Evaluation of susceptibility status of invasive pneumococcal isolates to various antibiotics and risk factors associated with invasive penicillin-nonsusceptible pneumococcal infection: Bangkok 1997-1998.

The antibiotic susceptibility pattern of Streptococcus pneumoniae isolated from specimens of invasive infections was examined at Siriraj Hospital, a tertiary care center in Bangkok, during December 1996 April 1998. The percentage of S. pneumoniae isolates intermediate and resistant to various antibiotics were: penicillin, 25% and 21%; amoxicillin-clavulanate, 24% and 0%; cefuroxime, 6% and 36%; cefotaxime, 6% and 1.4%; ceftibuten, 5% and 42%; imipenem 22% and 0%; co-trimoxazole, 6% and 41%; chloramphenicol, 2% and 26%; erythromycin, 12% and 16%; azithromycin, 0% and 30%; and roxithromycin 0% and 33%. Most of the penicillin-nonsusceptible S. pneumoniae (PNSP) were also nonsusceptible to other antibiotics except cefotaxime, and imipenem. The isolates from respiratory specimens have a higher rate of resistance to all antimicrobial agents with a significant rise in MIC50 of beta-lactam antibiotics. There was no difference in the outcome of infections caused by penicillin-susceptible and -nonsuscetible S. pneumoniae. The only identifiable risk factor associated with PNSP infection was prior use of antibiotic within 3 weeks.

Comparison of BACTEC automated blood culture system and conventional system in hospitalized pediatric patients.

A prospective study in pediatric patients compared the BACTEC system, an automated blood culture system using Bactec Ped Plus/F broth media, with the conventional system using Brain Heart Infusion broth media. Each single blood sample drawn for culture from hospitalized children was evaluated by both systems simultaneously. Of 244 pairs of blood samples, 44 (18%) were positive for microorganisms. Of these isolates, 24 (55%) were detected by both systems, 10 (23%) were detected by the BACTEC system only, and 10 (23%) were detected by the conventional system only. The mean turn around time of the BACTEC system (0.56 +/- 0.34, range 0.08-1.55 days) was significantly shorter than that of the conventional system (3.36 +/- 2.72, range 1-7 days, p < 0.001). Seven isolates strongly suspected to be due to contaminants grew out after 5 days of incubation and were detected by the conventional system only. In this study the BACTEC system and the conventional system were equally effective in detecting microorganisms in the patients' blood samples even if antibiotic therapy had been previously administered. However, the results from the BACTEC system were available much sooner and less likely to be contaminants.

Bacterial pathogens (non-Mycobacterium) from sputum culture and antimicrobial susceptibility.

Sputum culture of patients at Siriraj Hospital, Bangkok was 49.84% positive for bacterial pathogens in 1994 and 40.95% in 1995. The average incidence of gram-negative rods was 3.11 fold more than the combination of gram-positive cocci and gram-negative cocci. The most common gram-negative rod was Pseudomonas aeruginosa, followed by either Klebsiella pneumoniae or Acinetobacter anitratus depending on year. The most common coccus was Staphylococcus aureus. From both years, the number of Haemophilus influenzae, Streptococcus pneumoniae, Burkholderia pseudomallei and Nocardia spp isolated were 122, 93, 13 and 11 strains respectively. For antimicrobial susceptibility, P. aeruginosa was sensitive to ceftazidime, imipenem, gentamicin, amikacin, netilmicin, ciprofloxacin (range 56-89%). S. aureus (MSSA) was sensitive to common used drugs. S. aureus (MRSA) was sensitive to co-trimoxazole, fosfomycin, vancomycin (range 57-100%) and resistant to most drugs.

Streptococcus suis toxic-shock syndrome and meningitis.

Three cases with S. suis bacteremia and meningitis were reported. The first case was a 23-year-old butcher who was a regular drinker of alcohol for two years and developed streptococcal toxic-shock syndrome. The organism was transmitted to him through a minor cut in his right arm. The second cases was a 49-year-old female laborer who had been consuming locally produced alcohol for 20 years and developed fever and meningitis. Unfortunately, she succumbed in seven days despite intensive supportive and cefotaxime treatments. The third case was a 45-year-old regular alcoholic drinker and car painter who was seen at a private hospital due to contusion at his left lateral chest wall. However, fever and confusion due to meningitis was detected upon admission. Irreversible deafness developed within 48 hours of ceftriaxone therapy for meningitis. He finally recovered with deafness. S. suis was isolated from blood and cerebrospinal fluid cultures in all three cases though initially reported to be viridans group of streptococci.

Serogroup distribution and antimicrobial susceptibility of beta-hemolytic streptococci in clinical isolates.

Three hundred and four strains of beta-hemolytic streptococci were isolated from different patients at Siriraj Hospital during 1989-1990. Among these strains, 24.01% were group A, 23.03% were group B, 2.96% were group C, 29.61% were group D, 0.66% were group F, 6.25% were group G and 13.48% could not be grouped by using the Lancefield reference method. The distribution of each serogroup according to the types of clinical specimens was also studied. From pus, group A Streptococcus (44.8%) was the most frequent isolate. From vagina/cervix/urethra specimens, group B Streptococcus (47.95%) was the most frequent isolate. From urine, group D Streptococcus (82.5%) was the most frequent isolate. From blood, group B Streptococcus (43.33%) was the most frequent isolate. From throat/sputum specimens, only group A Streptococcus was isolated. There were some differences in susceptibility to 19 antimicrobial agents among various groups of streptococci. Resistance to penicillin was not found in groups A, B, C, F and G streptococci except for group D (91.1% resistance for enterococci and 33.3% resistance for non-enterococci) and nongroupable streptococci (12.2% resistance).

Epidemiological study of Pseudomonas aeruginosa isolated from clinical specimens.

The epidemiology of Pseudomonas aeruginosa infection was studied in Siriraj Hospital. During April 1989-June 1990, P. aeruginosa 436 strains were isolated from clinical specimens of 260 patients, ie blood (19 strains), pus (192 strains), sputum (159 strains) and urine (66 strains). By using a combination of serogroups and pyocin types as epidemiological markers, it was found that there were 10 serogroups and 8 pyocin types which can be differentiated into 33 serogroup/pyocin types or patterns. The most common pattern was E 211111 (26.3%) followed by B 121614 (24.5%), G 373112 (13%) and L 888888 (7.1%), respectively.