There’s a guy at my office just out of the hosp., with pneumonia, on antibiotics. After tut-tutting and sympathizing, I asked, “so, you’re not contagious, are you?” and he laughed, “I dunno, they didn’t say.”
It’s not like I’m French-kissing him or anything, but . . . Should we steer clear of him for awhile?
IANAD but according to Parents (for Parents) - Nemours KidsHealth it is.
Contagiousness
The viruses and bacteria that cause pneumonia are contagious and are usually found in fluid from the mouth or nose of an infected person. Illness can spread when an infected person coughs or sneezes on a person, by sharing drinking glasses and eating utensils, and when a person touches the used tissues or handkerchiefs of an infected person.
It seems to be, but not as contagious as other sicknesses.
Here are a couple of links:
If he’s on antibiotics, it’s most likely been identified as bacterial pneumonia, rather than viral pneumonia.
Antibiotics make some bacterial infections less contagious once the person is on them for some period of time. That period of time is different for different bacteria; strep, staph, scarlet fever: 24 hours on antibiotics, diptheria: 4 days on antibiotics, whooping cough: 5 days on antibiotics. cite.
But I can’t find any direct info on bacterial pneumonia, and whether treating it with antibiotics reduces contagiousness.
There is a prophylactic antibiotic for pneumonia that can be given if anyone in your office is immunocompromised or has a preemie at home. There are also several vaccines for various critters that are likely to cause pneumonia.
It’s important to note that pneumonia can be due to bacteria (common), viruses (less common), and fungi (usually only in people whose immune systems are weak).
As a rule, bacterial pneumonia is NOT contagious. However, certain viral pneumonias are higly contagious (eg. Influenzae, SARS) as well as pneumonia due to TB and mycoplasma (with mycoplasma being a germ which most commonly causes pneumonia in young adults and teens). Legionella is NOT contagious.
The typical ‘community acquired’ pneumonias (eg. from Strept. pneumoniae, Haemophilus influenzae) are due to microaspiration of one’s own saliva. Normally, we all inhale little bits of our saliva (i.e. microaspirate), especially when sleeping. If your saliva contains Strept pneumo, and especially if your lungs are already weakend from, say, a recent viral illness, you may well develop Strept pneumo puneumonia (same goes for H. influenzae). But, again, it’s not contagious (unless you call catching it from yourself contagious 
)
This was me this time last year, sort of. Except that I was going into the office while I was sick until my doctor sent me to hospital for a test and they said I was too sick to go home. No-one else got infected and they didn’t take any special precautions at the hospital. Like it says in FormerMarineGuy’s second link you usually get pneumonia as a secondary infection.
I don’t like the look of this:
But aren’t you always at risk anyway?
Well, fortunately, I don’t have to work with this guy, other than to smile and say “good morning” as I pass his desk. We do have one guy here with a newborn at home, I guess he should really steer clear.
We have no “sick days” here (get sick = lose vacation day), so people coming in sick is a problem.
Well, if his newborn is healthy and full-term, there’s no real reason to panic. Like **KarlGauss **says, pneumonia is usually a secondary infection.
Preemies are a special case because their lungs are undeveloped and often damage themselves, and so are more suseptible to an opportunistic pneumonia, but a full-term baby is pretty hardy. Of course, I wouldn’t let the guy sneeze on my baby (or hold him, really), but casual work contact with the parent is probably fine.
For a couple years after the infection you tend to have more repiratory maladies.
I’m not trying to be difficult, but cite please.
Sure, it’s possible to have respiratory maladies after a bout of pneumonia (and possibly due to the same predisposing condition that caused the pneumonia in the first palce). But, “tend to have more respiratory maladies”?