in the study together with control organisms. The coagulase test gave no false positive results but 39/406 clinical isolates of S. aureus were negative at 2h and one half were only weakly positive. At 18 h, all but 2 of 406 isolates gave a positive reaction. The thermostable nuclease test was very specific; no clinical isolates of S. aureus gave negative results and no "coagulase-negative" clinical isolates gave a definite positive reaction. The indirect haemagglutination method was sometimes difficult to interpret and frequently gave negative or doubtful results for S. aureus. The SeroSTAT test was easy to use and interpret and was specific; the method is suitable for routine laboratory use, particularly when a rapid result is desirable.

Evaluation of the Anaerobe-Tek system for the identification of Bacteroides and Fusobacterium species.

Reference strains and clinical isolates of Bacteroides and Fusobacterium species were examined by the Anaerobe-Tek System (A/T-system). Of 104 strain, only 57 (54.8%) were identified correctly to species level. 38 strains (36.5%) were incorrectly identified and for 9 strains (8.7%) there were no codes in the manufacturers' data base manual. The results indicate that, in our hands, the A/T-system in its present form, is not suitable for the identification of clinical isolates of Bacteroides and Fusobacterium species.