A reader asked if Streptococcus was known to be associated with any psychiatric disorders. My immediate response is YES, Dr Philippe Bottero had an reported remission rate of over 75% in treating patients at a psychiatric hospital with antibiotics back in the late 1990’s. His success with a non-conventional approach resulted in his ability to practise being severely restricted by the establishment (according to private information) – Report is here on treatment.
Jump ahead a few decades and what do we find on PubMed?
- Detection of anti-streptococcal, antienolase, and anti-neural antibodies in subjects with early-onsetpsychiatric disorders.
- “Infection with group A Streptococcus (StrepA) can cause post-infectious sequelae, including a spectrum of childhood-onset obsessive-compulsive (OCD) and tic disorders with autoimmune origin (PANDAS, Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infections)…The simultaneous detection of all three of these antibodies could provide valuable information for the etiologic diagnosis of individuals with early-onset obsessive-compulsive disorders associated with streptococcal infection and, consequently, for prescribing suitable therapy.
- Detecting pediatric autoimmune neuropsychiatric disorders associated with streptococcus in children with obsessive-compulsive disorder and tics. 
- Neurocognitive functioning in youth with pediatric autoimmune neuropsychiatric disorders associated with streptococcus. 
- Pediatric autoimmune neuropsychiatric disorders associated with Streptococcus in identical siblings. 
- Association between streptococcal infection and obsessive-compulsive disorder, Tourette’s syndrome, and tic disorder. 
And for other bacteria:
- Psychiatric symptoms in patients with Shiga toxin-producing E. coli O104:H4 induced haemolytic-uraemic syndrome.
- Clinical and neuropsychological characteristics of general paresis misdiagnosed as primarypsychiatric disease.  – “Our findings reinforce the importance of performing serologic testing for syphilis. This should be a part of the evaluation of patients with psychiatric disorders, especially patients with cognitive impairment. “
- Bacterial neuroactive compounds produced by psychobiotics.
- [A psychiatric disorder reveals a neurobrucellosis]. 2016
- Possible association of Bifidobacterium and Lactobacillus in the gut microbiota of patients with major depressive disorder.  “Our results provide direct evidence, for the first time, that individuals with lower Bifidobacterium and/or Lactobacillus counts are more common in patients with major depressive disorder compared to controls.”
The presence or absence of some bacteria can cause psychiatric effects. This is not restricted to Streptococcus.