The pathological changes present in 300 red tilapias (Oreochromis spp.) naturally infected by Streptococcus agalactiae are described. The most consistent gross findings were marked congestion of internal organs, particularly the liver, spleen and kidneys. Other features included exophthalmos, softening of the brain and the occasional accumulation of fluid within the abdominal cavity. Microscopical examination confirmed the presence of marked congestion of the liver, spleen and kidneys. The endothelial cells lining major blood vessels of the liver and occasionally the spleen were swollen and vacuolated. There was evidence of vascular thrombosis with infarction of surrounding tissue. Bacterial colonies were noted within and immediately surrounding the affected blood vessels. The meninges were thickened by the infiltration of numerous heterophils. Similar infiltrates of heterophils and lymphocytes were observed in the lamina propria of the intestine. The kidneys were severely congested and haemorrhagic, with extensive interstitial nephritis.
This study determines the median lethal dose, and describes the clinico-pathological changes and disease development following Streptococcus agalactiae infection in Javanese medaka model. Javanese medakas were infected with S. agalactiae via intraperitoneal (IP) from 104 to 108 CFU/mL, and immersion (IM) route from 103 to 107 CFU/mL. The LD50-240h and clinico-pathological changes of the fish was determined until 240 h post infection (hpi). Next, the disease development was determined for 96 hpi in the fish following IP and IM infection at 103 CFU/mL and 104 CFU/mL, respectively. The LD50-240h of S. agalactiae in Javanese medaka was lower following IP injection (4.5 × 102 CFU/mL), compared to IM route (3.5 × 103 CFU/mL). The clinical signs included separating from the schooling group, swimming at the surface of water column, lethargy, erratic swimming pattern, corneal opacity and exophthalmia. Histopathological examinations revealed generalized congestion in almost all internal organs, particularly in liver and brain, while the kidney displayed tubular necrosis. Both IP and IM routes showed significant positive correlation (p
This study describes the susceptibility of different fish gender following acute Streptococcus agalactiae infection by using Javanese medaka Oryzias javanicus as test fish. The fish were grouped into four groups, which were: (1) all-male; (2) all-female; (3) mixed-gender (1 male: 1 female ratio); and (4) control non-infected (1 male: 1 female ratio). The fish in group 1, 2 and 3 were intraperitoneally exposed to 5.4 × 108 CFU/mL of S. agalactiae, while for group 4, the fish were exposed using sterile broth. The main clinical signs and histopathological changes of infected Javanese medaka were commonly observed in S. agalactiae infected fishes. However, no difference on clinical signs and histopathological changes of fish in group 1, 2 and 3 were noticed. The Javanese medaka mortality in group 1, 2 and 3 were observed from 4 h post infection (hpi) to 6 hpi, with the cumulative mortality from 3% to 30%. Then, the mortality increased at 12 hpi, with the range from 53% to 80%. However, 100% of the infected fish dead at 24 hpi. No clinical sign, histopathological change and fish mortality recorded in group 4. Generally, the clinical signs, mortality patterns, cumulative mortality and histopathological changes of Javanese medaka infected by S. agalactiae did not show any difference between the all-male, all-female and mixed-gender groups. This indicates that the susceptibility of fish to S. agalactiae infection is not influenced by their gender.
Streptococcal toxic shock syndrome is a serious health problem in developed and developing countries. We here report a case of severe protracted disease after a minor skin infection in a young traveler returning from West Malaysia which was caused by an unusual emm-type strain harboring speG and smeZ superantigen genes.
BACKGROUND/PURPOSE: The purpose of this study is to characterize GBS isolates that were collected from three major hospitals in a densely populated area of Klang Valley for their demographics, serotypes, antibiotic susceptibility patterns and genetic background.
METHODS: Sixty GBS isolates from sterile and non-sterile samples in three major hospitals in the Klang Valley area of Malaysia were collected by convenience sampling from 2012 until March 2014. These isolates were studied for their antimicrobial susceptibilities, serotypes and genotypes. Patients' demographic data and clinical information were collected from lab request forms.
RESULTS: Diabetes mellitus was the only underlying condition (7 patients, 23.3%); the remaining samples were from patients who were immunocompromised due to medications. Fifty-nine (98%) isolates were sensitive to penicillin, while 78.3% and 88.3% of the isolates were sensitive to erythromycin and clindamycin, respectively. Serotype Ia was the most common serotype (n=27, 45%), followed by serotype III (n=10, 16.7%), V (n=9, 15%), VI (n=8, 13.3%), VIII (n=2, 3.3%) and VII (n=1, 1.7%). Random Amplified Polymorphic DNA (RAPD) typing showed a diverse genetic pedigree for all isolates, including four major groups that clustered according to geographical location.
CONCLUSION: This preliminary study determines the prevalence of limited common serotypes and antimicrobial resistance in distinct GBS isolates. Nonetheless, the RAPD clustering pattern suggests a close genetic lineage of the GBS isolates based on their isolation sites and location of hospitals.
This study describes the isolation and pathogenicity of Streptococcus iniae in cultured red hybrid tilapia (Nile Tilapia Oreochromis niloticus × Mozambique Tilapia O. mossambicus) in Malaysia. The isolated gram-positive S. iniae appeared punctiform, transparently white, catalase and oxidase negative and produced complete β-hemolysis on blood agar, while a PCR assay resulted in the amplification of the 16 S rRNA gene and lactate oxidase encoded genes. The isolate was sensitive to tetracycline, vancomycin, and bacitracin but was resistant to streptomycin, ampicillin, penicillin, and erythromycin. Pathogenicity trials conducted in local red hybrid tilapia (mean ± SE = 20.00 ± 0.45 g) showed 90.0, 96.7, and 100.0% mortality within 14 d postinfection following intraperitoneal exposure to 104, 106, and 108 CFU/mL of the pathogen, respectively. The clinical signs included erratic swimming, lethargy, and inappetance at 6 h postinfection, while mortality was recorded at less than 24 h postinfection in all infected groups. The LD50-336 h of S. iniae against the red hybrid tilapia was 102 CFU/mL. The post mortem examinations revealed congested livers, kidneys, and spleens of the infected fish. This is the first report of S. iniae experimental infection in cultured red hybrid tilapia in Malaysia. Received January 20, 2017; accepted July 16, 2017.