Diagnosis of orthopaedic-implant-associated infections caused by slow-growing Gram-positive anaerobed

 Slow-growing Gram-positive anaerobic bacteria (SGAB) such as Cutibacterium acnes are increasingly recognized as causative agents of implant-associated infections (IAIs) in orthopaedic surgeries. SGAB IAIs are difficult to diagnose because of their non-specific clinical and laboratory findings as well as the fastidious growth conditions required by these bacteria. A high degree of clinical suspicion and awareness of the various available diagnostic methods is therefore important. A review by Ponraj et al.  overviews the current knowledge regarding SGAB IAI, providing details about clinical features and available diagnostic methodologies. In recent years, new methods for the diagnosis of IAI were developed, but there is limited knowledge about their usefulness in SGAB IAI. The authors conclude that further studies are required to determine the ideal diagnostic methodology to identify these infections so that they are not overlooked and mistakenly classified as aseptic failure.

                                                   Cutibacterium acnes gram stain

Complications of Otitis Media and Sinusitis Caused by Streptococcus anginosus Group Organisms in Children.

McNeil et al. from Texas Children'sHospital studied 95 children seen between 2011 to 2018 with complications of otitis media and sinusitis caused by Streptococcus anginosus Group (SAG) organisms.  SAG are nonmotile facultative anaerobes that are part of the normal oral cavity, throat, stool, and vagina flora. Cases included were those with Pott's puffy tumor, orbital abscesses, mastoiditis, epidural abscesses, subdural empyema, brain parenchymal abscesses or dural enhancement by imaging.

Streptococcus intermedius was most commonly isolated (80%) followed by Streptococcus constellatus (12.6%) and Streptococcus anginosus (7.4%); 50.5% of cases were polymicrobial. Among polymicrobial cases, Staphylococcus aureus was most frequently isolated. All patients underwent surgical intervention and 8.4% had persistent neurologic deficits. Complications of otitis media and sinusitis caused by SAG are associated with substantial morbidity.

The researchers concluded that intraorbital and intracranial infections in general and SAG in particular are becoming increasingly common at their medical center.

Streptococcus anginosus (Gram stain)

Increased Antimicrobial Resistance against metronidazole and carbapenem in clinical anaerobic isolates from Pakistan.

Increased Antimicrobial Resistance against metronidazole and carbapenem in clinical anaerobic isolates from Pakistan was recently reported by reported by Shafquat and colleagues  from , Aga Khan University Hospital,in Karachi, Pakistan.

 Of the 223 clinically significant isolates collected between 2014 and 2017, 39 (17.5%) were metronidazole resistant. Imipenem resistance was determined in 29 metronidazole resistant isolates and of these 7 (24.1%) were found to be resistant. Proportion of metronidazole resistant strains was highest amongst Bacteroides species. A significant increase in metronidazole resistance from 12.3% in 2010-2011 to 17.5% in the current study was found. Carbapenem resistance also emerged in the period 2014-2017.

Isolates from malignancy and transplant patients showed lower odds of developing metronidazole resistance. Prolonged hospital stay was not associated with metronidazole resistance.

The worldwide rising trend of metronidazole resistance and emergence of carbapenem resistance in anaerobic bacteria is alarming. Continued surveillance with strengthening of laboratory capacity regarding anaerobic susceptibility testing is urgently needed.