Antibiotic management of acute pharyngitis in primary care

The Centre for Health Protection of the Department of Health has convened the Advisory Group on Antibiotic Stewardship Programme in Primary Care (the Advisory Group) to formulate guidance notes and strategies for optimising judicious use of antibiotics and enhancing the Antibiotic Stewardship Programme in Primary Care. Acute pharyngitis is one of the most common conditions among out-patients in primary care in Hong Kong. Practical recommendations on the diagnosis and antibiotic treatment of acute streptococcal pharyngitis are made by the Advisory Group based on the best available clinical evidence, local prevalence of pathogens and associated antibiotic susceptibility profiles, and common local practice.

Tsukamurella serpentis sp. nov., isolated from the oral cavity of Chinese cobras (Naja atra)

Two bacterial strains, HKU54T and HKU55, were isolated from the oral cavity of two Chinese cobras (Naja atra) in Hong Kong. 16S rRNA gene sequence analysis revealed 100 % sequence identity between HKU54T and HKU55, and the two strains shared 99.0 % sequence identities with Tsukamurella inchonensis ATCC 700082T. The two strains had unique biochemical profiles distinguishable from closely related species of the genus Tsukamurella. DNA-DNA hybridization confirmed that they belonged to the same species (≥92.1±7.9 % DNA-DNA relatedness) but were distinct from all other known species of the genus Tsukamurella (≤52.6±5.3 % DNA-DNA relatedness). Chemotaxonomic and morphological analyses of the two strains also demonstrated results consistent with their classification in the genus Tsukamurella. The DNA G+C contents of strains HKU54T and HKU55 were 69.2±1.5 mol% and 69.2±1.3 mol% (mean±sd; n=3) respectively. A novel species, Tsukamurella serpentis sp. nov., is proposed to accommodate strains HKU54T and HKU55, with HKU54T (=JCM 31017T=DSM 100915T) designated as the type strain.

Resequencing microarray for detection of human adenoviruses in patients with conjunctivitis

Background

Although high-density resequencing microarray is useful for detection and tracking the evolution of viruses associated with respiratory tract infections, no report on using this technology for the detection of viruses in patients with conjunctivitis is available.

Objectives

To test if high-density resequencing microarray can be applied to detection of viruses in conjunctival swabs for patients with conjunctivitis.

Study design

In this prospective proof-of-concept study, every 4 or 5 bacterial culture-negative conjunctival swab samples were pooled and subject to viral detection using TessArray™ Resequencing Pathogen Microarrays-Flu 3.1 (RPM-Flu-3.1). Results were compared with human adenovirus (HAdV) hexon gene PCR sequencing and viral culture.

Results

Thirty-two of the 38 conjunctival swab samples were bacterial culture-negative. Four of the 7 pooled samples were positive for HAdV using RPM-Flu-3.1. Hexon gene PCR sequencing on the 38 original individual samples showed that 3 and 4 samples contained HAdVs species D and B respectively. All the 6 samples that were positive for hexon gene PCR but negative for bacterial culture were also positive by the resequencing microarray. Viral culture was positive for HAdV type 3 in 1 sample, which was also positive by PCR and resequencing microarray.

Conclusions

Resequencing microarray is as sensitive as PCR for detection of HAdV in conjunctival swabs. Unlike viral culture and hexon gene PCR sequencing, resequencing microarray was not able to differentiate the type and species of HAdV. Development of microarrays for conjunctivitis can be performed for rapid diagnosis of the viral cause of conjunctivitis.

Oral bacterial flora of the Chinese cobra (Naja atra) and bamboo pit viper (Trimeresurus albolabris) in Hong Kong SAR, China

OBJECTIVE

To determine the oral bacterial flora associated with two common local venomous snakes in Hong Kong, namely the Chinese cobra (Naja atra) and the bamboo pit viper (Trimeresurus albolabris).

DESIGN

Cross-sectional study.

SETTING

A non-government organisation and a regional hospital in Hong Kong.

SUBJECTS

Thirty-two Chinese cobras and seven bamboo pit vipers.

MAIN OUTCOME MEASURES

Species identification of bacteria in the oral cavity of both snakes and their antibiotic susceptibilities.

RESULTS

The oral cavity of Chinese cobra harbour a wide range of pathogenic bacteria, including: Gram-negative bacterial species like Morganella morganii, Aeromonas hydrophila and Proteus, and Gram-positive bacteria like Enterococcus faecalis, coagulase-negative Staphylococcus as well as anaerobic species (clostridia). The oral cavity of the Chinese cobra is more likely than that of the bamboo pit viper to harbour pathogenic bacteria associated with snakebite infection (P<0.001). The median number of pathogenic bacteria per snake was significantly higher in the Chinese cobra (P<0.001). All pathogenic Gram-negative bacteria isolated were susceptible to levofloxacin. Amoxicillin/clavulanate provided good coverage against pathogenic Gram-positive bacteria (Enterococcus faecalis) and anaerobes.

CONCLUSION

'Prophylactic' antibiotic treatment for Chinese cobra bites may be beneficial, owing to the multiple pathogenic bacteria in its oral cavity and the higher risk of ensuing necrosis. The regimen of levofloxacin plus amoxicillin/clavulanate appears promising for this purpose, but further study is required to confirm its clinical utility in patients.

Effect of antibiotics on the bacterial load of meticillin-resistant Staphylococcus aureus colonisation in anterior nares

Prevalence of hospital-acquired meticillin-resistant Staphylococcus aureus (MRSA) infection or colonisation has been associated with antimicrobial consumption. The impact of antibiotic treatment on nasal colonisation is unknown. We conducted a three-month prospective study of 116 patients with extranasal MRSA infection or colonisation, whose nasal MRSA bacterial loads were determined during and after various antibiotic courses over a period of three weeks. Environmental swabs were also taken from the near patient environment. Concomitant nasal MRSA carriage was observed in 76.7% of extranasal MRSA-colonised or -infected patients. The median nasal MRSA bacterial load increased significantly from 2.78 (range 0-6.15) to 5.30 (range 2.90-8.41) log(10) cfu per swab (cfu/swab) (P<0.001) over 21 days during beta-lactam therapy. It also increased from 0 (range 0-4.00) to 4.30 (range 0-7.46) log(10)cfu/swab (P=0.039) over 14 days during fluoroquinolone therapy. Median bacterial loads were significantly higher for beta-lactam- and fluoroquinolone-treated patients on day 7 [4.78, range 0-7.30], day 14 [4.30, range 0-7.60] and day 21 [5.30, range 2.90-8.41] than controls not receiving antibiotics (P<0.05). These loads then decreased by 2-5log(10)cfu/swab 2 weeks after discontinuation of antibiotics. The environment of patients receiving beta-lactam agents (relative risk: 3.55; 95% confidence interval: 1.30-9.62; P=0.018) or fluoroquinolones (4.32; 1.52-12.31; P=0.008) demonstrated more MRSA contamination than the environment around control patients (0.79; 0.67-0.93; P=0.002). Patients on beta-lactam or fluoroquinolone therapy have increased incidence of MRSA colonisation and higher nasal bacterial loads, and appear to spread their MRSA into the near patient environment.

Bacteremia caused by Solobacterium moorei in a patient with acute proctitis and carcinoma of the cervix

We describe a case of Solobacterium moorei bacteremia in a 43-year-old woman presenting with acute proctitis complicating radiotherapy for cervical carcinoma. Phenotypic tests failed to identify the bacterium, which was subsequently identified by 16S rRNA gene sequencing. 16S rRNA gene sequencing could help better define the pathogenicity of S. moorei.

Globicatella bacteraemia identified by 16S ribosomal RNA gene sequencing

BACKGROUND

Globicatella are streptococcus-like organisms that have been rarely isolated from clinical specimens. Their epidemiology and clinical significance remain largely unknown.

AIMS

To describe two cases of Globicatella bacteraemia identified by 16S ribosomal RNA (rRNA) gene sequencing.

METHODS

Two unidentified streptococcus-like bacteria isolated from blood cultures of patients were subject to 16S rRNA gene sequencing.

RESULTS

Two cases of Globicatella bacteraemia were identified by 16S rRNA gene sequencing. In the first case, a gram positive coccus was isolated from the blood culture of an 80 year old woman with diabetes mellitus and nosocomial sepsis, who died the day after developing the bacteraemia. The bacterium was unidentified by conventional phenotypic tests, the Vitek (gram positive identification) and the ATB expression (ID32 Strep) systems. In the second case, a similar bacterium was isolated from the blood culture of a 92 year old woman with polymicrobial acute pyelonephritis complicated by septic shock, who subsequently recovered after antibiotic treatment. 16S rRNA gene sequencing of the two isolates showed 0.5% nucleotide difference from that of G. sulfidifaciens and 0.7% nucleotide difference from that of G. sanguinis, indicating that they were Globicatella species.

CONCLUSIONS

Because Globicatella is rarely encountered in clinical microbiology laboratories, it may have been overlooked or misidentified in these cases. 16S rRNA gene sequencing is a useful tool to better characterise the epidemiology and clinical significance of Globicatella.

Usefulness of the MicroSeq 500 16S rDNA bacterial identification system for identification of anaerobic Gram positive bacilli isolated from blood cultures

Using full 16S ribosomal RNA (rRNA) gene sequencing as the gold standard, 20 non-duplicating anaerobic Gram positive bacilli isolated from blood cultures were analysed by the MicroSeq 500 16S rDNA bacterial identification system. The MicroSeq system successfully identified 13 of the 20 isolates. Four and three isolates were misidentified at the genus and species level, respectively. Although the MicroSeq 500 16S rDNA bacterial identification system is better than three commercially available identification systems also evaluated, its database needs to be expanded for accurate identification of anaerobic Gram positive bacilli.

A case of Streptococcus mitis endocarditis successfully treated by linezolid

We report the successful treatment of infective endocarditis caused by Streptococcus mitis with linezolid in a patient with pre-existing valvular heart disease. The patient had multiple allergies to conventional antibiotics. Linezolid may provide an oral alternative in the treatment of infective endocarditis in patients with adverse drug reactions to traditional antibiotic regimens.

Pulmonary artery thrombosis in a patient with severe acute respiratory syndrome

Severe acute respiratory syndrome (SARS) is an emerging infectious disease with both pulmonary and extra-pulmonary manifestations. Although coagulation abnormalities are common in these patients, clinically overt thromboembolic events are rarely reported. This report describes the first case of pulmonary artery thrombosis in a patient with laboratory confirmed SARS.

"Streptococcus milleri" endocarditis caused by Streptococcus anginosus

Unlike other viridans streptococci, members of the "Streptococcus milleri group" are often associated with abscess formation, but are only rare causes of infective endocarditis. Although it has been shown that almost all S. intermedius isolates and most S. constellatus isolates, but only 19% of S. anginosus isolates, were associated with abscess formation, no report has addressed the relative importance of the 3 species of the "S. milleri group" in infective endocarditis. During a 5-year period (April 1997 through March 2002), 6 cases of "S. milleri" endocarditis (out of 377 cases of infective endocarditis), that fulfil the Duke's criteria for the diagnosis of infective endocarditis, were encountered. All 6 "S. milleri" isolates were identified as S. anginosus by 16S ribosomal RNA (rRNA) gene sequencing. Three patients had underlying chronic rheumatic heart disease and 1 was an IV drug abuser. Five had monomicrobial bacteremia, and 1 had polymicrobial (S. anginosus, S. mitis, Granulicatella adiacens, and Slackia exigua) bacteremia. Two patients died. None of the 6 isolates were identified by the Vitek system (GPI) or the API system (20 STREP) at >95% confidence. All 6 isolates were sensitive to penicillin G (MIC 0.008-0.064 microg/mL), cefalothin, erythromycin, clindamycin, and vancomycin. Accurate identification to the species level, by 16S rRNA gene sequencing, in cases of bacteremia caused by members of the "S. milleri group", would have direct implication on the underlying disease process, hence guiding diagnosis and treatment. Infective endocarditis should be actively looked for in cases of monomicrobial S. anginosus bacteremia, especially if the organism is recovered in multiple blood cultures.

A case of oral myiasis due to Chrysomya bezziana

Chrysomya bezziana is a causative agent of obligatory myiasis. We report the first case of human infestation of Chrysomya bezziana in Hong Kong in an 89-year-old woman who had previously had a stroke. One day after hospital admission for fever, a small fissure at the labial gingiva of the upper incisors and several ulcerative lesions at the hard palate were noticed during routine mouth care. A live maggot was seen protruding from the small fissure. In the following few days, a total of seven maggots were removed by forceps. Urgent computed tomography and magnetic resonance imaging of the oral cavity showed an ulcerative soft-tissue lesion over the anterior palate, with a fistula communicating to the labial gingiva. The tissue loss was limited to the bony margin of the hard palate. The infestation was managed by manual removal of maggots and surgical debridement. Medical personnel taking care of old or debilitated patients need to bear in mind the possibility of Chrysomya bezziana infestation to be able to make a prompt diagnosis and implement relevant intervention to prevent extensive tissue destruction.

Usefulness of the MicroSeq 500 16S ribosomal DNA-based bacterial identification system for identification of clinically significant bacterial isolates with ambiguous biochemical profiles

Due to the inadequate automation in the amplification and sequencing procedures, the use of 16S rRNA gene sequence-based methods in clinical microbiology laboratories is largely limited to identification of strains that are difficult to identify by phenotypic methods. In this study, using conventional full-sequence 16S rRNA gene sequencing as the "gold standard," we evaluated the usefulness of the MicroSeq 500 16S ribosomal DNA (rDNA)-based bacterial identification system, which involves amplification and sequencing of the first 527-bp fragment of the 16S rRNA genes of bacterial strains and analysis of the sequences using the database of the system, for identification of clinically significant bacterial isolates with ambiguous biochemical profiles. Among 37 clinically significant bacterial strains that showed ambiguous biochemical profiles, representing 37 nonduplicating aerobic gram-positive and gram-negative, anaerobic, and Mycobacterium species, the MicroSeq 500 16S rDNA-based bacterial identification system was successful in identifying 30 (81.1%) of them. Five (13.5%) isolates were misidentified at the genus level (Granulicatella adiacens was misidentified as Abiotrophia defectiva, Helcococcus kunzii was misidentified as Clostridium hastiforme, Olsenella uli was misidentified as Atopobium rimae, Leptotrichia buccalis was misidentified as Fusobacterium mortiferum, and Bergeyella zoohelcum was misidentified as Rimerella anatipestifer), and two (5.4%) were misidentified at the species level (Actinomyces odontolyticus was misidentified as Actinomyces meyeri and Arcobacter cryaerophilus was misidentified as Arcobacter butzleri). When the same 527-bp DNA sequences of these seven isolates were compared to the known 16S rRNA gene sequences in the GenBank, five yielded the correct identity, with good discrimination between the best and second best match sequences, meaning that the reason for misidentification in these five isolates was due to a lack of the 16S rRNA gene sequences of these bacteria in the database of the MicroSeq 500 16S rDNA-based bacterial identification system. In conclusion, the MicroSeq 500 16S rDNA-based bacterial identification system is useful for identification of most clinically important bacterial strains with ambiguous biochemical profiles, but the database of the MicroSeq 500 16S rDNA-based bacterial identification system has to be expanded in order to encompass the rarely encountered bacterial species and achieve better accuracy in bacterial identification.