International links between Streptococcus pneumoniae vaccine serotype 4 sequence type (ST) 801 in Northern European shipyard outbreaks of invasive pneumococcal disease.

BACKGROUND: Pneumococcal disease outbreaks of vaccine preventable serotype 4 sequence type (ST)801 in shipyards have been reported in several countries. We aimed to use genomics to establish any international links between them. METHODS: Sequence data from ST801-related outbreak isolates from Norway (n = 17), Finland (n = 11) and Northern Ireland (n = 2) were combined with invasive pneumococcal disease surveillance from the respective countries, and ST801-related genomes from an international collection (n = 41 of > 40,000), totalling 106 genomes. Raw data were mapped and recombination excluded before phylogenetic dating. RESULTS: Outbreak isolates were relatively diverse, with up to 100 SNPs (single nucleotide polymorphisms) and a common ancestor estimated around the year 2000. However, 19 Norwegian and Finnish isolates were nearly indistinguishable (0-2 SNPs) with the common ancestor dated around 2017. CONCLUSION: The total diversity of ST801 within the outbreaks could not be explained by recent transmission alone, suggesting that harsh environmental and associated living conditions reported in the shipyards may facilitate invasion of colonising pneumococci. However, near identical strains in the Norwegian and Finnish outbreaks does suggest that transmission between international shipyards also contributed to those outbreaks. This indicates the need for improved preventative measures in this working population including pneumococcal vaccination.

Rifampin resistance in carbapenem-resistant Acinetobacter baumannii in Siriraj Hospital, Thailand.

There is a growing evidence on emergence of carbapenem-resistant Acinetobacter baumannii (CRAB) in Thailand and recent treatment guidelines recommend a combination therapy using carbapenem and/or polymyxin with rifampin. Rifampin would be added in a combination therapy. The susceptibility of this pathogen to rifampin is not known, so we studied the rifampin susceptibility and possible mechanisms of resistance used by CRAB. The disk diffusion test was performed on 111 clinical isolates using 5 microg rifampin disk following CLSI guidelines. The inhibition zone was interpreted based upon the recommendation for Staphylococcus aureus (inhibition zone < 20 mm = resistant). Polymerase chain reaction (PCR) using the primers specific for arr-2 encoding rifampin ADP-ribosyltransferase was performed in all isolates. The rpoB DNA sequences from two isolates, with or without arr-2, were compared. All isolates under study were rifampin resistant. Inhibition zone was < 14 mm for all isolates. The arr-2 was positive for 35 isolates (31.5%) and these isolates correlated with high level of resistance (inhibition zone < 10mm). The DNA sequences of rpoB genes in arr-2 negative isolate showed mutations L904S, P906R, K909N and M1262K that might have roles in rifampin resistance. Mutations of rpoB genes in some isolates and possession of arr-2 in class 1 integron element were mechanisms for rifampin resistance and these resistant determinants can disseminate through both vertical and horizontal gene transfer. Under this circumstance, it is not recommended to use rifampin in the treatment of carbapenem-resistant A. baumannii in Thailand.

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.