# Can medical technology ID sex abusers through shared bacteria? **URL:** \ **Category:** Factual Questions\ **Created:** [August 27, 2014, 2:06am UTC](https://boards.straightdope.com/t/can-medical-technology-id-sex-abusers-through-shared-bacteria/696607 "2014-08-27T02:06:23Z")\ **Posts on this page:** 17\ **Page:** 1
**Author:** ![CairoCarol](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cairocarol/32/3825_2.png) [@CairoCarol](https://boards.straightdope.com/u/CairoCarol)\ **Post date:** [August 27, 2014, 2:06am UTC](https://boards.straightdope.com/t/can-medical-technology-id-sex-abusers-through-shared-bacteria/696607/1 "2014-08-27T02:06:23Z")
There is a terrible case of alleged sexual abuse going on at my son’s school right now. Unfortunately, media reporting and surrounding gossip have been incomplete at best and wildly inaccurate at worst (I live in Jakarta, so American assumptions about police procedures and media ethics do not apply). The press has talked about “herpes bacteria” which is obviously incorrect since herpes is a virus. However, if one does one’s best to parse what the police seem to be saying, it is that bacteria in the victim’s anus match bacteria found on the genitals of one or more accused perpetrators. My questions: Is identifying shared bacteria an accepted method of legal/medical investigation into sex abuse? If yes, how difficult is it? For example, as a layperson I would not be surprised to hear that e.coli bacteria were found on both the victim and the alleged perp. However, e.coli is pretty common in everyone’s gut, isn’t it? But if you told me that gene sequencing had been done and the two strains were absolutely identical, I’d be easy to convince that this was evidence of something. Am I spouting nonsense, or am I on the right track? Is it plausible that the police in Indonesia would have access to the needed technology? How long would it take until results were available? Thank you in advance for any clarification - especially if you can give links to scientific studies/articles that provide information I could share with colleagues. ---
**Author:** ![Kent\_Clark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kent_clark/32/105_2.png) [@Kent\_Clark](https://boards.straightdope.com/u/Kent_Clark)\ **Post date:** [August 27, 2014, 2:58am UTC](https://boards.straightdope.com/t/can-medical-technology-id-sex-abusers-through-shared-bacteria/696607/2 "2014-08-27T02:58:41Z")
I sympathize with your plight and hope the prepetrators are rounded up and throwin in jail to rot. Everything I know about DNA I learned while preparing a business plan for a client, so this information is exactly worth what you’re paying for it. The TLDR answer is, theoretically possible but maybe not conclusive at this time. If a particular strain of DNA is in the world database, then it can be located and matched to the DNA found in the bacteria of person A and person B. If that particular strain isn’t in the database, or if the germ hasn’t been typed with enough unique markers (that is, enough different points to tell the difference between two strains of the same germ) you won’t know how rare or common the strain is. Most reasonably advanced countries have the equipment needed to do DNA sequencing. Depending on the test and the equipment, it can take anywhere from 1-24 hours to prepare a single sample. However, the equipment is limited in how many markers it can test for in a single pass. It might take only a few passes lasting a few minutes each to identify a bacterium as _E. coli,_ but take hundreds of passes to identify precisely which particular strain the bacterium is. Once you do that, you have to figure out how common the strain is, and make sure the entire city doesn’t share it just because it’s in the environment. Multiply that by all the various germs you get from each person, and you see the testing goes up exponentially. Now I know for a fact that sometimes the authorities can trace various types of food contamination back to a single farm or processing plant, but all they’re looking for is harmful vs. unharmful germs. Whether enough unique markers have been mapped to identify my \*E. coli \*vs. your _E. coli_, I don’t know. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [August 27, 2014, 4:24am UTC](https://boards.straightdope.com/t/can-medical-technology-id-sex-abusers-through-shared-bacteria/696607/3 "2014-08-27T04:24:08Z")
Even if the bacteria were a perfect match, it wouldn’t necessarily prove anything. All it takes is one single bacterium making it over somehow and growing into a colony, and you’ve got a match. This is of course easiest if there’s direct contact between the surfaces, but one can imagine other plausible ways that it could happen. ---
**Author:** ![si\_blakely](https://avatars.discourse-cdn.com/v4/letter/s/d9b06d/32.png) [@si\_blakely](https://boards.straightdope.com/u/si_blakely)\ **Post date:** [August 27, 2014, 4:49am UTC](https://boards.straightdope.com/t/can-medical-technology-id-sex-abusers-through-shared-bacteria/696607/4 "2014-08-27T04:49:15Z")
Certainly, chains of infection can be established via DNA genotyping to establish the source and mutation patterns of both bacterial and viral infections. The increasing availability of DNA sequencing equipment has made this a valuable tool for epidemiology (particularly when tracking new antibiotic resistant infections like tuberculosis and STDs). If they are actually talking about the herpes virus (reporters often seem pretty fuzzy on the difference between bacteria and viruses), then there are several factors to consider - the similarity of the viruses, the prevalence of that variant in the overall population, and likelyhood of the virus being in either location specified (penis, anus). If the statistics add up, it could well be considered indicative, if not conclusive beyond reasonable doubt. Herpes viruses do have preferred locations, but can infect (if not establish) in nonpreferential locations if suitable exposure occurs - so type 1 herpes (oral herpes) can infect genitals (usually home to type 2 herpes), but may not establish a recurrent infection. If the pattern of infection in this case is atypical, then it adds to the body of evidence. ---
**Author:** ![si\_blakely](https://avatars.discourse-cdn.com/v4/letter/s/d9b06d/32.png) [@si\_blakely](https://boards.straightdope.com/u/si_blakely)\ **Post date:** [August 27, 2014, 5:04am UTC](https://boards.straightdope.com/t/can-medical-technology-id-sex-abusers-through-shared-bacteria/696607/5 "2014-08-27T05:04:47Z")
For an example of how this works … Abstract only … > [@](#): > > [A large outbreak of conjunctivitis caused by a single genotype of Neisseria gonorrhoeae distinct from those causing genital tract infections - PubMed](http://www.ncbi.nlm.nih.gov/pubmed/11467794) > > Several epidemics of gonococcal conjunctivitis have occurred in Aboriginal populations in Central Australia. In 1997, the first outbreak in the Kimberley region of Western Australia occurred, spreading to Central Australia with a total of 447 cases. A genotyping method was applied directly to DNA extracted from patient samples to characterize the gonococcus causing the epidemic and to compare it with contemporaneous genital isolates. Those positive conjunctival specimens from Kimberley and Central Australia that could be genotyped were all indistinguishable, but were distinct from the genital gonococci, even when they shared the same auxotype and serotype. This suggested that the outbreak was due to a single genotype of Neisseria gonorrhoeae that had probably been carried between communities by infected individuals. We did not find evidence to support the existence of a genital reservoir of the types causing epidemic gonococcal conjunctivitis. Also, oral bacteria DNA has potntial to be used to link a bite mark (which may be indistinct or non-identifying) to the source mouth due to the unique bacterial makeup of each persons mouth… > **[Bite mark bacteria provide potential forensic clues](https://medicalxpress.com/news/2012-06-bacteria-potential-forensic-clues.html)** > > (Medical Xpress) -- Oral bacteria lifted from bite marks may provide a new source of clues for forensic experts, thanks to research projects completed by students at the Sir John Walsh Research Institute in the University of Otago's School of... > [@](#): > > Forensic application of Epstein-Barr virus genotype: correlation between viral genotype and geographical area. > > [Forensic application of Epstein-Barr virus genotype: correlation between viral genotype and geographical area - PubMed](http://www.ncbi.nlm.nih.gov/pubmed/17868913) > > Abstract > > Using 50 forensic blood samples, the latent membrane protein 2A (LMP-2A) gene of Epstein-Barr virus (EBV) DNA was amplified to find a geographic correlation among the EBV genotypes. EBV DNA was detected in nine samples. From a phylogenetic analysis using 18 reported sequences as a reference, six EBV subtypes (Ia, Ib, Ic IIa, IIb, and IIc) were found. Japanese isolates were included in subtypes Ia or IIa. All the Asian reference isolates, except isolate D6, were included in subtype Ia or IIa. Mediterranean, an Alaskan and other African isolates were included in types Ib, Ic, IIb and IIc. The EBV genotype in the LMP-2A gene was thus demonstrated as being correlated with the host’s geographical location. Typing in the EBV-associated nuclear antigen 2 gene was not related to that in the LMP-2A gene. Detection of the EBV genotype in the LMP-2A gene may be useful for determining the geographical origins of unidentified cadavers. These are just a few datapoints to get you started … ---
**Author:** ![Urbanredneck](https://avatars.discourse-cdn.com/v4/letter/u/ea5d25/32.png) [@Urbanredneck](https://boards.straightdope.com/u/Urbanredneck)\ **Post date:** [August 27, 2014, 5:10am UTC](https://boards.straightdope.com/t/can-medical-technology-id-sex-abusers-through-shared-bacteria/696607/6 "2014-08-27T05:10:42Z")
Who’s going to pay for all these tests? I read that in some states they have backlogs of rape-tests waiting to be tested for DNA matching but they dont have the budgets for them. ---
**Author:** ![si\_blakely](https://avatars.discourse-cdn.com/v4/letter/s/d9b06d/32.png) [@si\_blakely](https://boards.straightdope.com/u/si_blakely)\ **Post date:** [August 27, 2014, 5:11am UTC](https://boards.straightdope.com/t/can-medical-technology-id-sex-abusers-through-shared-bacteria/696607/7 "2014-08-27T05:11:45Z")
Last post, I promise, and not an abstract … [Medical and Legal Implications of Testing for Sexually Transmitted Infections in Children](http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2901660/) Discusses HSV amongst others. ---
**Author:** ![si\_blakely](https://avatars.discourse-cdn.com/v4/letter/s/d9b06d/32.png) [@si\_blakely](https://boards.straightdope.com/u/si_blakely)\ **Post date:** [August 27, 2014, 5:20am UTC](https://boards.straightdope.com/t/can-medical-technology-id-sex-abusers-through-shared-bacteria/696607/8 "2014-08-27T05:20:00Z")
> [@Urbanredneck](#): > > I read that in some states they have backlogs of rape-tests waiting to be tested for DNA matching but they dont have the budgets for them. I don’t care who pays - the evidence needs to speak. In the UK there have been a number of cold cases resolved by retesting DNA, and criminals identified and/or imprisoned. The failure to test DNA evidence in rape cases is a criminal act of it’s own, and contrary to any concept of justice. I can well believe that the cost to society of unpursued rape cases is much higher than the cost of actually running the tests - and the cost of procecuting and imprisoning the rapist is lower than the eventual cost to society of leaving them in the community to commit further rapes. ---
**Author:** ![CairoCarol](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cairocarol/32/3825_2.png) [@CairoCarol](https://boards.straightdope.com/u/CairoCarol)\ **Post date:** [August 27, 2014, 6:05am UTC](https://boards.straightdope.com/t/can-medical-technology-id-sex-abusers-through-shared-bacteria/696607/9 "2014-08-27T06:05:49Z")
Thanks everyone - I’ll have to digest what’s been presented and may come back with questions.\*\* si\_blakely\*\*, please don’t feel you should stop posting if you think of/come across something else. More information is better. GQ is not the best location for a synopsis of the case, but here are a few points relevant to comments that have been made: - At present the focus is really on “bacteria” and not herpes, in terms of evidence. (Herpes was discussed a lot at the beginning.) The police now say that the child has herpes but the first person being tried does not (so according to the police, the person being tried must be guilty AND there are others who are guilty too). - beats me who would pay for testing. Money is probably at the core of everything about this case, though. The mother who originally made the abuse claims is suing the school for USD 125 million. Since corruption is a well-established problem in Indonesia, it’s not outlandish to speculate that the police are promised part of the pay-off if they help her to show that the school was at fault. - My questions are directed at finding the truth, rather than defending any particular opinion about what actually occurred in this unbelievably complicated situation. But in this case, “truth” seems to mean that innocent people are being accused, not that guilty people are getting away with something. Although the two are not mutually exclusive, and it may very well be the case that sexual abuse _did_ occur and the actual perpetrator(s) is not in custody. It’s pointless to speculate on this as too many facts are unknown. (BTW, if any readers are Canadian, you may be somewhat aware of this case - it’s getting more international press these days.) ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [August 27, 2014, 6:56am UTC](https://boards.straightdope.com/t/can-medical-technology-id-sex-abusers-through-shared-bacteria/696607/10 "2014-08-27T06:56:29Z")
> [@Chronos](#): > > Even if the bacteria were a perfect match, it wouldn’t necessarily prove anything. All it takes is one single bacterium making it over somehow and growing into a colony, and you’ve got a match. This is of course easiest if there’s direct contact between the surfaces, but one can imagine other plausible ways that it could happen. Yes. This is one case where “I got it off a toilet seat” might be a quite plausible excuse. ---
**Author:** ![grude](https://avatars.discourse-cdn.com/v4/letter/g/e47774/32.png) [@grude](https://boards.straightdope.com/u/grude)\ **Post date:** [August 27, 2014, 8:18am UTC](https://boards.straightdope.com/t/can-medical-technology-id-sex-abusers-through-shared-bacteria/696607/11 "2014-08-27T08:18:20Z")
How likely is it the police’s message was garbled by the media, and they were simply saying since the alleged victim and suspect both have herpes they see this as evidence of abuse? Oh and also gross as it may be there would be no way prove anything with related(non STD) bacteria shared between people. They are spending time together in a room, touching the same surfaces, using the same toilets, sorry germophobes. ---
**Author:** ![si\_blakely](https://avatars.discourse-cdn.com/v4/letter/s/d9b06d/32.png) [@si\_blakely](https://boards.straightdope.com/u/si_blakely)\ **Post date:** [August 27, 2014, 11:18am UTC](https://boards.straightdope.com/t/can-medical-technology-id-sex-abusers-through-shared-bacteria/696607/12 "2014-08-27T11:18:31Z")
From one of the earlier links, **if** the child has anogenital HSV, then that would be unusual absent prior sexual abuse unless causality can be established (like a transferred oral herpes infection). > [@](#): > > The presence of genital herpes in a prepubertal child can also raise the probability of sexual abuse. However, available data are too limited to allow an estimation of the likelihood of sexual transmission after an episode of abuse. It is also fair to say that modifying intestinal or colorectal flora (of the bacterial kind) is not quite as simple as other posters have suggested. We do not just pick up any old bacteria lying around - acquired bacteria has to compete with the existing bacterial load already in place that we acquired as a baby. Doctors still don’t understand this process fully, but when it takes a drastic measure like fecal transplant to re-establish balanced gut flora in intractable cases of c. difficle, it seems unlikely to me that a toilet seat acquired bacteria can colonise and outcompete prior established biota. I would expect the same sort of criteria as I discussed regarding HSV to be applied to the bacterial evidence: Are the bacterial identical (as established via DNA genotyping) How common is the bacterial strain in the population Is the infection site typical for either party I’m generally sceptical about claims of pedofile rings and large scale (possibly ritual) sexual abuse - both current and especially historic. Tools such as DNA genotyping can provide some much-needed evidence, but can also be used poorly to feed into the surrounding hysteria - it is up to you and others to judge the evidence that you are hearing. Given the claims being made, I’d be wanting some much better evidence, and I hope the courts do too. ---
**Author:** ![grude](https://avatars.discourse-cdn.com/v4/letter/g/e47774/32.png) [@grude](https://boards.straightdope.com/u/grude)\ **Post date:** [August 27, 2014, 11:42am UTC](https://boards.straightdope.com/t/can-medical-technology-id-sex-abusers-through-shared-bacteria/696607/13 "2014-08-27T11:42:26Z")
> [@si\_blakely](#): > > It is also fair to say that modifying intestinal or colorectal flora (of the bacterial kind) is not quite as simple as other posters have suggested. We do not just pick up any old bacteria lying around - acquired bacteria has to compete with the existing bacterial load already in place that we acquired as a baby. Doctors still don’t understand this process fully, but when it takes a drastic measure like fecal transplant to re-establish balanced gut flora in intractable cases of c. difficle, it seems unlikely to me that a toilet seat acquired bacteria can colonise and outcompete prior established biota. There are events like a course of antibiotics which can wipe out someone’s native intestinal flora, might that leave them open to recolonization by bacteria from the environment? I’ve heard that cohabiting couples eventually come to share intestinal flora, but it did not mention how of this was due to sexual contact vs. bacteria on surfaces. ---
**Author:** ![CairoCarol](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cairocarol/32/3825_2.png) [@CairoCarol](https://boards.straightdope.com/u/CairoCarol)\ **Post date:** [August 27, 2014, 12:16pm UTC](https://boards.straightdope.com/t/can-medical-technology-id-sex-abusers-through-shared-bacteria/696607/14 "2014-08-27T12:16:35Z")
> [@grude](#): > > How likely is it the police’s message was garbled by the media, and they were simply saying since the alleged victim and suspect both have herpes they see this as evidence of abuse? The likelihood that the media misreported/sensationalized the story is very high, and the likelihood that the police made illogical statements is also high. There’s plenty of blame to go around. It’s a movie-of-the-week story with crazy rumors and accusations flying, and plot twists that no one saw coming when the story first began to emerge. It’ll be a great book if it’s ever resolved. ---
**Author:** ![BrotherCadfael](https://avatars.discourse-cdn.com/v4/letter/b/977dab/32.png) [@BrotherCadfael](https://boards.straightdope.com/u/BrotherCadfael)\ **Post date:** [August 27, 2014, 12:55pm UTC](https://boards.straightdope.com/t/can-medical-technology-id-sex-abusers-through-shared-bacteria/696607/15 "2014-08-27T12:55:47Z")
> [@si\_blakely](#): > > I don’t care who pays Fine. We’ll send you the bill. ---
**Author:** ![si\_blakely](https://avatars.discourse-cdn.com/v4/letter/s/d9b06d/32.png) [@si\_blakely](https://boards.straightdope.com/u/si_blakely)\ **Post date:** [August 27, 2014, 2:48pm UTC](https://boards.straightdope.com/t/can-medical-technology-id-sex-abusers-through-shared-bacteria/696607/16 "2014-08-27T14:48:56Z")
> [@grude](#): > > There are events like a course of antibiotics which can wipe out someone’s native intestinal flora, might that leave them open to recolonization by bacteria from the environment? > > I’ve heard that cohabiting couples eventually come to share intestinal flora, but it did not mention how of this was due to sexual contact vs. bacteria on surfaces. The evidence suggests (the claims of yogurt manufacturers notwithstanding) that few bacteria make it past the stomach - leaving recolonisation to remaining existing bacteria (and thus the problem of intractable c. difficle infection). Fecal transplants have to bypass the stomach to be effective. As far as I can tell, couples will share some skin bacterial and oral bacteria, but generally not much else. Penises, vaginas and anuses are mostly separate biological zones, so there isn’t much transfer - the consequence of inappropriate zone transfer are usually noticable (UTIs in the case of anal/penis/vaginal e. coli transfer, candida infections of the foreskin/vagina/anus/mouth, full STIs). There is a reason that condoms are recommended for anal sex, and that anal/oral contact is considered risky. It may happen over time, but I suspect that a shared diet and living habits may help bring couples closer in terms of internal biota than bacterial transfer - I’m not really an expert, but I try to keep up with the play. Viruses do transfer and colonise all those areas - HSV and HPV can and do transfer between partners, and in all combinations (oral, genital, anal). This can and has been used forensically, as there are may subtypes of HPV and a few of HSV. ---
**Author:** ![md2000](https://avatars.discourse-cdn.com/v4/letter/m/73ab20/32.png) [@md2000](https://boards.straightdope.com/u/md2000)\ **Post date:** [August 27, 2014, 4:16pm UTC](https://boards.straightdope.com/t/can-medical-technology-id-sex-abusers-through-shared-bacteria/696607/17 "2014-08-27T16:16:30Z")
IANABiologist, but it seems to me - Similar bacteria might be an indicator - like “we found footprints at the scene that match the perp’s shoes”. The question is of course, how rare is that bacteria or shoeprint? This requires control group, and similarity tests unless there’s and established database. The “one in 99 billion” assertions about human DNA, for example, are based on extensive testing of a huge variety of populations to determine the distributions of DNA characteristics. If everyone in the community has the same bacteria strain, of course those two will have it. If you wipe your ass (or in Indonesia, hose it off) you have a small amount of fecal bacteria there that as you walk around, the back-and-forth of your underwear will shift all over. This is why it’s a good idea to wash hands after handling the trouser snake even if you only do #1. After handling this, you leave bacteria on the flusher, taps, the door handle, the paper dispenser handle, etc. The moral of the story is that this stuff can get anywhere - whereas herpes usually only happens from direct contact of the genitals. The fact that the alleged perp did NOT have HSV and the victim did, suggests the fellow is innocent, absent other serious evidence. Once the lawsuits start flying and millions of dollars are mentioned, one wonders how reliable any eyewitness statement is. (Old lawyer joke; judge asks very young girl on witness stand: “Do you know what happens if you tell a lie?” She replies “My mommy said we hit the jackpot.”)